Lithium-sulfur(Li-S) batteries are promising energy-storage devices for future generations of portable electronics and electric vehicles because of the outstanding energy density,low cost,and nontoxic nature of S.In t...Lithium-sulfur(Li-S) batteries are promising energy-storage devices for future generations of portable electronics and electric vehicles because of the outstanding energy density,low cost,and nontoxic nature of S.In the past decades,various novel electrodes and electrolytes have been studied to improve the performance of Li-S batteries.However,the very limited lifespan and rate performance of Li-S batteries originating from the dissolution and diffusion of long-chain polysulfides in liquid electrolytes,and the intrinsic poor conductivity of S severely hinder their practical application.Herein,an electrospinning method was developed to fabricate a thin conductive interlayer consisting of meso-/microporous N/O dual-doping carbon nanofiber(CNF).The freestanding 3 D interwoven structure with conductive pathways for electrons and ions can enhance the contact between polysulfides and N/O atoms to realize the highly robust trapping of polysulfides via the extremely polar interaction.Consequently,combining the meso-microporous N/O dual-doping CNF interlayer with a monodispersed S nanoparticle cathode results in a superior electrochemical performance of 862.5 mAh/g after 200 cycles at 0.2 C and a cycle decay as low as 0.08% per cycle.An area specific capacity of 5.22 mAh/cm^(2) can be obtained after 100 cycles at 0.1 C with a high S loading of 7.5 mg/cm^(2).展开更多
In this study, poly(vinilydene fluoride-co-hexafluoropropylene)(PVDF-HFP) was used for preparation of hydrophobic membranes using non-solvent induced phase inversion(NIPS) technique. PVDF-HFP copolymer with concentrat...In this study, poly(vinilydene fluoride-co-hexafluoropropylene)(PVDF-HFP) was used for preparation of hydrophobic membranes using non-solvent induced phase inversion(NIPS) technique. PVDF-HFP copolymer with concentrations of 10 wt% and 12 wt% was prepared to investigate the effect of polymer concentration on pore structure,morphology, hydrophobicity and performance of prepared membranes. Besides, the use of two coagulation baths with the effects of parameters such as coagulant time, polymer type and concentration, and the amount of nonsolvent were studied. The performance of prepared membranes was evaluated based on the permeability and selectivity of oxygen and nitrogen from a gas mixture of nitrogen/oxygen under operating conditions of feed flow rate(1–5 L·min-1), inlet pressure to membrane module(0.1–0.5 MPa) and temperatures between 25 and 45 °C. The results showed that the use of two coagulation baths with different compositions of distillated water and isopropanol,coagulant time, polymer type and concentration, and the amount of non-solvent additive have the most effect on pore structure, morphology, thickness, roughness and crystallinity of fabricated membranes. Porosity ranges for the three fabricated membranes were determined, where the maximum porosity was 73.889% and the minimum value was 56.837%. Also, the maximum and minimum average thicknesses of membrane were 320.85 μm and115 μm. Besides, the values of 4.7504 × 10-7 mol· m-2· s-1· Pa-1, 0.525 and 902.126 nm were achieved for maximum oxygen permeance, O2/N2 selectivity and roughness, respectively.展开更多
The Arno River Basin(Central Italy)is affected by a considerable anthropogenic pressure due to the presence of large cities and widespread industrial and agricultural practices.In this work,26 water samples from the A...The Arno River Basin(Central Italy)is affected by a considerable anthropogenic pressure due to the presence of large cities and widespread industrial and agricultural practices.In this work,26 water samples from the Arno River and its main tributaries were analyzed to assess the water pollution status.The geochemical composition of the Arno River changes from the source(dominated by a Ca-HCO_(3) facies)to the mouth(where a Na-Cl(SO4)chemistry prevails)with an increasing quality deterioration,as suggested by the Chemical Water Quality Index,due to anthropogenic contributions and seawater intrusion before flowing into the Ligurian Sea.The Ombrone and Usciana tributaries introduce anthropogenic pollutants into the Arno River,whilst Elsa tributary supplies significant contents of geogenic sulfate.The concentrations of dissolved nitrate and nitrite(up to 63 and 9 mg/L,respectively)and the respective isotopic values of𝛿15N and𝛿18O were also determined to understand origin and fate of the N-species in the Arno River Basin surface waters.The combined application of𝛿15N-NO_(3) and𝛿18O-NO_(3) and N-source apportionment modelling allowed the identification of soil organic nitrogen and sewage and domestic wastes as primary sources for dissolved NO_(3)-.The𝛿15N-NO_(2) and𝛿18O-NO_(2) values suggest that the nitrification process affects the ARB waters,thus controlling the abundances and proportion of the N-species.Our work indicates that additional efforts are needed to improve management strategies to reduce the release of nitrogenated species to the surface waters of the Arno River Basin,since little progress has been made from the early 2000s.展开更多
The efficient utilization of photogenerated electrons and the effective activation of reactive molecules are among the major challenges in photocatalytic nitrogen reduction.Defect engineering can enhance the catalyst&...The efficient utilization of photogenerated electrons and the effective activation of reactive molecules are among the major challenges in photocatalytic nitrogen reduction.Defect engineering can enhance the catalyst's ability to adsorb and activate N_(2)and H_(2)O,while the ultrathin structure with maximized active crystal facets can maximize the enrichment of effective photogenerated electrons.This work employs a two-step synergistic method to fabricate ultrathin BiVO_(4)with oxygen vacancies and bismuth vacancies(2D-V_(Bi+O)-BVO,thickness<20 nm)for photocatalytic nitrogen reduction.Scanning electron microscopy,transmission electron microscopy(TEM),and atomic force microscopy characterization confirm the transformation of BiVO_(4)from bulk material(bulk-BVO,~1300 nm)to an ultrathin structure(~15 nm).TEM,X-ray photoelectron spectroscopy,electron paramagnetic resonance characterizations,and density functional theory(DFT)calculations verify the construction of oxygen and bismuth vacancies in the ultrathin BiVO_(4).Compared to bulk-BVO,the photocatalytic nitrogen fixation efficiency of 2D-V_(Bi+O)-BVO is increased by 4.7 times,with the highest activity reaching 158.73μmol·g^(-1)·h^(-1).N_(2)-temperature programmed desorption and DFT calculations demonstrate that the oxygen and bismuth vacancies in BiVO_(4),respectively,promote the adsorption/activation of N_(2)and H_(2)O,which is crucial for the overall nitrogen reduction reaction.Photo-deposition experiments prove that the(040)plane is the active surface for electrons.And the ultrathin structure maximizes the(040)facet of BiVO_(4),which is conducive to the high enrichment of electrons.Meanwhile,more active sites can be exposed for the activation of N_(2)and H_(2)O.In situ infrared spectroscopy confirms that N_(2)can be effectively adsorbed onto 2D-V_(Bi+O)-BVO,and the presence of NH_(2)-NH_(2)active species is consistent with the alternating reaction pathway.This study provides new insights into the development of green and efficient photocatalysts with dual vacancies and ultrathin structures.展开更多
The development of highly efficient non-precious metal-nitrogen-carbon(M-N-C)electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells.Due to the symmetric charge d...The development of highly efficient non-precious metal-nitrogen-carbon(M-N-C)electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells.Due to the symmetric charge distribution of the traditional M-N_(4)active site,the adsorption energy of the key oxygen intermediates in the process of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is difficult to reach the optimal value,which seriously limits the catalytic efficiency.The core of solving this problem lies in the accurate modulation of the coordination environment of the M-N_(4)site,which can realize the breakthrough improvement of the catalytic performance by synergistically optimizing the geometric configuration and electronic structure.In this paper,we systematically analyze the ORR/OER reaction mechanism and then comprehensively review the four main strategies to optimize the coordination environment of M-N-C:metal site regulation,coordination number engineering,non-metal atom doping,and carbon support regulation.Through an in-depth analysis of the structure-activity relationship between the coordination configuration and catalytic performance,the core challenges faced by current research are pointed out,and future research directions are envisioned.This work aims to provide theoretical references for the directional construction of highly efficient M-N-C catalysts with optimized coordination environments.展开更多
