Urea holds promise as an alternative water-oxidation substrate in electrolytic cells.High-valence nickelbased spinel,especially after heteroatom doping,excels in urea oxidation reactions(UOR).However,traditional spine...Urea holds promise as an alternative water-oxidation substrate in electrolytic cells.High-valence nickelbased spinel,especially after heteroatom doping,excels in urea oxidation reactions(UOR).However,traditional spinel synthesis methods with prolonged high-temperature reactions lack kinetic precision,hindering the balance between controlled doping and highly active two-dimensional(2D)porous structures design.This significantly impedes the identification of electron configuration-dependent active sites in doped 2D nickel-based spinels.Herein,we present a microwave shock method for the preparation of 2D porous NiCo_(2)O_(4)spinel.Utilizing the transient on-off property of microwave pulses for precise heteroatom doping and 2D porous structural design,non-metal doping(boron,phosphorus,and sulfur)with distinct extranuclear electron disparities serves as straightforward examples for investigation.Precise tuning of lattice parameter reveals the impact of covalent bond strength on NiCo_(2)O_(4)structural stability.The introduced defect levels induce unpaired d-electrons in transition metals,enhancing the adsorption of electron-donating amino groups in urea molecules.Simultaneously,Bode plots confirm the impact mechanism of rapid electron migration caused by reduced band gaps on UOR activity.The prepared phosphorus-doped 2D porous NiCo_(2)O_(4),with optimal electron configuration control,outperforms most reported spinels.This controlled modification strategy advances understanding theoretical structure-activity mechanisms of high-performance 2D spinels in UOR.展开更多
Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electr...Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.展开更多
Urea oxidation reaction(UOR)is an auxiliary water electrolysis hydrogen production technology developed in recent years to replace oxygen evolution reaction and reduce energy consumption,which can produce hydrogen mor...Urea oxidation reaction(UOR)is an auxiliary water electrolysis hydrogen production technology developed in recent years to replace oxygen evolution reaction and reduce energy consumption,which can produce hydrogen more efficiently by low theoretical potential,reduce the average cost of electrochemical hydrogen production,and is a frontier research hotspot for renewable hydrogen energy.Two-dimensional(2D)nanomaterials as electrocatalysts have many favorable potential,such as it can effectively reduce the resistivity of materials and increase the specific surface area with certainty.This paper reviews the application of 2D materials in UOR in alkaline electrolytes.And a cross-sectional comparison of various material performance data including overpotential,Tafel slope,electrochemical active surface area(ECSA)and it stability test was conducted,which could illustrate the differences between materials composed of different elements.In addition,the main challenges hindering the progress of research on 2D materials in urea electrocatalysis processes and promising materials in this field in future are summarized and prospected.It is believed that this review will contribute to designing and analyzing highperformance 2D urea electrocatalysts for water splitting.展开更多
Renewable energy-driven water electrolysis is considered as an environmentally friendly hydrogen(H2)production technology.Replacing the oxygen evolution reaction(OER)with the urea oxidation reaction(UOR)is a more effe...Renewable energy-driven water electrolysis is considered as an environmentally friendly hydrogen(H2)production technology.Replacing the oxygen evolution reaction(OER)with the urea oxidation reaction(UOR)is a more effective way to improve the energy efficiency of H2 generation.Herein,a highly effi-cient 2D NiFeMo-based UOR catalyst and 1D NiFeMo-based HER catalyst are prepared by adjusting the concentration of MoO_(4)^(-).The MoO_(4)^(-)can serve as the key regulator to adjust the balance between the electrolytic dissociation(α)of the reactants and the supersaturation(S)to modulate the morphological and electronic structure.The prepared 2D NiFeMo nanosheet UOR catalyst and 1D NiFeMo nanorod HER catalyst can achieve a current density of 100 mA cm^(−2)at a potential of 1.36 and 0.062 V,respectively.In a HER/UOR system,a cell voltage of 1.58 V is needed to achieve a current density of 100 mA cm^(−2).The HER/UOR system operated stably for over 60 h with 3 times the direct water electrolysis current den-sity.Moreover,the in situ Raman characterization coupled with XPS analysis clarifies that the addition of high-valence Mo can lower the transition energy barrier between the low and high oxidation state of Ni,which in turn lowers the overpotential of UOR.This work provides a novel strategy for synthesizing morphology-dependent electrocatalysts for different catalytic systems.展开更多
Corrosion engineering is an effective way to improve the oxygen evolution reaction(OER)activity of al-loys.However,the impact of grain boundary corrosion on the structure and electrochemical performance of alloy is st...Corrosion engineering is an effective way to improve the oxygen evolution reaction(OER)activity of al-loys.However,the impact of grain boundary corrosion on the structure and electrochemical performance of alloy is still unknown.Herein,the vacuum arc-melted CrCoNiFe alloys with interlaced network struc-tures via grain boundary corrosion methods were fabricated.The grain boundaries that existed as de-fects were severely corroded and an interlaced network structure was formed,promoting the exposure of the active site and the release of gas bubbles.Besides,the(oxy)hydroxides layer(25 nm)on the sur-face could act as the true active center and improve the surface wettability.Benefiting from the unique structure and constructed surface,the CrCoNiFe-12 affords a high urea oxidation reaction(UOR)perfor-mance with the lowest overpotential of 250 mV at 10 mA/cm^(2)in 1 M KOH adding 0.33 M urea.The CrCoNiFe-12||Pt only required a cell voltage of 1.485 V to afford 10 mA/cm^(2)for UOR and long-term sta-bility of 100 h at 10 mA/cm^(2)(27.6 mV decrease).These findings offer a facile strategy for designing bulk multiple-principal-element alloy electrodes for energy conversion.展开更多
Urea oxidation reaction (UOR),which has favorable thermodynamic energy barriers compared with oxygen evolution reaction (OER),can provide more cost-effective electrons for the renewable energy systems,but is trapped b...Urea oxidation reaction (UOR),which has favorable thermodynamic energy barriers compared with oxygen evolution reaction (OER),can provide more cost-effective electrons for the renewable energy systems,but is trapped by its sluggish UOR kinetics and intricate reaction intermediates formation/desorption process.Herein,we report a novel and effective electrocatalyst consisting of carbon cloth supported nitrogen vacancies-enriched Ce-doped Ni_(3)N hierarchical nanosheets (Ce-Ni_(3)N @CC) to optimize the flat-footed UOR kinetics,especially the stiff rate-determine CO_(2)desorption step of UOR.Upon the introduction of valance state variable Ce,the resultant nitrogen vacancies enriched Ce-Ni_(3)N @CC exhibits an enhanced UOR performance where the operation voltage requires only 1.31 V to deliver the current density of 10 mA cm^(-2),which is superior to that of Ni_(3)N @CC catalyst (1.36 V) and other counterparts.Density functional theory (DFT) results demonstrate that the incorporation of Ce in Ni_(3)N lowers the formation energy of nitrogen vacancies,resulting in rich nitrogen vacancies in Ce-Ni_(3)N @CC.Moreover,the nitrogen vacancies together with Ce doping optimize the local charge distribution around Ni sites,and balance the adsorption energy of CO_(2)in the rate-determining step (RDS),as well as affect the initial adsorption structure of urea,leading to the superior UOR catalytic performance of Ce-Ni_(3)N @CC.When integrating the Ce-Ni_(3)N catalyst in UOR//HER and UOR//CO_(2)R flow electrolyzer,both of them perform well with low operation voltage and robust long-term stability,proofing that the thermodynamically favorable UOR can act as a suitable substitute anodic reaction compared with that of OER.Our findings here not only provide a novel UOR catalyst but also offer a promising design strategy for the future development of energy-related devices.展开更多
