SbS/SbSe heterojunction for high-performance photodetection and hydrogen production.

Photoelectrochemical (PEC)-type devices provide promising ways for harvesting solar energy and converting it to electric and chemical energy with a low-cost and simple manufacturing process. However, the high light absorption, fast carrier separation, and low carrier recombination are still great challenges in reaching high performance for PEC devices. As emergent two-dimensional (2D) materials, SbSe and SbS exhibit desirable photoelectric properties due to the narrow bandgap, large optical absorption, and high carrier mobility. Herein, SbS/SbSe heterojunction is synthesized by a two-step physical vapor deposition method. The type-II SbS/SbSe heterojunction displays excellentphotoelectric properties such as a high photocurrent density (I ∼ 162 µA cm), a high photoresponsivity (R ∼ 3700 µA W), and a fast time response speed (rising time ∼ 2 ms and falling time ∼ 4.5 ms) even in harsh environment (HSO electrolyte). Especially, the SbS/SbSe shows an excellent self-powered photoresponse (I ∼ 40 µA cm, R ∼ 850 µA W). This increment is attributed to the improvement in light absorption, charge separation, and charge transfer efficiency. Taking these advantages, the SbS/SbSe heterojunction also exhibits higher PEC water splitting synergically, which is approximately 3 times larger than that of SbSe and SbS. These results pave the way for high-performance PEC devices by integrating 2D narrow bandgap semiconductors.