Designing highly active electrocatalysts for the hydrogen evolution reaction(HER)and oxygen evolution and reduction reactions(OER and ORR)is pivotal to renewable energy technology.Herein,based on density functional th...Designing highly active electrocatalysts for the hydrogen evolution reaction(HER)and oxygen evolution and reduction reactions(OER and ORR)is pivotal to renewable energy technology.Herein,based on density functional theory(DFT)calculations,we systematically investigate the catalytic activity of iron-nitrogen-carbon based covalent organic frameworks(COF)monolayers with axially coordinated ligands(denotes as Fe N_(4)-X@COF,X refers to axial ligand,X=-SCN,-I,-H,-SH,-NO_(2),-Br,-ClO,-Cl,-HCO_(3),-NO,-ClO_(2),-OH,-CN and-F).The calculated results demonstrate that all the catalysts possess good thermodynamic and electrochemical stabilities.The different ligands axially ligated to the Fe active center could induce changes in the charge of the Fe center,which further regulates the interaction strength between intermediates and catalysts that governs the catalytic activity.Importantly,FeN_(4)-SH@COF and Fe N_(4)-OH@COF are efficient bifunctional catalysts for HER and OER,FeN_(4)-OH@COF and FeN_(4)-I@COF are promising bifunctional catalysts for OER and ORR.These findings not only reveal promising bifunctional HER/OER and OER/ORR catalysts but also provide theoretical guidance for designing optimum ironnitrogen-carbon based catalysts.展开更多
It is necessary to adopt a specific strategy to construct an efficient and low-cost transition metal-based composite to replace the precious metal-based electrocatalyst for OER catalytic processes.In this work,a beade...It is necessary to adopt a specific strategy to construct an efficient and low-cost transition metal-based composite to replace the precious metal-based electrocatalyst for OER catalytic processes.In this work,a beaded stream-like N and P-codoped carbon-coated Fe_(3)O_(4)nanocomposite(N,P-Fe_(3)O_(4)@C)is derived from MIL-88A by two-step annealing.The unique 3D nanostructure and amorphous N-doped carbon layer enlarge the number of active sites,and P doping changes the pathway from AEM to LOM.The synergistic effect of these factors results in N,P-Fe_(3)O_(4)@C presenting excellent OER catalytic activity with an overpotential of 201 mV(η10),a Tafel slope of 57.1 mV/dec and stable operation for 100 h(the current density is 10 mA/cm^(2)).Density functional theory calculations and electrochemical tests reveal that the P doping enhances the overlap of Fe 3d orbital bands and O 2p orbitals,and thus significantly increases the metaloxygen covalency,triggering the pathway transition from AEM to LOM.This work provides a new way to construct more efficient transition metal-based composite carbon materials.展开更多
Solar-induced water oxidation reaction(WOR)for oxygen evolution is a critical step in the transformation of Earth's atmosphere from a reducing to an oxidation one during its primordial stages.WOR is also associate...Solar-induced water oxidation reaction(WOR)for oxygen evolution is a critical step in the transformation of Earth's atmosphere from a reducing to an oxidation one during its primordial stages.WOR is also associated with important reduction reactions,such as oxygen reduction reaction(ORR),which leads to the production of hydrogen peroxide(H_(2)O_(2)).These transitions are instrumental in the emergence and evolution of life.In this study,transition metals were loaded onto nitrogen-doped carbon(NDC)prepared under the primitive Earth's atmospheric conditions.These metal-loaded NDC samples were found to catalyze both WOR and ORR under light illumination.The chemical pathways initiated by the pristine and metal-loaded NDC were investigated.This study provides valuable insights into potential mechanisms relevant to the early evolution of our planet.展开更多
As a catalyst of the air cathode in zinc-air batteries,tungstic acid ferrous(FeWO_(4)),a nanoscale transition metal tungstate,shows a broad application prospect in the oxygen reduction reaction(ORR).While FeWO_(4)poss...As a catalyst of the air cathode in zinc-air batteries,tungstic acid ferrous(FeWO_(4)),a nanoscale transition metal tungstate,shows a broad application prospect in the oxygen reduction reaction(ORR).While FeWO_(4)possesses favorable electrochemical properties and thermodynamic stability,its intrinsic semiconductor characteristics result in a relatively slow electron transfer rate,limiting the ORR catalytic activity.In this work,the electronic structure of FeWO_(4)is significantly modulated by introducing phosphorus(P)atoms with abundant valence electrons.The P doping can adjust the electronic structure of FeWO_(4)and then optimize oxygen-containing intermediates'absorption/desorption efficiency to achieve improved ORR activity.Furthermore,the sodium chloride template is utilized to construct a porous carbon framework for anchoring phosphorus-doped iron tungstate(P-FeWO_(4)/PNC).The porous carbon skeleton provides numerous active sites for the absorption/desorption and redox reactions on the P-FeWO_(4)/PNC surface and serves as mass transport channels for reactants and intermediates.The P-FeWO_(4)/PNC demonstrates ORR performance(E1/2=0.86 V vs.RHE).Furthermore,the zinc-air batteries incorporating the P-FeWO_(4)/PNC composite demonstrate an increased peak power density(172.2 mW·cm^(-2)),high specific capacity(810.1 mAh·g^(-1)),and sustained long-term cycling stability lasting up to 240 h.This research not only contributes to the advancement of cost-effective tungsten-based non-precious metallic ORR catalysts,but also guides their utilization in zinc-air batteries.展开更多
Transition metal-nitrogen-carbon(M-N-C)with 3d transition metals as noble metal-free catalyzing oxygen reduction reaction(ORR)electrocatalysts still face critical challenges in activity and durability due to the Fento...Transition metal-nitrogen-carbon(M-N-C)with 3d transition metals as noble metal-free catalyzing oxygen reduction reaction(ORR)electrocatalysts still face critical challenges in activity and durability due to the Fenton effect associated with these metals in practical application.To tackle the issue,herein,we report Fenton-inactive rare earth metal La-N-C with dual active sites for efficient ORR,which was synthesized by pyrolyzing a mixed complexing compound of 1,10-phenanthroline as ligand with LaCl_(3)and MgCl_(2)as an activation agent.The as-synthesized La-N-C features an abundant microporous structure with atomically dispersed LaN_(4)O moieties as new active sites,exhibiting outstanding ORR performance.Its half-wave potentials are 0.92 and 0.76 V in 0.1 M KOH and 0.5 M H_(2)SO_(4)respectively,and only a 10 mV half-wave potential loss after 50 K cycles in 0.1 M KOH,achieving the highest level of current non-3d M-N-C ORR electrocatalysts.Meanwhile,the ORR activity is further validated by efficient performance with a power density output of 211 and 480 mW cm^(-2)on a single Zn-air battery and proton exchange membrane fuel cell respectively.Furthermore,theoretical calculations confirm that the unique LaN_(4)O moiety adjacent to the microspore vacancy with graphitic N dopant not only presents a negative shift of the La 5d orbitals,significantly lowering the adsorption energy of*OOH in ORR,but also induces the carbon atom near the graphitic N as one more active site for ORR.This work highlights the potential application of La-N-C as an efficient ORR catalyst in green energy conversion devices.展开更多
