Membrane electrode assembly(MEA)is widely considered to be the most promising type of electrolyzer for the practical application of electrochemical CO_(2) reduction reaction(CO_(2)RR).In MEAs,a square-shaped cross-sec...Membrane electrode assembly(MEA)is widely considered to be the most promising type of electrolyzer for the practical application of electrochemical CO_(2) reduction reaction(CO_(2)RR).In MEAs,a square-shaped cross-section in the flow channel is normally adopted,the configuration optimization of which could potentially enhance the performance of the electrolyzer.This paper describes the numerical simulation study on the impact of the flow-channel cross-section shapes in the MEA electrolyzer for CO_(2)RR.The results show that wide flow channels with low heights are beneficial to the CO_(2)RR by providing a uniform flow field of CO_(2),especially at high current densities.Moreover,the larger the electrolyzer,the more significant the effect is.This study provides a theoretical basis for the design of high-performance MEA electrolyzers for CO_(2)RR.展开更多
A unitized regenerative fuel cell(URFC)is a device that may function reversibly as either a fuel cell(FC)or water elec-trolysis(WE).An important component of this device is the Membrane electrode assembly(MEA).Therefo...A unitized regenerative fuel cell(URFC)is a device that may function reversibly as either a fuel cell(FC)or water elec-trolysis(WE).An important component of this device is the Membrane electrode assembly(MEA).Therefore,this study aimed to compare the performance outcomes of MEA using electrodes with single and three catalyst layers.This study measured Electrochemical Surface Area(ECSA),Electrochemical Impedance Spectroscopy(EIS),X-ray Diffraction analysis(XRD),and X-ray Fluorescence(XRF).Furthermore,the round-trip efficiency(RTE)of the MEA,as w ell as the performance in FC and WE mode,was measured.In comparison,The ECSA values of Pt-Ru/C and Pt/C with three catalyst layers were higher than the single catalyst layer.This result was supported by electrode characterization data for XRD and XRF.The respective electrical conductivity values of Pt-Ru/C and Pt/C with three catalyst layers are also higher than the single cata-lyst layer,and the performance of URFC using MEA with three catalyst layers has the highest value of RTE among the MEA performances of URFC,which is 100%at a current density of 4 mA·cm-2.展开更多
Anion exchange membrane fuel cells(AEMFCs)are considered a more affordable technology compared to proton exchange membrane fuel cells(PEMFCs),but the performance and durability of AEMFCs are still not competent with P...Anion exchange membrane fuel cells(AEMFCs)are considered a more affordable technology compared to proton exchange membrane fuel cells(PEMFCs),but the performance and durability of AEMFCs are still not competent with PEMFCs owing to the more challenging water management,which severely hinders its development and real-life applications.In this study,we introduce the strategy to boost the performance and stability of the membrane electrode assembly(MEA)of AEMFCs by regulating the hydrophilicity of the anode and cathode ionomers.Two poly(biphenyl alkylene)ionomers with different hydrophilicity are synthesized and used to fabricate MEAs with asymmetric or symmetric ionomer configurations in the anodic and cathodic catalyst layers(CLs)for AEMFCs.Molecular dynamics(MD)simulations have revealed different diffusion rates of water in the hydrophobic anode and the hydrophilic cathode,which show the potential of this design to improve water management in AEMFCs,The effectiveness of this design is also confirmed by experimental results that the MEA with this asymmetric configuration exhibits the highest power and current densities of 1.58 W cm^(-2)or 5.58 A cm^(-2),respectively,among all configurations.Furthermore,this configuration also enhances the durability,with the MEA showing a voltage decay rate of only 313.1μV h^(-1)after 500 h of in-situ durability test at 0.2 A cm^(-2).This study provides new insights into the rational design of more efficient water management in MEA for high-performance AEMFCs.展开更多
A fuel cell is an energy conversion device that can continuously input fuel and oxidant into the device through an electrochemical reaction to release electrical energy.Although noble metals show good activity in fuel...A fuel cell is an energy conversion device that can continuously input fuel and oxidant into the device through an electrochemical reaction to release electrical energy.Although noble metals show good activity in fuel cell-related electrochemical reactions,their ever-increasing price considerably hinders their industrial application.Improvement of atom utilization efficiency is considered one of the most effective strategies to improve the mass activity of catalysts,and this allows for the use of fewer catalysts,saving greatly on the cost.Thus,single-atom catalysts(SACs)with an atom utilization efficiency of 100%have been widely developed,which show remarkable performance in fuel cells.In this review,we will describe recent progress on the development of SACs for membrane electrode assembly of fuel cell applications.First,we will introduce several effective routes for the synthesis of SACs.The reaction mechanism of the involved reactions will also be introduced as it is highly determinant of the final activity.Then,we will systematically summarize the application of Pt group metal(PGM)and nonprecious group metal(non-PGM)catalysts in membrane electrode assembly of fuel cells.This review will offer numerous experiences for developing potential industrialized fuel cell catalysts in the future.展开更多
Currently, the electrochemical CO_(2) reduction reaction (CO_(2) RR) can realize the resource conversion of CO_(2) , which is a promising approach to carbon resource use. Important advancements have been made in explo...Currently, the electrochemical CO_(2) reduction reaction (CO_(2) RR) can realize the resource conversion of CO_(2) , which is a promising approach to carbon resource use. Important advancements have been made in exploring the CO_(2) RR performance and mechanism because of the rational design of electrolyzer systems, such as H-cells, flow cells, and catalysts. Considering the future development direction of this technology and large-scale application needs, membrane electrode assembly (MEA) systems can improve energy use efficiency and achieve large-scale CO_(2) conversion, which is considered the most promising technology for industrial applications. This review will concentrate on the research progress and present situation of the MEA component structure. This paper begins with the composition and construction of a gas diff usion electrode. Then, the application of ion-exchange membranes in MEA is introduced. Furthermore, the eff ects of pH and the anion and cation of the anolyte on MEA performance are explored. Additionally, we present the anode reaction type in MEA. Finally, the challenges in this field are summarized, and upcoming trends are projected. This review should offer researchers a clearer picture of MEA systems and provide important, timely, and valuable insights into rational electrolyzer design to facilitate further development of CO_(2) electrochemical reduction.展开更多
