Modulation Of Solid Liquid Reaction Interface Microenvironment And Performance Optimization Of Nickel Based Water-Splitting Electrocatalysts

Hydrogen production from electrocatalytic water splitting,driven by the electric power from fluctuating renewable energy,is a research hotspot in the context of"dual carbon".The key to the electrocatalytic water splitting reaction is an efficient and stable electrocatalysts.Electrocatalytic reactions occur at the nanoscale space formed at the interface between the electrocatalyst and electrolyte,where the chemisorption properties and microenvironmental structure of the catalytic sites jointly determine the catalytic performance.The conventional modulation of chemisorption is based on the ideal situation of maintaining stability of the catalyst surface and satisfying the reaction requirements of the interface microenvironment.In actual reaction processes,the migration,enrichment,and configuration of small-molecule reactants in the interface microenvironment often limit the subsequent multi-electron transfer reactions of intermediate activation;while the dynamic dissolution and deposition behavior of active ions in the interface microenvironment determines the dynamic stability of the catalyst surface.Therefore,understanding the structural and dynamic properties of reactant molecules and active ions in the interface microenvironment is the key to realizing industrial production and multiple-scenario applications of electrocatalytic water splitting technology.Nickel-based materials are inexpensive,abundant,highly conductive and active,with adjustable elemental composition and stoichiometry.Based on this,this paper chooses nickel-based materials as electrocatalysts to study the relationship between the structure and dynamic properties of reactant molecules and active ions in the interface microenvironment and the electrocatalytic activity and stability,aiming to construct the reactant-friendly and stable reaction interface and reduce the energy consumption of hydrogen production from water splitting.The main research contents are as follows:（1）To solve the problem of slow reaction kinetics of hydrogen evolution at high current,the Ni/Ni₃C heterostructure with rich-OH groups coated on carbon layer was prepared by rapid heat treatment,which realized the effective enrichment of reactant water molecules in the microenvironment of the alkaline hydrogen evolution reaction interface.The localized hydrogen bond force field introduced by the anchored-OH groups favor to breaking the water hydrogen bond network,and thus promoting the spontaneous migration and effective enrichment of reactant water molecules in the interface microenvironment,which are further evolving into free water molecule configuration which is easy to dissociate,achieving high current alkaline hydrogen evolution activity exceeding Pt/C(0.276 V@500 m A cm^-2).（2）Due to the high energy consumption and difficulty in the separation of gases during oxygen evolution reaction,the anodic propylamine oxidation coupled with water splitting is used for hydrogen production.To solve the problem of low catalytic conversion efficiency of amine,Ni（OH）₂ nanosheets doped with chalcogen were prepared,realizing the effective enrichment of reactant amine molecule in the microenvironment of the alkaline amine oxidation reaction interface.Utilizing the operando structural variation,Ni OOH nanosheets with surface chalcogenates was obtained.Using surface charged groups and their electron-withdrawing effect on the substrate,the charged chalcogenates induce the local electric field that pushes the polar amines through the inner Helmholtz plane to enrich in the interface microenvironment,thus achieving efficient oxidation of amine(1.327 V@100 m A cm^-2).（3）To solve the problem of deactivation of oxygen evolution catalysts,the dual-ions co-doping and in situ leaching effect was proposed,which achieved the dynamic balance of the dissolution and redeposition rate of active ions in the microenvironment of the alkaline oxygen evolution reaction interface.On the basis of studying and analyzing the active ion dissolution and redeposition behavior of Ni Fe bimetallic hydroxides and their deactivation mechanism,the dual-ions co-doping and in-situ leaching effect was proposed.The in situ leaching of S will reduce surface energy,and the M-O bond energy is then enhanced by Co dopants and anchored chalcogenates,thus inhibiting the dissolution of active Fe ions.The Co²⁺sites generated from the valence oscillations of electron-withdrawing Co³⁺sites act as the redeposition reaction sites,achieving dynamic stability of active sites and the industrial-level stability of hydrogen production(～4,000 h@400 m A cm^-2).This article reveals that the local force field can optimize the spatial distribution and configuration of reactants,and the enrichment of reactants on the surface and favorable configurations can accelerate reaction kinetics.The dissolution and redeposition behavior of active ions are directly related to the catalyst surface state,and a balanced dissolution and redeposition rate of active ions can achieve dynamic stability of the reaction interface.