Understanding and improving photoelectrochemical performance of Bi2O3/Bi2S3 composite

Simple, fast synthesis methods for well-aligned semiconductors on a substrate are necessary for the practical application of photoelectrochemical (PEC) reactions. A well-defined Bi2O3/Bi2S3 composite was successfully synthesized using an ultrasonic-assisted synthetic method on a conductive substrate. During the sonochemical reaction, the Bi2O3 layer reacted with S2- ions to form Bi2S3. Because no other Bi3+ sources were present during the synthetic process, the Bi2O3 layer acted as both the substrate and Bi3+ source for the formation of the Bi2S3 film. The resulting Bi2O3/Bi2S3 composite showed highly enhanced PEC activity, with a photocurrent more than twice that of other Bi2O3/Bi2S3 samples at 0.80 V (vs. RHE). This enhanced activity was attributed to the composite interface with low interfacial resistance achieved by in situ growth, which enhanced photogenerated electron transfer from the Bi2S3 conduction band to that of Bi2O3. Furthermore, the stability of the Bi2O3/Bi2S3 composite during water oxidation was examined by using substrate generation-tip collection scanning electrochemical microscopy.