The frame of membrane electrode assembly(MEA)influences the durability of proton exchange membrane fuel cell(PEMFC).In this paper,the thermal shock bench was applied as an accelerated aging test to explore the effect ...The frame of membrane electrode assembly(MEA)influences the durability of proton exchange membrane fuel cell(PEMFC).In this paper,the thermal shock bench was applied as an accelerated aging test to explore the effect of frame sealing structure on MEA durability at different temperatures.Analysis of scanning electron microscope(SEM)images reveals that thermal shock results in the formation of cracks on the exposed proton exchange membrane(PEM)at the gap between the frame and the active area.Moreover,it breaks the bonding interface between the frame and the membrane and leads to the debonding of the adhesive,which exacerbates the risk of crossover of the reactant gas.A comparison of the single-layer and improved double-layer frame structures reveal that the mechanical damage is caused by frequent membrane wrinkles in the gap under temperature shock.However,addition of a cushion layer improves the continuity between the frame and the active area,and reduces deformation of the membrane,thereby preventing membrane damage.展开更多
The electrochemical CO_(2)reduction reaction(CO_(2)RR)is a promising approach for converting CO_(2)into valuable chemicals and promoting carbon cycling.Among the products of CO_(2)RR,ethylene(C_(2)H_(4)),as a crucial ...The electrochemical CO_(2)reduction reaction(CO_(2)RR)is a promising approach for converting CO_(2)into valuable chemicals and promoting carbon cycling.Among the products of CO_(2)RR,ethylene(C_(2)H_(4)),as a crucial chemical feedstock,holds significant market demand and economic value.The design of an electrolyte-free cathode in membrane electrode assemblies(MEAs)can effectively mitigate mass transfer limitations,reduce ohmic losses,and enhance interfacial efficiency,thereby significantly improving current density and product selectivity.The integration of copper-based catalysts into MEAs is considered a promising strategy for the industrial-scale production of C_(2)H_(4) via CO_(2)RR.However,comprehensive reviews on the application of copper-based catalysts in MEAs for CO_(2)RR to C_(2)H_(4)remain limited,particularly regarding systematic analyses of catalyst design strategies,optimization of MEA components and operating conditions,and MEA device configurations.This review systematically summarizes the latest research progress on copper-based catalysts in MEAs for CO_(2)RR to C_(2)H_(4).Firstly,the reaction mechanism of CO_(2)RR to C_(2)H_(4) was summarized and the role of intermediate adsorption regulation was highlighted in MEA systems.Secondly,strategies applied to optimize ethylene production using copper-based catalysts in MEAs were also summarized accordingly.Next,the influence of components,operational conditions,and device design for MEA was discussed.Finally,the opportunities and challenges of using copper-based catalysts in MEAs for C_(2)H_(4)production were outlined.This review aims to provide insights and inspire further research efforts toward optimizing the performance of CO_(2)RR to C_(2)H_(4)in MEAs.展开更多
The utilization of environmentally friendly hydrogen energy requires proton exchange membrane fuel cell de-vices that offer high power output while remaining affordable.However,the current optimization of their key co...The utilization of environmentally friendly hydrogen energy requires proton exchange membrane fuel cell de-vices that offer high power output while remaining affordable.However,the current optimization of their key component,i.e.,the membrane electrode assembly,is still based on intuition-guided,inefficient trial-and-error cycles due to its complexity.Hence,we introduce an innovative,explainable artificial intelligence(AI)tool trained as a reliable assistant for a variable analysis and optimum-value prediction.Among the 8 algorithms considered,the surrogate model built with an artificial neural network achieves high replaceability in the experimentally validated multiphysics simulation(R^(2)=0.99845)and a much lower computational cost.For interpretation,partial dependence plots and the Shapley value method are applied to black-box models to intelligently simulate the impact of each parameter on performance.These methods show that a tradeoff existed in the catalyst layer thickness.The AI-guided optimization suggestions regarding catalyst loading and the ion-omer content are fully supported by the experimental results,and the final product achieves 3.2 times the Pt utilization of commercial products with a time cost orders of magnitude smaller.展开更多
The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focus...The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone（SPEEK） based membranes and caesium salt of silico-tungstic acid（Cs Si WA） matrix compared with one of the transition metal oxides such as titanium dioxide（TiO2）, silicon dioxide（SiO2） and zirconium dioxide（ZrO2）. The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity（IEC）, water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface.展开更多
