| In recent years,in order to solve the technological problems of energy crisis and environmental pollution,semiconductor photocatalysis technology has shown great potential.BiOBr in BiOX（X=Cl,Br,I）has been given a lot of attention.However,the crystal structure of BiOBr prepared by different synthesis processes is quite different,and the hydrogen production efficiency is not ideal.Aiming at the above problems of photocatalytic performance,this paper modified BiOBr successively by changing the acid-base conditions of the precursor solution and introducing metal deposition and oxygen vacancy.The main research results are as follows:（1）BiOBr samples were prepared by solvothermal method with ethylene glycol as the precursor solution by adjusting different p H,and BiOBr-OVs with different p H values were prepared by UV-visible light driving method.The experimental results show that the p H value of precursor solution has a certain effect on the crystal growth orientation of BiOBr crystal.It can be clearly found that when the p H value of precursor solution is 2,the BiOBr orientation is preferred along the crystal surface of（0 0 1）.By electrochemical analysis,the introduction of oxygen vacancies reduces the impedance of BiOBr and has lower overpotential and reduction potential.The hydrogen yield of BiOBr-OVs sample at p H=2 was 0.0131 mmol·g-1 at 4 h due to the exposure of high reactive surface（0 0 1）and oxygen vacancies.（2）The BiOBr with p H=2 prepared in（1）was deposited on the surface of BiOBr by light deposition method,and then oxygen vacancies were prepared by UV-visible light driving method to obtain BiOBr/BiOBr-OVs/Pt sample.It is found that BiOBr/BiOBr-OVs/Pt sample has the lowest impedance and the lowest Tafel slope by electrochemical characterization.The finite element simulation revealed that the array structure formed in the BiOBr/BiOBr-OVs/Pt sample effectively accelerated the electron transfer rate,and that each Pt particle in the sample would form an independent deposition area of photogenerated electrons,resulting in better electron separation efficiency.Because of the unique array structure of BiOBr/BiOBr-OVs/Pt sample and the presence of internal electric field,the hydrogen production of BiOBr/BiOBr-OVs/Pt sample at 4 h was 0.0931 mmol·g-1,which was significantly improved compared with BiOBr and BiOBr-OVs at p H=2. |
