Hydrothermal synthesis of Ni-doped ZnS solid solution photocatalysts for photocatalytic H2 production.

When the Ni doping amount is < 0.02, Ni2+ ions enter into the ZnS lattices to form solid solution, which could inhibit the effect of Ni impurities on the quick recombination of photo-generated electron–hole pairs and provide more active sites for photocatalytic H2 production. However, with further increasing the value of Ni2+, the photocatalytic activity of the samples decreases. In particular, when the doping of Ni is > 0.3, excessive Ni doping will result in NiS impurity levels (IL). NiS IL will increase the probability of recombination of photogenerated electron–hole pairs, which has negative influence on the photocatalytic H2 production. Moreover, Zn0.98Ni0.02S photocatalyst prepared at 180 °C for 12 h exhibits the best photocatalytic activity for photocatalytic hydrogen evolution reaction (PHER) with an initial rate of 457.11 μmol h−1 g−1, which is about 5 times higher than that over pure ZnS. [ABSTRACT FROM AUTHOR]