To evaluate the H_(2)O_(2)‐tolerance of non‐Pt oxygen reduction reaction(ORR)catalysts as well as in‐vestigate the H_(2)O_(2)‐induced decay mechanism,the selection of an appropriate H_(2)O_(2) concentration is a p...To evaluate the H_(2)O_(2)‐tolerance of non‐Pt oxygen reduction reaction(ORR)catalysts as well as in‐vestigate the H_(2)O_(2)‐induced decay mechanism,the selection of an appropriate H_(2)O_(2) concentration is a prerequisite.However,the concentration criterion is still unclear because of the lack of in‐operando methods to determine the actual concentration of H_(2)O_(2) in fuel cell catalyst layers.In this work,an electrochemical probe method was successfully established to in‐operando monitor the H_(2)O_(2) in non‐Pt catalyst layers for the first time.The local concentration of H_(2)O_(2) was revealed to reach 17 mmol/L,which is one order of magnitude higher than that under aqueous electrodes test conditions.Powered by the new knowledge,a concentration criterion of at least 17 mmol/L is suggested.This work fills in the large gap between aqueous electrode tests and the real fuel cell working conditions,and highlights the importance of in‐operando monitoring methods.展开更多
The stability of cathode catalyst layers(CCLs)in proton exchange membrane fuel cells(PEMFCs)is critically undermined by Pt dissolution and the loss of effective gas-water management associated with carbon support corr...The stability of cathode catalyst layers(CCLs)in proton exchange membrane fuel cells(PEMFCs)is critically undermined by Pt dissolution and the loss of effective gas-water management associated with carbon support corrosion.In this work,we develop a porous TiN nanotube-supported Pt(i.e.,Pt/TiN NTs)CCL that integrates robust Pt-Ti interfacial bonding with a highly accessible nanotube network to address these persistent challenges.The formation of abundant Pt-Ti bonds at the interface markedly strengthens Pt anchoring,resulting in a 2.3-fold reduction in Pt dissolution and minimal particle coarsening after accelerated durability testing compared to nanoflows-based controls dominated by Pt-N-Ti interactions.The membrane electrode assembly fabricated with this CCL achieves a peak power density of 0.81 W/cm^(2) and demonstrates exceptional durability,retaining 77%of its initial mass activity and 87.3%of its power density following aggressive square-wave potential cycling,meeting the 2025 U.S.Department of Energy benchmarks.Computational fluid dynamics simulation further reveal that the unique porous architecture facilitates efficient oxygen transport and rapid water removal,sustaining high catalytic utilization under operational conditions.This strategy establishes TiN NTs scaffolds as a generalizable solution for the next generation of carbon-free,high-stability catalyst layers,offering practical guidance for durable and efficient fuel cell design.展开更多
Developing cathode catalyst layers(CCL)with efficient mass transport capability is crucial to developing ultra-low Pt loading(<50μg·cm^(-2))proton exchange membrane fuel cells(PEMFCs).Herein,CCLs with various...Developing cathode catalyst layers(CCL)with efficient mass transport capability is crucial to developing ultra-low Pt loading(<50μg·cm^(-2))proton exchange membrane fuel cells(PEMFCs).Herein,CCLs with various pore distributions were constructed by depositing Pt onto the integrated carbonaceous films consisting of carbon nanoparticles(CNs),three-dimensional(3D)graphene nanosheets(GNs),and nanocomposites of CNs and GNs(CNs-GNs),respectively.The hierarchical mesoporous pore distributions of CCLs strongly affect the effective exposure of Pt active sites,proton-transfer resistance,and oxygen mass transport efficiencies related to Knudsen diffusion and local resistance at the Pt/ionomer interface.The CCL with Pt/CNs-GNs(50.0μgPt·cm^(-2))features a unique tri-modal pore distribution concentrated at 10.2,20.4,and 43.7 nm,providing efficient three-phase boundaries with a significantly higher active surface area of 49.67 m2·g^(-1),lower oxygen transport resistance and proton resistance of down to 18.68 s·m^(-1) and 0.0603Ω·cm^(2),compared with Pt/CNs(31.48 m^(2)·g^(-1),41.17 s·m^(-1),and 0.0702Ω·cm^(2))with a single-modal pore distribution at 9.5 nm and Pt/GNs(38.21 m^(2)·g^(-1),33.40 s·m^(-1),and 0.0654Ω·cm^(2))with a bi-modal pore distribution at 9.8 and 20.9 nm.Correspondingly,the cell with Pt/CNs-GNs delivers a high power output of up to 1.01 W·cm^(-2) and presents a high durability that satisfies the 2025 targets set by the U.S.Department of Energy.This work provides new insights into the critical role of hierarchically mesoporous pore distribution of CCL for constructing high-performance PEMFCs with ultra-low Pt loading<50μg·cm^(-2).展开更多
Electrochemical CO_(2)reduction(CO_(2)RR)is a promising technology for mitigating global climate change.The catalyst layer(CL),where the reduction reaction occurs,plays a pivotal role in determining mass transport and...Electrochemical CO_(2)reduction(CO_(2)RR)is a promising technology for mitigating global climate change.The catalyst layer(CL),where the reduction reaction occurs,plays a pivotal role in determining mass transport and electrochemical performance.However,accurately characterizing local structures and quantifying mass transport remains a significant challenge.To address these limitations,a systematic characterization framework based on deep learning(DL)is proposed.Five semantic segmentation models,including Segformer and DeepLabV3plus,were compared with conventional image processing techniques,among which DeepLabV3plus achieved the highest segmentation accuracy(>91.29%),significantly outperforming traditional thresholding methods(72.35%–77.42%).Experimental validation via mercury intrusion porosimetry(MIP)confirmed its capability to precisely extract key structural parameters,such as porosity and pore size distribution.Furthermore,a series of ionomer content gradient experiments revealed that a CL with an ionomer/catalyst(I/C)ratio of 0.2 had the optimal pore network structure.Numerical simulations and electrochemical tests demonstrated that this CL enabled a twofold increase in gas diffusion distance,thereby promoting long-range mass transport and significantly enhancing CO production rates.This work establishes a multi-scale analysis framework integrating“structural characterization,mass transport simulation,and performance validation,”offering both theoretical insights and practical guidance for the rational design of CO_(2)RR CLs.展开更多
Catalyst layer(CL)is the core component of proton exchange membrane(PEM)fuel cells,which determines the performance,durability,and cost.However,difficulties remain for a thorough understanding of the CLs’inhomogeneou...Catalyst layer(CL)is the core component of proton exchange membrane(PEM)fuel cells,which determines the performance,durability,and cost.However,difficulties remain for a thorough understanding of the CLs’inhomogeneous structure,and its impact on the physicochemical and electrochemical properties,operating performance,and durability.The inhomogeneous structure of the CLs is formed during the manufacturing process,which is sensitive to the associated materials,composi-tion,fabrication methods,procedures,and conditions.The state-of-the-art visualization and characterization techniques are crucial to examine the CL structure.The structure-dependent physicochemical and electrochemical properties are then thoroughly scrutinized in terms of fundamental concepts,theories,and recent progress in advanced experimental techniques.The relation between the CL structure and the associated effective properties is also examined based on experimental and theoretical findings.Recent studies indicated that the CL inhomogeneous structure also strongly affects the performance and degradation of the whole fuel cell,and thus,the interconnection between the fuel cell performance,failure modes,and CL structure is comprehensively reviewed.An analytical model is established to understand the effect of the CL structure on the effective properties,performance,and durability of the PEM fuel cells.Finally,the challenges and prospects of the CL structure-associated studies are highlighted for the development of high-performing PEM fuel cells.展开更多
