Development of high-efficiency bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalysts is vital for the widespread application of zinc-air batteries(ZABs).However,it still remains...Development of high-efficiency bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalysts is vital for the widespread application of zinc-air batteries(ZABs).However,it still remains a great challenge to avoid the inhomogeneous distribution and aggregation of metal single-atomic active centers in the construction of bifunctional electrocatalysts with atomically dispersed multimetallic sites because of the common calcination method.Herein,we report a novel catalyst with phthalocyanine-assembled Fe-Co-Ni single-atomic triple sites dispersed on sulfur-doped graphene using a simple ultrasonic procedure without calcination,and X-ray absorption fine structure(XAFS),aberration-corrected scanning transmission electron microscopy(AC-STEM),and other detailed characterizations are performed to demonstrate the successful synthesis.The novel catalyst shows extraordinary bifunctional ORR/OER activities with a fairly low potential difference(ΔE=0.621 V)between the OER overpotential(Ej10=315 mV at 10 m A cm^(-2))and the ORR half-wave potential(Ehalf-wave=0.924 V).Moreover,the above catalyst shows excellent ZAB performance,with an outstanding specific capacity(786 mAh g^(-1)),noteworthy maximum power density(139 mW cm^(-2)),and extraordinary rechargeability(discharged and charged at 5 mA cm^(-2) for more than 1000 h).Theoretical calculations reveal the vital importance of the preferable synergetic coupling effect between adjacent active sites in the Fe-Co-Ni trimetallic single-atomic sites during the ORR/OER processes.This study provides a new avenue for the investigation of bifunctional electrocatalysts with atomically dispersed trimetallic sites,which is intended for enhancing the ORR/OER performance in ZABs.展开更多
ABO_(3)-type perovskite oxides(e.g.,LaCoO_(3))with flexible and adjustable A-and B-sites are ideal model catalysts to unravel the relationship between the electronic structure and electrocatalytic activity(e.g.,oxygen...ABO_(3)-type perovskite oxides(e.g.,LaCoO_(3))with flexible and adjustable A-and B-sites are ideal model catalysts to unravel the relationship between the electronic structure and electrocatalytic activity(e.g.,oxygen reduction/evolution reactions,ORR/OER).It has been well understood in our recent work that the secondary metal dopant at B-site(e.g.,Mn in LaMn_(x)Co_(1-x)O_(3))can regulate the electronic structure and improve the ORR/OER activity.In this work,the Mn-Ni pairs are employed as the dual dopant in LaMn_(x)Ni_(y)Co_(z)O_(3)(x+y+z=1)catalysts toward bifunctional ORR and OER.The structure-property relationships between the triple metal B-site(Mn,Ni and Co)and the electrochemical performance are particularly investigated.Compared to the individual Mn doping(e.g.,LaMnCoO3(Mn:Co=1:3)catalyst),the dual Mn-Ni doping significantly improves the ORR mass activity@0.8 V by 1.54 times;meanwhile,the OER overpotential@10 mA cm^(-2) is reduced from 420 to 370 mV,and the OER current density at 1.55 V is increased by 2.43 times.Reasonably,the potential gap between EDRR@-1 mA cm^(-2) and EDER@10 mA cm^(-2) is achieved as only 0.76 V by using the optimal LaMn_(x)Ni_(y)Co_(z)O_(3)(x:y:z=1:2:3)catalyst.It is revealed that the dual Mn-Ni dopant efficiently optimizes electron structures of the LaMnNiCoO_(3)(1:2:3)catalyst,which not only decreases the e_(g) orbital electron number,but also modulates the O 2 p-band closer to the Femi level,accounting for the enhanced bifunctional activity.展开更多
Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation.However,the sluggish kinetics of oxygen evolution reaction(OER)and poor selectivity of CO_(2) reduction seri...Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation.However,the sluggish kinetics of oxygen evolution reaction(OER)and poor selectivity of CO_(2) reduction seriously limited the overall conversion efficiencies of solar energy to chemical fuels.Herein,we demonstrated a facile and feasible strategy to rationally regulate the coordination environment and electronic structure of surface-active sites on both photoanode and cathode.More specifically,the defect engineering has been employed to reduce the coordination number of ultrathin FeNi catalysts decorated on BiVO4 photoanodes,resulting in one of the highest OER activities of 6.51 mA cm^(−2)(1.23 VRHE,AM 1.5G).Additionally,single-atom cobalt(II)phthalocyanine anchoring on the N-rich carbon substrates to increase Co–N coordination number remarkably promotes CO_(2) adsorption and activation for high selective CO production.Their integration achieved a record activity of 109.4μmol cm^(−2) h−1 for CO production with a faradaic efficiency of>90%,and an outstanding solar conversion efficiency of 5.41%has been achieved by further integrating a photovoltaic utilizing the sunlight(>500 nm).展开更多
Inspired by hexaazanaphthalene-based conjugated copper metal-organic framework(HATNA-Cu-MOF),we designed 161 HATNA-TM-MOF-based SACs(TM@N_(x)O_(4-x)-HATNA)with varying TM or ligands creating distinct coordination envi...Inspired by hexaazanaphthalene-based conjugated copper metal-organic framework(HATNA-Cu-MOF),we designed 161 HATNA-TM-MOF-based SACs(TM@N_(x)O_(4-x)-HATNA)with varying TM or ligands creating distinct coordination environments(x=0-4)with superior thermodynamic and electrochemical stabilities.Volcano plots can be constructed using(AGOOH^(*)-ΔGO^(*))/ΔGO^(*)as descriptors for oxygen evolution/reduction reaction(OER/ORR)activity,also serving as target parameters for machine learning(ML)models to identify high-performance OER/ORR catalysts.The efficient monofunctional and bifunctional electrocatalysts were successfully predicted,where the ML prediction results well matched the DFT calculation results.We employed Shapley additive explanations(SHAP)for feature analysis and utilized sure independence screening and sparsification operator(SISSO)for generalization.ML analyses reveal that TM-based OER/ORR activities predominantly correlate with three key descriptors:metallic atomic radius,d-orbital electron population,and the heat of formation of the oxide,demonstrating the pivotal role of TM's inherent electronic configuration and physicochemical characteristics in governing electrocatalytic efficacy.The constant-potential approach emphasizes the key role of electric double-layer capacitance in adjusting the kinetic barrier,where changes in the Fermi level influence the occupation of d-orbitals.Variations in electrochemical potential significantly alter the electronic structure of representative Rh@N_(1)O_(3)-HATNA,affecting both the Fermi level and adsorption properties,with the unique 4d^(8)5s^(1)configuration leading to inverted O_(2)adsorption energies as the potential decreases.This study contributes insights into the origin of oxygen evolution-reduction activity for the HATNA-TM-MOF-based SACs and reveals the fundamentals of structure-activity relationships for future applications.展开更多
Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-prot...Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-proton transfers more complex when determining kinetics and mass transfer information.Understanding how HER competes with other electrochemical reduction reactions is crucial for both fundamental studies and system performance improvements.In this study,we employed the oxygen reduction reaction(ORR)as a model reaction to investigate HER competition on a polycrystalline-Au surface,using a rotating ring and disk electrode.It’s proved that water molecules serve as the proton source for ORR in alkaline,neutral,and even acidic electrolytes,and a 4-electron process can be achieved when the overpotential is sufficiently high.The competition from H⁺reduction becomes noticeable at the H⁺concentration higher than 2 mmol L^(–1)and intensi-fies as the H^(+)concentration increases.Based on the electrochemical results,we obtained an equivalent circuit diagram for the ORR system with competition from the H+reduction reaction,showing that these reactions occur in parallel and compete with each other.Electrochemical impedance spectroscopy measurements further confirm this argument.Additionally,we discover that the contribution of H+mass transfer to the total H^(+)reduction current is significant and comparable to the kinetic current.We believe this work will deepen our understanding of HER and its competition in electrochemical reduction systems.展开更多
The development of single atom catalysts(SACs)with asymmetric active sites by defect regulation provides an encourage potential for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER),but highly challen...The development of single atom catalysts(SACs)with asymmetric active sites by defect regulation provides an encourage potential for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER),but highly challenging.Herein,N-doped carbon(N-C)anchored atomically dispersed Ni-N_(3)site with proximity defects(Ni-N_(3)D)induced by Te atoms doping is reported.Benefitting from the inductive effect of proximity defect,the Ni-N_(3)D/Te-N-C catalyst performs excellent ORR and HER performance in alkaline and acid condition.Both in situ characterization and theoretical calculation reveal that the existence of proximity defect effect is conducive to lower rate-determining-step energy barrier of ORR and HER,thus accelerating the multielectron reaction kinetics.This work paves a novel strategy for constructing highactivity bifunctional SACs by defect engineering for development of sustainable energy.展开更多
The rational design of Ni-based catalysts is essential due to their abundance and low cost for advancing sustainable energy technologies,particularly for water splitting and fuel cells.This study employs spinpolarized...The rational design of Ni-based catalysts is essential due to their abundance and low cost for advancing sustainable energy technologies,particularly for water splitting and fuel cells.This study employs spinpolarized density functional theory(DFT)to examine the influence of anchoring rare-earth elements on the γ-NiOOH lattice surface,aiming to identify the optimal catalytic site for the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Following the identification of an appropriate active site through Ni vacancy,a rare earth element(REE_(1))is introduced as a dopant for single-atom catalysis(SACs).The structural,thermodynamic,and catalytic characteristics of all newly designed REE_(1)/γ-NiOOH catalysts have been extensively studied.Among the newly developed catalysts,Tb_(1)/γ-NiOOH exhibits the lowest OER overpotential of(0.36 V),while Ce_(1)/γ-NiOOH and Pr_(1)/γ-NiOOH also demonstrate excellent OER performance(0.51 and 0.41 V),respectively.Notably,Nd_(1)/γ-NiOOH and Pm_(1)/γ-NiOOH exhibit efficient ORR activity,with low overpotentials of(0.63 and 0.61 V)due to their balanced adsorption and desorption energies of intermediates.Bader charge analysis reveals strong electron donation from doped REE1to the surface.This study identified Ce_(1),Pr_(1),Nd_(1),and Tb_(1) anchoring catalysts as highly promising for water-splitting applications.Moreover,Nd_(1) and Pm_(1) doping markedly improve ORR performance,underscoring their promise for enhanced electrochemical applications in metal-air batteries.The catalytic performance of all newly developed catalysts was further evaluated using electronic descriptors.The catalytic performance was further assessed using the volcano curve and scaling relationships for the adsorbed intermediates.This study offers an extensive theoretical foundation for designing cost-effective and high-performance REE_(1)/γ-NiOOH electrocatalysts.展开更多
Optimizing active sites and enhancing mass transfer capability are of paramount importance for the improvement of electrocatalyst activity.On this basis,CoFe_(2)O_(4)/CoFe nanoparticles(NPs)loaded N-doped carbon(NC)th...Optimizing active sites and enhancing mass transfer capability are of paramount importance for the improvement of electrocatalyst activity.On this basis,CoFe_(2)O_(4)/CoFe nanoparticles(NPs)loaded N-doped carbon(NC)that featured with interconnected three-dimensional(3D)ordered porous hierarchies(3DOM FeCo/NC)are prepared,and its electrocatalytic activity is studied.Due to the open structure of 3D ordered macro-pores that greatly improves the mass transfer capacity of the catalytic process and enhances the utilization of active sites inside the catalyst,as well as the uniform distribution of Fe and Co bimetallic sites on the porous skeleton,3DOM FeCo/NC exhibits superior bi-functional catalytic activities for both hydrogen evolution reaction(HER)and oxygen reduction reaction(ORR).The overpotential of HER is lower than that of commercial Pt/C when performed at high current density(>235 mA cm^(-2))in1.0 M KOH,and the half-wave potential(0.896 V)of ORR in 0.1 M KOH is also superior to that of 20% commercial Pt/C and most other similar catalysts.The effective utilization and synergistic effect of CoFe_(2)O_(4)and CoFe hetero-metallic sites remarkably enhance the electrocatalytic activity.Furthermore,3DOM FeCo/NC is assembled as an air electrode in Zn-air battery,and exhibits satisfactory maximum power density,open-circuit voltage,and charge/discharge stability over benchmark Pt/C+IrO_(2).This work contributes new insights into the design of transition-metal-based multifunctional catalysts,and has great potential for energy conversion and storage.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
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
Heteroatom-doped carbon is considered a promising alternative to commercial Pt/C as an efficient catalyst for the oxygen reduction reaction(ORR).This study presents the synthesis of iron-loaded,sulfur and nitrogen co-...Heteroatom-doped carbon is considered a promising alternative to commercial Pt/C as an efficient catalyst for the oxygen reduction reaction(ORR).This study presents the synthesis of iron-loaded,sulfur and nitrogen co-doped carbon(Fe/SNC)via in situ incorporation of 2-aminothiazole molecules into zeolitic imidazolate framework-8(ZIF-8)through coordination between metal ions and organic ligands.Sulfur and nitrogen doping in carbon supports effectively modulates the electronic structure of the catalyst,increases the Brunauer-Emmett-Teller surface area,and exposes more Fe-N_(x)active centers.Fe-loaded,S and N co-doped carbon with Fe/S molar ratio of 1:10(Fe/SNC-10)exhibits a half-wave potential of 0.902 V vs.RHE.After 5000 cycles of cyclic voltammetry,its half-wave potential decreases by only 20 mV vs.RHE,indicating excellent stability.Due to sulfur s lower electronegativity,the electronic structure of the Fe-N_(x)active center is modulated.Additionally,the larger atomic radius of sulfur introduces defects into the carbon support.As a result,Fe/SNC-10 demonstrates superior ORR activity and stability in alkaline solution compared with Fe-loaded N-doped carbon(Fe/NC).Furthermore,the zinc-air battery assembled with the Fe/SNC-10 catalyst shows enhanced performance relative to those assembled with Fe/NC and Pt/C catalysts.This work offers a novel design strategy for advanced energy storage and conversion applications.展开更多