Highly active and low-cost catalytic electrodes for urea oxidation reaction(UOR)are always crucial for exploration of urea fuel cells.Herein,novel york-shell-structural Ni_(2)P/C na nosphere hybrids(Ni_(2)P/C-YS)are r...Highly active and low-cost catalytic electrodes for urea oxidation reaction(UOR)are always crucial for exploration of urea fuel cells.Herein,novel york-shell-structural Ni_(2)P/C na nosphere hybrids(Ni_(2)P/C-YS)are rationally constructed via a hydrothermal method and subsequent phosphidation treatment under different temperature ranging from 250℃to 450℃for UOR applications.In the in-situ constructed hollow york-shell structure,the coupling of conductive carbon materials and active Ni_(2)P allows numerous interfaces facilitating the electron transfer and thereby accelerating the catalytic kinetics.The results demonstrate that Ni_(2)P/C-YS-350 nanocomposite can boost the UOR process with a low potential of 1.366 V vs.RHE at a current density of 50 mA/cm^(2) in alkaline electrolyte and afford the superior durability with negligible potential decay after 23 h.This study presents that the carbon coated Ni_(2)P hybrid with the optimized crystallinities and hollow york-shell configurations can be a promising candidate for application in urea fuel cells.展开更多
Urea oxidation is a significant reaction for utilizing urea-rich wastewater or human urine as sustainable power sources which can ease the water eutrophication while generate electricity. A direct urea-hydrogen peroxi...Urea oxidation is a significant reaction for utilizing urea-rich wastewater or human urine as sustainable power sources which can ease the water eutrophication while generate electricity. A direct urea-hydrogen peroxide fuel cell is a new kind of fuel cell employing urea as fuel and hydrogen peroxide as oxidant which possesses a larger cell voltage. Herein, this work tries to promote the kinetics process of urea oxidation by preparing low-cost and high-efficient NiCo2S4 nanowires modified carbon sponge electrode. The carbon sponge used in this work with a similar three-dimensional multi-channel structure to Ni foam, is prepared by carbonizing recycled polyurethane sponge which is also a process of recycling waste. The performance of the prepared catalyst in an alkaline solution is investigated in a three-electrode system.With the introduction of Co element to the catalyst, a reduced initial urea oxidation potential and a high performance are obtained. Furthermore, a direct urea-hydrogen peroxide fuel cell is assembled using the NiCo2S4 nanowires modified carbon sponge anode. Results indicate that the prepared catalyst provides a chance to solve the current problems that hinder the development of urea electrooxidation(high initial urea oxidation potential, low performance, and high electrode costs).展开更多
Two-dimensional coordination polymers(CPs) have aroused tremendous interest as electrocatalysts because the catalytic performance could be fine-tuned by their well-designed coordination layers with highly accessible a...Two-dimensional coordination polymers(CPs) have aroused tremendous interest as electrocatalysts because the catalytic performance could be fine-tuned by their well-designed coordination layers with highly accessible and active metal sites.However,it remains great challenge for CP-based catalysts to be utilized for electrocatalytic oxidation reactions due to their inefficient activities and low catalytic stabilities.Herein,we applied a mixed-metal strategy to fabricate two-dimensional Co_xNi_(1-x)-CPs with dual active sites for electrocatalytic water and urea oxidation.By metal ratio regulation in the twodimensional layer,an optimized Co_(2/3)Ni_(1/3)-CP exhibits a water oxidation performance with an overpotential of 325 mV at a current density of 10 mA cm^(-2) and a Tafel slope of 86 mV dec^(-1) in alkaline solution for oxygen evolution reaction.Importantly,a lower potential than that of commercial RuO_(2) is observed over20 mA cm^(-2).Co_(2/3)Ni_(1/3)-CP also displays a potential of 1.381 V at 10 mA cm^(-2) for urea oxidation reaction and a Tafel slope of 124 mV dec^(-1).This mixed-metal strategy to maximize synergistic effect of different metal centers may ultimately lead to promising electrocatalysts for small molecule oxidation reaction.展开更多
From the perspective of electronic structure modulation,it is highly desirable to rationally design the active urea oxidation reaction(UOR)catalysts through interface engineering.The binary cooperative heterostructure...From the perspective of electronic structure modulation,it is highly desirable to rationally design the active urea oxidation reaction(UOR)catalysts through interface engineering.The binary cooperative heterostructure systems have been shown significant enhancement for catalyzing UOR,but their performance still remains unsatisfactory for industrialization because of the unfavorable intermediate adsorption/desorption and deficient electron transfer channels.In response,taking the ternary cooperative Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4) heterostructure as the proof-of-concept paradigm,a catalytic model is rationally put forward to elucidate the UOR promotion mechanism at the molecular level.The rod-like Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4) nanoarrays with three-phase heterojunction are experimentally fabricated on Ni foam(named as Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4)/NF)via simple two-step processes.The density functional theory calculations disclose that construction of Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4) heterostructure model not only induce charge redistribution at the interfacial region for creating innumerable electron transfer channels,but also endow it with a moderate d-band center that could help to build a balance between adsorption and desorption of diverse UOR intermediates.Benefiting from the unique rod-like nanoarrays with large specific surface area and the optimized electronic structure,the well-designed Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4)/NF could act as a robust catalyst for driving UOR at industrial-level current densities under tough environments,offering great potential for commercial applications.展开更多
