Controllable Crystal Growth and Improved Photocatalytic Activity of Porous BiO-BiS Composite Sheets.

Porous BiO-BiS composite sheets were constructed through a combinational methodology of chemical bath deposition and hydrothermal reaction. The NaS precursor concentration in the hydrothermal solution was varied to understand the correlation between the vulcanization degree and structure evolution of the porous BiO-BiS composite sheets. The control of the etching rate of the BiO sheet template and the regrowth rate of BiS crystallites via suitable sulfide precursor concentration during the hydrothermal reaction utilizes the formation of porous BiO-BiS sheets. Due to the presence of BiS crystallites and porous structure in the BiO-BiS composites, the improved visible-light absorption ability and separation efficiency of photogenerated charge carriers are achieved. Furthermore, the as-synthesized BiO-BiS composite sheets obtained from vulcanization with a 0.01M NaS precursor display highly enhanced photocatalytic degradation toward methyl orange (MO) dyes compared with the pristine BiO and BiS. The porous BiO-BiS 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 BiO-based Z-scheme composites with a suitable microstructure and BiO/BiS phase ratio for photoactive device applications.