Preparation of Ni@C–Cd0.8Zn0.2S nanocomposites with highly efficient and stable photocatalytic hydrogen production activity

Abstract

A series of carbon-coated Ni (Ni@C)–Cd_0.8Zn_0.2S nanocomposites were fabricated via a facile hydrothermal process using pre-prepared Ni@C as a starting material. The obtained products were characterized by X-ray diffraction, UV-Vis diffuse reflectance absorption spectroscopy, X-ray photoelectron spectroscopy and electron microscopy. It was found that the introduction of Ni@C nanoparticles can improve both the visible light-induced photocatalytic H₂ production activity and stability of the Cd_0.8Zn_0.2S solid solution, and the Ni nanoparticles encapsulated by several graphite-like carbon layers show high chemical and thermal stability. Among those products with various Ni@C contents, the 5 wt% Ni@C–Cd_0.8Zn_0.2S nanocomposite exhibits the maximum photoactivity (969.5 μmol h⁻¹) for H₂ production, which is ∼3.10 times higher than that (312.6 μmol h⁻¹) of pristine Cd_0.8Zn_0.2S. This significant enhancement in the photoactivity by loading Ni@C nanoparticles can be attributed to the metallic Ni in the Ni@C acting as a co-catalyst, while the graphite-like carbon shells acting as the Cd_0.8Zn_0.2S nanoparticles' support and electron acceptor, which causes an effective photogenerated carrier separation in space and an improvement in the photoactivity and stability for H₂ production. The present findings demonstrate a cost reduction strategy by using a non-noble metal co-catalyst for efficient and stable light-to-hydrogen energy conversion.