A composite electrocatalyst,CoMoNiO-S/NF-110(NF is nickel foam),was synthesized through electrodeposition,followed by pyrolysis and then the vulcanization process.CoMoNiO-S/NF-110 exhibited a structure where Ni3S2 and...A composite electrocatalyst,CoMoNiO-S/NF-110(NF is nickel foam),was synthesized through electrodeposition,followed by pyrolysis and then the vulcanization process.CoMoNiO-S/NF-110 exhibited a structure where Ni3S2 and Mo2S3 nanoparticles were integrated at the edges of Co3O4 nanosheets,creating a rich,heterogeneous interface that enhances the synergistic effects of each component.In an alkaline electrolyte,the synthesized CoMoNiO-S/NF-110 exhibited superior electrocatalytic performance for oxygen evolution reaction(OER),achieving current densities of 100 and 200 mA·cm^(-2) with low overpotentials of 199.4 and 224.4 mV,respectively,outperforming RuO2 and several high-performance Mo and Ni-based catalysts.This excellent performance is attributed to the rich interface formed between the components and active sites exposed by the defect structure.展开更多
Appropriate non-metallic element doping is promising to improve the intrinsic electrocatalytic oxygen reduction reaction(ORR)performance of nitrogen-doped carbon candidates,yet challenges still remain to rationally de...Appropriate non-metallic element doping is promising to improve the intrinsic electrocatalytic oxygen reduction reaction(ORR)performance of nitrogen-doped carbon candidates,yet challenges still remain to rationally design of the catalyst configuration with kinetically favorable state.Herein,we propose the metalloid element to regulate the local electronic environment,and a novel metal-free electrocatalyst,namely,atomically dispersed Te-N_(2) on nitrogen-doped carbon frameworks was developed.Characterization and theoretical analyses demonstrate that the heteroatoms tellurium integrated with nitrogen-doped carbon substrate forms a Te-N covalent coordination as the active center that empowers both improved ORR kinetics and structural stability.As expected,the optimized composite of Te-N-C 900 delivers considerable electrocatalytic ORR activity in alkaline media(E_(1/2)=0.871 V,0.1 M KOH),along with encouraging durability(over 10,000 cycles with 13 mV decay),which is also responsible for Zn-air batteries operating with high uplifting peak power density and long lifespan.As a proof-of-concept,this work elucidates the key influence of heteroatom interaction of metalloid element,achieves the synthesis of Te-N_(2) metal-free ORR catalysts,and provides guidance for the development of high-performance metal-free ORR catalysts.展开更多
Herein,vacancy engineering is utilized reasonably to explore molybdenum tungsten oxide nanowires(W_(4)MoO_(3)NWs)rich in O-vacancies as an advanced electrochemical nitrogen reduction reaction(eNRR)electrocatalyst,real...Herein,vacancy engineering is utilized reasonably to explore molybdenum tungsten oxide nanowires(W_(4)MoO_(3)NWs)rich in O-vacancies as an advanced electrochemical nitrogen reduction reaction(eNRR)electrocatalyst,realizing further enhancement of NRR performance.In 0.1 mol/L Na_(2)SO_(4),W_(4)MoO_(3)NWs rich in O vacancies(CTAB-D-W_(4)MoO_(3))achieve a large NH3yield of 60.77μg h^(-1)mg^(-1)cat.at-0.70 V vs.RHE and a high faradaic efficiency of 56.42%at-0.60 V,much superior to the W_(4)MoO_(3)NWs deficient in oxygen vacancies(20.26μg h^(-1)mg^(-1)cat.and 17.1%at-0.70 V vs.RHE).Meanwhile,W_(4)MoO_(3)NWs rich in O-vacancies also show high electrochemical stability.Density functional theory(DFT)calculations present that O vacancies in CTAB-D-W_(4)MoO_(3)reduce the energy barrier formed by the intermediate of^(*)N-NH,facilitate the activation and further hydrogenation of^(*)N-N,promote the NRR process,and improve NRR activity.展开更多
Rational design of defected carbons adjacent to nitrogen(N)dopants is a fascinating but challenging approach for enhancing the catalytic performance of N-doped carbon.Meanwhile,the combined effect of heteroatom doping...Rational design of defected carbons adjacent to nitrogen(N)dopants is a fascinating but challenging approach for enhancing the catalytic performance of N-doped carbon.Meanwhile,the combined effect of heteroatom doping and defect engineering can efficiently increase the oxygen reduction reaction(ORR)ability of inactive carbons through charge redistribution.Herein,we report that an enhanced built-in electric field caused by the combined effect of N-doping and carbon defects in the twodimensional(2D)mesoporous N-doped carbon nano flakes(NCNF)is a promising technique for improving ORR performance.As a result,the NCNF exhibits more promising ORR activity than Pt/C and similar performance with reported robust catalysts.Comprehensive experimental and theoretical investigations suggest that topologically defected carbon adjacent to the graphitic valley nitrogen is a real active site,rendering optimal energy for the adsorption of ORR intermediates and lowering the total energy barrier for ORR.Also,NCNF-based Zn-air batteries exhibited an excellent power density and specific capacity of~121.10 mW cm^(-2)and~679.86 mA h g_(Zn)^(-1),respectively.This study not only offers new insights into defected carbons with graphitic valley N for ORR but also proposes novel catalyst design principles and provides a solid grasp of the built-in electric field effect on the ORR performance of defective catalysts.展开更多
The poor electrical conductivity of metal-organic frameworks(MOFs)limits their electrocatalytic performance in the oxygen evolution reaction(OER).In this study,a Py@Co-MOF composite material based on pyrene(Py)molecul...The poor electrical conductivity of metal-organic frameworks(MOFs)limits their electrocatalytic performance in the oxygen evolution reaction(OER).In this study,a Py@Co-MOF composite material based on pyrene(Py)molecules and{[Co2(BINDI)(DMA)_(2)]·DMA}_(n)(Co-MOF,H4BINDI=N,N'-bis(5-isophthalic acid)naphthalenediimide,DMA=N,N-dimethylacetamide)was synthesized via a one-pot method,leveragingπ-πinteractions between pyrene and Co-MOF to modulate electrical conductivity.Results demonstrate that the Py@Co-MOF catalyst exhibited significantly enhanced OER performance compared to pure Co-MOF or pyrene-based electrodes,achieving an overpotential of 246 mV at a current density of 10 mA·cm^(-2) along with excellent stability.Density functional theory(DFT)calculations reveal that the formation of O*in the second step is the rate-determining step(RDS)during the OER process on Co-MOF,with an energy barrier of 0.85 eV due to the weak adsorption affinity of the OH*intermediate for Co sites.CCDC:2419276.展开更多
Developing efficient and durable electrocatalysts for acidic oxygen evolution reaction(OER)is pivotal for advancing proton exchange membrane water electrolysis(PEMWEs),yet balancing activity and stability remains a fo...Developing efficient and durable electrocatalysts for acidic oxygen evolution reaction(OER)is pivotal for advancing proton exchange membrane water electrolysis(PEMWEs),yet balancing activity and stability remains a formidable challenge.Herein,we propose a dual-engineering strategy to stabilize Ru-based catalysts by synergizing the oxygen vacancy site-synergized mechanism-lattice oxygen mechanism(OVSM-LOM)with Ru-N bond stabilization.The engineered RuO_(2)@NCC catalyst exhibits exceptional OER performance in 0.5 M H2SO4,achieving an ultralow overpotential of 215 mV at 10 mA cm^(-2) and prolonged stability for over 327 h.The catalyst delivers 300 h of continuous operation at 1 A cm^(-2),with a negligible degradation rate of only 0.067 mV h-1,further demonstrating its potential for practical application.Oxygen vacancies unlock the OVSM-LOM pathway,bypassing the sluggish adsorbate evolution mechanism(AEM)and accelerating reaction kinetics,while the Ru-N bonds suppress Ru dissolution by anchoring low-valent Ru centers.Quasi-in situ X-ray photoelectron spectroscopy(XPS),X-ray absorption spectroscopy(XAS),and isotopic labeling experiments confirm the lattice oxygen participation with *O formation as the rate-determining step.The Ru-N bonds reinforce the structural integrity by stabilizing low-valent Ru centers and inhibiting overoxidation.Theoretical calculations further verify that the synergistic interaction between OVs and Ru-O(N)active sites optimizes the Ru d-band center and stabilizes intermediates,while Ru-N coordination enhances structural integrity.This study establishes a novel paradigm for designing robust acidic OER catalysts through defect and coordination engineering,bridging the gap between activity and stability for sustainable energy technologies.展开更多
