p-n Heterojunction Photocatalyst MnCdS/CuCoS for Highly Efficient Visible Light-Driven H Production.

It is highly important to develop efficient and cheap photocatalysts for hydrogen production. Herein, a series of p-n heterojunction MnCdS/CuCoS has been successfully synthesized for the first time by the hydrothermal impregnation method. MnCdS/CuCoS loading with 12 wt % CuCoS shows the highest H evolution rate of 15.74 mmol h g under visible light (λ ≥ 420 nm) irradiation, which is about 3.15 and 15.28 times higher than that of bare MnCdS (4.99 mmol h g) and CuCoS (1.03 mmol h g), respectively. In addition, it shows a relatively good stability during the five recycle tests, with about 20% loss of reaction rate compared to that of the first cycle. The superior photocatalytic performance is attributed to the effective separation and transfer of photogenerated charge carriers because of the formation of the p-n junction. The samples are systematically characterized by X-ray diffraction, ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, photoluminescence, EIS, and so on. UV-vis and EIS show that CuCoS can effectively improve the visible light response of MnCdS/CuCoS and promote the electron transfer from CuCoS to the conduction band of MnCdS, so as to improve the photocatalytic efficiency. This study reveals that the p-n heterojunction MnCdS/CuCoS is a promising photocatalyst to explore the photocatalysts without noble metals.