Controllable Crystal Growth and Improved Photocatalytic Activity of Porous Bi₂O₃-Bi₂S₃ Composite Sheets

Porous Bi₂O₃-Bi₂S₃ composite sheets were constructed through a combinational methodology of chemical bath deposition and hydrothermal reaction. The Na₂S precursor concentration in the hydrothermal solution was varied to understand the correlation between the vulcanization degree and structure evolution of the porous Bi₂O₃-Bi₂S₃ composite sheets. The control of the etching rate of the Bi₂O₃ sheet template and the regrowth rate of Bi₂S₃ crystallites via suitable sulfide precursor concentration during the hydrothermal reaction utilizes the formation of porous Bi₂O₃-Bi₂S₃ sheets. Due to the presence of Bi₂S₃ crystallites and porous structure in the Bi₂O₃-Bi₂S₃ composites, the improved visible-light absorption ability and separation efficiency of photogenerated charge carriers are achieved. Furthermore, the as-synthesized Bi₂O₃-Bi₂S₃ composite sheets obtained from vulcanization with a 0.01M Na₂S precursor display highly enhanced photocatalytic degradation toward methyl orange (MO) dyes compared with the pristine Bi₂O₃ and Bi₂S₃. The porous Bi₂O₃-Bi₂S₃ sheet system shows high surface active sites, fast transfer, high-efficiency separation of photoinduced charge carriers, and enhanced redox capacity concerning their constituent counterparts. This study affords a promising approach to constructing Bi₂O₃-based Z-scheme composites with a suitable microstructure and Bi₂O₃/Bi₂S₃ phase ratio for photoactive device applications.