Lithium-oxygen(Li-O2)batteries are perceived as a promising breakthrough in sustainable electrochemical energy storage,utilizing ambient air as an energy source,eliminating the need for costly cathode materials,and of...Lithium-oxygen(Li-O2)batteries are perceived as a promising breakthrough in sustainable electrochemical energy storage,utilizing ambient air as an energy source,eliminating the need for costly cathode materials,and offering the highest theoretical energy density(~3.5 k Wh kg^(-1))among discussed candidates.Contributing to the poor cycle life of currently reported Li-O_(2)cells is singlet oxygen(1O_(2))formation,inducing parasitic reactions,degrading key components,and severely deteriorating cell performance.Here,we harness the chirality-induced spin selectivity effect of chiral cobalt oxide nanosheets(Co_(3)O_(4)NSs)as cathode materials to suppress 1O_(2)in Li-O_(2)batteries for the first time.Operando photoluminescence spectroscopy reveals a 3.7-fold and 3.23-fold reduction in 1O_(2)during discharge and charge,respectively,compared to conventional carbon paperbased cells,consistent with differential electrochemical mass spectrometry results,which indicate a near-theoretical charge-to-O_(2)ratio(2.04 e-/O_(2)).Density functional theory calculations demonstrate that chirality induces a peak shift near the Fermi level,enhancing Co 3d-O 2p hybridization,stabilizing reaction intermediates,and lowering activation barriers for Li_(2)O_(2)formation and decomposition.These findings establish a new strategy for improving the stability and energy efficiency of sustainable Li-O_(2)batteries,abridging the current gap to commercialization.展开更多
Proton-exchange membrane fuel cell and water electrolyzer(PEMFC and PEMWE)with high conversion efficiency and zero-carbon emission stand out as an attractive strategy for efficient conversion between hydrogen energy a...Proton-exchange membrane fuel cell and water electrolyzer(PEMFC and PEMWE)with high conversion efficiency and zero-carbon emission stand out as an attractive strategy for efficient conversion between hydrogen energy and renewable electricity.As a key component,efficient oxygen electrocatalyst for promoting sluggish reaction kinetics of oxygen reduction and evolution reaction(ORR and OER)under harsh operation conditions severely limited progress of these devices.Among various candidates,Ptgroup(Pt,Ir,and Ru)-based electrocatalysts are still the most active ORR/OER catalysts.However,the scarcity,high cost,and questionable stability restrict the widespread applications and the commercialization of PEMWE/PEMFC.Progresses in synthesizing atomically dispersed single/multiple-atom catalysts(SACs/MACs)offer new opportunities to Pt-group ORR/OER catalysts owing to nearly 100% metal utilization and high catalytic activities.Extensive efforts have been continuously devoted to optimizing the local structure of Pt-group OER/ORR catalysts at atom-level for further enhancing stability and activity.In this review,universal synthesis methods to prepare Ptgroup SACs are discussed first,highlighting crucial factors which affect the structure and catalytic performance.Afterward,advanced characterization techniques for directly confirming atomic dispersed metal atoms were introduced,including aberration-corrected high-angle-annular-dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy.Importantly,considerations for rational catalyst design and typical Pt-group SACs/MACs are summarized regarding the regulation strategy of atomically dispersed metal sites and various supports,and effects of metal-support interaction on the catalytic performance.Finally,key challenges and proposed perspectives for future development of atomically dispersed Pt-group oxygen electrocatalysts for fuel cell and electrolyzer are briefly discussed.展开更多
Climate warming and atmospheric nitrogen(N)deposition have profound influences on the terrestrial biosphere.However,how these two global change drivers affect phytoplankton which are important primary producers in wet...Climate warming and atmospheric nitrogen(N)deposition have profound influences on the terrestrial biosphere.However,how these two global change drivers affect phytoplankton which are important primary producers in wetlands with large carbon stocks and complex hydrological fluctuations remain largely unclear.As part of a two-year field experiment in a freshwater wetland,this study was conducted to investigate the effects of nighttime warming and N addition on phytoplankton biomass in the North China Plain.The results showed that neither nighttime warming nor N addition influenced the Shannon-Wiener index of phytoplankton community.Nighttime warming did not change phytoplankton biomass,likely due to the different warming impacts on dominant phyla and in different seasons.Decreased phytoplankton biomass in spring because of the increased water pH and submerged plant coverage was compensated by the enhanced biomass in autumn due to the reduced dissolved oxygen and submerged plant coverage,leading to the neutral change of phytoplankton biomass under warming.Nitrogen addition elevated phytoplankton biomass by 11.6%,which could be attributed to the enhanced nutrient availability and reduced submerged plant coverage.Positive relationships of methane(CH4)emission rates at the water-air interface with phytoplankton biomass indicated the potentially crucial role of phytoplankton in mediating wetland CH4 cycling through photosynthesis-driven metabolisms.The findings suggested the seasonal variation of phytoplankton and their potential responses to nighttime warming and N deposition,which may provide a more accurate basis for assessing the global change-carbon feedback in wetland ecosystems.展开更多
The development of Pt-free catalysts for the oxygen reduction reaction(ORR)is a great issue for meeting the cost challenges of proton exchange membrane fuel cells(PEMFCs)in commercial applications.In this work,a serie...The development of Pt-free catalysts for the oxygen reduction reaction(ORR)is a great issue for meeting the cost challenges of proton exchange membrane fuel cells(PEMFCs)in commercial applications.In this work,a series of RuCo/C catalysts were synthesized by NaBH4 reduction method under the premise that the total metal mass percentage was 20%.X-ray diffraction(XRD)patterns and scanning electron microscopy(SEM)confirmed the formation of single-phase nanoparticles with an average size of 33 nm.Cyclic voltammograms(CV)and linear sweep voltammograms(LSV)tests indicated that RuCo(2:1)/C catalyst had the optimal ORR properties.Additionally,the RuCo(2:1)/C catalyst remarkably sustained 98.1% of its activity even after 3000 cycles,surpassing the performance of Pt/C(84.8%).Analysis of the elemental state of the catalyst surface after cycling using X-ray photoelectron spectroscopy(XPS)revealed that the Ru^(0) percentage of RuCo(2:1)/C decreased by 2.2%(from 66.3% to 64.1%),while the Pt^(0) percentage of Pt/C decreased by 7.1%(from 53.3% to 46.2%).It is suggested that the synergy between Ru and Co holds the potential to pave the way for future low-cost and highly stable ORR catalysts,offering significant promise in the context of PEMFCs.展开更多
基金the support from the National Key Research and Development Program(No.2018YFB1107500)the Liao Ning Revitalization Talents Program(No.XLYC1907144)+1 种基金the National Natural Science Foundation of China(No.51503024)the Dalian Youth Science and Technology Star Project Support Program(No.2017RQ104)。
文摘Lithium-sulfur(Li-S) batteries are promising energy-storage devices for future generations of portable electronics and electric vehicles because of the outstanding energy density,low cost,and nontoxic nature of S.In the past decades,various novel electrodes and electrolytes have been studied to improve the performance of Li-S batteries.However,the very limited lifespan and rate performance of Li-S batteries originating from the dissolution and diffusion of long-chain polysulfides in liquid electrolytes,and the intrinsic poor conductivity of S severely hinder their practical application.Herein,an electrospinning method was developed to fabricate a thin conductive interlayer consisting of meso-/microporous N/O dual-doping carbon nanofiber(CNF).The freestanding 3 D interwoven structure with conductive pathways for electrons and ions can enhance the contact between polysulfides and N/O atoms to realize the highly robust trapping of polysulfides via the extremely polar interaction.Consequently,combining the meso-microporous N/O dual-doping CNF interlayer with a monodispersed S nanoparticle cathode results in a superior electrochemical performance of 862.5 mAh/g after 200 cycles at 0.2 C and a cycle decay as low as 0.08% per cycle.An area specific capacity of 5.22 mAh/cm^(2) can be obtained after 100 cycles at 0.1 C with a high S loading of 7.5 mg/cm^(2).
