The Application Of Two-Dimensional Materials In The Field Of Photoelectrocatalysis:A First-Principles Study

The energy shortage and environmental pollution is the main crisis in nowadays society,searching the catalysts with low cost,high efficiency and high stability is the best one of solution.Two-dimensional materials have attracted extensive attention due to their unique physical and chemical properties,studying and exploring their application value in the field of catalysis is one of the main tasks to researcher.Comparing with the experimental means of trial-and-error research,theoretical prediction can guide the experimentalists to avoid the wrong direction and reduce the consumption of resources.According to the scientific methodology based on first principles,we study the physicochemical property of novel two-dimensional materials,including boron monolayer at?₁₂ phase,g-C₂N,GaTe and g-C₆N₆,and make deep analysis on the application of photoelectric catalysis.The research contents are as follows:1.A single boron monolayer a?₁₂ phase is used as the substrate,doping single transition metal atom into the hexagonal hole of boron monolayer,and investigating its performance in electrocatalytic nitrogen reduction reaction.The results show that the adsorption capacity of boron monolayer to nitrogen can be improved by doping transition metal,the mechanism of the adsorption of N₂ to catalyst is"accept-donate"mechanism,and the adsorption mode can be divided into end-on and side-on patterns.When N₂ is adsorbed on V-doped boron monolayer,the material shows the most excellent electrocatalytic performance,and the onset overpotential is only 0.28 V.This is because N₂ can obtain more electrons from d orbital of metal atom and the bonding?orbital of N₂ occurs largest cleave due to the electron transfer to metal atom.In addition,the transition potential barrier of a single V atom in boron monolayer nearest hexagonal hole reached 2.50 eV,the geometric structure of the material remains basically unchanged at a temperature of up to 800 K,showing extremely high stability.Therefore,a single V atom doped boron monolayer can be used as an excellent catalyst for electrocatalytic nitrogen reduction.2.Similar to the previous work,the photocatalytic nitrogen reduction performance of g-C₂N interstitial doped with a single boron atom was studied.The doping of B atom can introduce an impurity level into the band gap of g-C₂N material and endow it with a magnetic moment of 1?_B,which greatly improves the light absorption performance of g-C₂N.Thereinto,the BN₂ moiety of B/g-C₂N plays a key role in photocatalytic nitrogen reduction,which act as nitrogen capture and activation center and electron transport center of nitrogen reduction reaction.The thermodynamic reaction free energy change and kinetic reaction free energy barrier of nitrogen reduction are 0.07 eV and 0.50 eV,respectively.3.Heterostructure is built by GaTe and g-C₆N₆ to study its application prospect in the field of photocatalytic water-splitting.Research results show that the GaTe/g-C₆N₆ heterojunction type is the type II structure,which can effectively separate photo-generated carriers and improve carrier life.The positions of valence-band maximum and conduction-band minimum of the constructed GaTe/g-C₆N₆ heterojunction also span the potential energy positions of water oxidation and reduction,moreover,the band gap can be further reduced to extend the light absorption in the visible range.The research preliminarily proves that GaTe/g-C₆N₆heterojunction has the ability of photocatalytic water-splitting.