Black phosphorus with a superior theoretical capacity(2596 mAh g^(-1))and high conductivity is regarded as one of the powerful candidates for lithium-ion battery(LIB)anode materials,whereas the severe volume expansion...Black phosphorus with a superior theoretical capacity(2596 mAh g^(-1))and high conductivity is regarded as one of the powerful candidates for lithium-ion battery(LIB)anode materials,whereas the severe volume expansion and sluggish kinetics still impede its applications in LIBs.By contrast,the exfoliated two-dimensional phosphorene owns negligible volume variation,and its intrinsic piezoelectricity is considered to be beneficial to the Li-ion transfer kinetics,while its positive influence has not been discussed yet.Herein,a phosphorene/MXene heterostructure-textured nanopiezocomposite is proposed with even phosphorene distribution and enhanced piezo-electrochemical coupling as an applicable free-standing asymmetric membrane electrode beyond the skin effect for enhanced Li-ion storage.The experimental and simulation analysis reveals that the embedded phosphorene nanosheets not only provide abundant active sites for Li-ions,but also endow the nanocomposite with favorable piezoelectricity,thus promoting the Li-ion transfer kinetics by generating the piezoelectric field serving as an extra accelerator.By waltzing with the MXene framework,the optimized electrode exhibits enhanced kinetics and stability,achieving stable cycling performances for 1,000 cycles at 2 A g^(-1),and delivering a high reversible capacity of 524 m Ah g^(-1)at-20℃,indicating the positive influence of the structural merits of self-assembled nanopiezocomposites on promoting stability and kinetics.展开更多
Understanding the degradation phenomenon of proton exchange membrane fuel cells under electrochemical cycling requires an analysis of the porous carbon support structure.Key factors contributing to this phenomenon inc...Understanding the degradation phenomenon of proton exchange membrane fuel cells under electrochemical cycling requires an analysis of the porous carbon support structure.Key factors contributing to this phenomenon include changes in the total porosity and viable surface area for electrochemical reactions.Electron tomography-based serial section imaging using focused ion beam-scanning electron microscopy(FIB-SEM)can elucidate this phenomenon at a nanoscale resolution.However,this highresolution tomographic analysis requires a huge image dataset and manual inputs in rule-based workflows;these requirements are time-consuming and often cause experimental difficulties and unreliable interpretations.We propose a deep learning-empowered approach comprising a two-step automated process for image interpolation and semantic segmentation to address the practical issues encountered in FIB-SEM electron tomography.An optimally trained interpolation model can reduce the image data requirement by more than 95%to analyze the structural degradation of carbon supports after electrochemical cycling while maintaining the reliability obtained in conventional tomographic analysis with several hundred images.Because the subsequent image segmentation model excludes a complicated manual filtering process,the relevant structural parameters can be reliably measured without human bias.Our sparse-section imaging-based deep learning process can allow cost-efficient analysis and reliable measurement of the degree of cycling-induced carbon corrosion.展开更多
Proton exchange membrane fuel cells(PEMFCs)have been identified as a highly promising means of achieving sustainable energy conversion.A crucial factor in enhancing the performance of PEMFCs for further potential ener...Proton exchange membrane fuel cells(PEMFCs)have been identified as a highly promising means of achieving sustainable energy conversion.A crucial factor in enhancing the performance of PEMFCs for further potential energy applications is the advancement in the field of catalyst engineering that has led to remarkable performance enhancement in facilitating the oxygen reduction reaction(ORR).Subsequently,it is important to acknowledge that the techniques used in preparation of membrane electrode assemblies(MEAs),the vital constituents of PEMFCs,also possess direct and critical influence on exhibiting the full catalytic activity of meticulously crafted catalysts.Here,a succinct summary of the most recent advancements in Pt catalysts for ORR was offered and their underly catalytic mechanism were discussed.Then,both laboratory-scale and industrial-scale MEA fabrication techniques of Pt catalysts were summarized.Furthermore,a detailed analysis of the connections between materials,process,and performance in MEA fabrication was presented in order to facilitate the development of optimal catalyst layers.展开更多
The performance of proton exchange membrane fuel cells is heavily dependent on the microstructure of electrode catalyst especially at low catalyst loadings.This work shows a hybrid electrocatalyst consisting of PtNi-W...The performance of proton exchange membrane fuel cells is heavily dependent on the microstructure of electrode catalyst especially at low catalyst loadings.This work shows a hybrid electrocatalyst consisting of PtNi-W alloy nanocrystals loaded on carbon surface with atomically dispersed W sites by a two-step straightforward method.Single-atomic W can be found on the carbon surface,which can form protonic acid sites and establish an extended proton transport network at the catalyst surface.When implemented in membrane electrode assembly as cathode at ultra-low loading of 0.05 mgPt cm^(−2),the peak power density of the cell is enhanced by 64.4%compared to that with the commercial Pt/C catalyst.The theoretical calculation suggests that the single-atomic W possesses a favorable energetics toward the formation of*OOH whereby the intermediates can be efficiently converted and further reduced to water,revealing a interfacial cascade catalysis facilitated by the single-atomic W.This work highlights a novel functional hybrid electrocatalyst design from the atomic level that enables to solve the bottle-neck issues at device level.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
The rational construction of high-performance and stable electrocatalyst for oxygen evolution reaction(OER)is a prerequisite for efficient water electrolysis.Herein,we develop a broccoli-like Ni_(3)S_(2)@NiFeP_(x)(Ni_...The rational construction of high-performance and stable electrocatalyst for oxygen evolution reaction(OER)is a prerequisite for efficient water electrolysis.Herein,we develop a broccoli-like Ni_(3)S_(2)@NiFeP_(x)(Ni_(3)S_(2)@NFP)catalyst on nickel foam(NF)via a sequential two-step layer-by-layer assembly electrodeposition method.X-ray diffraction,in situ Raman and Fourier-transform infrared spectra have mutually validated the element segregation and phase refusion during OER condition.The reconstruction of double layer Ni_(3)S_(2)@NFP facilitates the formation of the active(oxy)hydroxides,which is modulated by the dual anionic layer with mixed sulfate and phosphate ions.As a result,the obtained Ni_(3)S_(2)@NFP electrode exhibits low overpotential(329 mV)and long-term durability(∼500 h)for OER at current density of 500mA/cm^(2).Moreover,the self-supported Ni_(3)S_(2)@NFP can act as an efficient and durable anode in alkaline anion exchange membrane water electrolysis device(AEMWE).This work provides a facile and scaled-up strategy to construct self-supported electrocatalyst and emphasizes the crucial role of anions in pre-catalyst reconstruction and enhancing OER performance.展开更多