文摘In this study, poly(vinilydene fluoride-co-hexafluoropropylene)(PVDF-HFP) was used for preparation of hydrophobic membranes using non-solvent induced phase inversion(NIPS) technique. PVDF-HFP copolymer with concentrations of 10 wt% and 12 wt% was prepared to investigate the effect of polymer concentration on pore structure,morphology, hydrophobicity and performance of prepared membranes. Besides, the use of two coagulation baths with the effects of parameters such as coagulant time, polymer type and concentration, and the amount of nonsolvent were studied. The performance of prepared membranes was evaluated based on the permeability and selectivity of oxygen and nitrogen from a gas mixture of nitrogen/oxygen under operating conditions of feed flow rate(1–5 L·min-1), inlet pressure to membrane module(0.1–0.5 MPa) and temperatures between 25 and 45 °C. The results showed that the use of two coagulation baths with different compositions of distillated water and isopropanol,coagulant time, polymer type and concentration, and the amount of non-solvent additive have the most effect on pore structure, morphology, thickness, roughness and crystallinity of fabricated membranes. Porosity ranges for the three fabricated membranes were determined, where the maximum porosity was 73.889% and the minimum value was 56.837%. Also, the maximum and minimum average thicknesses of membrane were 320.85 μm and115 μm. Besides, the values of 4.7504 × 10-7 mol· m-2· s-1· Pa-1, 0.525 and 902.126 nm were achieved for maximum oxygen permeance, O2/N2 selectivity and roughness, respectively.
文摘The Arno River Basin(Central Italy)is affected by a considerable anthropogenic pressure due to the presence of large cities and widespread industrial and agricultural practices.In this work,26 water samples from the Arno River and its main tributaries were analyzed to assess the water pollution status.The geochemical composition of the Arno River changes from the source(dominated by a Ca-HCO_(3) facies)to the mouth(where a Na-Cl(SO4)chemistry prevails)with an increasing quality deterioration,as suggested by the Chemical Water Quality Index,due to anthropogenic contributions and seawater intrusion before flowing into the Ligurian Sea.The Ombrone and Usciana tributaries introduce anthropogenic pollutants into the Arno River,whilst Elsa tributary supplies significant contents of geogenic sulfate.The concentrations of dissolved nitrate and nitrite(up to 63 and 9 mg/L,respectively)and the respective isotopic values of𝛿15N and𝛿18O were also determined to understand origin and fate of the N-species in the Arno River Basin surface waters.The combined application of𝛿15N-NO_(3) and𝛿18O-NO_(3) and N-source apportionment modelling allowed the identification of soil organic nitrogen and sewage and domestic wastes as primary sources for dissolved NO_(3)-.The𝛿15N-NO_(2) and𝛿18O-NO_(2) values suggest that the nitrification process affects the ARB waters,thus controlling the abundances and proportion of the N-species.Our work indicates that additional efforts are needed to improve management strategies to reduce the release of nitrogenated species to the surface waters of the Arno River Basin,since little progress has been made from the early 2000s.
文摘The efficient utilization of photogenerated electrons and the effective activation of reactive molecules are among the major challenges in photocatalytic nitrogen reduction.Defect engineering can enhance the catalyst's ability to adsorb and activate N_(2)and H_(2)O,while the ultrathin structure with maximized active crystal facets can maximize the enrichment of effective photogenerated electrons.This work employs a two-step synergistic method to fabricate ultrathin BiVO_(4)with oxygen vacancies and bismuth vacancies(2D-V_(Bi+O)-BVO,thickness<20 nm)for photocatalytic nitrogen reduction.Scanning electron microscopy,transmission electron microscopy(TEM),and atomic force microscopy characterization confirm the transformation of BiVO_(4)from bulk material(bulk-BVO,~1300 nm)to an ultrathin structure(~15 nm).TEM,X-ray photoelectron spectroscopy,electron paramagnetic resonance characterizations,and density functional theory(DFT)calculations verify the construction of oxygen and bismuth vacancies in the ultrathin BiVO_(4).Compared to bulk-BVO,the photocatalytic nitrogen fixation efficiency of 2D-V_(Bi+O)-BVO is increased by 4.7 times,with the highest activity reaching 158.73μmol·g^(-1)·h^(-1).N_(2)-temperature programmed desorption and DFT calculations demonstrate that the oxygen and bismuth vacancies in BiVO_(4),respectively,promote the adsorption/activation of N_(2)and H_(2)O,which is crucial for the overall nitrogen reduction reaction.Photo-deposition experiments prove that the(040)plane is the active surface for electrons.And the ultrathin structure maximizes the(040)facet of BiVO_(4),which is conducive to the high enrichment of electrons.Meanwhile,more active sites can be exposed for the activation of N_(2)and H_(2)O.In situ infrared spectroscopy confirms that N_(2)can be effectively adsorbed onto 2D-V_(Bi+O)-BVO,and the presence of NH_(2)-NH_(2)active species is consistent with the alternating reaction pathway.This study provides new insights into the development of green and efficient photocatalysts with dual vacancies and ultrathin structures.
基金supported by the Natural Science Foundation of Hebei Province(no.E2024501010)the National Natural Science Foundation of China(no.52374301)+1 种基金the Shijiazhuang Basic Research Project(no.241790667A)the Performance Subsidy Fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(no.22567627H)。
文摘The development of highly efficient non-precious metal-nitrogen-carbon(M-N-C)electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells.Due to the symmetric charge distribution of the traditional M-N_(4)active site,the adsorption energy of the key oxygen intermediates in the process of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is difficult to reach the optimal value,which seriously limits the catalytic efficiency.The core of solving this problem lies in the accurate modulation of the coordination environment of the M-N_(4)site,which can realize the breakthrough improvement of the catalytic performance by synergistically optimizing the geometric configuration and electronic structure.In this paper,we systematically analyze the ORR/OER reaction mechanism and then comprehensively review the four main strategies to optimize the coordination environment of M-N-C:metal site regulation,coordination number engineering,non-metal atom doping,and carbon support regulation.Through an in-depth analysis of the structure-activity relationship between the coordination configuration and catalytic performance,the core challenges faced by current research are pointed out,and future research directions are envisioned.This work aims to provide theoretical references for the directional construction of highly efficient M-N-C catalysts with optimized coordination environments.
