Preparation of a novel Bi 9 O 7.5 S 6 /SnS composite film with improved photoelectric properties.

Atomically thin two-dimensional (2D) bismuth oxychalcogenides have been considered as promising candidates for high-speed and low-power photoelectronic devices due to their high charge carrier mobility and excellent environmental stability. However, the photoelectric performance of their bulk materials still falls short of expectations. Herein, a novel Bi 9 O 7.5 S 6 /SnS composite film with a type-II heterojunction was successfully prepared by combining hydrothermal and knife-coating techniques. The crystal structure, morphology, and optical properties were systematically investigated. Under 1 V bias voltage, the photocurrent of the Bi 9 O 7.5 S 6 /SnS composite film can be obtained as 107 μA cm -2 , which is about 29.9 times and 93.9 times higher than that of bare Bi 9 O 7.5 S 6 and SnS, respectively. The type-II heterojunction has played a significant role in improving the photoelectric performance of the Bi 9 O 7.5 S 6 /SnS composite film by facilitating the separation and transfer of photo-generated carriers. This work sheds light on the design and development of new bismuth-based composite materials for advanced photoelectric and photocatalytic applications.