Guided Design Of Low-dimensional Multi-level Transition Metal Compounds And Application Of Electrocatalytic Water Decomposition

As the aggravation of the energy crisis and the problems of air pollution and global warming by the abuse of fossil fuels,it is urgent to develop the efficient and clean renewable energy.Among numerous renewable energy,hydrogen is regarded as a very promising new clean energy with the advantages of environmental friendly and high energy density.Among the now available strategies of producting hydrogen,the electrolysis of water process converting electric energy to hydrogen energy is a efficient,economic and environmentally friendly way.At normal temperatures and pressures,the theory of voltage window required by the electrolysis of water is 1.23 V.However,in practice,in order to reduce the electrode reaction overpotential,recognized efficiency improvement strategy is to use the electrocatalysty as the electrode material.The catalysts based on the noble metals show the highest catalytic efficiency in the existing catalyst.Nevertheless,the elements scarcity and the expensive price immensely limit the industrial application.Therefore,it is imperative to develop non-noble metal electrocatalyst with high activity.In this paper,selecting the earth-abundant transition metal compounds as the research object,authors optimize the active sites and electrical conductivity of the catalyst by defect engineering,disordered structure engineering,element doping and combining with the conductive materials,realizing the significantly enhanced catalytic performance.This paper provides a guiding role for the design and development of the electrocatalyst in the future.This paper includes two contents as follows:1.Authors synthesized the vertical alignment oxygen doping molybdenum disulfide electrocatalyst on the carbon cloth by element doping,disordered structure engineering and combing with the materials,realizing the optimized synergistic effect between active sites and electrical conductivity,thus achieving the significantly enhanced activity of hydrogen evolution reaction.In this composite electrocatalyst,highly disordered MoS2 nanosheets provide the rich catalytic active sites,and the oxygen doping and combing with the carbon-containing materials improve the electrical conductivity,making more electrical connected active sites involving in the catalytic process effectively,realizing synergistic optimization promotion of the hydrogen evolution reaction performance.After the synergistic optimization,oxygen doping MoS2/carbon cloth catalyst shows the ultra-low onset overpotential,superior catalytic current density and excellent stability.The synergistic optimization stratregy reported in this work provide the method can be used for reference for designing a new catalyst.2.Authors synthesized NiFe layered double hydroxides(LDH)ultrathin nanomesh with abundant uniform 2~3 nm nanopore by a etching-aging method using ternary NiFeZn LDH as precursor,realizing the significantly enhanced performance of oxygen evolution reaction.The amphoteric Zn ion in the ternary precursor can be selectively etched by alkaline solution treatment,realizing preliminary into the hole in the sheet,while subsequent aging process induced the homogenization of the nanopore.The introduction of nanopores can promote the produce of the high valence phase with catalytic activity,providing more sites for the oxygen evolution reaction.In addition,the space provided by nanopores can effectively avoid the structural damage in the repeated redox reaction,ensuring the excellent electrochemical stability,which makes it promising for industrial water decomposition.This work provides a effective strategy for the optimization of oxygen evolution reaction performance,and the inspiration for designing the electrocatalysts in the future.