Theoretical Design Of Two-Dimensional Transition Metal Compounds-based Eletrocatalysts For Low Carbon Reduction

Fossil energy is the main energy supply for industrial development.Since the Industrial revolution,the massive consumption of fossil fuels has led to a sharp rise in atmospheric carbon dioxide（CO₂）concentration.As a greenhouse gas,excessive CO₂concentration will undoubtedly cause the greenhouse effect,and then cause a serious climate crisis.At present,many researchers have invested in the research of CO₂transformation,and have made some scientific research progress.Among them,electrochemical CO₂ reduction has been widely recognized as the most promising CO₂conversion technology.The electrochemical CO₂ reduction is driven by renewable electricity,the reaction conditions are mild,the operation is simple,and the control is strong.However,there are still some problems such as high overpotential and low reaction efficiency.Carbon monoxide（CO）is an important intermediate in CO₂ reduction reaction,and electrochemical CO reduction and CO₂ reduction have similar product distribution.In-depth exploration of CO electrocatalytic reduction is conducive to the study of CO₂reduction reaction mechanism.Therefore,it is necessary to design and develop new electrocatalysts with high stability and catalytic activity,and further study their reaction mechanism.In this thesis,the catalytic activities of Pt₂P₃ for hydrogen evolution and CO₂electrochemical reduction were predicted by density functional theory（DFT）.The catalytic performance of subnanometer copper clusters supported by g-C₃N₄ for the electrochemical reduction of CO was investigated.The results are as follows:（1）Based on first principles calculations and CALYPSO structure search,a previously unreported 2D Pt₂P₃ monolayer with good thermodynamic and kinetic stability and excellent mechanical properties has been discovered.The different active sites of the material showed good catalytic activity against both HER and CO₂ER.This is mainly due to the fact that the p-band center of the P atom in the 2D monolayer Pt₂P₃plays a crucial role in the catalytic properties of HER and CO₂ER,thus highlighting the important role of p electrons in advanced catalyst design.（2）Subnanometer copper clusters Cu_n（n=1-6）loaded on 2D g-C₃N₄ monolayer materials exhibit good thermodynamic stability and excellent electronic properties.The catalytic activity of these materials for COER depends on the size of the anchored Cu cluster,among which Cu₃@g-C₃N₄ has the best catalytic activity for COER.At low coverage,the product is methane（CH₄）,and the limiting potential is-0.45 V.However,at high coverage,the product is propylene（C₃H₆）,the limiting potential is-0.40 V,and the C-C coupling energy barrier is 0.43 e V,which can effectively inhibit the competitive hydrogen development reaction,opening a new door for the design of multi-purpose multi-carbon product catalysts.