The urea oxidization reaction(UOR)is an important anodic reaction in electro-catalytic energy conversion.However,the sluggish reaction kinetics and complex catalyst transformation in electrocatalysis require activity ...The urea oxidization reaction(UOR)is an important anodic reaction in electro-catalytic energy conversion.However,the sluggish reaction kinetics and complex catalyst transformation in electrocatalysis require activity improvement and better mechanistic understanding of the state-of-the-art Ni(OH)_(2) catalyst.Herein,by utilizing low-temperature argon(Ar)plasma processing,tooth-wheel Ni(OH)_(2) nanosheets self-supported on Ni foam(Ni(OH)_(2)-Ar)are demonstrated to have improved UOR activity compared to conventional Ni(OH)_(2).The theoretical assessment confirms that the edge has a smaller cation vacancy formation energy than the basal plane,consequently explaining the structural formation.Operando and quasi-operando methods are employed to investigate the dynamic evolution of the Ni(OH)_(2) film in UOR.The crucial dehydrogenation products of Ni(OH)_(5)O^(-)intermediates are identified to be stable on the etched edge and explain the enhanced UOR in the low potential region.In addition,the dynamic active sites are monitored to elucidate the reaction mechanism in different potential ranges.展开更多
The electrochemical conversion of carbon dioxide(CO_(2))into chemical fuels represents a promising approach for addressing global carbon balance issues.However,this process is hindered by the kinetic limitations of an...The electrochemical conversion of carbon dioxide(CO_(2))into chemical fuels represents a promising approach for addressing global carbon balance issues.However,this process is hindered by the kinetic limitations of anodic reactions,usually the oxygen evolution reaction,resulting in less efficient production of high value-added products.Here,we report an integrated electrocatalytic system that couples CO_(2)reduction reaction(CO_(2)RR)with urea oxidation reaction(UOR)using a bifunctional electrocatalyst with atomically dispersed dual-metal CuNi sites anchored on bamboo-like nitrogen-doped carbon nanotubes(CuNi-CNT),which were synthesized through a one-step pyrolysis process.The bifunctional CuNi-CNT catalyst exhibits a near 100%CO Faraday efficiency for CO_(2)RR over a wide potential range and outstanding UOR performance with a negatively shifted potential of 210 mV at 10 mA·cm^(-2).In addition,we assemble a two-electrode electrolyzer using bifunctional CuNi-CNT-modified carbon fiber paper electrodes as both cathode and anode,capable of operating at a remarkably low cell voltage of 1.81 V at 10 mA·cm-2,significantly lower than conventional setups.The study provides a novel avenue to achieving an efficient carbon cycle with reduced electric power consumption.展开更多
The electrocatalytic urea oxidation reaction(UOR)is a promising strategy for addressing both environmental remediation and energy conversion challenges.Recently,heterojunction catalysts have gained significant attenti...The electrocatalytic urea oxidation reaction(UOR)is a promising strategy for addressing both environmental remediation and energy conversion challenges.Recently,heterojunction catalysts have gained significant attention due to their enhanced catalytic activity and stability.This review provides a comprehensive analysis of recent advancements in heterojunction catalysts for UOR.We begin by outlining the fundamental principles of UOR and key catalyst evaluation parameters.Next,we discuss the unique features of heterojunction catalysts,highlighting their structural and electronic advantages.The applications of various heterojunction architectures—including those based on transition metals,alloys,metal(hydro)oxides,chalcogenides,pnictides,and metal-organic frameworks—are then examined in detail.A particular focus is placed on structure-performance relationships and rational design strategies to optimize catalytic efficiency.This review offers valuable insights into the development of next-generation heterojunction catalysts for efficient and sustainable UOR applications.展开更多
Urea oxidation reaction(UOR)instead of anodic oxygen evolution reaction(OER)is considered an effective way to reduce energy consumption in electrocatalytic water splitting for hydrogen production.Nevertheless,the slow...Urea oxidation reaction(UOR)instead of anodic oxygen evolution reaction(OER)is considered an effective way to reduce energy consumption in electrocatalytic water splitting for hydrogen production.Nevertheless,the slow rate of reaction of UOR,which entails a procedure of transferring six electrons,has hindered its widespread use.Therefore,it is crucial to design highly effective electrocatalysts for the implementation of UOR.Herein,a novel NiCo-hydroxysulfide(NiCo-HOS)electrocatalyst has been reported for UOR,which is obtained by the exchange of sulfur ions in NiCo layered double hydroxide(NiCo-LDH)nanosheets at room temperature.Benefitting from the sulfurization process,the composition,electronic structure,and surface properties of electrocatalysts have undergone significant changes and optimizations.Following sulfurization treatment,the resulting NiCo-HOS showed enhanced chemical resistance to alkaline electrolytes and improved electrical conductivity.In a 40 h operation test,it maintained high stability and provided a stable current density of 100 mA cm^(-2)at a relatively low potential of 1.33 V(vs.RHE)in a solution of 1 mol L^(-1)KOH+0.5 mol L^(-1)urea.Subsequently,the anode electrolytic product is analyzed through gas chromatography(GC),and N_2 is detected as the product without the presence of CO,indicating that the urea has undergone complete oxidation.展开更多
Urea oxidation reaction(UOR)electrocatalysis,a promising anodic reaction with lower overpotentials than the oxygen evolution reaction,can work in tandem with many cathodic reactions to improve energy-conversion effici...Urea oxidation reaction(UOR)electrocatalysis,a promising anodic reaction with lower overpotentials than the oxygen evolution reaction,can work in tandem with many cathodic reactions to improve energy-conversion efficiencies.Among other catalysts,single-atom catalysts(SACs)possess immense potential as high-performance and low-cost catalysts towards UOR,owing to their numerous advantages such as metal-utilization efficiency and low-coordination metal sites.Nevertheless,systematic studies remain unexplored for the local coordination structures of SACs regulating their UOR pathways,which severely impedes further performance advancement.Here,we aim to construct the mechanistic picture of UOR pathways on SACs,using two nickel-single-atom enriched conjugated coordination polymers(named Ni-N-CP and Ni-O-CP)with well-defined NiN_(4)and NiO4 coordination structures for the proof-of-concept studies.The Ni-O-CP exhibits exceptional UOR performance with a turnover frequency of 0.51 s^(-1),significantly outperforming the Ni-N-CP(0.38 s^(-1))and other state-of-the-art SACs towards UOR.Our theoretical calculations combined with in-situ Fourier transform infrared and ultraviolet-visible spectroscopy measurements elucidate that two UOR pathways towards NO_(2)^(-)and N_(2)products were identified,which critically depends on the participation of the as-generated ammonia species in the UOR process.This work provides insights for regulating the activity and selectivity of UOR electrocatalysis.展开更多
Ni-based electrocatalysts are considered a promising choice for urea-assisted hydrogen production.However,its application remains challenging owing to the high occupancy of d orbital at the Ni site,which suppresses th...Ni-based electrocatalysts are considered a promising choice for urea-assisted hydrogen production.However,its application remains challenging owing to the high occupancy of d orbital at the Ni site,which suppresses the reactant adsorption to achieve satisfactory urea oxidation reaction(UOR)and hydrogen evolution reaction(HER)activity.Herein,the WO_(3) site with empty d orbital is introduced into Ni_(3)S_(2) to construct dual active sites for regulating the adsorption of reactive molecules.Experimental and theoretical calculations indicate that the electron transfer from Ni_(3)S_(2) to WO_(3) forms electron-deficient Ni with sufficient empty d orbitals for optimizing urea/H_(2)O adsorption and tuning the adsorption behavior of the amino and carbonyl groups in urea.Consequently,the Ni_(3)S_(2)-WO_(3)/NF presents a remarkably low potential of 1.38 V to reach 10 mA cm^(-2) for UOR-assisted HER.This work highlights the significance of constructing synergistic dual active sites toward developing advanced catalysts for urea-assisted hydrogen production.展开更多
Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierar...Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary structure.Notably,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical NiCo-LDH.Employing NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of OER.This work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.展开更多
Developing efficient bifunctional catalysts for urea oxidation reaction(UOR)/hydrogen evolution reaction(HER)is important for energy-saving hydrogen production.Herein,a catalyst with crystalline-amorphous hetero-struc...Developing efficient bifunctional catalysts for urea oxidation reaction(UOR)/hydrogen evolution reaction(HER)is important for energy-saving hydrogen production.Herein,a catalyst with crystalline-amorphous hetero-structure supported by NiCo alloy on nickel foam(NiCoO-MoOx/NC)is reported for the first time.Through simple molybdenum salt etching,2D NiCo alloy nanosheets are transformed into a unique 3D cycad-leaf-like structure with a super-hydrophilic surface.Simultaneously,the synergistic effect between crystalline NiCoO and amor-phous MoOx improves the UOR and HER activity,merely requiring 1.28 V and-45 mV potentials to reach±10 mA cm-2,respectively.Particularly,the UOR kinetics of NiCoO-MoOx/NC is enhanced significantly compared to that of NiCoO/NC.The electronic structure of NiCoO is modified by MoOx,enabling the rapid generation of NiOOH and CoOOH active species,which would accelerate the synergistic electrocatalytic oxidation of urea molecules.This work inspires the design of highly active and stable bifunctional catalysts for urea assisted H2 production.展开更多
To address the high cost and limited electrochemical endurance of Pt-based electrocatalysts,the appropriate introduction of transition metal-based compounds as supports to disperse and anchor Pt species offers a promi...To address the high cost and limited electrochemical endurance of Pt-based electrocatalysts,the appropriate introduction of transition metal-based compounds as supports to disperse and anchor Pt species offers a promising approach for improving catalytic efficiency.In this study,sub-1 nm Pt nanoclusters were uniformly confined on NiO supports with a hierarchical nanotube/nanosheet structure(Pt/NiO/NF)through a combination of spatial domain confinement and annealing.The resulting catalyst exhibited excellent electrocatalytic activity and stability for hydrogen evolution(HER)and urea oxidation reactions(UOR)under alkaline conditions.Structural characterization and density functional theory calculations demonstrated that sub-1 nm Pt nanoclusters were immobilized on the NiO supports by Pt–O–Ni bonds at the interface.The strong metal-support interaction induced massive charge redistribution around the heterointerface,leading to the formation of multiple active sites.The Pt/NiO/NF catalyst only required an overpotential of 12 and 136 mV to actuate current densities of 10 and 100 mA cm^(-2) for the HER,respectively,and maintained a voltage retention of 96%for 260 h of continuous operation at a current density of 500 mA cm^(-2).Notably,in energy-efficient hydrogen production systems coupled with the HER and UOR,the catalyst required cell voltages of 1.37 and 1.53 V to drive current densities of 10 and 50 mA cm^(-2),respectively—approximately 300 mV lower than conventional water electrolysis systems.This study presents a novel pathway for designing highly efficient and robust sub-nanometer metal cluster catalysts.展开更多
Urea-assisted water electrolysis offers a promising route to reduce energy consumption for hydrogen production and meanwhile treat urea-rich wastewater.Herein,we devised a shear force-involved polyoxometalate-organic ...Urea-assisted water electrolysis offers a promising route to reduce energy consumption for hydrogen production and meanwhile treat urea-rich wastewater.Herein,we devised a shear force-involved polyoxometalate-organic supramolecular self-assembly strategy to fabricate 3D hierarchical porous nanoribbon assembly Mn-VN cardoons.A bimetallic polyoxovanadate(POV)with the inherent structural feature of Mn surrounded by[VO_(6)]octahedrons was introduced to trigger precise Mn incorporation in VN lattice,thereby achieving simultaneous morphology engineering and electronic structure modulation.The lattice contraction of VN caused by Mn incorporation drives electron redistribution.The unique hierarchical architecture with modulated electronic structure that provides more exposed active sites,facilitates mass and charge transfer,and optimizes the associated adsorption behavior.Mn-VN exhibits excellent activity with low overpotentials of 86 m V and 1.346 V at 10 m A/cm^(2)for hydrogen evolution reaction(HER)and urea oxidation reaction(UOR),respectively.Accordingly,in the two-electrode urea-assisted water electrolyzer utilizing Mn-VN as a bifunctional catalyst,hydrogen production can occur at low voltage(1.456 V@10 m A/cm^(2)),which has the advantages of energy saving and competitive durability over traditional water electrolysis.This work provides a simple and mild route to construct nanostructures and modulate electronic structure for designing high-efficiency electrocatalysts.展开更多
基金financial support from the National Natural Science Foundation of China(52203070)the Open Fund of State Key Laboratory of New Textile Materials and Advanced Processing Technologies(FZ2022005)+2 种基金the Open Fund of Hubei Key Laboratory of Biomass Fiber and Ecological Dyeing and Finishing(STRZ202203)the financial support provided by the China Scholarship Council(CSC)Visiting Scholar Programfinancial support from Institute for Sustainability,Energy and Resources,The University of Adelaide,Future Making Fellowship。
文摘Urea holds promise as an alternative water-oxidation substrate in electrolytic cells.High-valence nickelbased spinel,especially after heteroatom doping,excels in urea oxidation reactions(UOR).However,traditional spinel synthesis methods with prolonged high-temperature reactions lack kinetic precision,hindering the balance between controlled doping and highly active two-dimensional(2D)porous structures design.This significantly impedes the identification of electron configuration-dependent active sites in doped 2D nickel-based spinels.Herein,we present a microwave shock method for the preparation of 2D porous NiCo_(2)O_(4)spinel.Utilizing the transient on-off property of microwave pulses for precise heteroatom doping and 2D porous structural design,non-metal doping(boron,phosphorus,and sulfur)with distinct extranuclear electron disparities serves as straightforward examples for investigation.Precise tuning of lattice parameter reveals the impact of covalent bond strength on NiCo_(2)O_(4)structural stability.The introduced defect levels induce unpaired d-electrons in transition metals,enhancing the adsorption of electron-donating amino groups in urea molecules.Simultaneously,Bode plots confirm the impact mechanism of rapid electron migration caused by reduced band gaps on UOR activity.The prepared phosphorus-doped 2D porous NiCo_(2)O_(4),with optimal electron configuration control,outperforms most reported spinels.This controlled modification strategy advances understanding theoretical structure-activity mechanisms of high-performance 2D spinels in UOR.