Anion exchange membrane(AEM)electrolysis is a promising membrane-based green hydrogen production technology.However,AEM electrolysis still remains in its infancy,and the performance of AEM electrolyzers is far behind ...Anion exchange membrane(AEM)electrolysis is a promising membrane-based green hydrogen production technology.However,AEM electrolysis still remains in its infancy,and the performance of AEM electrolyzers is far behind that of well-developed alkaline and proton exchange membrane electrolyzers.Therefore,breaking through the technical barriers of AEM electrolyzers is critical.On the basis of the analysis of the electrochemical performance tested in a single cell,electrochemical impedance spectroscopy,and the number of active sites,we evaluated the main technical factors that affect AEM electrolyzers.These factors included catalyst layer manufacturing(e.g.,catalyst,carbon black,and anionic ionomer)loadings,membrane electrode assembly,and testing conditions(e.g.,the KOH concentration in the electrolyte,electrolyte feeding mode,and operating temperature).The underlying mechanisms of the effects of these factors on AEM electrolyzer performance were also revealed.The irreversible voltage loss in the AEM electrolyzer was concluded to be mainly associated with the kinetics of the electrode reaction and the transport of electrons,ions,and gas-phase products involved in electrolysis.Based on the study results,the performance and stability of AEM electrolyzers were significantly improved.展开更多
Proton exchange membrane fuel cells(PEMFCs)are regarded as one of the most promising clean energy technology because of their high energy density,silent emission-free operation,and wide applications[1].Recently,anion ...Proton exchange membrane fuel cells(PEMFCs)are regarded as one of the most promising clean energy technology because of their high energy density,silent emission-free operation,and wide applications[1].Recently,anion exchange membrane fuel cells(AEMFCs)has emerged as an alternative to PEMFCs.展开更多
The variation of the three-dimensional(3D)structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon support.The increasing degradation of the car...The variation of the three-dimensional(3D)structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon support.The increasing degradation of the carbon structure continuously reduces the electrocatalytic performance of proton exchange membrane fuel cells(PEM-FCs).This phenomenon can be explained by performing 3D tomographic analysis at the nanoscale.However,conventional tomographic approaches which present limited experimental feasibility,cannot perform such evaluation and have not provided sufficient structural information with statistical significance thus far.Therefore,a reliable methodology is required for the 3D geometrical evaluation of the carbon structure.Here,we propose a segmented tomographic approach which employs pore network analysis that enables the visualization of the geometrical parameters corresponding to the porous carbon structure at a high resolution.This approach can be utilized to evaluate the 3D structural degradation of the porous carbon structure after cycling in terms of local surface area,pore size distribution,and their 3D networking.These geometrical parameters of the carbon body were demonstrated to be substantially reduced owing to the cycling-induced degradation.This information enables a deeper understanding of the degradation phenomenon of carbon supports and can contribute to the development of stable PEM-FC electrodes.展开更多
PPMG-based composite electrolytes were fabricated via the solution method using the polyvinyl alcohol and polyvinylpyrrolidone blend reinforced with various contents of sulfonated inorganic filler.Sulfuric acid was em...PPMG-based composite electrolytes were fabricated via the solution method using the polyvinyl alcohol and polyvinylpyrrolidone blend reinforced with various contents of sulfonated inorganic filler.Sulfuric acid was employed as the sulfonating agent to functionalize the external surface of the inorganic filler,i.e.,graphene oxide.The proton conductivities of the newly prepared proton exchange membranes(PEMs)were increased by increasing the temperature and content of sulfonated graphene oxide(SGO),i.e.,ranging from 0.025 S/cm to 0.060 S/cm.The induction of the optimum level of SGO is determined to be an excellent route to enhance ionic conductivity.The single-cell performance test was conducted by sandwiching the newly prepared PEMs between an anode(0.2 mg/cm^(2) Pt/Ru)and a cathode(0.2 mg/cm^(2) Pt)to prepare membrane electrode assemblies,followed by hot pressing under a pressure of approximately 100 kg/cm^(2) at 60℃for 5–10 min.The highest power densities achieved with PPMG PEMs were 14.9 and 35.60 mW/cm^(2) at 25℃and 70℃,respectively,at ambient pressure with 100%relative humidity.Results showed that the newly prepared PEMs exhibit good electrochemical performance.The results indicated that the prepared composite membrane with 6 wt%filler can be used as an alternative membrane for applications of high-performance proton exchange membrane fuel cell.展开更多
基金the National Key R&D Program of China(No.2021YFA1501503)the National Natural Science Foundation of China(Nos.22250008,22121004,22108197)+3 种基金the Haihe Laboratory of Sustainable Chemical Transformations(No.CYZC202107)the Natural Science Foundation of Tianjin City(No.21JCZXJC00060)the Program of Introducing Talents of Discipline to Universities(No.BP0618007)the Xplorer Prize for financial support。
文摘Membrane electrode assembly(MEA)is widely considered to be the most promising type of electrolyzer for the practical application of electrochemical CO_(2) reduction reaction(CO_(2)RR).In MEAs,a square-shaped cross-section in the flow channel is normally adopted,the configuration optimization of which could potentially enhance the performance of the electrolyzer.This paper describes the numerical simulation study on the impact of the flow-channel cross-section shapes in the MEA electrolyzer for CO_(2)RR.The results show that wide flow channels with low heights are beneficial to the CO_(2)RR by providing a uniform flow field of CO_(2),especially at high current densities.Moreover,the larger the electrolyzer,the more significant the effect is.This study provides a theoretical basis for the design of high-performance MEA electrolyzers for CO_(2)RR.