The oxygen reduction/evolution reactions(ORR/OER) are a key electrode process in the development of electrochemical energy conversion and storage devices,such as metal-air batteries and reversible fuel cells.The searc...The oxygen reduction/evolution reactions(ORR/OER) are a key electrode process in the development of electrochemical energy conversion and storage devices,such as metal-air batteries and reversible fuel cells.The search for low-cost high-performance nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for ORR/OER alternatives to the widely-used noble metal-based catalysts is a research focus.This review aims to outline the opportunities and available options for these nanocarbon-based bifunctional electrocatalysts.Through discussion of some current scientific issues,we summarize the development and breakthroughs of these electrocatalysts.Then we provide our perspectives on these issues and suggestions for some areas in the further work.We hope that this review can improve the interest in nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for ORR/OER.展开更多
Protonic ceramic electrochemical cells(PCECs)have demonstrated great promise for applications in the generation of electricity,and the synthesis of chemicals(for example,ethylene).However,enhancing the electrochemical...Protonic ceramic electrochemical cells(PCECs)have demonstrated great promise for applications in the generation of electricity,and the synthesis of chemicals(for example,ethylene).However,enhancing the electrochemical reactions kinetics and stability of PCECs electrodes is one grand challenge.Here,we present a novel electrode material via a co-doping of cesium(Cs)and niobium(Nb)on PrBaCo_(2)O_(6-δ)with the composition of PrBa_(0.9)Cs_(0.1)Co_(1.9)Nb_(0.1)O_(6-δ)(PBCCN),which naturally decomposes into dual phases of a double-perovskite PBCCN(DP-PBCCN,~92.3 wt%)and a single-perovskite Ba_(0.9)Cs_(0.1)Co_(0.95)Nb_(0.05)O_(3-δ)(SP-BCCN,~7.7 wt%)under typical powder processing conditions.PBCCN exhibits a low area-specific resistance(ASR)value of 0.107Ωcm^(2),an outstanding performance of 2.04Wcm^(-2)in fuel cell(FC)mode,a current density of-2.84 A cm^(-2)at 1.3 V in electrolysis cell(EC)mode,and promising reversible operational durability of 53 cycles in~212 h at+/-0.5 A cm^(-2)and 650。C.Cs doping generates more oxygen vacancies and accelerates the oxygen exchange kinetics,while Nb doping effectively enhances the stability,as illustrated by the analyses of X-ray photoelectron spectroscopy,and electrical conductivity relaxations.When applied as the positrode for electrochemical non-oxidative dehydrogenation of ethane(C2H6)to ethylene(C2H4)on PCECs,it displays an encouraging C2H6 conversion of 12.75%and a C2H4 selectivity of 98.4%at 1.2 V.展开更多
Noble metals, such as platinum, ruthenium and iridium‐group metals, are often used as oxygen reduction or evolution reaction （ORR/OER） electrocatalysts. To reduce the cost and provide an application of bifunctional...Noble metals, such as platinum, ruthenium and iridium‐group metals, are often used as oxygen reduction or evolution reaction （ORR/OER） electrocatalysts. To reduce the cost and provide an application of bifunctional catalysis, in this work, cobalt oxide supported on nitrogen and phospho‐rus co‐doped carbon （Co3O4/NPC） was fabricated and examined as a bifunctional electrocatalyst for OER and ORR. To prepare Co3O4/NPC, NPC was pyrolyzed from melamine and phytic acid support‐ed on carbon, followed by the solvothermal synthesis of Co3O4 on NPC. Linear sweep voltammetry was used to evaluate the activity for OER and ORR. For OER, Co3O4/NPC showed an onset potential of 0.54 V （versus the saturated calomel electrode） and a current density of 21.95 mA/cm2 at 0.80 V, which was better than both Co3O4/C and NPC. The high activity of Co3O4/NPC was attributed to a synergistic effect of the N, P co‐dopants and Co3O4. For ORR, Co3O4/NPC exhibited an activity close to commercial Pt/C in terms of the diffusion limited current density （–4.49 vs–4.76 mA/cm2 at–0.80 V）, and Co3O4 played the key role for the catalysis. Chronoamperometry （current versus time） was used to evaluate the stability, which showed that Co3O4/NPC maintained 46%current after the chronoamperometry test for OER and 95% current for ORR. Overall, Co3O4/NPC exhibited high activity and improved stability for both OER and ORR.展开更多
A novel photocatalytic cocatalyst, MoC quantum dots integrated into N-doped carbon microflowers (MoC–NC), was synthesized, establishing a key Mo–N interfacial bond. The Mo–N bond's regulation was achieved by ad...A novel photocatalytic cocatalyst, MoC quantum dots integrated into N-doped carbon microflowers (MoC–NC), was synthesized, establishing a key Mo–N interfacial bond. The Mo–N bond's regulation was achieved by adjusting the pH of Mo-polydopamine precursor solutions. A composite photocatalyst, MoC–NC/CdS (MNS), was formed by in situ growth of nano-CdS on MoC–NC. The pH during synthesis, crucial for Mo–N bond formation, significantly influenced Cr(Ⅵ) reduction and H_(2) evolution performance. The optimal MNS, created at pH 9.0, demonstrated 99.2% reduction efficiency for Cr(Ⅵ) in 20 min and H_(2) evolution rate of 11.4 mmol g^(-1) h^(-1) over 3 h, outperforming Pt/CdS. Mechanistic studies and density functional theory revealed MoC–NC's role in enhancing light absorption, reaction kinetics, and electron transport, attributing to its ultra-small quantum dots and abundant Mo–N bonds.展开更多
Developing low-cost and highly-efficient electrocatalysts for renewable energy conversion technologies has attracted even-increasing attention. Molybdenum carbide materials have recently emerged as a type of promising...Developing low-cost and highly-efficient electrocatalysts for renewable energy conversion technologies has attracted even-increasing attention. Molybdenum carbide materials have recently emerged as a type of promising catalysts for electrocatalytic reactions due to the earth-abundance and Pt-resembled electrical properties. In this work, taking the advantage of the interaction between the basic groups of the Mo(VI)-melamine polymer and the acidic groups on the surface of the oxidized carbon nanotubes(CNTs), N-doped CNTs supported Mo2C nanoparticles(Mo2C/NCNT) are prepared, which exhibit outstanding electrocatalytic activity and durability for both the hydrogen evolution and oxygen reduction reactions. The impressive performance of Mo2C/NCNT can be attributed to the small size of Mo2C particles, the large exposure ratio of surface sites and the presence of N-doped CNTs. This work enlarges the multi-field applications of molybdenum carbide-base materials as promising non-precious metal electrocatalysts, which is of great significance for sustainable energy-related technologies.展开更多
