Highly efficient and noble metal-free NiS modified MnxCd1-xS solid solutions with enhanced photocatalytic activity for hydrogen evolution under visible light irradiation

- Highly efficient and noble metal-free NiS modified MnxCd1-xS nanocomposites were synthesized via a simple direct in suit precipitation process.
- Photocatalytic H2 evolution activity of 0.3 wt% NiS/Mn0.5Cd0.5S is nearly 18.6 and 3.1 times than that of pure Mn0.5Cd0.5S and 1.0 wt% Pt/Mn0.5Cd0.5S.
- NiS acts as electron-trapping center and high active site to prevent charge recombination, and improve the photocatalytic H2 evolution activity.
- Low cost and earth-abundant NiS can replace noble metal Pt as a highly efficient co-catalyst in photocatalytic H2 evolution.
- Due to the intimate contact, the photogenerated electrons in the CB of Mn0.5Cd0.5S can be easily transferred to the surface NiS nanoparticles.

In this work, a serious of highly efficient and noble metal-free NiS modified MnxCd1-xS nanocomposites were synthesized via a simple direct in suit precipitation process. The as-synthesized products were characterized by XRD, UV-vis DRS, SEM, EDS, TEM, HRTEM, XPS, PL and TRFIA (the time resolved fluorescence spectra). Hydrogen evolution of as-synthesized NiS/MnxCd1-xS composites in the presence of Na2S-Na2SO3 under visible light irradiation (λ ≥ 420 nm) was investigated. The results demonstrated that photocatalytic hydrogen evolution of Mn0.5Cd0.5S was significantly enhanced by loading NiS nanoparticles. As a highly efficient co-catalyst, the optimal NiS loading content was found to be 0.3 wt%, giving a H2 evolution rate of 419.3 μmol/h with an apparent quantum efficiency (QE) of 5.21% (420 nm), which was nearly 18.6 and 3.1 times than that of Mn0.5Cd0.5S and 1.0 wt% Pt/Mn0.5Cd0.5S under the same condition. This work reveals that low cost and earth-abundant NiS can replace noble metals as a highly efficient co-catalyst in hydrogen evolution.

NiS is an efficient cocatalyst on Mn0.5Cd0.5S solid solution for visible light-driven H2 production in water.132