基金support from the Ministry of Higher Education Malaysia under grant HICOE-2023-005.
文摘A unitized regenerative fuel cell(URFC)is a device that may function reversibly as either a fuel cell(FC)or water elec-trolysis(WE).An important component of this device is the Membrane electrode assembly(MEA).Therefore,this study aimed to compare the performance outcomes of MEA using electrodes with single and three catalyst layers.This study measured Electrochemical Surface Area(ECSA),Electrochemical Impedance Spectroscopy(EIS),X-ray Diffraction analysis(XRD),and X-ray Fluorescence(XRF).Furthermore,the round-trip efficiency(RTE)of the MEA,as w ell as the performance in FC and WE mode,was measured.In comparison,The ECSA values of Pt-Ru/C and Pt/C with three catalyst layers were higher than the single catalyst layer.This result was supported by electrode characterization data for XRD and XRF.The respective electrical conductivity values of Pt-Ru/C and Pt/C with three catalyst layers are also higher than the single cata-lyst layer,and the performance of URFC using MEA with three catalyst layers has the highest value of RTE among the MEA performances of URFC,which is 100%at a current density of 4 mA·cm-2.
基金supported by the National Key R&D Program of China(No.2023YFB4004700)。
文摘Anion exchange membrane fuel cells(AEMFCs)are considered a more affordable technology compared to proton exchange membrane fuel cells(PEMFCs),but the performance and durability of AEMFCs are still not competent with PEMFCs owing to the more challenging water management,which severely hinders its development and real-life applications.In this study,we introduce the strategy to boost the performance and stability of the membrane electrode assembly(MEA)of AEMFCs by regulating the hydrophilicity of the anode and cathode ionomers.Two poly(biphenyl alkylene)ionomers with different hydrophilicity are synthesized and used to fabricate MEAs with asymmetric or symmetric ionomer configurations in the anodic and cathodic catalyst layers(CLs)for AEMFCs.Molecular dynamics(MD)simulations have revealed different diffusion rates of water in the hydrophobic anode and the hydrophilic cathode,which show the potential of this design to improve water management in AEMFCs,The effectiveness of this design is also confirmed by experimental results that the MEA with this asymmetric configuration exhibits the highest power and current densities of 1.58 W cm^(-2)or 5.58 A cm^(-2),respectively,among all configurations.Furthermore,this configuration also enhances the durability,with the MEA showing a voltage decay rate of only 313.1μV h^(-1)after 500 h of in-situ durability test at 0.2 A cm^(-2).This study provides new insights into the rational design of more efficient water management in MEA for high-performance AEMFCs.
基金National Natural Science Foundation of China,Grant/Award Numbers:22075203,22279079,21905179Guangdong Science and Technology Department Program,Grant/Award Number:2021QN02L252+1 种基金Shenzhen Science and Technology Department Program,Grant/Award Numbers:20220810133521001,20220809165014001Natural Science Foundation of SZU,Grant/Award Numbers:000002111605,000002112215。
文摘A fuel cell is an energy conversion device that can continuously input fuel and oxidant into the device through an electrochemical reaction to release electrical energy.Although noble metals show good activity in fuel cell-related electrochemical reactions,their ever-increasing price considerably hinders their industrial application.Improvement of atom utilization efficiency is considered one of the most effective strategies to improve the mass activity of catalysts,and this allows for the use of fewer catalysts,saving greatly on the cost.Thus,single-atom catalysts(SACs)with an atom utilization efficiency of 100%have been widely developed,which show remarkable performance in fuel cells.In this review,we will describe recent progress on the development of SACs for membrane electrode assembly of fuel cell applications.First,we will introduce several effective routes for the synthesis of SACs.The reaction mechanism of the involved reactions will also be introduced as it is highly determinant of the final activity.Then,we will systematically summarize the application of Pt group metal(PGM)and nonprecious group metal(non-PGM)catalysts in membrane electrode assembly of fuel cells.This review will offer numerous experiences for developing potential industrialized fuel cell catalysts in the future.
基金The financial assistance for this work was provided by the National Natural Science Foundation of China (Nos. 51773092, 21975124, 20210283, and 22109070)the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure (No. SKL201911SIC).
文摘Currently, the electrochemical CO_(2) reduction reaction (CO_(2) RR) can realize the resource conversion of CO_(2) , which is a promising approach to carbon resource use. Important advancements have been made in exploring the CO_(2) RR performance and mechanism because of the rational design of electrolyzer systems, such as H-cells, flow cells, and catalysts. Considering the future development direction of this technology and large-scale application needs, membrane electrode assembly (MEA) systems can improve energy use efficiency and achieve large-scale CO_(2) conversion, which is considered the most promising technology for industrial applications. This review will concentrate on the research progress and present situation of the MEA component structure. This paper begins with the composition and construction of a gas diff usion electrode. Then, the application of ion-exchange membranes in MEA is introduced. Furthermore, the eff ects of pH and the anion and cation of the anolyte on MEA performance are explored. Additionally, we present the anode reaction type in MEA. Finally, the challenges in this field are summarized, and upcoming trends are projected. This review should offer researchers a clearer picture of MEA systems and provide important, timely, and valuable insights into rational electrolyzer design to facilitate further development of CO_(2) electrochemical reduction.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB4001801).
