Preparation Of Thin Films Of Several Bi-based Core-shell Nano Semiconductors And Their Photoelectrochemical Properties

For their unique staggered band edge alignment, the type-II core-shell semiconductors have been widely used in optics, optoelectronics, photoelectrochemical （PEC） solar cells, PEC sensors, photocatalysis and so on. In this paper, we studied the preparation and characterization of thin films of the type-II Bi₂O_x@Bi₂S₃, surface-sulfurized BiOC1（SS-BiOC1） and surface-sulfurized BiOBr （SS-BiOBr） core-shell semiconductor, as well as their PEC properties. The main contents are as follows:（1） The Bi₂O_x@Bi₂S₃core-shell structured porous semiconductor thin films were prepared by pyrolysis of Bi（NO3）3and subsequent surface sulfurization of resulted Bi2_Ox. XRD and XPS confirmed the thin films of Bi₂O_x@Bi₂S₃core-shell have been obtained under our experimental conditions. The influence of concentration of the original Bi（NO₃）₃solution and sulfurization time on the PEC performance was investigated and the reasons were discussed.（2） Surface-sulfurized nanoflake-like BiOC1（SS-BiOC1） shell-core structured semiconductor thin films were prepared by anodization of smooth Bi electrodes in NaCl solution and subsequent surface sulfurization in Na2S solution through anionic exchange of interbedded Cl^-with S^2-. XRD, XPS and Raman spectra confirmed that the thin films of SS-BiOC1with a shell-core structure have been obtained under our experimental conditions. The PEC performances of BiOCl thin films with interbedded S^2-prepared by varying the applied potentials, polarization times and sulfurization times were investigated and the reasons were discussed.（3） Surface-sulfurized nanoflake-like BiOBr （SS-BiOBr） shell-core structured semiconductor thin films were prepared by anodization of smooth Bi electrodes in KBr solution and subsequent surface sulfurization in Na2S solution through anionic exchange of interbedded Br^-with S^2-. XRD, XPS and Raman spectra confirmed that the thin films of SS-BiOBr with a shell-core structure have been obtained under our experimental conditions. The PEC performances of BiOBr thin films with interbedded S-prepared by varying the applied potentials, polarization times and sulfurization times were investigated and the reasons were discussed.