Enhanced photocatalytic hydrogen evolution under visible light irradiation by p-type MoS2 n-type Ni2P doped g-C3N4

Solar energy conversion by photocatalytic hydrogen generation provides a clean alternative to fossil fuels. However, designing more efficient, chemically stable and affordable catalytic systems remains a great challenge for industrial application. In this study, p-type MoS2 is innovatively introduced on the n-type g-C3N4 loaded with Ni2P, which forms a new earth-abundant and environmentally benign photocatalyst for solar hydrogen generation. Firstly, we prepared the ternary MoS2-g-C3N4/Ni2P composite by ultrasonically mixing MoS2 nanosheets with g-C3N4/Ni2P by simple annealing process. The as-synthesized MoS2-g-C3N4/Ni2P catalyst is well characterized by X-Ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The 2% MoS2-g-C3N4/Ni2P exhibited the best hydrogen generation rate of 298.1 mu mol.g(-1).h(-1) under visible light illumination, which is 69 times more than that of pure g-C3N4. Based on the evaluation of hydrogen generation rate and characteristic results, a possible mechanism is proposed, where 2D MoS2-g-C3N4 p-n heterojunction could efficiently promote the electron-hole pair separation and Ni2P could significantly accelerate the hydrogen reduction step. The mechanism is supported by the results of PL and electrochemical analyses.