基金supported by the National Natural Science Foundation of China(Nos.22102167 and U21A20317)。
文摘Designing highly active electrocatalysts for the hydrogen evolution reaction(HER)and oxygen evolution and reduction reactions(OER and ORR)is pivotal to renewable energy technology.Herein,based on density functional theory(DFT)calculations,we systematically investigate the catalytic activity of iron-nitrogen-carbon based covalent organic frameworks(COF)monolayers with axially coordinated ligands(denotes as Fe N_(4)-X@COF,X refers to axial ligand,X=-SCN,-I,-H,-SH,-NO_(2),-Br,-ClO,-Cl,-HCO_(3),-NO,-ClO_(2),-OH,-CN and-F).The calculated results demonstrate that all the catalysts possess good thermodynamic and electrochemical stabilities.The different ligands axially ligated to the Fe active center could induce changes in the charge of the Fe center,which further regulates the interaction strength between intermediates and catalysts that governs the catalytic activity.Importantly,FeN_(4)-SH@COF and Fe N_(4)-OH@COF are efficient bifunctional catalysts for HER and OER,FeN_(4)-OH@COF and FeN_(4)-I@COF are promising bifunctional catalysts for OER and ORR.These findings not only reveal promising bifunctional HER/OER and OER/ORR catalysts but also provide theoretical guidance for designing optimum ironnitrogen-carbon based catalysts.
基金the National Nature Science Foundation of China(No.22304021)National Key Research and Development Project(No.2022YFA1505300)Sichuan Department of Science and Technology Program of China(No.2022YFG0312)for financial support。
文摘It is necessary to adopt a specific strategy to construct an efficient and low-cost transition metal-based composite to replace the precious metal-based electrocatalyst for OER catalytic processes.In this work,a beaded stream-like N and P-codoped carbon-coated Fe_(3)O_(4)nanocomposite(N,P-Fe_(3)O_(4)@C)is derived from MIL-88A by two-step annealing.The unique 3D nanostructure and amorphous N-doped carbon layer enlarge the number of active sites,and P doping changes the pathway from AEM to LOM.The synergistic effect of these factors results in N,P-Fe_(3)O_(4)@C presenting excellent OER catalytic activity with an overpotential of 201 mV(η10),a Tafel slope of 57.1 mV/dec and stable operation for 100 h(the current density is 10 mA/cm^(2)).Density functional theory calculations and electrochemical tests reveal that the P doping enhances the overlap of Fe 3d orbital bands and O 2p orbitals,and thus significantly increases the metaloxygen covalency,triggering the pathway transition from AEM to LOM.This work provides a new way to construct more efficient transition metal-based composite carbon materials.
基金supported by the National Key Technologies R&D Program of China(Nos.2022YFE0114800 and 2021YFA1502100)National Natural Science Foundation of China(Nos.22075047,22032002,U1905214,21961142019)the 111 Project(Nos.D16008)。
文摘Solar-induced water oxidation reaction(WOR)for oxygen evolution is a critical step in the transformation of Earth's atmosphere from a reducing to an oxidation one during its primordial stages.WOR is also associated with important reduction reactions,such as oxygen reduction reaction(ORR),which leads to the production of hydrogen peroxide(H_(2)O_(2)).These transitions are instrumental in the emergence and evolution of life.In this study,transition metals were loaded onto nitrogen-doped carbon(NDC)prepared under the primitive Earth's atmospheric conditions.These metal-loaded NDC samples were found to catalyze both WOR and ORR under light illumination.The chemical pathways initiated by the pristine and metal-loaded NDC were investigated.This study provides valuable insights into potential mechanisms relevant to the early evolution of our planet.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.22178148 and 22278193)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘As a catalyst of the air cathode in zinc-air batteries,tungstic acid ferrous(FeWO_(4)),a nanoscale transition metal tungstate,shows a broad application prospect in the oxygen reduction reaction(ORR).While FeWO_(4)possesses favorable electrochemical properties and thermodynamic stability,its intrinsic semiconductor characteristics result in a relatively slow electron transfer rate,limiting the ORR catalytic activity.In this work,the electronic structure of FeWO_(4)is significantly modulated by introducing phosphorus(P)atoms with abundant valence electrons.The P doping can adjust the electronic structure of FeWO_(4)and then optimize oxygen-containing intermediates'absorption/desorption efficiency to achieve improved ORR activity.Furthermore,the sodium chloride template is utilized to construct a porous carbon framework for anchoring phosphorus-doped iron tungstate(P-FeWO_(4)/PNC).The porous carbon skeleton provides numerous active sites for the absorption/desorption and redox reactions on the P-FeWO_(4)/PNC surface and serves as mass transport channels for reactants and intermediates.The P-FeWO_(4)/PNC demonstrates ORR performance(E1/2=0.86 V vs.RHE).Furthermore,the zinc-air batteries incorporating the P-FeWO_(4)/PNC composite demonstrate an increased peak power density(172.2 mW·cm^(-2)),high specific capacity(810.1 mAh·g^(-1)),and sustained long-term cycling stability lasting up to 240 h.This research not only contributes to the advancement of cost-effective tungsten-based non-precious metallic ORR catalysts,but also guides their utilization in zinc-air batteries.
基金financially supported by the National Natural Science Foundation of China(22075055)the Guangxi Science and Technology Project(AB16380030)。
文摘Transition metal-nitrogen-carbon(M-N-C)with 3d transition metals as noble metal-free catalyzing oxygen reduction reaction(ORR)electrocatalysts still face critical challenges in activity and durability due to the Fenton effect associated with these metals in practical application.To tackle the issue,herein,we report Fenton-inactive rare earth metal La-N-C with dual active sites for efficient ORR,which was synthesized by pyrolyzing a mixed complexing compound of 1,10-phenanthroline as ligand with LaCl_(3)and MgCl_(2)as an activation agent.The as-synthesized La-N-C features an abundant microporous structure with atomically dispersed LaN_(4)O moieties as new active sites,exhibiting outstanding ORR performance.Its half-wave potentials are 0.92 and 0.76 V in 0.1 M KOH and 0.5 M H_(2)SO_(4)respectively,and only a 10 mV half-wave potential loss after 50 K cycles in 0.1 M KOH,achieving the highest level of current non-3d M-N-C ORR electrocatalysts.Meanwhile,the ORR activity is further validated by efficient performance with a power density output of 211 and 480 mW cm^(-2)on a single Zn-air battery and proton exchange membrane fuel cell respectively.Furthermore,theoretical calculations confirm that the unique LaN_(4)O moiety adjacent to the microspore vacancy with graphitic N dopant not only presents a negative shift of the La 5d orbitals,significantly lowering the adsorption energy of*OOH in ORR,but also induces the carbon atom near the graphitic N as one more active site for ORR.This work highlights the potential application of La-N-C as an efficient ORR catalyst in green energy conversion devices.