Improving the performance of proton exchange membrane fuel cells(PEMFCs)requires deep understanding of the reac-tive transport processes inside the catalyst layers(CLs).In this study,a particle-overlapping model is de...Improving the performance of proton exchange membrane fuel cells(PEMFCs)requires deep understanding of the reac-tive transport processes inside the catalyst layers(CLs).In this study,a particle-overlapping model is developed for accu-rately describing the hierarchical structures and oxygen reactive transport processes in CLs.The analytical solutions derived from this model indicate that carbon particle overlap increases ionomer thickness,reduces specific surface areas of ionomer and carbon,and further intensifies the local oxygen transport resistance(R_(other)).The relationship between Rother and roughness factor predicted by the model in the range of 800-1600 sm^(-1) agrees well with the experiments.Then,a multiscale model is developed by coupling the particle-overlapping model with cell-scale models,which is validated by comparing with the polarization curves and local current density distribution obtained in experiments.The relative error of local current density distribution is below 15%in the ohmic polarization region.Finally,the multiscale model is employed to explore effects of CL structural parameters including Pt loading,I/C,ionomer coverage and carbon particle radius on the cell performance as well as the phase-change-induced(PCI)flow and capillary-driven(CD)flow in CL.The result demonstrates that the CL structural parameters have significant effects on the cell performance as well as the PCI and CD flows.Optimizing the CL structure can increase the current density and further enhance the heat-pipe effect within the CL,leading to overall higher PCI and CD rates.The maximum increase of PCI and CD rates can exceed 145%.Besides,the enhanced heat-pipe effect causes the reverse flow regions of PCI and CD near the CL/PEM interface,which can occupy about 30%of the CL.The multiscale model significantly contributes to a deep understanding of reactive trans-port and multiphase heat transfer processes inside PEMFCs.展开更多
This study introduces an innovative composite cathode catalyst layer(CCL)design for proton exchange membrane fuel cells(PEMFCs),combining Pt-supported by Vulcan carbon(Pt/V)and Ketjenblack carbon(Pt/KB)to overcome mas...This study introduces an innovative composite cathode catalyst layer(CCL)design for proton exchange membrane fuel cells(PEMFCs),combining Pt-supported by Vulcan carbon(Pt/V)and Ketjenblack carbon(Pt/KB)to overcome mass transport limitations and ionomer-induced catalyst poisoning.The composite architecture strategically positions Pt/V layer with lower ionomer-to-carbon ratio(I/C=0.6)near the proton exchange membrane to maximize surface Pt accessibility and oxygen transport efficiency,whereas Pt/KB layer(I/C=0.9)adjacent to the gas diffusion layer leverages its porous structure to shield Pt from sulfonate group poisoning and enhance proton conduction under low-humidity conditions.This synergistic carbon support engineering achieves a balance between reactant accessibility and catalyst utilization,as demonstrated by improved power density,reduced transport resistance,and higher Pt utilization under dry conditions.These findings establish a new paradigm for low-Pt CCL design through rational carbon support hybridization and ionomer gradient engineering,offering a scalable solution for high-performance PEMFCs in energy-critical applications.展开更多
The catalyst layer is an essential component of fuel cells,exerting a decisive influence on performance,particularly under degradation processes.Characterization derived from accelerated stress tests(ASTs)provide valu...The catalyst layer is an essential component of fuel cells,exerting a decisive influence on performance,particularly under degradation processes.Characterization derived from accelerated stress tests(ASTs)provide valuable insights into the long-term degradation from the perspective of changes in physical and chemical properties,thereby offering a scientific foundation for evaluating advanced materials and strategies.In this review,multidimensional and multi-characterization application scenarios based on ASTs data are systematically summarized.Firstly,the degradation mechanism of catalyst layer(CL)under AST conditions is discussed,with an emphasis on platinum aging and carbon support corrosion.In addition,electrochemical and microphysical characterization tools applicable to different AST test protocols,such as electrochemical surface area(ECSA),electrochemical impedance spectrum(EIS)mapping combined with distribution of relaxation times(DRT),and microscopic physical evolution and tracking techniques for each internal chemical component,are also presented in detail.Finally,through the existing research progress and hotspots,the application prospect of data fusion is elaborated and the important research direction of material optimization and performance prediction based on AST data is emphasized,aiming to provide insights into the study of catalytic layer degradation in fuel cells and promote the continuous development of the field.展开更多
To achieve palm oil conversion along with a high yield of long‐chain alkane,a series of NiFe layered double oxide catalysts were prepared and employed in the deoxygenation of palm oil.The layered structure of these c...To achieve palm oil conversion along with a high yield of long‐chain alkane,a series of NiFe layered double oxide catalysts were prepared and employed in the deoxygenation of palm oil.The layered structure of these catalysts was confirmed by XRD and SEM analyses,and Ni and Fe species existed primarily in the forms of Ni^(2+)and Fe^(3+),respectively.It was found that Ni/Fe molar ratio influenced the H_(2)reducibility and surface properties of NiFe catalysts.Specifically,Ni_(2)Fe‐LDO and Ni_(3)Fe‐LDO exhibited higher reducibility under H_(2)atmosphere.Moreover,the Ni_(2)Fe‐LDO catalyst contained a higher concentration of surface oxygen species(Osurf).Deoxygenation results demonstrated that the Ni_(2)Fe‐LDO catalyst achieved superior palm oil conversion,higher liquid product yield and enhanced selectivity toward C_(15)–C_(18)hydrocarbons compared to other catalysts.This improved performance was attributed to its higher hydrogen dissociation activity and enhanced adsorption capacity for palm oil molecules.Furthermore,reaction condition studies revealed that palm oil was completely converted,yielding 86.8%liquid product with 81.8%selectivity of C_(15)–C_(18)hydrocarbons at 350℃under 7 MPa H_(2)pressure.This finding provides an insight into the development of efficient catalysts for the deoxygenation of fatty compounds to biofuels.展开更多
Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells(PEMFCs).To achieve this goal,constructing optimized structure ...Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells(PEMFCs).To achieve this goal,constructing optimized structure of catalyst layers with efficient mass transportation channels plays a vital role.Herein,PEMFCs with order-structured cathodic electrodes were fabricated by depositing Pt nanoparticles by Ebeam onto vertically aligned carbon nanotubes(VACNTs)growth on Al foil via plasma-enhanced chemical vapor deposition.Results demonstrate that the proportion of hydrophilic Pt-deposited region along VACNTs and residual hydrophobic region of VANCTs without Pt strongly influences the cell performance,in particular at high current densities.When Pt nanoparticles deposit on the top depth of around 600 nm on VACNTs with a length of 4.6μm,the cell shows the highest performance,compared with others with various lengths of VACNTs.It delivers a maximum power output of 1.61 W cm^(-2)(H_(2)/O_(2),150 k Pa)and 0.79 W cm^(-2)(H_(2)/Air,150 k Pa)at Pt loading of 50μg cm^(-2),exceeding most of previously reported PEMFCs with Pt loading of<100μg cm^(-2).Even though the Pt loading is down to 30μg cm^(-2)(1.36 W cm^(-2)),the performance is also better than 100μg cm^(-2)(1.24 W cm^(-2))of commercial Pt/C,and presents better stability.This excellent performance is critical attributed to the ordered hydrophobic region providing sufficient mass passages to facilitate the fast water drainage at high current densities.This work gives a new understanding for oxygen reduction reaction occurred in VACNTs-based ordered electrodes,demonstrating the most possibility to achieve a substantial reduction in Pt loading<100μg cm^(-2) without sacrificing in performance.展开更多