The demand for efficient and environmentally-benign electrocatalysts that help availably harness the renewable energy resources is growing rapidly. In recent years, increasing insights into the design of water electro...The demand for efficient and environmentally-benign electrocatalysts that help availably harness the renewable energy resources is growing rapidly. In recent years, increasing insights into the design of water electrolysers, fuel cells, and metal–air batteries emerge in response to the need for developing sustainable energy carriers, in which the oxygen evolution reaction and the oxygen reduction reaction play key roles. However, both reactions suffer from sluggish kinetics that restricts the reactivity. Therefore, it is vital to probe into the structure of the catalysts to exploit high-performance bifunctional oxygen electrocatalysts. Spinel-type catalysts are a class of materials with advantages of versatility, low toxicity, low expense, high abundance, flexible ion arrangement, and multivalence structure. In this review, we afford a basic overview of spinel-type materials and then introduce the relevant theoretical principles for electrocatalytic activity, following that we shed light on the structure–property relationship strategies for spinel-type catalysts including electronic structure, microstructure, phase and composition regulation,and coupling with electrically conductive supports. We elaborate the relationship between structure and property, in order to provide some insights into the design of spinel-type bifunctional oxygen electrocatalysts.展开更多
Electrocatalysts are one of the essential components for the devices of high-efficiency green energy storage and conversion,such as metal-air cells,fuel cells,and water electrolysis systems.While catalysts made from n...Electrocatalysts are one of the essential components for the devices of high-efficiency green energy storage and conversion,such as metal-air cells,fuel cells,and water electrolysis systems.While catalysts made from noble metals possess high catalytic performance in both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),their scarcity and expensiveness significantly limit large-scale applications.In this regard,metal-free/non-noble metal carbon-based catalysts have become competitive alternatives to replace catalysts made of noble metals.Nevertheless,low catalytic ORR/OER performance is the challenge of carbon-based catalysts for the commercial applications of metal-air batteries.To solve the problem of poor catalytic performance,two strategies have been proposed:(1)controlling the microstructure of the catalysts to expose more active sites as the channels of rapid mass and electron transfer;and(2)reducing the reaction energy barrier by optimizing the electronic structures of the catalysts via surface engineering.Here,we review different types of bifunctional ORR/OER electrocatalysts with the activated surface sites.We focus on how the challenge can be overcome with different methods of material synthesis,structural and surface characterization,performance validation/optimization,to outline the principles of surface modifications behind catalyst designs.In particular,we provide critical analysis in the challenges that we are facing in structural design and surface engineering of bifunctional ORR/OER catalysts and indicate the possible solution for these problems,providing the society with clearer ideas on the practical prospects of noble-metal-free electrocatalysts for their future applications.展开更多
To develop more ideal bifunctional heteroatom-doped carbon electrocatalysts toward the oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) for regenerative fuel cells and rechargeable metal–air batterie...To develop more ideal bifunctional heteroatom-doped carbon electrocatalysts toward the oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) for regenerative fuel cells and rechargeable metal–air batteries, herein, tobacco-derived N-containing ordered mesoporous carbon(N-OMC) electrocatalysts with different N species distributions are designed. Results indicate that the as-prepared N-OMC with more pyrrolic and pyridinic Ns exhibits much higher activities for the ORR and OER than N-OMC with more graphitic N in both acidic and alkaline media, suggesting that the increase of pyrrolic and pyridinic Ns favors the improvement of ORR and OER activities of the N-containing carbon catalysts, and showing a great potential for the designing of more effective, lower-cost ORR and OER bifunctional electrocatalysts for future regenerative fuel cells and rechargeable metal–air batteries.展开更多
Cobalt and nitrogen codoped carbon materials(Co-N-C) were fabricated by pyrolysis of the mixture of poly(4-vinylpyridine) and cobalt chloride using SiO_2 nanoparticles as hard template, which were the first transition...Cobalt and nitrogen codoped carbon materials(Co-N-C) were fabricated by pyrolysis of the mixture of poly(4-vinylpyridine) and cobalt chloride using SiO_2 nanoparticles as hard template, which were the first transition metal/nitrogen-codoped carbon bifunctional electrocatalyst derived from noncarbonizable polymer for ORR and HER. The as-made Co-N-C possessed hierarchical pore structure and high specific surface area, achieving excellent electrocatalytic performances for ORR and HER. Its ORR catalytic performances were comparable to those of Pt/C catalyst and its HER catalytic performances were superior to those of most doped carbon catalysts in KOH electrolyte. Moreover, its bifunctional electrocatalytic performances for ORR and HER were better than those of most bifunctional doped carbon catalysts in alkaline electrolyte.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.22305071,52472200,52271176,and52072114)the 111 Project(Grant No.D17007)+3 种基金Henan Center for Outstanding Overseas Scientists(Grant No.GZS2022017)the China Postdoctoral Science Foundation(Grant No.2022M721049)the Henan Province Key Research and Development Project(Grant No.231111520500)the Natural Science Foundation of Henan Province(Grant No.252300421556)。
文摘Development of high-efficiency bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalysts is vital for the widespread application of zinc-air batteries(ZABs).However,it still remains a great challenge to avoid the inhomogeneous distribution and aggregation of metal single-atomic active centers in the construction of bifunctional electrocatalysts with atomically dispersed multimetallic sites because of the common calcination method.Herein,we report a novel catalyst with phthalocyanine-assembled Fe-Co-Ni single-atomic triple sites dispersed on sulfur-doped graphene using a simple ultrasonic procedure without calcination,and X-ray absorption fine structure(XAFS),aberration-corrected scanning transmission electron microscopy(AC-STEM),and other detailed characterizations are performed to demonstrate the successful synthesis.The novel catalyst shows extraordinary bifunctional ORR/OER activities with a fairly low potential difference(ΔE=0.621 V)between the OER overpotential(Ej10=315 mV at 10 m A cm^(-2))and the ORR half-wave potential(Ehalf-wave=0.924 V).Moreover,the above catalyst shows excellent ZAB performance,with an outstanding specific capacity(786 mAh g^(-1)),noteworthy maximum power density(139 mW cm^(-2)),and extraordinary rechargeability(discharged and charged at 5 mA cm^(-2) for more than 1000 h).Theoretical calculations reveal the vital importance of the preferable synergetic coupling effect between adjacent active sites in the Fe-Co-Ni trimetallic single-atomic sites during the ORR/OER processes.This study provides a new avenue for the investigation of bifunctional electrocatalysts with atomically dispersed trimetallic sites,which is intended for enhancing the ORR/OER performance in ZABs.
