Defect-rich MoS/NiS nanosheets loaded on SiNWs for efficient and stable photoelectrochemical hydrogen production.

Photoelectrochemical (PEC) reaction with efficient, stable, and cost-effective photocathodes using non-precious metals will be one of the most environmentally friendly technologies for hydrogen (H) generation under the worldwide pressure for carbon neutrality. Herein, a new 3-dimentional (3D) SiNWs@MoS/NiS photocathode was designed and synthesized. Defect-rich MoS/NiS nanosheets on silicon nanowires (SiNWs) provide more active sites to promote charge transfer and photo-generated electron-hole separation. Meanwhile, the 3D structure of the photocathode provides an effective charge transfer mode and an open channel for rapid H release. The SiNWs@MoS/NiS photocathode exhibits the maximum photocurrent density (21.4 mA·cm at 0.9 V vs. RHE), highest H production rate (183 μmol·h), smallest diffusion resistance (34.7 Ω), and excellent catalytic stability for more than 10 h at pH = 7. Based on density function theory calculation, the MoS/NiS nanosheets are conducive to chemical adsorption of H intermediates, which are crucial for the maintenance of the composite photocathode in PEC H production.