Theoretical Investigation On The Transition Metal Cluster Catalysts For Hydrogen Evolution Reaction And The Correlative Catalytic Mechanism

The rapid development of society and industry caused the rapid consumption of traditional fossil energy,which gave rise to environmental pollution and energy shortage.Thus,we must to develop new green energy as soon as possible to meet energy requirement of future and build a more habitable environment.Hydrogen energy is identified as the most ideal energy in the future because of its high temperature solubility,high energy density,good combustion performance and no harmful substances produced during the combustion process.Among hydrogen preparation methods,electrolysis of water is the most potential preparation method for its simple operation and high hydrogen purity.Pt and its alloys are continuing to be the best catalyst for hydrogen evolution reaction（HER）in electrolytic water.However,the high price of Pt leads to high cost of hydrogen production,and the reserve of Pt is too small to meet the demand of large-scale commercial hydrogen production.Therefore,it is necessary to develop a new catalyst with high-performance and low-cost for electrocatalytic hydrogen evolution to reduce the cost of hydrogen production while meeting the social demand of hydrogen energy.This paper used the quantum mechanics search for the configurations of the transition metal clusters and systematically study the electronic structure and electrocatalytic activity of clusters.The effects of size,composition elements,and doping atoms on the catalytic performance of clusters were analyzed.Thus,it provides a theoretical basis for designing new high-performance clusters catalyst for HER.The main results are as follows:1、Structure search,stability and HER catalytic activity of transition metal clusters（TM_n,TM=Co,Ni,Cu,Pd,Pt,n=4～10）A batch of initial configurations of cluster were established by the cluster conformation searching program.Then,density functional theory（DFT）was used to optimize structures and determine the most stable clusters’configuration.Subsequently,HER catalytic performance of clusters was studied.The calculation results show that the structure of clusters changes greatly with the change of elements or the number of atoms.The research of catalytic activity indicate that Cu_nhave excellent catalytic activity,which of Cu₄,Cu₇ and Cu₉ are better than Pt,their Gibbs free energies（ΔG_H*）are-0.06 e V,-0.03 e V and-0.01 e V respectively.Further analysis of the catalytic mechanism found that Cu_n have the most suitable structural stability and chemical stability,including suitable frontier orbitals and surface electron activity,which are the keys to improve the HER catalytic performance.2、Structure search,stability and HER catalytic activity of Cu₅X（X=F,Cl,Br,I,C,S,O,Si,P,B,N）A batch of initial configurations of Cu₅X were established by the cluster conformation searching program.Then,using DFT optimized and determined the most stable configuration of Cu₅X.Finally,we studied HER catalytic activity of Cu₅X.The results show that Cu₅X can exist stably at room temperature.Although doping non-metal can improve the HER catalytic performance of Cu₅,the structure of some clusters unstable under acidic conditions due to the high-reactivity between the doping non-metal and H,they will form hydride.However,C-doped Cu₅ has ultrahigh-symmetry structure,suitable electron structure and surface activity,which make it has a high HER catalytic activity（ΔG_H*=0.005 e V）and its geometry is stable during involved in HER.3、Structure search,stability and HER catalytic activity of Cu₅TM（TM=Co,Fe,Mn,Mo,Nb,Ni,Pd,Pt,W）A batch of initial configurations of Cu₅TM were established by the cluster conformation searching program.Afterwards,optimizing initial configurations and determining the most stable configuration of Cu₅TM with DFT.Then,we studied HER catalytic performance of Cu₅TM.The calculations indicate that the most stable structures of Cu₅ doped with transition metal is very similar.Compared with Cu₅X,Cu₅TM have more stable geometries,which are steady during the HER process.Among them,Cu₅ doped with Pt and Ni have appropriate frontier orbitals and the change of frontier orbitals after adsorption H are also conducive to maintaining the structure stability（the interaction between cluster and H is maintained in a range that cluster stable adsorption of H and conducive to the release of H₂）.Ultimately,both Cu₅Pt and Cu₅Ni exhibit excellent HER catalytic performance（ΔG_H*=0.01 eV）.