文摘A composite electrocatalyst,CoMoNiO-S/NF-110(NF is nickel foam),was synthesized through electrodeposition,followed by pyrolysis and then the vulcanization process.CoMoNiO-S/NF-110 exhibited a structure where Ni3S2 and Mo2S3 nanoparticles were integrated at the edges of Co3O4 nanosheets,creating a rich,heterogeneous interface that enhances the synergistic effects of each component.In an alkaline electrolyte,the synthesized CoMoNiO-S/NF-110 exhibited superior electrocatalytic performance for oxygen evolution reaction(OER),achieving current densities of 100 and 200 mA·cm^(-2) with low overpotentials of 199.4 and 224.4 mV,respectively,outperforming RuO2 and several high-performance Mo and Ni-based catalysts.This excellent performance is attributed to the rich interface formed between the components and active sites exposed by the defect structure.
基金supported by the National Natural Science Foundation of China(No.22278097)the Postdoctoral fellowship of Heilongjiang Province(No.LBH-Z23156)+3 种基金the Postdoctoral Fellowship Program of CPSF(No.GZC20233449)the Shandong Provincial Natural Science Foundation(No.ZR2024QB383)the Natural Science Foundation of Jiangsu Province(No.BK20230635)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.23KJB150002).
文摘Appropriate non-metallic element doping is promising to improve the intrinsic electrocatalytic oxygen reduction reaction(ORR)performance of nitrogen-doped carbon candidates,yet challenges still remain to rationally design of the catalyst configuration with kinetically favorable state.Herein,we propose the metalloid element to regulate the local electronic environment,and a novel metal-free electrocatalyst,namely,atomically dispersed Te-N_(2) on nitrogen-doped carbon frameworks was developed.Characterization and theoretical analyses demonstrate that the heteroatoms tellurium integrated with nitrogen-doped carbon substrate forms a Te-N covalent coordination as the active center that empowers both improved ORR kinetics and structural stability.As expected,the optimized composite of Te-N-C 900 delivers considerable electrocatalytic ORR activity in alkaline media(E_(1/2)=0.871 V,0.1 M KOH),along with encouraging durability(over 10,000 cycles with 13 mV decay),which is also responsible for Zn-air batteries operating with high uplifting peak power density and long lifespan.As a proof-of-concept,this work elucidates the key influence of heteroatom interaction of metalloid element,achieves the synthesis of Te-N_(2) metal-free ORR catalysts,and provides guidance for the development of high-performance metal-free ORR catalysts.
基金supported by the National Natural Science Foundation of China(No.51872173)Natural Science Foundation of Shandong Province(No.ZR2022JQ21)。
文摘Herein,vacancy engineering is utilized reasonably to explore molybdenum tungsten oxide nanowires(W_(4)MoO_(3)NWs)rich in O-vacancies as an advanced electrochemical nitrogen reduction reaction(eNRR)electrocatalyst,realizing further enhancement of NRR performance.In 0.1 mol/L Na_(2)SO_(4),W_(4)MoO_(3)NWs rich in O vacancies(CTAB-D-W_(4)MoO_(3))achieve a large NH3yield of 60.77μg h^(-1)mg^(-1)cat.at-0.70 V vs.RHE and a high faradaic efficiency of 56.42%at-0.60 V,much superior to the W_(4)MoO_(3)NWs deficient in oxygen vacancies(20.26μg h^(-1)mg^(-1)cat.and 17.1%at-0.70 V vs.RHE).Meanwhile,W_(4)MoO_(3)NWs rich in O-vacancies also show high electrochemical stability.Density functional theory(DFT)calculations present that O vacancies in CTAB-D-W_(4)MoO_(3)reduce the energy barrier formed by the intermediate of^(*)N-NH,facilitate the activation and further hydrogenation of^(*)N-N,promote the NRR process,and improve NRR activity.
基金supported by the National Natural Science Foundation of China(22262010,22062005,22165005,U20A20128)Guangxi Science and Technology Fund for Distinguished HighTalent Introduction Program(AC22035091)Guangxi Science Fund for Distinguished Young Scholars(2019GXNSFFA245016)。
文摘Rational design of defected carbons adjacent to nitrogen(N)dopants is a fascinating but challenging approach for enhancing the catalytic performance of N-doped carbon.Meanwhile,the combined effect of heteroatom doping and defect engineering can efficiently increase the oxygen reduction reaction(ORR)ability of inactive carbons through charge redistribution.Herein,we report that an enhanced built-in electric field caused by the combined effect of N-doping and carbon defects in the twodimensional(2D)mesoporous N-doped carbon nano flakes(NCNF)is a promising technique for improving ORR performance.As a result,the NCNF exhibits more promising ORR activity than Pt/C and similar performance with reported robust catalysts.Comprehensive experimental and theoretical investigations suggest that topologically defected carbon adjacent to the graphitic valley nitrogen is a real active site,rendering optimal energy for the adsorption of ORR intermediates and lowering the total energy barrier for ORR.Also,NCNF-based Zn-air batteries exhibited an excellent power density and specific capacity of~121.10 mW cm^(-2)and~679.86 mA h g_(Zn)^(-1),respectively.This study not only offers new insights into defected carbons with graphitic valley N for ORR but also proposes novel catalyst design principles and provides a solid grasp of the built-in electric field effect on the ORR performance of defective catalysts.
文摘The poor electrical conductivity of metal-organic frameworks(MOFs)limits their electrocatalytic performance in the oxygen evolution reaction(OER).In this study,a Py@Co-MOF composite material based on pyrene(Py)molecules and{[Co2(BINDI)(DMA)_(2)]·DMA}_(n)(Co-MOF,H4BINDI=N,N'-bis(5-isophthalic acid)naphthalenediimide,DMA=N,N-dimethylacetamide)was synthesized via a one-pot method,leveragingπ-πinteractions between pyrene and Co-MOF to modulate electrical conductivity.Results demonstrate that the Py@Co-MOF catalyst exhibited significantly enhanced OER performance compared to pure Co-MOF or pyrene-based electrodes,achieving an overpotential of 246 mV at a current density of 10 mA·cm^(-2) along with excellent stability.Density functional theory(DFT)calculations reveal that the formation of O*in the second step is the rate-determining step(RDS)during the OER process on Co-MOF,with an energy barrier of 0.85 eV due to the weak adsorption affinity of the OH*intermediate for Co sites.CCDC:2419276.
基金support from the National Natural Science Foundation of China(Nos.12305373 and 52276220)the Guangzhou Basic Research Program(No.SL2024A04J00234).
文摘Developing efficient and durable electrocatalysts for acidic oxygen evolution reaction(OER)is pivotal for advancing proton exchange membrane water electrolysis(PEMWEs),yet balancing activity and stability remains a formidable challenge.Herein,we propose a dual-engineering strategy to stabilize Ru-based catalysts by synergizing the oxygen vacancy site-synergized mechanism-lattice oxygen mechanism(OVSM-LOM)with Ru-N bond stabilization.The engineered RuO_(2)@NCC catalyst exhibits exceptional OER performance in 0.5 M H2SO4,achieving an ultralow overpotential of 215 mV at 10 mA cm^(-2) and prolonged stability for over 327 h.The catalyst delivers 300 h of continuous operation at 1 A cm^(-2),with a negligible degradation rate of only 0.067 mV h-1,further demonstrating its potential for practical application.Oxygen vacancies unlock the OVSM-LOM pathway,bypassing the sluggish adsorbate evolution mechanism(AEM)and accelerating reaction kinetics,while the Ru-N bonds suppress Ru dissolution by anchoring low-valent Ru centers.Quasi-in situ X-ray photoelectron spectroscopy(XPS),X-ray absorption spectroscopy(XAS),and isotopic labeling experiments confirm the lattice oxygen participation with *O formation as the rate-determining step.The Ru-N bonds reinforce the structural integrity by stabilizing low-valent Ru centers and inhibiting overoxidation.Theoretical calculations further verify that the synergistic interaction between OVs and Ru-O(N)active sites optimizes the Ru d-band center and stabilizes intermediates,while Ru-N coordination enhances structural integrity.This study establishes a novel paradigm for designing robust acidic OER catalysts through defect and coordination engineering,bridging the gap between activity and stability for sustainable energy technologies.