基金supported by the National Natural Science Foundation of China(Grant Nos.21433003,21805064 and 21773049)National Key Research and Development Program of China(Program No.2016YFB0101207)。
文摘ABO_(3)-type perovskite oxides(e.g.,LaCoO_(3))with flexible and adjustable A-and B-sites are ideal model catalysts to unravel the relationship between the electronic structure and electrocatalytic activity(e.g.,oxygen reduction/evolution reactions,ORR/OER).It has been well understood in our recent work that the secondary metal dopant at B-site(e.g.,Mn in LaMn_(x)Co_(1-x)O_(3))can regulate the electronic structure and improve the ORR/OER activity.In this work,the Mn-Ni pairs are employed as the dual dopant in LaMn_(x)Ni_(y)Co_(z)O_(3)(x+y+z=1)catalysts toward bifunctional ORR and OER.The structure-property relationships between the triple metal B-site(Mn,Ni and Co)and the electrochemical performance are particularly investigated.Compared to the individual Mn doping(e.g.,LaMnCoO3(Mn:Co=1:3)catalyst),the dual Mn-Ni doping significantly improves the ORR mass activity@0.8 V by 1.54 times;meanwhile,the OER overpotential@10 mA cm^(-2) is reduced from 420 to 370 mV,and the OER current density at 1.55 V is increased by 2.43 times.Reasonably,the potential gap between EDRR@-1 mA cm^(-2) and EDER@10 mA cm^(-2) is achieved as only 0.76 V by using the optimal LaMn_(x)Ni_(y)Co_(z)O_(3)(x:y:z=1:2:3)catalyst.It is revealed that the dual Mn-Ni dopant efficiently optimizes electron structures of the LaMnNiCoO_(3)(1:2:3)catalyst,which not only decreases the e_(g) orbital electron number,but also modulates the O 2 p-band closer to the Femi level,accounting for the enhanced bifunctional activity.
基金supported by the National Natural Science Foundation of China(21832005,22072168,22002175)Major Program of the Lanzhou Institute of Chemical Physics,CAS(No.ZYFZFX-3)+1 种基金Major Science and Technology Projects in Gansu Province(22ZD6GA003)West Light Foundation of The Chinese Academy of Sciences(xbzg-zdsys-202209).
文摘Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation.However,the sluggish kinetics of oxygen evolution reaction(OER)and poor selectivity of CO_(2) reduction seriously limited the overall conversion efficiencies of solar energy to chemical fuels.Herein,we demonstrated a facile and feasible strategy to rationally regulate the coordination environment and electronic structure of surface-active sites on both photoanode and cathode.More specifically,the defect engineering has been employed to reduce the coordination number of ultrathin FeNi catalysts decorated on BiVO4 photoanodes,resulting in one of the highest OER activities of 6.51 mA cm^(−2)(1.23 VRHE,AM 1.5G).Additionally,single-atom cobalt(II)phthalocyanine anchoring on the N-rich carbon substrates to increase Co–N coordination number remarkably promotes CO_(2) adsorption and activation for high selective CO production.Their integration achieved a record activity of 109.4μmol cm^(−2) h−1 for CO production with a faradaic efficiency of>90%,and an outstanding solar conversion efficiency of 5.41%has been achieved by further integrating a photovoltaic utilizing the sunlight(>500 nm).
基金financially supported by the National Natural Science Foundation of China(Nos.62264015 and U2233206)the Civil Aviation Administration of China(No.U1933109)Hubei Province Technology Innovation Program Project(No.2024BCB073)
文摘Inspired by hexaazanaphthalene-based conjugated copper metal-organic framework(HATNA-Cu-MOF),we designed 161 HATNA-TM-MOF-based SACs(TM@N_(x)O_(4-x)-HATNA)with varying TM or ligands creating distinct coordination environments(x=0-4)with superior thermodynamic and electrochemical stabilities.Volcano plots can be constructed using(AGOOH^(*)-ΔGO^(*))/ΔGO^(*)as descriptors for oxygen evolution/reduction reaction(OER/ORR)activity,also serving as target parameters for machine learning(ML)models to identify high-performance OER/ORR catalysts.The efficient monofunctional and bifunctional electrocatalysts were successfully predicted,where the ML prediction results well matched the DFT calculation results.We employed Shapley additive explanations(SHAP)for feature analysis and utilized sure independence screening and sparsification operator(SISSO)for generalization.ML analyses reveal that TM-based OER/ORR activities predominantly correlate with three key descriptors:metallic atomic radius,d-orbital electron population,and the heat of formation of the oxide,demonstrating the pivotal role of TM's inherent electronic configuration and physicochemical characteristics in governing electrocatalytic efficacy.The constant-potential approach emphasizes the key role of electric double-layer capacitance in adjusting the kinetic barrier,where changes in the Fermi level influence the occupation of d-orbitals.Variations in electrochemical potential significantly alter the electronic structure of representative Rh@N_(1)O_(3)-HATNA,affecting both the Fermi level and adsorption properties,with the unique 4d^(8)5s^(1)configuration leading to inverted O_(2)adsorption energies as the potential decreases.This study contributes insights into the origin of oxygen evolution-reduction activity for the HATNA-TM-MOF-based SACs and reveals the fundamentals of structure-activity relationships for future applications.