文摘The frame of membrane electrode assembly(MEA)influences the durability of proton exchange membrane fuel cell(PEMFC).In this paper,the thermal shock bench was applied as an accelerated aging test to explore the effect of frame sealing structure on MEA durability at different temperatures.Analysis of scanning electron microscope(SEM)images reveals that thermal shock results in the formation of cracks on the exposed proton exchange membrane(PEM)at the gap between the frame and the active area.Moreover,it breaks the bonding interface between the frame and the membrane and leads to the debonding of the adhesive,which exacerbates the risk of crossover of the reactant gas.A comparison of the single-layer and improved double-layer frame structures reveal that the mechanical damage is caused by frequent membrane wrinkles in the gap under temperature shock.However,addition of a cushion layer improves the continuity between the frame and the active area,and reduces deformation of the membrane,thereby preventing membrane damage.
基金supported by the Taishan Scholars Program(Nos.tsqn202306309,tstp20221151)Natural Science Foundation of Shandong Province(Nos.ZR2023YQ012,ZR2024QB295)the National Natural Science Foundation of China(Nos.52261145700,22261132517).
文摘The electrochemical CO_(2)reduction reaction(CO_(2)RR)is a promising approach for converting CO_(2)into valuable chemicals and promoting carbon cycling.Among the products of CO_(2)RR,ethylene(C_(2)H_(4)),as a crucial chemical feedstock,holds significant market demand and economic value.The design of an electrolyte-free cathode in membrane electrode assemblies(MEAs)can effectively mitigate mass transfer limitations,reduce ohmic losses,and enhance interfacial efficiency,thereby significantly improving current density and product selectivity.The integration of copper-based catalysts into MEAs is considered a promising strategy for the industrial-scale production of C_(2)H_(4) via CO_(2)RR.However,comprehensive reviews on the application of copper-based catalysts in MEAs for CO_(2)RR to C_(2)H_(4)remain limited,particularly regarding systematic analyses of catalyst design strategies,optimization of MEA components and operating conditions,and MEA device configurations.This review systematically summarizes the latest research progress on copper-based catalysts in MEAs for CO_(2)RR to C_(2)H_(4).Firstly,the reaction mechanism of CO_(2)RR to C_(2)H_(4) was summarized and the role of intermediate adsorption regulation was highlighted in MEA systems.Secondly,strategies applied to optimize ethylene production using copper-based catalysts in MEAs were also summarized accordingly.Next,the influence of components,operational conditions,and device design for MEA was discussed.Finally,the opportunities and challenges of using copper-based catalysts in MEAs for C_(2)H_(4)production were outlined.This review aims to provide insights and inspire further research efforts toward optimizing the performance of CO_(2)RR to C_(2)H_(4)in MEAs.
基金This work was partially supported by the National Key R&D Plan of China[2019YFB1504503]the National Natural Science Foundation of China[21802069]the Key R&D plan of Zhejiang Province[2020C01006].The database generation from the multiphysics simu-lation model was performed at the High-Performance Computing Center of the Collaborative Innovation Center of Advanced Microstructures,Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210,093,China.
文摘The utilization of environmentally friendly hydrogen energy requires proton exchange membrane fuel cell de-vices that offer high power output while remaining affordable.However,the current optimization of their key component,i.e.,the membrane electrode assembly,is still based on intuition-guided,inefficient trial-and-error cycles due to its complexity.Hence,we introduce an innovative,explainable artificial intelligence(AI)tool trained as a reliable assistant for a variable analysis and optimum-value prediction.Among the 8 algorithms considered,the surrogate model built with an artificial neural network achieves high replaceability in the experimentally validated multiphysics simulation(R^(2)=0.99845)and a much lower computational cost.For interpretation,partial dependence plots and the Shapley value method are applied to black-box models to intelligently simulate the impact of each parameter on performance.These methods show that a tradeoff existed in the catalyst layer thickness.The AI-guided optimization suggestions regarding catalyst loading and the ion-omer content are fully supported by the experimental results,and the final product achieves 3.2 times the Pt utilization of commercial products with a time cost orders of magnitude smaller.
文摘The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone（SPEEK） based membranes and caesium salt of silico-tungstic acid（Cs Si WA） matrix compared with one of the transition metal oxides such as titanium dioxide（TiO2）, silicon dioxide（SiO2） and zirconium dioxide（ZrO2）. The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity（IEC）, water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface.
