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

Abstract: 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, Zn_0.98Ni_0.02S 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. Graphic abstract: [Figure not available: see fulltext.].