First-principles Study Of Metal Atoms Modified BiOBr Photocatalytic Materials

Semiconductor photocatalysis technology uses inexhaustible solar energy to solve the problems that seriously affect the happy life of human beings such as environmental pollution and energy crisis.When looking for suitable photocatalytic materials,BiOBr semiconductors have become a research hotspot in the field of photocatalysis due to unique structure-dependent photocatalytic performance,chemical stability and non-toxicity.However,BiOBr materials have low quantum efficiency and poor photoresponse ability.In response to this defect,many research teams have introduced metal atoms to improve the photocatalytic performance of BiOBr materials.With the continuous development of computer technology,quantitative calculation has become a practical and low-cost ideal tool in the scientific research field.Therefore,with the help of simulation calculations,we discussed the general laws of two types of typical metal atom modified BiOBr photocatalytic materials,understood the microscopic mechanism of metal atoms and semiconductor materials,and explained the internal relationship between electronic structure and optical properties for design and preparation new BiOBr-based photocatalytic materials provide theoretical basic data.The main research contents of this paper are as follows:(1)First-principles study of 3d transition metal doped BiOBr photocatalytic material.Use Material Studio software to clarify the construction method of 3d transition metal(TMs = Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn)doped BiOBr supercell,and adopt the firstprinciples method of DFT + U to study the energy band structure,density of states,optical properties,redox potential,effective carrier mass and formation energy of these doped systems.It can be seen that the introduction of different metal atoms in the system can change the electronic properties of the material and affect the visible light response,but the band gap of the system is not the only factor that determines the visible light response of the system.The position and source of the impurity energy levels also affect the richness of the optical properties of the system.According to the calculation results,photo response priority order,structural stability and recombination probability of photo-generated carrier for 3d TMs doped BiOBr systems are summarized,Mn,Co,Ni,and Cu doped BiOBr systems perform well.(2)First-principles study of noble metal atoms loaded on BiOBr{001} planes exposed to different atomic terminals.The first-principles method based on density functional theory is used to study the geometric structure,surface energy,adsorption energy,electronic properties,optical properties and charge transfer behaviors of the BiOBr{001} planes loaded on the BiOBr{001} planes exposed to different atomic terminals.The results show that the BiOBr{001} system with the exposed Bi O terminal has obvious surface reconstruction,the highest surface energy,the smallest work function,the narrowest band gap,and optical absorption band edge has obvious red shift;the strength of the interaction between the metal and semiconductors in the BiOBr{001}-Bi O system loaded with different noble metal atoms(NMs = Pd,Ag,Pt,Au)has been summarized;the order of forbidden band width,the richness of optical properties and the number of charge transfers of these adsorption systems has been given;and taking the noble metal Pt atoms loaded on the different adsorption positions on the BiOBr{001}-Bi O surface as an example,it is proved that the optical absorption band edge of the hollow(H)Pt shifts to the long-wave direction,the light response ability is enhanced,and the electron accepting ability is the strongest,up to 0.920 e.By controlling the adsorption of noble metal atoms on the BiOBr{001}-Bi O surface to achieve single-atom anchoring,it has great significance for the development of low-content noble metal-supported,high-activity catalysts to achieve energy conversion applications.The theoretical calculation results not only provide predictive basic data for understanding the local electronic structure of the metal atom-modified BiOBr-based photocatalyst deeply,but also provide a research method strategy for the further exploration and design of high-efficiency photocatalysts for other energy conversion applications.