High-Density Planar MoSe<sub>2</sub>/SnSe Heterojunction for Solar Energy Harvesting and Hydrogen Evolution Reaction
Jianyong Xiang, Yu Han, Jiaxiang Zhang, Jiang Xu, Congpu Mu, Fusheng Wen, Bochong Wang, Kun Zhai, Tianyu Xue, Anmin Nie, Shanhai Ge
Abstract
Optoelectronic and photoelectrochemical devices have long suffered from cost and energy-conversion efficiency. A two-dimensional (2D) layered metal chalcogenide (LMC) heterostructure is an optically active sensitizer in optoelectronic and photoelectrochemical electrodes. Here, we demonstrated a technology to fabricate planar heterojunctions by one-step electrophoretic deposition of MoSe 2 nanosheets on regularly spaced indium–tin oxide (ITO) cracks and SnSe nanocrystallines in the gaps. This thin film with grid-like planar MoSe 2 /SnSe heterojunction with tunable densities can be produced at a large scale. Unlike the vertically stacked pattern, the product lateral heterojunctions show effective charge transfer and high energy-conversion efficiency simultaneously, as evidenced by the 0.36 V open-circuit voltage, 3.02 mA/cm 2 short-circuit current density, 55% filling factor, and 0.55% energy-conversion efficiency in the photoelectrochemical cells. In addition, the heterojunctions facilitate the hydrogen evolution reaction (HER) as evidenced by overpotentials of 276 mV at a current density of 10 mA/cm 2 and Tafel slopes of 84.6 mV/dec in an alkaline medium. The heterojunction density reaches 12.1 junctions per 1000 μm 2 in the photoanode film. The high density of the heterojunction enables the photoelectric and electrocatalytic performances. The promising results provide avenues for the development of high-power, low-cost optoelectronic, and photoelectrochemical devices.