Design And OER Performance Study Of Ni-Based Metal-Organic Framework Material With Self Reconfiguration

Hydrogen produced through electrolysis of water is an emerging green energy technology that has the potential to solve the energy crisis and pollution problems.The oxygen evolution reaction（OER）in water electrolysis,however,greatly reduces the overall efficiency of hydrogen production from water electrolysis due to its slow kinetics.Therefore,the development of efficient OER electrocatalysts is crucial for advancing the development of water electrolysis for hydrogen production.Metal-Organic Frameworks（MOFs）are a class of porous crystalline materials formed by the self-assembly of organic ligands and metal centres via coordination bonds.MOFs are attracting much attention in the field of oxygen evolution reaction catalysis because of their highly tunable structure and function.According to recent studies,MOF catalysts are prone to surface reconstruction during the OER reaction,and the resulting oxyhydroxides（or hydroxides）are proven to be the real catalysts in the OER reaction.However,the majority of current catalysts based on low-dimensional MOFs,which have been thoroughly reconstituted,do not have a direct link to the intrinsic topology of MOFs.During the harsh OER reaction process,most MOFs are hydrolyzed and oxidized.Therefore,designing and constructing steady-state,partially reconfigured MOF systems,as well as in-depth analysis of the intrinsic mechanisms of MOFs intrinsic topology in regard to the remodelling process and the OER response are challenging,although significant.Based on a topology-based strategy and electrochemical activation method,this work has successfully designed and fabricated a stable MOF self-reconfigurable heterojunction.The effects of the intrinsic topology of MOFs on the remodeling process and OER response have been discussed in a variety of ways.This paper contains the following main research findings:Investigates the remodelling laws of similar Ni-based MOFs with different topologies and morphologies.First,Ni-BDC-1 and Ni-BDC-3 grown on conductive substrates were obtained by the solvothermal method,and then both precatalysts were reconstituted in situ by electrochemical anodization.Finally,the structure,composition,and morphology of the reconstructions before and after are characterized using various characterization methods.The results suggest that Ni-BDC-3 with hexagonal dense metal sites can be completely converted to nickel oxyhydroxide（Ni-BDC-3R）.As a result,the weak hydrogen bonds formed by the interlayer coordinated water molecules effectively inhibit the further reconfiguration of Ni-BDC-1,resulting in the formation of a steady-state self-reconfigurable MOF heterojunction（Ni-BDC-1R）.Analyzes the OER performance of two different reconstituted materials.This study indicates that the self-reconfigurable MOF heterojunction exhibits an overpotential of only225 m V at 10 m A cm^-2,which is much higher than the thoroughly reconfigured catalysts（332 m V）and outperforms the benchmark Ir O₂catalysts（353 m V）,thus becoming one of the MOF catalysts with the best OER performance.Furthermore,the heterojunction demonstrates stable long-term performance（over 100 hours）in industrial-scale high-current(100 m A cm^-2)OER reactions.With the aid of in situ impedance analysis and theoretical research methods,the mechanism of the influence of MOF’s intrinsic topology on OER activity in a self-reconfigurable MOF heterojunction is uncovered.An in situ impedance analysis has shown that the total charge transfer resistance of the MOF heterojunction drops sharply near the onset potential of OER（1.40 V）,therefore having a unique switching-like effect on OER activity.The mechanism behind this switch-like effect can be further explained through theoretical calculation analysis.According to the density functional theory calculation,the energy change diagram of the intermediate adsorption state of the OER reaction of Ni-BDC-1R under different applied voltage conditions can be obtained.In the present study,we demonstrate that^*OH adsorption,as the energy rate determining step of Ni-BDC-1R,can be significantly optimized at the onset potential.Due to the strong built-in potential field formed by the MOF heterojunction,this is the case.Among these,the intrinsic topology of MOF can serve as the electronic regulator of surface Ni OOH,thereby promoting the redox state of surface Ni active sites during OER,thereby reducing the reaction barrier.