Mass transport is crucial to the performance of proton exchange membrane fuel cells,especially at high current densities.Generally,the oxygen and the generated water share same transmission medium but move towards opp...Mass transport is crucial to the performance of proton exchange membrane fuel cells,especially at high current densities.Generally,the oxygen and the generated water share same transmission medium but move towards opposite direction,which leads to serious mass transfer problems.Herein,a series of patterned catalyst layer were prepared with a simple one-step impressing method using nylon sieves as templates.With grooves 100μm in width and 8μm in depth on the surface of cathode catalyst layer,the maximum power density of fuel cell increases by 10%without any additional durability loss while maintaining a similar electrochemical surface area.The concentration contours calculated by finite element analysis reveal that the grooves built on the surface of catalyst layer serve to accumulate the water nearby while oxygen tends to transfer through relatively convex region,which results from capillary pressure difference caused by the pore structure difference between the two regions.The separation of oxidant gas and generated water avoids mass confliction thus boosts mass transport efficiency.展开更多
The catalyst layer(CL)is the core component in determining the electrical-thermal-water performance and cost of proton exchange membrane fuel cell(PEMFC).Systemic analysis and rapid prediction tools are required to im...The catalyst layer(CL)is the core component in determining the electrical-thermal-water performance and cost of proton exchange membrane fuel cell(PEMFC).Systemic analysis and rapid prediction tools are required to improve the design efficiency of CL.In this study,a 3D multi-phase model integrated with the multi-level agglomerate model for CL is developed to describe the heat and mass transfer processes inside PEMFC.Moreover,a research framework combining the response surface method(RSM)and artificial neural network(ANN)model is proposed to conduct a quantitative analysis,and further a rapid and accurate prediction.With the help of this research framework,the effects of CL composition on the electrical-thermal-water performance of PEMFC are investigated.The results show that the mass of platinum,the mass of carbon,and the volume fraction of dry ionomer has a significant impact on the electrical-thermal-water performance.At the selected points,the sensitivity of the decision variables is ranked:volume fraction of dry ionomer>mass of platinum>mass of carbon>agglomerate radius.In particular,the sensitivity of the volume fraction of dry ionomer is over 50%at these points.Besides,the comparison results show that the ANN model could implement a more rapid and accurate prediction than the RSM model based on the same sample set.This in-depth study is beneficial to provide feasible guidance for high-performance CL design.展开更多
An extensive study has been conducted on the proton exchange membrane fuel cells （PEMFCs） with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the ...An extensive study has been conducted on the proton exchange membrane fuel cells （PEMFCs） with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode （GCE） to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic （IV） acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm （diameter） x l0 nm （length） by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry （CV） and scanning electron microscope （SEM） as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants （oxygen or hydrogen）.展开更多
The electrode ionomer plays a crucial role in the catalyst layer(CL) of a proton-exchange membrane fuel cell(PEMFC) and is closely associated with the proton conduction and gas transport properties,structural stabilit...The electrode ionomer plays a crucial role in the catalyst layer(CL) of a proton-exchange membrane fuel cell(PEMFC) and is closely associated with the proton conduction and gas transport properties,structural stability,and water management capability.In this review,we discuss the CL structural characteristics and highlight the latest advancements in ionomer material research.Additionally,we comprehensively introduce the design concepts and exceptional performances of porous electrode ionomers,elaborate on their structural properties and functions within the fuel cell CL,and investigate their effect on the CL microstructure and performance.Finally,we present a prospective evaluation of the developments in the electrode ionomer for fabricating CL,offering valuable insights for designing and synthesizing more efficient electrode ionomer materials.By addressing these facets,this review contributes to a comprehensive understanding of the role and potential of electrode ionomers for enhancing PEMFC performance.展开更多
The constant increase in energy demand and related environmental issues have made fuel cells an attractive technology as an alternative to conventional energy technologies.Like any technology,fuel cells face drawbacks...The constant increase in energy demand and related environmental issues have made fuel cells an attractive technology as an alternative to conventional energy technologies.Like any technology,fuel cells face drawbacks that scientific society has been focused on to improve and optimize the overall technology.Thus,the cost is the main inhibitor for this technology due to the significantly high cost of the materials used in catalyst layers.The current discussion mainly focuses on the fundamental electrochemical half-cell reaction of hydrogen oxidation reaction(HOR)and oxygen reduction reaction(ORR)that are taking place in the catalyst layers consisting of Platinum-based and Platinum-non noble metals.For this purpose,studies from the literature are presented and analyzed by highlighting and comparing the variations on the catalytic activity within the experimental catalyst layers and the conventional ones.Furthermore,an economic analysis of the main platinum group metals(PGMs)such as Platinum,Palladium and Ruthenium is introduced by presenting the economic trends for the last decade.展开更多
Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction(MOR)performance can fundamentally guide high efficient catalyst design.Herein,density...Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction(MOR)performance can fundamentally guide high efficient catalyst design.Herein,density functional theory(DFT)calculations were performed at first to study the d–d orbital interaction of metallic Pt Pd Cu,revealing that the incorporation of Pd and Cu atoms into Pt system can enhance d-d electron interaction via capturing antibonding orbital electrons of Pt to fill the surrounding Pd and Cu atoms.Under the theoretical guidance,Pt Pd Cu medium entropy alloy aerogels(Pt Pd Cu MEAAs)catalysts have been designed and systematically screened for MOR under acid,alkaline and neutral electrolyte.Furthermore,DFT calculation and in-situ fourier transform infrared spectroscopy analysis indicate that Pt Pd Cu MEAAs follow the direct pathway via formate as the reactive intermediate to be directly oxidized to CO_(2).For practical direct methanol fuel cells(DMFCs),the Pt Pd Cu MEAAs-integrated ultra-thin catalyst layer(4–5μm thickness)as anode exhibits higher peak power density of 35 m W/cm^(2) than commercial Pt/C of 20 m W/cm^(2)(~40μm thickness)under the similar noble metal loading and an impressive stability retention at a 50-m A/cm^(2) constant current for 10 h.This work clearly proves that optimizing the intermediate adsorption capacity via d-d orbital coupling is an effective strategy to design highly efficient catalysts for DMFCs.展开更多