基金financially supported by the National Key Research and Development Program of China(No.2017YFB1002900)the National Natural Science Foundation of China(No.51661145021)+5 种基金the Key Natural Science Program of Jiangsu Province(Nos.BE2022118,BE2021643 and BE2016772)the Traction Project of Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province(No.Q816000217)the Scholarship from Key Laboratory of Modern Optical Technologies of Ministry of Education of Chinathe Priority Academic Program Development(PAPD)of Jiangsu Higher Education InstitutionsChina Prosperity Green Industry Foundation of Ministry of Industry and Information Technologysupported by the open project of synchrotron radiation characterization of chain oriented/stacked polar topology and energy modulation of supramolecules(No.2100982)。
文摘Black phosphorus with a superior theoretical capacity(2596 mAh g^(-1))and high conductivity is regarded as one of the powerful candidates for lithium-ion battery(LIB)anode materials,whereas the severe volume expansion and sluggish kinetics still impede its applications in LIBs.By contrast,the exfoliated two-dimensional phosphorene owns negligible volume variation,and its intrinsic piezoelectricity is considered to be beneficial to the Li-ion transfer kinetics,while its positive influence has not been discussed yet.Herein,a phosphorene/MXene heterostructure-textured nanopiezocomposite is proposed with even phosphorene distribution and enhanced piezo-electrochemical coupling as an applicable free-standing asymmetric membrane electrode beyond the skin effect for enhanced Li-ion storage.The experimental and simulation analysis reveals that the embedded phosphorene nanosheets not only provide abundant active sites for Li-ions,but also endow the nanocomposite with favorable piezoelectricity,thus promoting the Li-ion transfer kinetics by generating the piezoelectric field serving as an extra accelerator.By waltzing with the MXene framework,the optimized electrode exhibits enhanced kinetics and stability,achieving stable cycling performances for 1,000 cycles at 2 A g^(-1),and delivering a high reversible capacity of 524 m Ah g^(-1)at-20℃,indicating the positive influence of the structural merits of self-assembled nanopiezocomposites on promoting stability and kinetics.
基金supported by the Technology Innovation Program(No.20011712)funded by the Ministry of Trade,Industry,and Energy(MOTIE,Korea)a National Research Foundation of Korea(NRF)grant funded by the Ministry of Science and ICT(MSIT)(No.2022M3J1A108538),Korea+2 种基金the support of the Nano&Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(RS-2024-00444986,50%)the Institute for Basic Science(IBS-R036-D1)。
文摘Understanding the degradation phenomenon of proton exchange membrane fuel cells under electrochemical cycling requires an analysis of the porous carbon support structure.Key factors contributing to this phenomenon include changes in the total porosity and viable surface area for electrochemical reactions.Electron tomography-based serial section imaging using focused ion beam-scanning electron microscopy(FIB-SEM)can elucidate this phenomenon at a nanoscale resolution.However,this highresolution tomographic analysis requires a huge image dataset and manual inputs in rule-based workflows;these requirements are time-consuming and often cause experimental difficulties and unreliable interpretations.We propose a deep learning-empowered approach comprising a two-step automated process for image interpolation and semantic segmentation to address the practical issues encountered in FIB-SEM electron tomography.An optimally trained interpolation model can reduce the image data requirement by more than 95%to analyze the structural degradation of carbon supports after electrochemical cycling while maintaining the reliability obtained in conventional tomographic analysis with several hundred images.Because the subsequent image segmentation model excludes a complicated manual filtering process,the relevant structural parameters can be reliably measured without human bias.Our sparse-section imaging-based deep learning process can allow cost-efficient analysis and reliable measurement of the degree of cycling-induced carbon corrosion.
基金financially supported by the National Natural Science Foundation of China(Nos.51802059,21905070 and 22075062)Shenzhen Science and Technology Program(Nos.JCYJ20210324120400002 and SGDX20210823103803017)+4 种基金the Key Research and Development Program of Shandong Province(No.2022CXGC010305)Heilongjiang Postdoctoral Fund(No.LBHZ18066),Heilongjiang Touyan Team(No.HITTY-20190033)the Fundamental Research Funds for the Central Universities(No.FRFCU5710051922)the High-Level Professional Team in Shenzhen(No.KQTD20210811090045006)Guangdong Basic and Applied Basic Research Foundation(No.2022B1515120001)。
文摘Proton exchange membrane fuel cells(PEMFCs)have been identified as a highly promising means of achieving sustainable energy conversion.A crucial factor in enhancing the performance of PEMFCs for further potential energy applications is the advancement in the field of catalyst engineering that has led to remarkable performance enhancement in facilitating the oxygen reduction reaction(ORR).Subsequently,it is important to acknowledge that the techniques used in preparation of membrane electrode assemblies(MEAs),the vital constituents of PEMFCs,also possess direct and critical influence on exhibiting the full catalytic activity of meticulously crafted catalysts.Here,a succinct summary of the most recent advancements in Pt catalysts for ORR was offered and their underly catalytic mechanism were discussed.Then,both laboratory-scale and industrial-scale MEA fabrication techniques of Pt catalysts were summarized.Furthermore,a detailed analysis of the connections between materials,process,and performance in MEA fabrication was presented in order to facilitate the development of optimal catalyst layers.
基金Y.Li acknowledges the financial support from the National Natural Science Foundation of China(No.52171199)X.Ke acknowledges the financial support from the National Natural Science Foundation of China(No.12074017).
文摘The performance of proton exchange membrane fuel cells is heavily dependent on the microstructure of electrode catalyst especially at low catalyst loadings.This work shows a hybrid electrocatalyst consisting of PtNi-W alloy nanocrystals loaded on carbon surface with atomically dispersed W sites by a two-step straightforward method.Single-atomic W can be found on the carbon surface,which can form protonic acid sites and establish an extended proton transport network at the catalyst surface.When implemented in membrane electrode assembly as cathode at ultra-low loading of 0.05 mgPt cm^(−2),the peak power density of the cell is enhanced by 64.4%compared to that with the commercial Pt/C catalyst.The theoretical calculation suggests that the single-atomic W possesses a favorable energetics toward the formation of*OOH whereby the intermediates can be efficiently converted and further reduced to water,revealing a interfacial cascade catalysis facilitated by the single-atomic W.This work highlights a novel functional hybrid electrocatalyst design from the atomic level that enables to solve the bottle-neck issues at device level.