基金supported by the National Natural Science Foundation of China(21872040,22162004)the Excellent Scholars and Innovation Team of Guangxi Universities,the Innovation Project of Guangxi Graduate Education(YCBZ2022038)the High-performance Computing Platform of Guangxi University.
文摘Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.
基金financially supported by the National Key Research and Development Program of China(No.2020YFB1713500)the Major Science and Technology Projects of Henan Province(No.221100230200)+3 种基金Program for Innovative Research Team(in Science and Technology)in University of Henan Province(No.23IRTSTHN009)the Project of Science and Technology Department of Henan Province(Nos.232102241034 and 222102240074)the Natural Science Foundation of Suzhou University of Science and Technology(No.XKQ2020002)the Natural Science Foundation of Jiangsu Higher Education Institutions of China(No.22KJB530009)。
文摘Urea oxidation reaction(UOR)is an auxiliary water electrolysis hydrogen production technology developed in recent years to replace oxygen evolution reaction and reduce energy consumption,which can produce hydrogen more efficiently by low theoretical potential,reduce the average cost of electrochemical hydrogen production,and is a frontier research hotspot for renewable hydrogen energy.Two-dimensional(2D)nanomaterials as electrocatalysts have many favorable potential,such as it can effectively reduce the resistivity of materials and increase the specific surface area with certainty.This paper reviews the application of 2D materials in UOR in alkaline electrolytes.And a cross-sectional comparison of various material performance data including overpotential,Tafel slope,electrochemical active surface area(ECSA)and it stability test was conducted,which could illustrate the differences between materials composed of different elements.In addition,the main challenges hindering the progress of research on 2D materials in urea electrocatalysis processes and promising materials in this field in future are summarized and prospected.It is believed that this review will contribute to designing and analyzing highperformance 2D urea electrocatalysts for water splitting.
基金supported by the National Natural Science Foundation of China(No.22308322)the Science Foundation of Donghai Laboratory(No.DH-2022ZY0010)the R&D Project of State Grid Corporation of China(No.5108-202218280A-2-439-XG).
文摘Renewable energy-driven water electrolysis is considered as an environmentally friendly hydrogen(H2)production technology.Replacing the oxygen evolution reaction(OER)with the urea oxidation reaction(UOR)is a more effective way to improve the energy efficiency of H2 generation.Herein,a highly effi-cient 2D NiFeMo-based UOR catalyst and 1D NiFeMo-based HER catalyst are prepared by adjusting the concentration of MoO_(4)^(-).The MoO_(4)^(-)can serve as the key regulator to adjust the balance between the electrolytic dissociation(α)of the reactants and the supersaturation(S)to modulate the morphological and electronic structure.The prepared 2D NiFeMo nanosheet UOR catalyst and 1D NiFeMo nanorod HER catalyst can achieve a current density of 100 mA cm^(−2)at a potential of 1.36 and 0.062 V,respectively.In a HER/UOR system,a cell voltage of 1.58 V is needed to achieve a current density of 100 mA cm^(−2).The HER/UOR system operated stably for over 60 h with 3 times the direct water electrolysis current den-sity.Moreover,the in situ Raman characterization coupled with XPS analysis clarifies that the addition of high-valence Mo can lower the transition energy barrier between the low and high oxidation state of Ni,which in turn lowers the overpotential of UOR.This work provides a novel strategy for synthesizing morphology-dependent electrocatalysts for different catalytic systems.
基金supported by the National Natu-ral Science Foundation of China(No.52102210)the Natural Sci-ence Foundation of Sichuan Province(Nos.2022NSFSC2005 and 2022NSFSC1255)+1 种基金the Opening Project of Key Laboratory of Op-toelectronic Chemical Materials and Devices of Ministry of Educa-tion,Jianghan University(No.JDGD-202218)Supplementary materials Supplementary material associated with this article can be found,in the online version,at doi:10.1016/j.jmst.2024.01.096.106。
文摘Corrosion engineering is an effective way to improve the oxygen evolution reaction(OER)activity of al-loys.However,the impact of grain boundary corrosion on the structure and electrochemical performance of alloy is still unknown.Herein,the vacuum arc-melted CrCoNiFe alloys with interlaced network struc-tures via grain boundary corrosion methods were fabricated.The grain boundaries that existed as de-fects were severely corroded and an interlaced network structure was formed,promoting the exposure of the active site and the release of gas bubbles.Besides,the(oxy)hydroxides layer(25 nm)on the sur-face could act as the true active center and improve the surface wettability.Benefiting from the unique structure and constructed surface,the CrCoNiFe-12 affords a high urea oxidation reaction(UOR)perfor-mance with the lowest overpotential of 250 mV at 10 mA/cm^(2)in 1 M KOH adding 0.33 M urea.The CrCoNiFe-12||Pt only required a cell voltage of 1.485 V to afford 10 mA/cm^(2)for UOR and long-term sta-bility of 100 h at 10 mA/cm^(2)(27.6 mV decrease).These findings offer a facile strategy for designing bulk multiple-principal-element alloy electrodes for energy conversion.
基金financially supported by the National Natural Science Foundation of China (22109073, 22072067 and 21875112)the supports from National and Local Joint Engineering Research Center of Biomedical Functional Materialsa project sponsored by the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Urea oxidation reaction (UOR),which has favorable thermodynamic energy barriers compared with oxygen evolution reaction (OER),can provide more cost-effective electrons for the renewable energy systems,but is trapped by its sluggish UOR kinetics and intricate reaction intermediates formation/desorption process.Herein,we report a novel and effective electrocatalyst consisting of carbon cloth supported nitrogen vacancies-enriched Ce-doped Ni_(3)N hierarchical nanosheets (Ce-Ni_(3)N @CC) to optimize the flat-footed UOR kinetics,especially the stiff rate-determine CO_(2)desorption step of UOR.Upon the introduction of valance state variable Ce,the resultant nitrogen vacancies enriched Ce-Ni_(3)N @CC exhibits an enhanced UOR performance where the operation voltage requires only 1.31 V to deliver the current density of 10 mA cm^(-2),which is superior to that of Ni_(3)N @CC catalyst (1.36 V) and other counterparts.Density functional theory (DFT) results demonstrate that the incorporation of Ce in Ni_(3)N lowers the formation energy of nitrogen vacancies,resulting in rich nitrogen vacancies in Ce-Ni_(3)N @CC.Moreover,the nitrogen vacancies together with Ce doping optimize the local charge distribution around Ni sites,and balance the adsorption energy of CO_(2)in the rate-determining step (RDS),as well as affect the initial adsorption structure of urea,leading to the superior UOR catalytic performance of Ce-Ni_(3)N @CC.When integrating the Ce-Ni_(3)N catalyst in UOR//HER and UOR//CO_(2)R flow electrolyzer,both of them perform well with low operation voltage and robust long-term stability,proofing that the thermodynamically favorable UOR can act as a suitable substitute anodic reaction compared with that of OER.Our findings here not only provide a novel UOR catalyst but also offer a promising design strategy for the future development of energy-related devices.