Reducing the Ir loading while preserving catalytic performance and mechanical robustness in anodic catalyst layers remains a critical challenge for the large-scale implementation of proton exchange membrane water elec...Reducing the Ir loading while preserving catalytic performance and mechanical robustness in anodic catalyst layers remains a critical challenge for the large-scale implementation of proton exchange membrane water electrolysis(PEMWE).Herein,we present a structural engineering strategy involving neodymium-doped Ir/IrO_(2)(Nd-Ir/IrO_(2))hollow nanospheres with precisely adjustable shell thickness and cavity dimensions.The optimized catalyst demonstrates excellent oxygen evolution reaction(OER)performance in acidic media,achieving a remarkably low overpotential of 259 mV at a benchmark current density of 10 mA cm^(-2) while exhibiting substantially enhanced durability compared to commercial IrO_(2) and Ir/IrO_(2) counterparts.Notably,the Nd-Ir/IrO_(2) catalyst delivers a mass activity of 541.6 A gIr^(-1) at 1.50 V vs RHE,representing a 74.5-fold enhancement over conventional IrO_(2).Through comprehensive electrochemical analysis and advanced characterization techniques reveal that,the hierarchical hollow architecture simultaneously addresses multiple critical requirements:(i)abundant exposed active sites enabled by an enhanced electrochemical surface area,(ii)optimized mass transport pathways through engineered porosity,and(iii)preserved structural integrity via a continuous conductive framework,collectively enabling significant Ir loading reduction without compromising catalytic layer performance.Fundamental mechanistic investigations further disclose that Nd doping induces critical interfacial Nd-O-Ir configurations that stabilize lattice oxygen,together with intensified electron effect among mixed valent Ir that inhibits the overoxidation of Ir active sites during the OER process,synergistically ensuring enhanced catalytic durability.Our work establishes a dual-modulation paradigm integrating nanoscale architectural engineering with atomic-level heteroatom doping,providing a viable pathway toward high-performance PEMWE systems with drastically reduced noble metal requirements.展开更多
Water management within the membrane electrode assemblies(MEAs)of electrochemical hydrogen compressors(EHCs)plays a crucial role in optimizing overall performance,particularly under low relative humidity(RH),where the...Water management within the membrane electrode assemblies(MEAs)of electrochemical hydrogen compressors(EHCs)plays a crucial role in optimizing overall performance,particularly under low relative humidity(RH),where the anode side tends to dry out.Hollow mesoporous silica nanoparticles functionalized with amino groups(HMSNs-NH_(2))were integrated into the anode catalyst layers of EHCs to establish humidity-independent proton pathways through acid-base interactions with Nafion ionomers.These acid-base pairs between grafted–NH_(2)and sulfonic acid groups create continuous“proton highways”,enabling efficient conduction via the Grotthuss mechanism even at 50%RH.With only 2.5 wt%HMSNs-NH_(2)in the anode catalyst layer,hydrogen was compressed to 0.9 MPa in 60±3 s at 50%RH,representing a 55%reduction in compression time compared to MEAs with conventional Pt/C catalyst layers under the same conditions.This work overcomes the critical water-management bottleneck in EHCs,advancing the deployment of hydrogen energy technologies in arid environments.展开更多
The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation.The c...The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation.The continuously operated radial flow cell consisted of a borehole electrode positioned 50μm above an internal reflection element enabling operando FTIR spectroscopy.It is identified as a suitable tool for facile and reproducible screening of electrocatalysts under well-defined conditions,additionally providing access to the selectivities in complex reaction networks such as glycerol oxidation.The fast product identification by ATR-IR spectroscopy was validated by the more time-consuming quantitative HPLC analysis of the pumped electrolyte.High degrees of glycerol conversion were achieved under the applied laminar flow conditions using 0.1 M glycerol and 1 M KOH in water and a flow rate of 5μL min^(–1).Conversion and selectivity were found to depend on the catalyst loading,which determined the catalyst layer thickness and roughness.The highest loading of 210μg cm^(–2)resulted in 73%conversion and a higher formate selectivity of almost 80%,which is ascribed to longer residence times in rougher films favoring readsorption and C–C bond scission.The lowest loading of 13μg cm^(–2)was sufficient to reach 63%conversion,a lower formate selectivity of 60%,and,correspondingly,higher selectivities of C_(2)species such as glycolate amounting to 8%.Thus,only low catalyst loadings resulting in very thin films in the fewμm thickness range are suitable for reliable catalyst screening.展开更多
The catalyst layer （CL） of proton exchange mem-brane fuel cell （PEMFC） involves various particles and pores in meso-scale, which has an important effect on the mass, charge （proton and electron） and heat transpo...The catalyst layer （CL） of proton exchange mem-brane fuel cell （PEMFC） involves various particles and pores in meso-scale, which has an important effect on the mass, charge （proton and electron） and heat transport coupled with the electrochemical reactions. The coarse-grained molecular dynamics （CG-MD） method is employed as a meso-scale structure reconstruction technique to mimic the self-organization phenomena in the fabrication steps of a CL. The meso-scale structure obtained at the equilibrium state is further analyzed by molecular dynamic （MD） software to provide the necessary microscopic parameters for understanding of multi-scale and-physics processes in CLs. The primary pore size distribution （PSD） and active platinum （Pt） surface areas are also calculated and then compared with the experiments. In addition, we also highlight the implementation method to combine microscopic elementary kinetic reaction schemes with the CG-MD approaches to provide insight into the reactions in CLs. The concepts from CG modeling with particle hydrodynamics （SPH） and the problems on coupling of SPH with finite element modeling （FEM） methods are further outlined and discussed to understand the effects of the meso-scale transport phenomena in fuel cells.展开更多
文摘To evaluate the H_(2)O_(2)‐tolerance of non‐Pt oxygen reduction reaction(ORR)catalysts as well as in‐vestigate the H_(2)O_(2)‐induced decay mechanism,the selection of an appropriate H_(2)O_(2) concentration is a prerequisite.However,the concentration criterion is still unclear because of the lack of in‐operando methods to determine the actual concentration of H_(2)O_(2) in fuel cell catalyst layers.In this work,an electrochemical probe method was successfully established to in‐operando monitor the H_(2)O_(2) in non‐Pt catalyst layers for the first time.The local concentration of H_(2)O_(2) was revealed to reach 17 mmol/L,which is one order of magnitude higher than that under aqueous electrodes test conditions.Powered by the new knowledge,a concentration criterion of at least 17 mmol/L is suggested.This work fills in the large gap between aqueous electrode tests and the real fuel cell working conditions,and highlights the importance of in‐operando monitoring methods.
