Understanding and improving photoelectrochemical performance of BiO/BiS 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 Bi 2 O 3 /Bi 2 S 3 composite was successfully synthesized using an ultrasonic-assisted synthetic method on a conductive substrate. During the sonochemical reaction, the Bi 2 O 3 layer reacted with S 2 ions to form Bi 2 S 3 . Because no other Bi 3+ sources were present during the synthetic process, the Bi 2 O 3 layer acted as both the substrate and Bi 3+ source for the formation of the Bi 2 S 3 film. The resulting Bi 2 O 3 /Bi 2 S 3 composite showed highly enhanced PEC activity, with a photocurrent more than twice that of other Bi 2 O 3 /Bi 2 S 3 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 Bi 2 S 3 conduction band to that of Bi 2 O 3 . Furthermore, the stability of the Bi 2 O 3 /Bi 2 S 3 composite during water oxidation was examined by using substrate generation-tip collection scanning electrochemical microscopy. The simple and fast ultrasonic-assisted synthesis of high-performance, low-interfacial-resistance Bi 2 O 3 /Bi 2 S 3 composite semiconductors is demonstrated.