文摘Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-proton transfers more complex when determining kinetics and mass transfer information.Understanding how HER competes with other electrochemical reduction reactions is crucial for both fundamental studies and system performance improvements.In this study,we employed the oxygen reduction reaction(ORR)as a model reaction to investigate HER competition on a polycrystalline-Au surface,using a rotating ring and disk electrode.It’s proved that water molecules serve as the proton source for ORR in alkaline,neutral,and even acidic electrolytes,and a 4-electron process can be achieved when the overpotential is sufficiently high.The competition from H⁺reduction becomes noticeable at the H⁺concentration higher than 2 mmol L^(–1)and intensi-fies as the H^(+)concentration increases.Based on the electrochemical results,we obtained an equivalent circuit diagram for the ORR system with competition from the H+reduction reaction,showing that these reactions occur in parallel and compete with each other.Electrochemical impedance spectroscopy measurements further confirm this argument.Additionally,we discover that the contribution of H+mass transfer to the total H^(+)reduction current is significant and comparable to the kinetic current.We believe this work will deepen our understanding of HER and its competition in electrochemical reduction systems.
基金financially supported by the National Natural Science Foundation of China(22478432,22108306,22178388)Taishan Scholars Program of Shandong Province(tsqn201909065)+2 种基金Shandong Provincial Natural Science Foundation(ZR2024JQ004)Innovation Fund Project for Graduate Student of China University of Petroleum(East China)the Fundamental Research Funds for the Central Universities(No.25CX04020A)。
文摘The development of single atom catalysts(SACs)with asymmetric active sites by defect regulation provides an encourage potential for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER),but highly challenging.Herein,N-doped carbon(N-C)anchored atomically dispersed Ni-N_(3)site with proximity defects(Ni-N_(3)D)induced by Te atoms doping is reported.Benefitting from the inductive effect of proximity defect,the Ni-N_(3)D/Te-N-C catalyst performs excellent ORR and HER performance in alkaline and acid condition.Both in situ characterization and theoretical calculation reveal that the existence of proximity defect effect is conducive to lower rate-determining-step energy barrier of ORR and HER,thus accelerating the multielectron reaction kinetics.This work paves a novel strategy for constructing highactivity bifunctional SACs by defect engineering for development of sustainable energy.
基金supported by the BRICS STI Framework Programme(No.52261145703)the Higher Education Discipline Innovation Project(National 111 Project,No.B16016)。
文摘The rational design of Ni-based catalysts is essential due to their abundance and low cost for advancing sustainable energy technologies,particularly for water splitting and fuel cells.This study employs spinpolarized density functional theory(DFT)to examine the influence of anchoring rare-earth elements on the γ-NiOOH lattice surface,aiming to identify the optimal catalytic site for the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Following the identification of an appropriate active site through Ni vacancy,a rare earth element(REE_(1))is introduced as a dopant for single-atom catalysis(SACs).The structural,thermodynamic,and catalytic characteristics of all newly designed REE_(1)/γ-NiOOH catalysts have been extensively studied.Among the newly developed catalysts,Tb_(1)/γ-NiOOH exhibits the lowest OER overpotential of(0.36 V),while Ce_(1)/γ-NiOOH and Pr_(1)/γ-NiOOH also demonstrate excellent OER performance(0.51 and 0.41 V),respectively.Notably,Nd_(1)/γ-NiOOH and Pm_(1)/γ-NiOOH exhibit efficient ORR activity,with low overpotentials of(0.63 and 0.61 V)due to their balanced adsorption and desorption energies of intermediates.Bader charge analysis reveals strong electron donation from doped REE1to the surface.This study identified Ce_(1),Pr_(1),Nd_(1),and Tb_(1) anchoring catalysts as highly promising for water-splitting applications.Moreover,Nd_(1) and Pm_(1) doping markedly improve ORR performance,underscoring their promise for enhanced electrochemical applications in metal-air batteries.The catalytic performance of all newly developed catalysts was further evaluated using electronic descriptors.The catalytic performance was further assessed using the volcano curve and scaling relationships for the adsorbed intermediates.This study offers an extensive theoretical foundation for designing cost-effective and high-performance REE_(1)/γ-NiOOH electrocatalysts.
基金financially supported by the National Natural Science Foundation of China(51902149,51674131,22305108)the Fundamental Research Funds for Public Universities in Liaoning(LJ232410140033)the Scientific Research Funding of the Education Department of Liaoning Province(JYTZD2023070,LJKFZ20220180,LJKMZ20220453)。
文摘Optimizing active sites and enhancing mass transfer capability are of paramount importance for the improvement of electrocatalyst activity.On this basis,CoFe_(2)O_(4)/CoFe nanoparticles(NPs)loaded N-doped carbon(NC)that featured with interconnected three-dimensional(3D)ordered porous hierarchies(3DOM FeCo/NC)are prepared,and its electrocatalytic activity is studied.Due to the open structure of 3D ordered macro-pores that greatly improves the mass transfer capacity of the catalytic process and enhances the utilization of active sites inside the catalyst,as well as the uniform distribution of Fe and Co bimetallic sites on the porous skeleton,3DOM FeCo/NC exhibits superior bi-functional catalytic activities for both hydrogen evolution reaction(HER)and oxygen reduction reaction(ORR).The overpotential of HER is lower than that of commercial Pt/C when performed at high current density(>235 mA cm^(-2))in1.0 M KOH,and the half-wave potential(0.896 V)of ORR in 0.1 M KOH is also superior to that of 20% commercial Pt/C and most other similar catalysts.The effective utilization and synergistic effect of CoFe_(2)O_(4)and CoFe hetero-metallic sites remarkably enhance the electrocatalytic activity.Furthermore,3DOM FeCo/NC is assembled as an air electrode in Zn-air battery,and exhibits satisfactory maximum power density,open-circuit voltage,and charge/discharge stability over benchmark Pt/C+IrO_(2).This work contributes new insights into the design of transition-metal-based multifunctional catalysts,and has great potential for energy conversion and storage.
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.