基金supported by the National Natural Science Foundation of China(Nos.52164028,22305054,52274297,22462006,22402043,52461041)the Hainan Provincial Natural Science Foundation of China(Nos.225YXQN586,224MS008)+3 种基金the Innovational Fund for Scientific and Technological Personnel of Hainan Province(No.KJRC2023C10)the Start-Up Research Foundation of Hainan University(Nos.KYQD(ZR)-21170,23169)the Collaborative Innovation Center of Marine Science and Technology,Hainan University(Nos.XTCX2022HYC01,XTCX2022HYC05)Innovative Research Project of Hainan Province(No.Qhyb2024-67)。
文摘The stability of cathode catalyst layers(CCLs)in proton exchange membrane fuel cells(PEMFCs)is critically undermined by Pt dissolution and the loss of effective gas-water management associated with carbon support corrosion.In this work,we develop a porous TiN nanotube-supported Pt(i.e.,Pt/TiN NTs)CCL that integrates robust Pt-Ti interfacial bonding with a highly accessible nanotube network to address these persistent challenges.The formation of abundant Pt-Ti bonds at the interface markedly strengthens Pt anchoring,resulting in a 2.3-fold reduction in Pt dissolution and minimal particle coarsening after accelerated durability testing compared to nanoflows-based controls dominated by Pt-N-Ti interactions.The membrane electrode assembly fabricated with this CCL achieves a peak power density of 0.81 W/cm^(2) and demonstrates exceptional durability,retaining 77%of its initial mass activity and 87.3%of its power density following aggressive square-wave potential cycling,meeting the 2025 U.S.Department of Energy benchmarks.Computational fluid dynamics simulation further reveal that the unique porous architecture facilitates efficient oxygen transport and rapid water removal,sustaining high catalytic utilization under operational conditions.This strategy establishes TiN NTs scaffolds as a generalizable solution for the next generation of carbon-free,high-stability catalyst layers,offering practical guidance for durable and efficient fuel cell design.
基金supported by the National Natural Science Foundation of China(No.22379031)the Guangxi Science and Technology Project of China(No.AB16380030)。
文摘Developing cathode catalyst layers(CCL)with efficient mass transport capability is crucial to developing ultra-low Pt loading(<50μg·cm^(-2))proton exchange membrane fuel cells(PEMFCs).Herein,CCLs with various pore distributions were constructed by depositing Pt onto the integrated carbonaceous films consisting of carbon nanoparticles(CNs),three-dimensional(3D)graphene nanosheets(GNs),and nanocomposites of CNs and GNs(CNs-GNs),respectively.The hierarchical mesoporous pore distributions of CCLs strongly affect the effective exposure of Pt active sites,proton-transfer resistance,and oxygen mass transport efficiencies related to Knudsen diffusion and local resistance at the Pt/ionomer interface.The CCL with Pt/CNs-GNs(50.0μgPt·cm^(-2))features a unique tri-modal pore distribution concentrated at 10.2,20.4,and 43.7 nm,providing efficient three-phase boundaries with a significantly higher active surface area of 49.67 m2·g^(-1),lower oxygen transport resistance and proton resistance of down to 18.68 s·m^(-1) and 0.0603Ω·cm^(2),compared with Pt/CNs(31.48 m^(2)·g^(-1),41.17 s·m^(-1),and 0.0702Ω·cm^(2))with a single-modal pore distribution at 9.5 nm and Pt/GNs(38.21 m^(2)·g^(-1),33.40 s·m^(-1),and 0.0654Ω·cm^(2))with a bi-modal pore distribution at 9.8 and 20.9 nm.Correspondingly,the cell with Pt/CNs-GNs delivers a high power output of up to 1.01 W·cm^(-2) and presents a high durability that satisfies the 2025 targets set by the U.S.Department of Energy.This work provides new insights into the critical role of hierarchically mesoporous pore distribution of CCL for constructing high-performance PEMFCs with ultra-low Pt loading<50μg·cm^(-2).
基金supported by the National Natural Science Foundation of China(Grant No.52394204)the Shanghai Municipal Science and Technology Major Project,and Shanghai Jiao Tong University Decision Consulting,China(JCZXSJB2024-12).
文摘Electrochemical CO_(2)reduction(CO_(2)RR)is a promising technology for mitigating global climate change.The catalyst layer(CL),where the reduction reaction occurs,plays a pivotal role in determining mass transport and electrochemical performance.However,accurately characterizing local structures and quantifying mass transport remains a significant challenge.To address these limitations,a systematic characterization framework based on deep learning(DL)is proposed.Five semantic segmentation models,including Segformer and DeepLabV3plus,were compared with conventional image processing techniques,among which DeepLabV3plus achieved the highest segmentation accuracy(>91.29%),significantly outperforming traditional thresholding methods(72.35%–77.42%).Experimental validation via mercury intrusion porosimetry(MIP)confirmed its capability to precisely extract key structural parameters,such as porosity and pore size distribution.Furthermore,a series of ionomer content gradient experiments revealed that a CL with an ionomer/catalyst(I/C)ratio of 0.2 had the optimal pore network structure.Numerical simulations and electrochemical tests demonstrated that this CL enabled a twofold increase in gas diffusion distance,thereby promoting long-range mass transport and significantly enhancing CO production rates.This work establishes a multi-scale analysis framework integrating“structural characterization,mass transport simulation,and performance validation,”offering both theoretical insights and practical guidance for the rational design of CO_(2)RR CLs.
基金financially supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)via a Discovery Grant,and Canadian Urban Transit Research&Innovation Consortium(CUTRIC)via Project No.160028.
文摘Catalyst layer(CL)is the core component of proton exchange membrane(PEM)fuel cells,which determines the performance,durability,and cost.However,difficulties remain for a thorough understanding of the CLs’inhomogeneous structure,and its impact on the physicochemical and electrochemical properties,operating performance,and durability.The inhomogeneous structure of the CLs is formed during the manufacturing process,which is sensitive to the associated materials,composi-tion,fabrication methods,procedures,and conditions.The state-of-the-art visualization and characterization techniques are crucial to examine the CL structure.The structure-dependent physicochemical and electrochemical properties are then thoroughly scrutinized in terms of fundamental concepts,theories,and recent progress in advanced experimental techniques.The relation between the CL structure and the associated effective properties is also examined based on experimental and theoretical findings.Recent studies indicated that the CL inhomogeneous structure also strongly affects the performance and degradation of the whole fuel cell,and thus,the interconnection between the fuel cell performance,failure modes,and CL structure is comprehensively reviewed.An analytical model is established to understand the effect of the CL structure on the effective properties,performance,and durability of the PEM fuel cells.Finally,the challenges and prospects of the CL structure-associated studies are highlighted for the development of high-performing PEM fuel cells.