基金financially supported by the National Key Research and Development Program of China(No.2017YFE0120500)the National Natural Science Foundation of China(Nos.51804223 and 51972129)+4 种基金CAS Key Laboratory of Nano-Bio Interface(No.19ZY01)the South Xinjiang Innovation and Development Program of Key Industries of Xinjiang Production and Construction Corps(No.2020DB002)the Scientific Research Foundation of Wuhan Institute of Technology(No.K201761)the Fundamental Research Funds for the Central Universities(Nos.HUST 2018KFYYXJJ051,2019KFYXMBZ076)the Hubei"Chu-Tian Young Scholar"Program。
文摘Highly active and low-cost catalytic electrodes for urea oxidation reaction(UOR)are always crucial for exploration of urea fuel cells.Herein,novel york-shell-structural Ni_(2)P/C na nosphere hybrids(Ni_(2)P/C-YS)are rationally constructed via a hydrothermal method and subsequent phosphidation treatment under different temperature ranging from 250℃to 450℃for UOR applications.In the in-situ constructed hollow york-shell structure,the coupling of conductive carbon materials and active Ni_(2)P allows numerous interfaces facilitating the electron transfer and thereby accelerating the catalytic kinetics.The results demonstrate that Ni_(2)P/C-YS-350 nanocomposite can boost the UOR process with a low potential of 1.366 V vs.RHE at a current density of 50 mA/cm^(2) in alkaline electrolyte and afford the superior durability with negligible potential decay after 23 h.This study presents that the carbon coated Ni_(2)P hybrid with the optimized crystallinities and hollow york-shell configurations can be a promising candidate for application in urea fuel cells.
基金the financial support of this study by the Ph.D.Student Research and Innovation Fund of the Fundamental Research Funds for the Central Universities(grant number GK6530260034)the National Natural Science Foundation of China(grant numbers:51572052)。
文摘Urea oxidation is a significant reaction for utilizing urea-rich wastewater or human urine as sustainable power sources which can ease the water eutrophication while generate electricity. A direct urea-hydrogen peroxide fuel cell is a new kind of fuel cell employing urea as fuel and hydrogen peroxide as oxidant which possesses a larger cell voltage. Herein, this work tries to promote the kinetics process of urea oxidation by preparing low-cost and high-efficient NiCo2S4 nanowires modified carbon sponge electrode. The carbon sponge used in this work with a similar three-dimensional multi-channel structure to Ni foam, is prepared by carbonizing recycled polyurethane sponge which is also a process of recycling waste. The performance of the prepared catalyst in an alkaline solution is investigated in a three-electrode system.With the introduction of Co element to the catalyst, a reduced initial urea oxidation potential and a high performance are obtained. Furthermore, a direct urea-hydrogen peroxide fuel cell is assembled using the NiCo2S4 nanowires modified carbon sponge anode. Results indicate that the prepared catalyst provides a chance to solve the current problems that hinder the development of urea electrooxidation(high initial urea oxidation potential, low performance, and high electrode costs).
基金supported by the National Natural Science Foundation of China (Grant number 21622105 and 21931004)the Natural Science Foundation of Tianjin (Grant number 18JCJQJC47200)+2 种基金the Fundamental Research Funds for the Central UniversitiesNankai University (63201016 and 63201043)the Ministry of Education of China (Grant number B12015)。
文摘Two-dimensional coordination polymers(CPs) have aroused tremendous interest as electrocatalysts because the catalytic performance could be fine-tuned by their well-designed coordination layers with highly accessible and active metal sites.However,it remains great challenge for CP-based catalysts to be utilized for electrocatalytic oxidation reactions due to their inefficient activities and low catalytic stabilities.Herein,we applied a mixed-metal strategy to fabricate two-dimensional Co_xNi_(1-x)-CPs with dual active sites for electrocatalytic water and urea oxidation.By metal ratio regulation in the twodimensional layer,an optimized Co_(2/3)Ni_(1/3)-CP exhibits a water oxidation performance with an overpotential of 325 mV at a current density of 10 mA cm^(-2) and a Tafel slope of 86 mV dec^(-1) in alkaline solution for oxygen evolution reaction.Importantly,a lower potential than that of commercial RuO_(2) is observed over20 mA cm^(-2).Co_(2/3)Ni_(1/3)-CP also displays a potential of 1.381 V at 10 mA cm^(-2) for urea oxidation reaction and a Tafel slope of 124 mV dec^(-1).This mixed-metal strategy to maximize synergistic effect of different metal centers may ultimately lead to promising electrocatalysts for small molecule oxidation reaction.
基金funding and supporting this work through Research Partnership Program(No.RP-21-09-75)。
文摘From the perspective of electronic structure modulation,it is highly desirable to rationally design the active urea oxidation reaction(UOR)catalysts through interface engineering.The binary cooperative heterostructure systems have been shown significant enhancement for catalyzing UOR,but their performance still remains unsatisfactory for industrialization because of the unfavorable intermediate adsorption/desorption and deficient electron transfer channels.In response,taking the ternary cooperative Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4) heterostructure as the proof-of-concept paradigm,a catalytic model is rationally put forward to elucidate the UOR promotion mechanism at the molecular level.The rod-like Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4) nanoarrays with three-phase heterojunction are experimentally fabricated on Ni foam(named as Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4)/NF)via simple two-step processes.The density functional theory calculations disclose that construction of Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4) heterostructure model not only induce charge redistribution at the interfacial region for creating innumerable electron transfer channels,but also endow it with a moderate d-band center that could help to build a balance between adsorption and desorption of diverse UOR intermediates.Benefiting from the unique rod-like nanoarrays with large specific surface area and the optimized electronic structure,the well-designed Ni_5P_(4)/NiSe_(2)/Ni_(3)Se_(4)/NF could act as a robust catalyst for driving UOR at industrial-level current densities under tough environments,offering great potential for commercial applications.