基金financial support of the National Natural Science Foundation of China(No.52472271)the National Key Research and Development Program of China(No.2023YFE0115800)。
文摘Heteroatom-doped carbon is considered a promising alternative to commercial Pt/C as an efficient catalyst for the oxygen reduction reaction(ORR).This study presents the synthesis of iron-loaded,sulfur and nitrogen co-doped carbon(Fe/SNC)via in situ incorporation of 2-aminothiazole molecules into zeolitic imidazolate framework-8(ZIF-8)through coordination between metal ions and organic ligands.Sulfur and nitrogen doping in carbon supports effectively modulates the electronic structure of the catalyst,increases the Brunauer-Emmett-Teller surface area,and exposes more Fe-N_(x)active centers.Fe-loaded,S and N co-doped carbon with Fe/S molar ratio of 1:10(Fe/SNC-10)exhibits a half-wave potential of 0.902 V vs.RHE.After 5000 cycles of cyclic voltammetry,its half-wave potential decreases by only 20 mV vs.RHE,indicating excellent stability.Due to sulfur s lower electronegativity,the electronic structure of the Fe-N_(x)active center is modulated.Additionally,the larger atomic radius of sulfur introduces defects into the carbon support.As a result,Fe/SNC-10 demonstrates superior ORR activity and stability in alkaline solution compared with Fe-loaded N-doped carbon(Fe/NC).Furthermore,the zinc-air battery assembled with the Fe/SNC-10 catalyst shows enhanced performance relative to those assembled with Fe/NC and Pt/C catalysts.This work offers a novel design strategy for advanced energy storage and conversion applications.
基金the financial support provided by the National Natural Science Foundation of China(Grant Nos.51932005 and 21773269)the Joint Research Fund LiaoningShenyang National Laboratory for Materials Science(Grant No.20180510047)Liao Ning Revitalization Talents Program(XLYC1807175)。
文摘The oxygen reduction/evolution reactions(ORR/OER) are a key electrode process in the development of electrochemical energy conversion and storage devices,such as metal-air batteries and reversible fuel cells.The search for low-cost high-performance nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for ORR/OER alternatives to the widely-used noble metal-based catalysts is a research focus.This review aims to outline the opportunities and available options for these nanocarbon-based bifunctional electrocatalysts.Through discussion of some current scientific issues,we summarize the development and breakthroughs of these electrocatalysts.Then we provide our perspectives on these issues and suggestions for some areas in the further work.We hope that this review can improve the interest in nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for ORR/OER.
基金supported by the National Natural Science Foundation of China(22179039)the Introduced Innovative R&D Team of Guangdong(2021ZT09L392)+4 种基金the Fundamental Research Funds for the Central Universities(2022ZYGXZR002)the Pearl River Talent Recruitment Program(2019QN01C693)the Guangdong Basic and Applied Basic Research Foundation(2024A1515010448)Guangzhou Science and Technology Project(2024A04J3079)Zijin Mining Group Co.,Ltd.(5405-ZC-202300008)。
文摘Protonic ceramic electrochemical cells(PCECs)have demonstrated great promise for applications in the generation of electricity,and the synthesis of chemicals(for example,ethylene).However,enhancing the electrochemical reactions kinetics and stability of PCECs electrodes is one grand challenge.Here,we present a novel electrode material via a co-doping of cesium(Cs)and niobium(Nb)on PrBaCo_(2)O_(6-δ)with the composition of PrBa_(0.9)Cs_(0.1)Co_(1.9)Nb_(0.1)O_(6-δ)(PBCCN),which naturally decomposes into dual phases of a double-perovskite PBCCN(DP-PBCCN,~92.3 wt%)and a single-perovskite Ba_(0.9)Cs_(0.1)Co_(0.95)Nb_(0.05)O_(3-δ)(SP-BCCN,~7.7 wt%)under typical powder processing conditions.PBCCN exhibits a low area-specific resistance(ASR)value of 0.107Ωcm^(2),an outstanding performance of 2.04Wcm^(-2)in fuel cell(FC)mode,a current density of-2.84 A cm^(-2)at 1.3 V in electrolysis cell(EC)mode,and promising reversible operational durability of 53 cycles in~212 h at+/-0.5 A cm^(-2)and 650。C.Cs doping generates more oxygen vacancies and accelerates the oxygen exchange kinetics,while Nb doping effectively enhances the stability,as illustrated by the analyses of X-ray photoelectron spectroscopy,and electrical conductivity relaxations.When applied as the positrode for electrochemical non-oxidative dehydrogenation of ethane(C2H6)to ethylene(C2H4)on PCECs,it displays an encouraging C2H6 conversion of 12.75%and a C2H4 selectivity of 98.4%at 1.2 V.
基金supported by the National Natural Science Foundation of China (21375016,20475022 and 21505019)~~
文摘Noble metals, such as platinum, ruthenium and iridium‐group metals, are often used as oxygen reduction or evolution reaction （ORR/OER） electrocatalysts. To reduce the cost and provide an application of bifunctional catalysis, in this work, cobalt oxide supported on nitrogen and phospho‐rus co‐doped carbon （Co3O4/NPC） was fabricated and examined as a bifunctional electrocatalyst for OER and ORR. To prepare Co3O4/NPC, NPC was pyrolyzed from melamine and phytic acid support‐ed on carbon, followed by the solvothermal synthesis of Co3O4 on NPC. Linear sweep voltammetry was used to evaluate the activity for OER and ORR. For OER, Co3O4/NPC showed an onset potential of 0.54 V （versus the saturated calomel electrode） and a current density of 21.95 mA/cm2 at 0.80 V, which was better than both Co3O4/C and NPC. The high activity of Co3O4/NPC was attributed to a synergistic effect of the N, P co‐dopants and Co3O4. For ORR, Co3O4/NPC exhibited an activity close to commercial Pt/C in terms of the diffusion limited current density （–4.49 vs–4.76 mA/cm2 at–0.80 V）, and Co3O4 played the key role for the catalysis. Chronoamperometry （current versus time） was used to evaluate the stability, which showed that Co3O4/NPC maintained 46%current after the chronoamperometry test for OER and 95% current for ORR. Overall, Co3O4/NPC exhibited high activity and improved stability for both OER and ORR.
基金supported by the National Natural Science Foundation of China(Nos.22078118 and 42277219)the Natural Science Foundation of Guangdong Province,China(No.2023A1515010740).