基金supported by the National Key Research and Development Program(2021YFB4001701)National Nature Science Foundation of China(52376074)the Fundamental Research Funds for the Central Universities.
文摘Improving the performance of proton exchange membrane fuel cells(PEMFCs)requires deep understanding of the reac-tive transport processes inside the catalyst layers(CLs).In this study,a particle-overlapping model is developed for accu-rately describing the hierarchical structures and oxygen reactive transport processes in CLs.The analytical solutions derived from this model indicate that carbon particle overlap increases ionomer thickness,reduces specific surface areas of ionomer and carbon,and further intensifies the local oxygen transport resistance(R_(other)).The relationship between Rother and roughness factor predicted by the model in the range of 800-1600 sm^(-1) agrees well with the experiments.Then,a multiscale model is developed by coupling the particle-overlapping model with cell-scale models,which is validated by comparing with the polarization curves and local current density distribution obtained in experiments.The relative error of local current density distribution is below 15%in the ohmic polarization region.Finally,the multiscale model is employed to explore effects of CL structural parameters including Pt loading,I/C,ionomer coverage and carbon particle radius on the cell performance as well as the phase-change-induced(PCI)flow and capillary-driven(CD)flow in CL.The result demonstrates that the CL structural parameters have significant effects on the cell performance as well as the PCI and CD flows.Optimizing the CL structure can increase the current density and further enhance the heat-pipe effect within the CL,leading to overall higher PCI and CD rates.The maximum increase of PCI and CD rates can exceed 145%.Besides,the enhanced heat-pipe effect causes the reverse flow regions of PCI and CD near the CL/PEM interface,which can occupy about 30%of the CL.The multiscale model significantly contributes to a deep understanding of reactive trans-port and multiphase heat transfer processes inside PEMFCs.
基金financially supported by National Natural Science Foundation of China(22202124 and UA22A20429)Shanxi Scholarship Council of China(2023-008 and 2023-009)+4 种基金Shanxi Outstanding Project Selection and Support Program for Overseas Scientific and Technological Activities(20230002)Science and Technology Innovation Teams of Shanxi Province(202304051001023)the Key Research and Development Program of Shanxi Province(No.202302060301009)Qingdao New Energy Shandong Laboratory Open Project(QNESL OP)Shandong Provincial Natural Science Foundation(Nos.ZR2024QB175 and ZR2023LFG005).
文摘This study introduces an innovative composite cathode catalyst layer(CCL)design for proton exchange membrane fuel cells(PEMFCs),combining Pt-supported by Vulcan carbon(Pt/V)and Ketjenblack carbon(Pt/KB)to overcome mass transport limitations and ionomer-induced catalyst poisoning.The composite architecture strategically positions Pt/V layer with lower ionomer-to-carbon ratio(I/C=0.6)near the proton exchange membrane to maximize surface Pt accessibility and oxygen transport efficiency,whereas Pt/KB layer(I/C=0.9)adjacent to the gas diffusion layer leverages its porous structure to shield Pt from sulfonate group poisoning and enhance proton conduction under low-humidity conditions.This synergistic carbon support engineering achieves a balance between reactant accessibility and catalyst utilization,as demonstrated by improved power density,reduced transport resistance,and higher Pt utilization under dry conditions.These findings establish a new paradigm for low-Pt CCL design through rational carbon support hybridization and ionomer gradient engineering,offering a scalable solution for high-performance PEMFCs in energy-critical applications.
基金supported by National Natural Science Foundation of China(22279091)Fundamental Funds for the Central Universities。
文摘The catalyst layer is an essential component of fuel cells,exerting a decisive influence on performance,particularly under degradation processes.Characterization derived from accelerated stress tests(ASTs)provide valuable insights into the long-term degradation from the perspective of changes in physical and chemical properties,thereby offering a scientific foundation for evaluating advanced materials and strategies.In this review,multidimensional and multi-characterization application scenarios based on ASTs data are systematically summarized.Firstly,the degradation mechanism of catalyst layer(CL)under AST conditions is discussed,with an emphasis on platinum aging and carbon support corrosion.In addition,electrochemical and microphysical characterization tools applicable to different AST test protocols,such as electrochemical surface area(ECSA),electrochemical impedance spectrum(EIS)mapping combined with distribution of relaxation times(DRT),and microscopic physical evolution and tracking techniques for each internal chemical component,are also presented in detail.Finally,through the existing research progress and hotspots,the application prospect of data fusion is elaborated and the important research direction of material optimization and performance prediction based on AST data is emphasized,aiming to provide insights into the study of catalytic layer degradation in fuel cells and promote the continuous development of the field.
基金National Natural Science Foundation of China(22278084)State Key Laboratory of Heavy Oil Processing(SKLHOP202402003)for financing this research.
文摘To achieve palm oil conversion along with a high yield of long‐chain alkane,a series of NiFe layered double oxide catalysts were prepared and employed in the deoxygenation of palm oil.The layered structure of these catalysts was confirmed by XRD and SEM analyses,and Ni and Fe species existed primarily in the forms of Ni^(2+)and Fe^(3+),respectively.It was found that Ni/Fe molar ratio influenced the H_(2)reducibility and surface properties of NiFe catalysts.Specifically,Ni_(2)Fe‐LDO and Ni_(3)Fe‐LDO exhibited higher reducibility under H_(2)atmosphere.Moreover,the Ni_(2)Fe‐LDO catalyst contained a higher concentration of surface oxygen species(Osurf).Deoxygenation results demonstrated that the Ni_(2)Fe‐LDO catalyst achieved superior palm oil conversion,higher liquid product yield and enhanced selectivity toward C_(15)–C_(18)hydrocarbons compared to other catalysts.This improved performance was attributed to its higher hydrogen dissociation activity and enhanced adsorption capacity for palm oil molecules.Furthermore,reaction condition studies revealed that palm oil was completely converted,yielding 86.8%liquid product with 81.8%selectivity of C_(15)–C_(18)hydrocarbons at 350℃under 7 MPa H_(2)pressure.This finding provides an insight into the development of efficient catalysts for the deoxygenation of fatty compounds to biofuels.
