Surface Epitaxial Growth of 2D/2D Bi2O2S/CdS Heterojunction Photoanodes and Their Photoelectrochemical Properties

Constructing high catalytic activity heterojunctions to compensate for the shortcomings of single catalysts has promoted the development of semiconductor catalysts in photoelectrochemical (PEC) water splitting. In this case, the 2D/2D Bi 2 O 2 S/CdS composite was successfully constructed by an in situ surface epitaxial growth method. At 1.23 V vs RHE, the catalytic activity of Bi 2 O 2 S/CdS with a 2D/2D heterojunction is the highest, and the current density of the Bi 2 O 2 S/CdS photoanode is 3.46 mA/cm 2 . Compared with the Bi 2 O 2 S photoanode (0.59 mA/cm 2 ), the performance has been improved by 5.86 times. In electrochemical impedance spectroscopy testing, the arc radius of 2D/2D Bi 2 O 2 S/CdS is smaller than that of Bi 2 O 2 S, indicating faster charge-transfer kinetics. The data show that the 2D/2D heterojunction with surface–surface contact successfully enhances the catalytic activity of Bi 2 O 2 S, greatly elevating the efficiency of charge separation and migration. This study provides a method to enhance the PEC activity in type-I heterojunction photoelectrodes, promoting the application of Bi 2 O 2 S-based materials in photoelectrochemistry.