| Energy and environmental are important crisis related to the sustainable development of the human society,and the development of green sustainable energy can not only satisfy the growing demand for energy,but also slow down the greenhouse gas emissions caused by the use of fossil energy.Hydrogen has the advantages of high energy density,storage,transportation,easy reforming,and so on,which can be used as an ideal clean energy carrier for future society.The use of photovoltaics,wind farms,hydropower and other renewable surplus electricity to electrolyze water to produce hydrogen is a sustainable path for the production of high-purity green hydrogen fuel,which can achieve deep decarbonization,in line with the "dual carbon" strategic requirements proposed by China’s National Two Sessions in 2021,that is,to achieve "carbon peaking" before 2030,achieve "carbon neutrality" in 2060,and gradually achieve zero emissions of greenhouse gases.At present,the bottleneck of the large-scale development of hydrogen production technology from electrolyzed water is that the high cost and the lack of market competitiveness compared with hydrogen production from coal chemical industries.In addition to decrease cost of electricity,electrolyzed water technology urgently needs to develop highly efficient,long-lived and low-cost catalysts to promote the kinetics of water oxidation-reduction reaction,minimize overpotential,achieve "cost-saving and profit-increasing",and reduce the power consumption cost of electrolyzer operation.In overall electrochemical water splitting process,hydrogen evolution reaction(HER)occurs at the cathode while oxygen evolution reaction(OER)take place at the anode,wherein the OER includes four proton-electron-transfer multistep reaction by the oxygen-oxygen bond formation involving adsorption of*OH,*O and*OOH has caused the sluggish reaction kinetics,which has become the bottleneck of water spliiting.Precious metal-based RuO2 and IrO2 have high OER activity,but their scarcity,high cost and poor stability greatly limit their industrial applications.Therefore,developing lowcost OER catalysts with high activity and superior durability properties,including oxides,sulfides,carbides,phosphides and other transition metal compounds have been reported to have superior basic OER activity,and some even exceed the precious metal RuO2/IrO2 benchmark catalyst.Among them,nickel(Ni)-based catalysts in particular show higher economical benefit,and the development of highly efficient and stable Ni-based OER catalysts is crucial to the industrial development of alkaline water electrolysis.With the development of in situ characterization,recent studies have continuously found that anode transition metal-based catalysts undergo dynamic self-reconstruction during alkaline OER,and the true active species and their structure-properties relationship need to be more carefully identified.More importantly,the in situ study of catalytic online is conducive to capturing reaction intermediates and revealing reaction pathways,which provides a new and effective path for understanding the catalytic mechanism and guiding the targeted design of surface-active sites.Therefore,this paper develops in situ characterization techniques to study the dynamic evolution details of catalyst surface states,reveals active species and their reaction pathways at the atomic/molecular level,constructs precise structure-properties relationship,and uses precursor components and electrochemical conditions to manipulate the reconstruction path to achieve targeted construction of high-performance catalysts.The main research results are as follows:1.Since the discovery of the electrochemical surface state reconstruction of catalysts,how to characterize the dynamic process of reconstruction and harness the reconstruction path to develop new highly efficient catalysts has maintained a high degree of research interest and challenge.We develop new and efficient OER catalysts by designing precatalysts that contain susceptible components to achieve rapid and deep electrochemical self-reconstruction(ECSR)under OER process.Specifically,NiFe layered double hydroxides(LDHs)with interlaminar anions as soluble molybdate(MoO42-)were constructed,and in situ tracking ECSR kinetic information during anodic oxidation,which including the dissolution of MoO42-,invasion coordination of hydroxyl(-OH)and formation of NiFe hydroxyoxide(NiFeOOH)active species.The reconstructional NiFeOOH exhibits excellent OER performance,requiring only an overpotential of 268 mV at a current density of 50 mA cm-2 and stability up to 45 h.Comparative studies show that the self-reconstruction of traditional CO32--linked NiFe-LDH is not significant,indicating that the design of precatalyst components is an effective means to regulate ECSR,which can be used to develop new high-activity OER catalysts.2.The fine research of electrochemical reconstruction is useful for revealing real active sites,understanding catalytic mechanism,and designing catalytic surface.In situ Raman technology for tracking the dynamic reconstruction behavior of nickel molybdate(NiMoO4)nanorods array as a precatalyst under the oxidation-reduction potential of alkaline water electrolysis,and found that sulfur dopant could promote the deep reconstruction of NiMoO4,and showed the environmental adaptability of "chameleon",and derived different NiOOH and Ni active species under oxidation and reduction conditions,respectively.The electrolyzer assembled by such two reconstructed electrodes demonstrated steady overall water splitting with an extraordinary 80%electricity-to-hydrogen(ETH)energy conversion efficiency.This study reveals the conditional adaptability of electrochemical reconstruction,providing an autoderivative path for the design of advanced catalysts,especially suitable for the development of catalysts for special environmental applications.3.Nickel-iron hydroxyoxide(NiFeOxHy)is currently recognized as a highly active basic OER catalyst,but Fe leakage usually occurs in continuous operation,resulting in activity attenuation,especially under high current density conditions.To solve this problem,we propose an ion-compensatory reconstruction derived from NiFeOxHy,which targets design of the Fe coordination binding to adapt the thermodynamic environment of strong oxidation.The NiFe-based Prussian blue Analogues(PBA)compound was designed as a precatalyst to reconstruct the strong oxidation conditions in an alkaline electrolyte with Fe cation compensation to obtain a stable NiFeOxHy nanosheet with Ni-Fe synergic active sites.Performance evaluations show that only 302 and 313 mV overpotentials are required to achieve a high current density catalytic OER of 500 and 1000 mA cm-2 for more than 500 h of smooth operation.A variety of online/offline studies have shown that dynamically reconstructing fixed Fe sites can not only enhance OER activation,but also prevent Fe leakage under high-current conditions at industrial level.This work opens up a simple,feasible,and effective strategy for engineering highly active and corrosion-resistant catalysts using thermodynamic adaptive reconstruction. |
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