Enhanced visible light photocatalytic hydrogen evolution by intimately contacted Ni2P decorated Ni-doped CdS nanospheres

Abstract

Ni-doped cadmium sulfide (CdS) nanospheres with nickel phosphide (Ni2P) loading (Ni2P@CdS-Ni) were successfully prepared via the two-step thermal treatment growth and chemical reduction method in this work. Firstly, the thermal treatment method was applied to introduce the Ni2+ into the lattice of CdS and induce the Ni-precursor loaded on surface of the CdS intimately. Then, the Ni-precursor was reduced into Ni(OH)2 by using the chemical reduction process. Furthermore, the Ni2P were loaded on the CdS via the second thermal phosphorization reaction. The loaded Ni2P would evidently accelerate the transfer of photo-generated electrons between CdS-Ni and Ni2P and meanwhile effectively decrease the charges recombination. Moreover, the results of UV–vis DR spectra and density functional theory (DFT) calculations confirmed that Ni cations doped in the lattice of CdS lead to a doping level at the bottom of the conduct band, which narrowed the bandgap. The work function indicated that doped Ni2+ helps to enhance the migration and separation of the photo-induced charge. Based on the synergistic effects, 3.7% Ni2P@CdS-Ni-3 presented a relatively high hydrogen evolution rate of 176.6 mmol h−1 g−1 under visible light irradiation (λ ≥ 420 nm), which is 63 times of the common CdS.