The Band Structure And Exchange Photocurrent Density Of Bi-based Oxides Under The Action Of Light Field

The energy band structure is an important thermodynamic parameter to judge whether the semiconductor photocatalytic materials has photocatalytic activity.The accurate determination of the energy band structure of the photocatalytic materials under darkness and irradiation plays a prerequisite role of the exact evaluation of the photocatalytic performance of the photocatalytic materials.Compared with thermodynamics,the kinetic activity determines the actual catalytic efficiency.As for the problem such as the detective of energy band structure under irradiation and the proper photocatalytic dynamic parameter,the prepared Bi-based oxide was used as the research system,the corresponding band gap,crystal structure,surface morphology and surface composition were obtained by UV-Vis DRS,XRD,SEM,TEM and XPS.Then based on electrochemical test technology to study its photocatalytic performance.The content is that it will establish the method on account of tafel curve for accurately measuring the flat band potential of Bi-based oxides and judging the n or p character of these materials under irradiation;the photocatalytic activity evaluation method in view of the exchange photocurrent density is proposed,and the reliability and effectiveness are compared with the actual photocatalytic performance of the semiconductor photocatalytic materials.Tafel curves indicate that a-Bi2O3,?-Bi2O3,Bi2S3,BiOCl and BiPO4 belong to n-type semiconductors.However their conduction band position changes with respect to the conduction band position measured under dark according to the Mott-Schottky curves.It is found that the exchange photocurrent density is the largest under UV-visible light when compared with the exchange photocurrent density of Bi-based oxides under different illumination conditions,which shows that the Bi-based oxides have a best separation of photogenerated electron-hole and photocatalytic activity,consistent with the results of the photocurrent-time curves and the AC impedance spectra.By measuring the actual photocatalytic performance of Bi-based oxides,it is found that the photocatalytic activity of Bi-based oxides was the best under UV-visible light.It is feasible to analyze the photocatalytic performance of semiconductor photocatalytic materials based on the exchange of photocurrent density.