文摘A novel photocatalytic cocatalyst, MoC quantum dots integrated into N-doped carbon microflowers (MoC–NC), was synthesized, establishing a key Mo–N interfacial bond. The Mo–N bond's regulation was achieved by adjusting the pH of Mo-polydopamine precursor solutions. A composite photocatalyst, MoC–NC/CdS (MNS), was formed by in situ growth of nano-CdS on MoC–NC. The pH during synthesis, crucial for Mo–N bond formation, significantly influenced Cr(Ⅵ) reduction and H_(2) evolution performance. The optimal MNS, created at pH 9.0, demonstrated 99.2% reduction efficiency for Cr(Ⅵ) in 20 min and H_(2) evolution rate of 11.4 mmol g^(-1) h^(-1) over 3 h, outperforming Pt/CdS. Mechanistic studies and density functional theory revealed MoC–NC's role in enhancing light absorption, reaction kinetics, and electron transport, attributing to its ultra-small quantum dots and abundant Mo–N bonds.
基金supported by the National Natural Science Foundation of China(21421001 , 21573115)the 111 project (B12015)+1 种基金the Fundamental Research Funds for the Central Universities(63185015)the Foundation of State Key Laboratory of Highefficiency Utilization of Coal and Green Chemical Engineering (2017-K13)
文摘Developing low-cost and highly-efficient electrocatalysts for renewable energy conversion technologies has attracted even-increasing attention. Molybdenum carbide materials have recently emerged as a type of promising catalysts for electrocatalytic reactions due to the earth-abundance and Pt-resembled electrical properties. In this work, taking the advantage of the interaction between the basic groups of the Mo(VI)-melamine polymer and the acidic groups on the surface of the oxidized carbon nanotubes(CNTs), N-doped CNTs supported Mo2C nanoparticles(Mo2C/NCNT) are prepared, which exhibit outstanding electrocatalytic activity and durability for both the hydrogen evolution and oxygen reduction reactions. The impressive performance of Mo2C/NCNT can be attributed to the small size of Mo2C particles, the large exposure ratio of surface sites and the presence of N-doped CNTs. This work enlarges the multi-field applications of molybdenum carbide-base materials as promising non-precious metal electrocatalysts, which is of great significance for sustainable energy-related technologies.
基金supported by the Natural Scientific Foundation of China (21825501)National Key Research and Development Program (2016YFA0202500 and 2016YFA0200102)+1 种基金Australian Research Council (DP160103107, FT170100224)Tsinghua University Initiative Scientific Research Program。
文摘The demand for efficient and environmentally-benign electrocatalysts that help availably harness the renewable energy resources is growing rapidly. In recent years, increasing insights into the design of water electrolysers, fuel cells, and metal–air batteries emerge in response to the need for developing sustainable energy carriers, in which the oxygen evolution reaction and the oxygen reduction reaction play key roles. However, both reactions suffer from sluggish kinetics that restricts the reactivity. Therefore, it is vital to probe into the structure of the catalysts to exploit high-performance bifunctional oxygen electrocatalysts. Spinel-type catalysts are a class of materials with advantages of versatility, low toxicity, low expense, high abundance, flexible ion arrangement, and multivalence structure. In this review, we afford a basic overview of spinel-type materials and then introduce the relevant theoretical principles for electrocatalytic activity, following that we shed light on the structure–property relationship strategies for spinel-type catalysts including electronic structure, microstructure, phase and composition regulation,and coupling with electrically conductive supports. We elaborate the relationship between structure and property, in order to provide some insights into the design of spinel-type bifunctional oxygen electrocatalysts.
基金financially supported by the National Natural Science Foundation of China(51572166)the project funded by China Postdoctoral Science Foundation(2021 M702073)support from the Program for Professors with Special Appointments(Eastern Scholar:TP2014041)at Shanghai Institutions of Higher Learning。
文摘Electrocatalysts are one of the essential components for the devices of high-efficiency green energy storage and conversion,such as metal-air cells,fuel cells,and water electrolysis systems.While catalysts made from noble metals possess high catalytic performance in both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),their scarcity and expensiveness significantly limit large-scale applications.In this regard,metal-free/non-noble metal carbon-based catalysts have become competitive alternatives to replace catalysts made of noble metals.Nevertheless,low catalytic ORR/OER performance is the challenge of carbon-based catalysts for the commercial applications of metal-air batteries.To solve the problem of poor catalytic performance,two strategies have been proposed:(1)controlling the microstructure of the catalysts to expose more active sites as the channels of rapid mass and electron transfer;and(2)reducing the reaction energy barrier by optimizing the electronic structures of the catalysts via surface engineering.Here,we review different types of bifunctional ORR/OER electrocatalysts with the activated surface sites.We focus on how the challenge can be overcome with different methods of material synthesis,structural and surface characterization,performance validation/optimization,to outline the principles of surface modifications behind catalyst designs.In particular,we provide critical analysis in the challenges that we are facing in structural design and surface engineering of bifunctional ORR/OER catalysts and indicate the possible solution for these problems,providing the society with clearer ideas on the practical prospects of noble-metal-free electrocatalysts for their future applications.
基金financial support from the National Natural Science Foundation of China(No.21376257)the Jiangsu Provincial Natural Science Foundation of China(No.BK20131112)
文摘To develop more ideal bifunctional heteroatom-doped carbon electrocatalysts toward the oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) for regenerative fuel cells and rechargeable metal–air batteries, herein, tobacco-derived N-containing ordered mesoporous carbon(N-OMC) electrocatalysts with different N species distributions are designed. Results indicate that the as-prepared N-OMC with more pyrrolic and pyridinic Ns exhibits much higher activities for the ORR and OER than N-OMC with more graphitic N in both acidic and alkaline media, suggesting that the increase of pyrrolic and pyridinic Ns favors the improvement of ORR and OER activities of the N-containing carbon catalysts, and showing a great potential for the designing of more effective, lower-cost ORR and OER bifunctional electrocatalysts for future regenerative fuel cells and rechargeable metal–air batteries.
基金supported by the National Natural Science Foundation of China(Nos.21774073,51690151,21404071,and 21320102006)the National Basic Research Program (No. 2016YFA0201500)
文摘Cobalt and nitrogen codoped carbon materials(Co-N-C) were fabricated by pyrolysis of the mixture of poly(4-vinylpyridine) and cobalt chloride using SiO_2 nanoparticles as hard template, which were the first transition metal/nitrogen-codoped carbon bifunctional electrocatalyst derived from noncarbonizable polymer for ORR and HER. The as-made Co-N-C possessed hierarchical pore structure and high specific surface area, achieving excellent electrocatalytic performances for ORR and HER. Its ORR catalytic performances were comparable to those of Pt/C catalyst and its HER catalytic performances were superior to those of most doped carbon catalysts in KOH electrolyte. Moreover, its bifunctional electrocatalytic performances for ORR and HER were better than those of most bifunctional doped carbon catalysts in alkaline electrolyte.