基金supported by Basic Science Research Program(Priority Research Institute)through the NRF of Korea funded by the Ministry of Education(2021R1A6A1A10039823)by the Korea Basic Science Institute(National Research Facilities and Equipment Center)grant funded by the Ministry of Education(2020R1A6C101B194)。
文摘Lithium-oxygen(Li-O2)batteries are perceived as a promising breakthrough in sustainable electrochemical energy storage,utilizing ambient air as an energy source,eliminating the need for costly cathode materials,and offering the highest theoretical energy density(~3.5 k Wh kg^(-1))among discussed candidates.Contributing to the poor cycle life of currently reported Li-O_(2)cells is singlet oxygen(1O_(2))formation,inducing parasitic reactions,degrading key components,and severely deteriorating cell performance.Here,we harness the chirality-induced spin selectivity effect of chiral cobalt oxide nanosheets(Co_(3)O_(4)NSs)as cathode materials to suppress 1O_(2)in Li-O_(2)batteries for the first time.Operando photoluminescence spectroscopy reveals a 3.7-fold and 3.23-fold reduction in 1O_(2)during discharge and charge,respectively,compared to conventional carbon paperbased cells,consistent with differential electrochemical mass spectrometry results,which indicate a near-theoretical charge-to-O_(2)ratio(2.04 e-/O_(2)).Density functional theory calculations demonstrate that chirality induces a peak shift near the Fermi level,enhancing Co 3d-O 2p hybridization,stabilizing reaction intermediates,and lowering activation barriers for Li_(2)O_(2)formation and decomposition.These findings establish a new strategy for improving the stability and energy efficiency of sustainable Li-O_(2)batteries,abridging the current gap to commercialization.
基金supported by the National Key Research and Development Program of China(No.2021YFB4000603)the National Natural Science Foundation of China(Nos.52273277 and U24A2062)+2 种基金Jilin Province Science and Technology Development Plan Funding Project(No.SKL202302039)Youth Innovation Promotion Association CAS(No.2021223)funding from National Natural Science Foundation of China Outstanding Youth Science Foundation of China(Overseas).
文摘Proton-exchange membrane fuel cell and water electrolyzer(PEMFC and PEMWE)with high conversion efficiency and zero-carbon emission stand out as an attractive strategy for efficient conversion between hydrogen energy and renewable electricity.As a key component,efficient oxygen electrocatalyst for promoting sluggish reaction kinetics of oxygen reduction and evolution reaction(ORR and OER)under harsh operation conditions severely limited progress of these devices.Among various candidates,Ptgroup(Pt,Ir,and Ru)-based electrocatalysts are still the most active ORR/OER catalysts.However,the scarcity,high cost,and questionable stability restrict the widespread applications and the commercialization of PEMWE/PEMFC.Progresses in synthesizing atomically dispersed single/multiple-atom catalysts(SACs/MACs)offer new opportunities to Pt-group ORR/OER catalysts owing to nearly 100% metal utilization and high catalytic activities.Extensive efforts have been continuously devoted to optimizing the local structure of Pt-group OER/ORR catalysts at atom-level for further enhancing stability and activity.In this review,universal synthesis methods to prepare Ptgroup SACs are discussed first,highlighting crucial factors which affect the structure and catalytic performance.Afterward,advanced characterization techniques for directly confirming atomic dispersed metal atoms were introduced,including aberration-corrected high-angle-annular-dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy.Importantly,considerations for rational catalyst design and typical Pt-group SACs/MACs are summarized regarding the regulation strategy of atomically dispersed metal sites and various supports,and effects of metal-support interaction on the catalytic performance.Finally,key challenges and proposed perspectives for future development of atomically dispersed Pt-group oxygen electrocatalysts for fuel cell and electrolyzer are briefly discussed.
基金supported by the Science and Technology Project of Hebei Education Department(No.QN2023028)the Natural Science Foundation of Hebei Province(No.C2022201042)+1 种基金the High-level Talent Research Funding Project of Hebei University(Nos.521000981405 and 521000981186)the Collaborative Innovation Center for Baiyangdian Basin Ecological Protection and Beijing-Tianjin-Hebei Sustainable Development.
文摘Climate warming and atmospheric nitrogen(N)deposition have profound influences on the terrestrial biosphere.However,how these two global change drivers affect phytoplankton which are important primary producers in wetlands with large carbon stocks and complex hydrological fluctuations remain largely unclear.As part of a two-year field experiment in a freshwater wetland,this study was conducted to investigate the effects of nighttime warming and N addition on phytoplankton biomass in the North China Plain.The results showed that neither nighttime warming nor N addition influenced the Shannon-Wiener index of phytoplankton community.Nighttime warming did not change phytoplankton biomass,likely due to the different warming impacts on dominant phyla and in different seasons.Decreased phytoplankton biomass in spring because of the increased water pH and submerged plant coverage was compensated by the enhanced biomass in autumn due to the reduced dissolved oxygen and submerged plant coverage,leading to the neutral change of phytoplankton biomass under warming.Nitrogen addition elevated phytoplankton biomass by 11.6%,which could be attributed to the enhanced nutrient availability and reduced submerged plant coverage.Positive relationships of methane(CH4)emission rates at the water-air interface with phytoplankton biomass indicated the potentially crucial role of phytoplankton in mediating wetland CH4 cycling through photosynthesis-driven metabolisms.The findings suggested the seasonal variation of phytoplankton and their potential responses to nighttime warming and N deposition,which may provide a more accurate basis for assessing the global change-carbon feedback in wetland ecosystems.
基金Funded by the 111 Project(No.B17034)Open Project of Hubei Key Laboratory of Power System Design and Test for Electrical Vehicle(No.ZDSYS202212)+1 种基金Innovative Research Team Development Program of Ministry of Education of China(No.IRT_17R83)the Science and Technology Project of China Southern Power Grid Co.,Ltd.(No.GDKJXM20222546)。
文摘The development of Pt-free catalysts for the oxygen reduction reaction(ORR)is a great issue for meeting the cost challenges of proton exchange membrane fuel cells(PEMFCs)in commercial applications.In this work,a series of RuCo/C catalysts were synthesized by NaBH4 reduction method under the premise that the total metal mass percentage was 20%.X-ray diffraction(XRD)patterns and scanning electron microscopy(SEM)confirmed the formation of single-phase nanoparticles with an average size of 33 nm.Cyclic voltammograms(CV)and linear sweep voltammograms(LSV)tests indicated that RuCo(2:1)/C catalyst had the optimal ORR properties.Additionally,the RuCo(2:1)/C catalyst remarkably sustained 98.1% of its activity even after 3000 cycles,surpassing the performance of Pt/C(84.8%).Analysis of the elemental state of the catalyst surface after cycling using X-ray photoelectron spectroscopy(XPS)revealed that the Ru^(0) percentage of RuCo(2:1)/C decreased by 2.2%(from 66.3% to 64.1%),while the Pt^(0) percentage of Pt/C decreased by 7.1%(from 53.3% to 46.2%).It is suggested that the synergy between Ru and Co holds the potential to pave the way for future low-cost and highly stable ORR catalysts,offering significant promise in the context of PEMFCs.