基金the financial support from City University of Hong Kong Strategic Research Grant(SRG)(7005505)the National Natural Science Foundation of China(51601136 and 51604202)。
文摘The urea oxidization reaction(UOR)is an important anodic reaction in electro-catalytic energy conversion.However,the sluggish reaction kinetics and complex catalyst transformation in electrocatalysis require activity improvement and better mechanistic understanding of the state-of-the-art Ni(OH)_(2) catalyst.Herein,by utilizing low-temperature argon(Ar)plasma processing,tooth-wheel Ni(OH)_(2) nanosheets self-supported on Ni foam(Ni(OH)_(2)-Ar)are demonstrated to have improved UOR activity compared to conventional Ni(OH)_(2).The theoretical assessment confirms that the edge has a smaller cation vacancy formation energy than the basal plane,consequently explaining the structural formation.Operando and quasi-operando methods are employed to investigate the dynamic evolution of the Ni(OH)_(2) film in UOR.The crucial dehydrogenation products of Ni(OH)_(5)O^(-)intermediates are identified to be stable on the etched edge and explain the enhanced UOR in the low potential region.In addition,the dynamic active sites are monitored to elucidate the reaction mechanism in different potential ranges.
基金support from the Natural Science Foundation of Beijing(No.2242028 for W.J.M.,No.Z230022 for P.Y.)the National Natural Science Foundation of China(Nos.22125406 and 22074149 for P.Y.)the National Basic Research Program of China(Nos.2022YFA1204500 and 2022YFA1204503).
文摘The electrochemical conversion of carbon dioxide(CO_(2))into chemical fuels represents a promising approach for addressing global carbon balance issues.However,this process is hindered by the kinetic limitations of anodic reactions,usually the oxygen evolution reaction,resulting in less efficient production of high value-added products.Here,we report an integrated electrocatalytic system that couples CO_(2)reduction reaction(CO_(2)RR)with urea oxidation reaction(UOR)using a bifunctional electrocatalyst with atomically dispersed dual-metal CuNi sites anchored on bamboo-like nitrogen-doped carbon nanotubes(CuNi-CNT),which were synthesized through a one-step pyrolysis process.The bifunctional CuNi-CNT catalyst exhibits a near 100%CO Faraday efficiency for CO_(2)RR over a wide potential range and outstanding UOR performance with a negatively shifted potential of 210 mV at 10 mA·cm^(-2).In addition,we assemble a two-electrode electrolyzer using bifunctional CuNi-CNT-modified carbon fiber paper electrodes as both cathode and anode,capable of operating at a remarkably low cell voltage of 1.81 V at 10 mA·cm-2,significantly lower than conventional setups.The study provides a novel avenue to achieving an efficient carbon cycle with reduced electric power consumption.
基金supported by the Australian Research Council(ARC)Discovery Project(DP220101139)and Linkage Project(LP240100542).
文摘The electrocatalytic urea oxidation reaction(UOR)is a promising strategy for addressing both environmental remediation and energy conversion challenges.Recently,heterojunction catalysts have gained significant attention due to their enhanced catalytic activity and stability.This review provides a comprehensive analysis of recent advancements in heterojunction catalysts for UOR.We begin by outlining the fundamental principles of UOR and key catalyst evaluation parameters.Next,we discuss the unique features of heterojunction catalysts,highlighting their structural and electronic advantages.The applications of various heterojunction architectures—including those based on transition metals,alloys,metal(hydro)oxides,chalcogenides,pnictides,and metal-organic frameworks—are then examined in detail.A particular focus is placed on structure-performance relationships and rational design strategies to optimize catalytic efficiency.This review offers valuable insights into the development of next-generation heterojunction catalysts for efficient and sustainable UOR applications.
基金supported by the National Natural Science Foundation of China(Grant No.62004143)the Key R&D Program of Hubei Province(Grant No.2022BAA084)+5 种基金the Natural Science Foundation of Hubei Province(Grant No.2021CFB133)the National Key R&D Program of China(Grant No.2022YFC3902703)the Innovation Project of Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education(Grant Nos.LCX2021003,LCX202304)the Scientific Research Foundation of Wuhan Institute of Technology(Grant No.K202253)the Open Research Fund of Key Laboratory of Material Chemistry for Energy Conversion and Storage(HUST),Ministry of Education(Grant No.2021JYBKF05)the 14th Graduate Education Innovation Fund of Wuhan Institute of Technology(Grant Nos.CX2022462,CX2023141)。
文摘Urea oxidation reaction(UOR)instead of anodic oxygen evolution reaction(OER)is considered an effective way to reduce energy consumption in electrocatalytic water splitting for hydrogen production.Nevertheless,the slow rate of reaction of UOR,which entails a procedure of transferring six electrons,has hindered its widespread use.Therefore,it is crucial to design highly effective electrocatalysts for the implementation of UOR.Herein,a novel NiCo-hydroxysulfide(NiCo-HOS)electrocatalyst has been reported for UOR,which is obtained by the exchange of sulfur ions in NiCo layered double hydroxide(NiCo-LDH)nanosheets at room temperature.Benefitting from the sulfurization process,the composition,electronic structure,and surface properties of electrocatalysts have undergone significant changes and optimizations.Following sulfurization treatment,the resulting NiCo-HOS showed enhanced chemical resistance to alkaline electrolytes and improved electrical conductivity.In a 40 h operation test,it maintained high stability and provided a stable current density of 100 mA cm^(-2)at a relatively low potential of 1.33 V(vs.RHE)in a solution of 1 mol L^(-1)KOH+0.5 mol L^(-1)urea.Subsequently,the anode electrolytic product is analyzed through gas chromatography(GC),and N_2 is detected as the product without the presence of CO,indicating that the urea has undergone complete oxidation.
基金supported by the National Natural Science Foundation of China(52373211)the China Postdoctoral Science Foundation(2023T160274,2021M690067).
文摘Urea oxidation reaction(UOR)electrocatalysis,a promising anodic reaction with lower overpotentials than the oxygen evolution reaction,can work in tandem with many cathodic reactions to improve energy-conversion efficiencies.Among other catalysts,single-atom catalysts(SACs)possess immense potential as high-performance and low-cost catalysts towards UOR,owing to their numerous advantages such as metal-utilization efficiency and low-coordination metal sites.Nevertheless,systematic studies remain unexplored for the local coordination structures of SACs regulating their UOR pathways,which severely impedes further performance advancement.Here,we aim to construct the mechanistic picture of UOR pathways on SACs,using two nickel-single-atom enriched conjugated coordination polymers(named Ni-N-CP and Ni-O-CP)with well-defined NiN_(4)and NiO4 coordination structures for the proof-of-concept studies.The Ni-O-CP exhibits exceptional UOR performance with a turnover frequency of 0.51 s^(-1),significantly outperforming the Ni-N-CP(0.38 s^(-1))and other state-of-the-art SACs towards UOR.Our theoretical calculations combined with in-situ Fourier transform infrared and ultraviolet-visible spectroscopy measurements elucidate that two UOR pathways towards NO_(2)^(-)and N_(2)products were identified,which critically depends on the participation of the as-generated ammonia species in the UOR process.This work provides insights for regulating the activity and selectivity of UOR electrocatalysis.