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(NSFC,Nos.21925503,22102076)the Ministry of Science and Technology of the People’s Republic of China(MOST,No.2022YFA1504001)+1 种基金the Ministry of Education of the People’s Republic of China(MOE,No.B12015)the Fundamental Research Funds for the Central Universities.
文摘The rational construction of high-performance and stable electrocatalyst for oxygen evolution reaction(OER)is a prerequisite for efficient water electrolysis.Herein,we develop a broccoli-like Ni_(3)S_(2)@NiFeP_(x)(Ni_(3)S_(2)@NFP)catalyst on nickel foam(NF)via a sequential two-step layer-by-layer assembly electrodeposition method.X-ray diffraction,in situ Raman and Fourier-transform infrared spectra have mutually validated the element segregation and phase refusion during OER condition.The reconstruction of double layer Ni_(3)S_(2)@NFP facilitates the formation of the active(oxy)hydroxides,which is modulated by the dual anionic layer with mixed sulfate and phosphate ions.As a result,the obtained Ni_(3)S_(2)@NFP electrode exhibits low overpotential(329 mV)and long-term durability(∼500 h)for OER at current density of 500mA/cm^(2).Moreover,the self-supported Ni_(3)S_(2)@NFP can act as an efficient and durable anode in alkaline anion exchange membrane water electrolysis device(AEMWE).This work provides a facile and scaled-up strategy to construct self-supported electrocatalyst and emphasizes the crucial role of anions in pre-catalyst reconstruction and enhancing OER performance.
基金National Natural Science Foundation of China(Nos.52071231,51722103)the Natural Science Foundation of Tianjin(No.19JCJQJC61900)。
文摘Anion exchange membrane(AEM)electrolysis is a promising membrane-based green hydrogen production technology.However,AEM electrolysis still remains in its infancy,and the performance of AEM electrolyzers is far behind that of well-developed alkaline and proton exchange membrane electrolyzers.Therefore,breaking through the technical barriers of AEM electrolyzers is critical.On the basis of the analysis of the electrochemical performance tested in a single cell,electrochemical impedance spectroscopy,and the number of active sites,we evaluated the main technical factors that affect AEM electrolyzers.These factors included catalyst layer manufacturing(e.g.,catalyst,carbon black,and anionic ionomer)loadings,membrane electrode assembly,and testing conditions(e.g.,the KOH concentration in the electrolyte,electrolyte feeding mode,and operating temperature).The underlying mechanisms of the effects of these factors on AEM electrolyzer performance were also revealed.The irreversible voltage loss in the AEM electrolyzer was concluded to be mainly associated with the kinetics of the electrode reaction and the transport of electrons,ions,and gas-phase products involved in electrolysis.Based on the study results,the performance and stability of AEM electrolyzers were significantly improved.
文摘Proton exchange membrane fuel cells(PEMFCs)are regarded as one of the most promising clean energy technology because of their high energy density,silent emission-free operation,and wide applications[1].Recently,anion exchange membrane fuel cells(AEMFCs)has emerged as an alternative to PEMFCs.
基金supported by the Technology Innovation Program(No.20011712)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)supported by Advanced Facility Center for Quantum Technology in SKKUthe National R&D Program through the National Research Foundation of Koera(NRF)funded by Ministry of Science and ICT(No.2020M3F3A2A01082618)。
文摘The variation of the three-dimensional(3D)structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon support.The increasing degradation of the carbon structure continuously reduces the electrocatalytic performance of proton exchange membrane fuel cells(PEM-FCs).This phenomenon can be explained by performing 3D tomographic analysis at the nanoscale.However,conventional tomographic approaches which present limited experimental feasibility,cannot perform such evaluation and have not provided sufficient structural information with statistical significance thus far.Therefore,a reliable methodology is required for the 3D geometrical evaluation of the carbon structure.Here,we propose a segmented tomographic approach which employs pore network analysis that enables the visualization of the geometrical parameters corresponding to the porous carbon structure at a high resolution.This approach can be utilized to evaluate the 3D structural degradation of the porous carbon structure after cycling in terms of local surface area,pore size distribution,and their 3D networking.These geometrical parameters of the carbon body were demonstrated to be substantially reduced owing to the cycling-induced degradation.This information enables a deeper understanding of the degradation phenomenon of carbon supports and can contribute to the development of stable PEM-FC electrodes.
文摘PPMG-based composite electrolytes were fabricated via the solution method using the polyvinyl alcohol and polyvinylpyrrolidone blend reinforced with various contents of sulfonated inorganic filler.Sulfuric acid was employed as the sulfonating agent to functionalize the external surface of the inorganic filler,i.e.,graphene oxide.The proton conductivities of the newly prepared proton exchange membranes(PEMs)were increased by increasing the temperature and content of sulfonated graphene oxide(SGO),i.e.,ranging from 0.025 S/cm to 0.060 S/cm.The induction of the optimum level of SGO is determined to be an excellent route to enhance ionic conductivity.The single-cell performance test was conducted by sandwiching the newly prepared PEMs between an anode(0.2 mg/cm^(2) Pt/Ru)and a cathode(0.2 mg/cm^(2) Pt)to prepare membrane electrode assemblies,followed by hot pressing under a pressure of approximately 100 kg/cm^(2) at 60℃for 5–10 min.The highest power densities achieved with PPMG PEMs were 14.9 and 35.60 mW/cm^(2) at 25℃and 70℃,respectively,at ambient pressure with 100%relative humidity.Results showed that the newly prepared PEMs exhibit good electrochemical performance.The results indicated that the prepared composite membrane with 6 wt%filler can be used as an alternative membrane for applications of high-performance proton exchange membrane fuel cell.