基金finically supported by the National Natural Science Foundation of China(22075055)the Guangxi Science and Technology Project(AB16380030)the Innovation Project of Guangxi Graduate Education(YCSW2020052)。
文摘Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells(PEMFCs).To achieve this goal,constructing optimized structure of catalyst layers with efficient mass transportation channels plays a vital role.Herein,PEMFCs with order-structured cathodic electrodes were fabricated by depositing Pt nanoparticles by Ebeam onto vertically aligned carbon nanotubes(VACNTs)growth on Al foil via plasma-enhanced chemical vapor deposition.Results demonstrate that the proportion of hydrophilic Pt-deposited region along VACNTs and residual hydrophobic region of VANCTs without Pt strongly influences the cell performance,in particular at high current densities.When Pt nanoparticles deposit on the top depth of around 600 nm on VACNTs with a length of 4.6μm,the cell shows the highest performance,compared with others with various lengths of VACNTs.It delivers a maximum power output of 1.61 W cm^(-2)(H_(2)/O_(2),150 k Pa)and 0.79 W cm^(-2)(H_(2)/Air,150 k Pa)at Pt loading of 50μg cm^(-2),exceeding most of previously reported PEMFCs with Pt loading of<100μg cm^(-2).Even though the Pt loading is down to 30μg cm^(-2)(1.36 W cm^(-2)),the performance is also better than 100μg cm^(-2)(1.24 W cm^(-2))of commercial Pt/C,and presents better stability.This excellent performance is critical attributed to the ordered hydrophobic region providing sufficient mass passages to facilitate the fast water drainage at high current densities.This work gives a new understanding for oxygen reduction reaction occurred in VACNTs-based ordered electrodes,demonstrating the most possibility to achieve a substantial reduction in Pt loading<100μg cm^(-2) without sacrificing in performance.
基金supported by the National Natural Science Foundation of China(21838003,91834301)the Shanghai Scientific and Technological Innovation Project(18JC1410600,19JC1410400)+2 种基金the Social Development Program of Shanghai(17DZ1200900)the Innovation Program of Shanghai Municipal Education Commissionthe Fundamental Research Funds for the Central Universities(222201718002)。
文摘Mass transport is crucial to the performance of proton exchange membrane fuel cells,especially at high current densities.Generally,the oxygen and the generated water share same transmission medium but move towards opposite direction,which leads to serious mass transfer problems.Herein,a series of patterned catalyst layer were prepared with a simple one-step impressing method using nylon sieves as templates.With grooves 100μm in width and 8μm in depth on the surface of cathode catalyst layer,the maximum power density of fuel cell increases by 10%without any additional durability loss while maintaining a similar electrochemical surface area.The concentration contours calculated by finite element analysis reveal that the grooves built on the surface of catalyst layer serve to accumulate the water nearby while oxygen tends to transfer through relatively convex region,which results from capillary pressure difference caused by the pore structure difference between the two regions.The separation of oxidant gas and generated water avoids mass confliction thus boosts mass transport efficiency.
基金financially supported by the National Key R&D Program of China (2022YFE0101300)the National Natural Science Foundation of China (52176203)。
文摘The catalyst layer(CL)is the core component in determining the electrical-thermal-water performance and cost of proton exchange membrane fuel cell(PEMFC).Systemic analysis and rapid prediction tools are required to improve the design efficiency of CL.In this study,a 3D multi-phase model integrated with the multi-level agglomerate model for CL is developed to describe the heat and mass transfer processes inside PEMFC.Moreover,a research framework combining the response surface method(RSM)and artificial neural network(ANN)model is proposed to conduct a quantitative analysis,and further a rapid and accurate prediction.With the help of this research framework,the effects of CL composition on the electrical-thermal-water performance of PEMFC are investigated.The results show that the mass of platinum,the mass of carbon,and the volume fraction of dry ionomer has a significant impact on the electrical-thermal-water performance.At the selected points,the sensitivity of the decision variables is ranked:volume fraction of dry ionomer>mass of platinum>mass of carbon>agglomerate radius.In particular,the sensitivity of the volume fraction of dry ionomer is over 50%at these points.Besides,the comparison results show that the ANN model could implement a more rapid and accurate prediction than the RSM model based on the same sample set.This in-depth study is beneficial to provide feasible guidance for high-performance CL design.
基金supported by the Royal Academy of Engineering,United Kingdom
文摘An extensive study has been conducted on the proton exchange membrane fuel cells （PEMFCs） with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode （GCE） to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic （IV） acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm （diameter） x l0 nm （length） by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry （CV） and scanning electron microscope （SEM） as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants （oxygen or hydrogen）.
基金supported by the National Natu-ral Science Foundation of China(Nos.21625102,21971017,and 22102008)National Key Research and Development Program of China(No.2020YFB1506300)Postdoctoral Fund of China(Nos.2020T130055 and 2020M670143).
文摘The electrode ionomer plays a crucial role in the catalyst layer(CL) of a proton-exchange membrane fuel cell(PEMFC) and is closely associated with the proton conduction and gas transport properties,structural stability,and water management capability.In this review,we discuss the CL structural characteristics and highlight the latest advancements in ionomer material research.Additionally,we comprehensively introduce the design concepts and exceptional performances of porous electrode ionomers,elaborate on their structural properties and functions within the fuel cell CL,and investigate their effect on the CL microstructure and performance.Finally,we present a prospective evaluation of the developments in the electrode ionomer for fabricating CL,offering valuable insights for designing and synthesizing more efficient electrode ionomer materials.By addressing these facets,this review contributes to a comprehensive understanding of the role and potential of electrode ionomers for enhancing PEMFC performance.
文摘The constant increase in energy demand and related environmental issues have made fuel cells an attractive technology as an alternative to conventional energy technologies.Like any technology,fuel cells face drawbacks that scientific society has been focused on to improve and optimize the overall technology.Thus,the cost is the main inhibitor for this technology due to the significantly high cost of the materials used in catalyst layers.The current discussion mainly focuses on the fundamental electrochemical half-cell reaction of hydrogen oxidation reaction(HOR)and oxygen reduction reaction(ORR)that are taking place in the catalyst layers consisting of Platinum-based and Platinum-non noble metals.For this purpose,studies from the literature are presented and analyzed by highlighting and comparing the variations on the catalytic activity within the experimental catalyst layers and the conventional ones.Furthermore,an economic analysis of the main platinum group metals(PGMs)such as Platinum,Palladium and Ruthenium is introduced by presenting the economic trends for the last decade.