基金supported by the National Natural Science Foundation of China(22162004)the Natural Science Foundation of Guangxi Province(2022JJD120011).
文摘Ni-based electrocatalysts are considered a promising choice for urea-assisted hydrogen production.However,its application remains challenging owing to the high occupancy of d orbital at the Ni site,which suppresses the reactant adsorption to achieve satisfactory urea oxidation reaction(UOR)and hydrogen evolution reaction(HER)activity.Herein,the WO_(3) site with empty d orbital is introduced into Ni_(3)S_(2) to construct dual active sites for regulating the adsorption of reactive molecules.Experimental and theoretical calculations indicate that the electron transfer from Ni_(3)S_(2) to WO_(3) forms electron-deficient Ni with sufficient empty d orbitals for optimizing urea/H_(2)O adsorption and tuning the adsorption behavior of the amino and carbonyl groups in urea.Consequently,the Ni_(3)S_(2)-WO_(3)/NF presents a remarkably low potential of 1.38 V to reach 10 mA cm^(-2) for UOR-assisted HER.This work highlights the significance of constructing synergistic dual active sites toward developing advanced catalysts for urea-assisted hydrogen production.
基金support of the National Natural Science Foundation of China(21901246,22105203 and 22175174)the Natural Science Foundation of Fujian Province(2020J01116 and 2021J06033)the China Postdoctoral Science Foundation(2021TQ0332 and 2021M703215).
文摘Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary structure.Notably,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical NiCo-LDH.Employing NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of OER.This work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.
基金supported by the National Natural Science Foundation of China(22162004)the Natural Science Foundation of Guangxi Province(2022JJD120011).
文摘Developing efficient bifunctional catalysts for urea oxidation reaction(UOR)/hydrogen evolution reaction(HER)is important for energy-saving hydrogen production.Herein,a catalyst with crystalline-amorphous hetero-structure supported by NiCo alloy on nickel foam(NiCoO-MoOx/NC)is reported for the first time.Through simple molybdenum salt etching,2D NiCo alloy nanosheets are transformed into a unique 3D cycad-leaf-like structure with a super-hydrophilic surface.Simultaneously,the synergistic effect between crystalline NiCoO and amor-phous MoOx improves the UOR and HER activity,merely requiring 1.28 V and-45 mV potentials to reach±10 mA cm-2,respectively.Particularly,the UOR kinetics of NiCoO-MoOx/NC is enhanced significantly compared to that of NiCoO/NC.The electronic structure of NiCoO is modified by MoOx,enabling the rapid generation of NiOOH and CoOOH active species,which would accelerate the synergistic electrocatalytic oxidation of urea molecules.This work inspires the design of highly active and stable bifunctional catalysts for urea assisted H2 production.
文摘To address the high cost and limited electrochemical endurance of Pt-based electrocatalysts,the appropriate introduction of transition metal-based compounds as supports to disperse and anchor Pt species offers a promising approach for improving catalytic efficiency.In this study,sub-1 nm Pt nanoclusters were uniformly confined on NiO supports with a hierarchical nanotube/nanosheet structure(Pt/NiO/NF)through a combination of spatial domain confinement and annealing.The resulting catalyst exhibited excellent electrocatalytic activity and stability for hydrogen evolution(HER)and urea oxidation reactions(UOR)under alkaline conditions.Structural characterization and density functional theory calculations demonstrated that sub-1 nm Pt nanoclusters were immobilized on the NiO supports by Pt–O–Ni bonds at the interface.The strong metal-support interaction induced massive charge redistribution around the heterointerface,leading to the formation of multiple active sites.The Pt/NiO/NF catalyst only required an overpotential of 12 and 136 mV to actuate current densities of 10 and 100 mA cm^(-2) for the HER,respectively,and maintained a voltage retention of 96%for 260 h of continuous operation at a current density of 500 mA cm^(-2).Notably,in energy-efficient hydrogen production systems coupled with the HER and UOR,the catalyst required cell voltages of 1.37 and 1.53 V to drive current densities of 10 and 50 mA cm^(-2),respectively—approximately 300 mV lower than conventional water electrolysis systems.This study presents a novel pathway for designing highly efficient and robust sub-nanometer metal cluster catalysts.
基金supported by the National Natural Science Foundation of China(Nos.22322104,22171074)the Natural Science Foundation of Heilongjiang Province(No.YQ2021B009)+3 种基金the Reform and Development Fund Project of Local University supported by the Central Government(Outstanding Youth Program)Heilongjiang Province Young Scientific and Technological Talent Lifting Project(No.2023QNTJ019)the Basic Research Support Project for Outstanding Young Teachers in Heilongjiang Provincial University(No.YQJH2023129)the Outstanding Youth Science Foundation of Heilongjiang University(No.JCL202301)。
文摘Urea-assisted water electrolysis offers a promising route to reduce energy consumption for hydrogen production and meanwhile treat urea-rich wastewater.Herein,we devised a shear force-involved polyoxometalate-organic supramolecular self-assembly strategy to fabricate 3D hierarchical porous nanoribbon assembly Mn-VN cardoons.A bimetallic polyoxovanadate(POV)with the inherent structural feature of Mn surrounded by[VO_(6)]octahedrons was introduced to trigger precise Mn incorporation in VN lattice,thereby achieving simultaneous morphology engineering and electronic structure modulation.The lattice contraction of VN caused by Mn incorporation drives electron redistribution.The unique hierarchical architecture with modulated electronic structure that provides more exposed active sites,facilitates mass and charge transfer,and optimizes the associated adsorption behavior.Mn-VN exhibits excellent activity with low overpotentials of 86 m V and 1.346 V at 10 m A/cm^(2)for hydrogen evolution reaction(HER)and urea oxidation reaction(UOR),respectively.Accordingly,in the two-electrode urea-assisted water electrolyzer utilizing Mn-VN as a bifunctional catalyst,hydrogen production can occur at low voltage(1.456 V@10 m A/cm^(2)),which has the advantages of energy saving and competitive durability over traditional water electrolysis.This work provides a simple and mild route to construct nanostructures and modulate electronic structure for designing high-efficiency electrocatalysts.
