In Situ Optimizing Thin Semiconductor Passive Films of Bismuth Oxides and Sulfides under Visible Light Illumination for Enhanced Photoelectrochemical Performances

Abstract

© 2015 The Electrochemical Society. We report here an in situ method to monitor and optimize formation of thin semiconductor passive films of bismuth oxides and sulfides for enhanced photoelectrochemical performances. It was conducted by cyclic voltammetry under visible light illumination in a mixed solution of Na 2 SO 3 and Na 2 S. Electrooxidation and sulfurization of Bi electrodes occurred simultaneously during the potential cyclings between -1 V and 0 V (vs. Hg|Hg 2 SO 4 (s)|K 2 SO 4 (saturated)), and the semiconductor passive film with an appropriate thickness was formed effectively under light illumination. In comparison with the composite film of Bi 2 S 3 /Bi 2 O 3 loaded on conductive glass, enhanced photoelectrochemical performances were observed in much wider potential ranges on the prepared semiconductor passive film due to its very compact coverage. Higher anodic photocurrent density was obtained from -1 V to 10 V on the semiconductor passive film prepared under light illumination than in dark, and under galvanostatic operation the anodic potential went back and forth between -1.1 V and 9.8 V rapidly while the visible light illumination was on and off. We expect that these photoelectrochemical characteristics will find applications in photoelectrochemical hydrogen production, photodetectors and photoswitches.