基金financially supported by the National Natural Science Foundation of China(Nos.52073214 and 22075211)Guangxi Natural Science Fund for Distinguished Young Scholars(No.2024GXNSFFA010008)+5 种基金Natural Science Foundation of Shandong Province(Nos.ZR2023MB049 and ZR2021QB129)China Postdoctoral Science Foundation(No.2020M670483)Science Foundation of Weifang University(No.2023BS11)supported by the open research fund of the Laboratory of Xinjiang Native Medicinal and Edible Plant Resources Chemistry at Kashi Universitysupported by the Tianhe Qingsuo Open Research Fund of TSYS in 2022 and NSCC-TJNankai University Large-scale Instrument Experimental Technology R&D Project(No.21NKSYJS09)。
文摘Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction(MOR)performance can fundamentally guide high efficient catalyst design.Herein,density functional theory(DFT)calculations were performed at first to study the d–d orbital interaction of metallic Pt Pd Cu,revealing that the incorporation of Pd and Cu atoms into Pt system can enhance d-d electron interaction via capturing antibonding orbital electrons of Pt to fill the surrounding Pd and Cu atoms.Under the theoretical guidance,Pt Pd Cu medium entropy alloy aerogels(Pt Pd Cu MEAAs)catalysts have been designed and systematically screened for MOR under acid,alkaline and neutral electrolyte.Furthermore,DFT calculation and in-situ fourier transform infrared spectroscopy analysis indicate that Pt Pd Cu MEAAs follow the direct pathway via formate as the reactive intermediate to be directly oxidized to CO_(2).For practical direct methanol fuel cells(DMFCs),the Pt Pd Cu MEAAs-integrated ultra-thin catalyst layer(4–5μm thickness)as anode exhibits higher peak power density of 35 m W/cm^(2) than commercial Pt/C of 20 m W/cm^(2)(~40μm thickness)under the similar noble metal loading and an impressive stability retention at a 50-m A/cm^(2) constant current for 10 h.This work clearly proves that optimizing the intermediate adsorption capacity via d-d orbital coupling is an effective strategy to design highly efficient catalysts for DMFCs.
基金supported by the Taishan Scholar Program of Shandong Province,China(tsqn202211162)National Natural Science Foundation of China(22372088 and 22102079)+1 种基金Natural Science Foundation of Shandong Province of China(ZR2021YQ10)the Materials/Parts Technology Development Program(RS-2024-00432627)funded by the Ministry of Trade,Industry and Energy,Korea.
文摘Reducing the Ir loading while preserving catalytic performance and mechanical robustness in anodic catalyst layers remains a critical challenge for the large-scale implementation of proton exchange membrane water electrolysis(PEMWE).Herein,we present a structural engineering strategy involving neodymium-doped Ir/IrO_(2)(Nd-Ir/IrO_(2))hollow nanospheres with precisely adjustable shell thickness and cavity dimensions.The optimized catalyst demonstrates excellent oxygen evolution reaction(OER)performance in acidic media,achieving a remarkably low overpotential of 259 mV at a benchmark current density of 10 mA cm^(-2) while exhibiting substantially enhanced durability compared to commercial IrO_(2) and Ir/IrO_(2) counterparts.Notably,the Nd-Ir/IrO_(2) catalyst delivers a mass activity of 541.6 A gIr^(-1) at 1.50 V vs RHE,representing a 74.5-fold enhancement over conventional IrO_(2).Through comprehensive electrochemical analysis and advanced characterization techniques reveal that,the hierarchical hollow architecture simultaneously addresses multiple critical requirements:(i)abundant exposed active sites enabled by an enhanced electrochemical surface area,(ii)optimized mass transport pathways through engineered porosity,and(iii)preserved structural integrity via a continuous conductive framework,collectively enabling significant Ir loading reduction without compromising catalytic layer performance.Fundamental mechanistic investigations further disclose that Nd doping induces critical interfacial Nd-O-Ir configurations that stabilize lattice oxygen,together with intensified electron effect among mixed valent Ir that inhibits the overoxidation of Ir active sites during the OER process,synergistically ensuring enhanced catalytic durability.Our work establishes a dual-modulation paradigm integrating nanoscale architectural engineering with atomic-level heteroatom doping,providing a viable pathway toward high-performance PEMWE systems with drastically reduced noble metal requirements.
基金supported by the National Natural Science Foundation of China(No.22208376,No.UA22A20429)the Fundamental Research Funds for the Central Universities(buctrc202118,No.25CX07002A)+1 种基金the Qingdao New Energy Shandong Laboratory Open Project(QNESL OP 202303)the Shandong Provincial Natural Science Foundation(ZR2024QB175 and ZR2023LFG005)。
文摘Water management within the membrane electrode assemblies(MEAs)of electrochemical hydrogen compressors(EHCs)plays a crucial role in optimizing overall performance,particularly under low relative humidity(RH),where the anode side tends to dry out.Hollow mesoporous silica nanoparticles functionalized with amino groups(HMSNs-NH_(2))were integrated into the anode catalyst layers of EHCs to establish humidity-independent proton pathways through acid-base interactions with Nafion ionomers.These acid-base pairs between grafted–NH_(2)and sulfonic acid groups create continuous“proton highways”,enabling efficient conduction via the Grotthuss mechanism even at 50%RH.With only 2.5 wt%HMSNs-NH_(2)in the anode catalyst layer,hydrogen was compressed to 0.9 MPa in 60±3 s at 50%RH,representing a 55%reduction in compression time compared to MEAs with conventional Pt/C catalyst layers under the same conditions.This work overcomes the critical water-management bottleneck in EHCs,advancing the deployment of hydrogen energy technologies in arid environments.
文摘The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation.The continuously operated radial flow cell consisted of a borehole electrode positioned 50μm above an internal reflection element enabling operando FTIR spectroscopy.It is identified as a suitable tool for facile and reproducible screening of electrocatalysts under well-defined conditions,additionally providing access to the selectivities in complex reaction networks such as glycerol oxidation.The fast product identification by ATR-IR spectroscopy was validated by the more time-consuming quantitative HPLC analysis of the pumped electrolyte.High degrees of glycerol conversion were achieved under the applied laminar flow conditions using 0.1 M glycerol and 1 M KOH in water and a flow rate of 5μL min^(–1).Conversion and selectivity were found to depend on the catalyst loading,which determined the catalyst layer thickness and roughness.The highest loading of 210μg cm^(–2)resulted in 73%conversion and a higher formate selectivity of almost 80%,which is ascribed to longer residence times in rougher films favoring readsorption and C–C bond scission.The lowest loading of 13μg cm^(–2)was sufficient to reach 63%conversion,a lower formate selectivity of 60%,and,correspondingly,higher selectivities of C_(2)species such as glycolate amounting to 8%.Thus,only low catalyst loadings resulting in very thin films in the fewμm thickness range are suitable for reliable catalyst screening.
文摘The catalyst layer （CL） of proton exchange mem-brane fuel cell （PEMFC） involves various particles and pores in meso-scale, which has an important effect on the mass, charge （proton and electron） and heat transport coupled with the electrochemical reactions. The coarse-grained molecular dynamics （CG-MD） method is employed as a meso-scale structure reconstruction technique to mimic the self-organization phenomena in the fabrication steps of a CL. The meso-scale structure obtained at the equilibrium state is further analyzed by molecular dynamic （MD） software to provide the necessary microscopic parameters for understanding of multi-scale and-physics processes in CLs. The primary pore size distribution （PSD） and active platinum （Pt） surface areas are also calculated and then compared with the experiments. In addition, we also highlight the implementation method to combine microscopic elementary kinetic reaction schemes with the CG-MD approaches to provide insight into the reactions in CLs. The concepts from CG modeling with particle hydrodynamics （SPH） and the problems on coupling of SPH with finite element modeling （FEM） methods are further outlined and discussed to understand the effects of the meso-scale transport phenomena in fuel cells.
