Effect of phase of NiS loaded on two-dimensional CdS nanosheets on photocatalytic hydrogen evolution

In this study, we constructed α-NiS/CdS and β-NiS/CdS nanocomposites through loading α-NiS or β-NiS cocatalysts onto the CdS nanosheets surface, and characterized them using different experimental techniqiues. Both α-NiS and β-NiS improved the CdS photocatalytic hydrogen evolution capacity in a NiS crystal phase-dependent manner. The hydrogen production rates of 10wt%-α-NiS/CdS and 10wt%-β-NiS/CdS were 5501.9 and 3793.1 μmol·g−1·h−1, 6.2 and 4.3 folds higher than pure CdS, separately. Moreover, 10wt%-α-NiS/CdS and 10wt%-β-NiS/CdS showed the hydrogen production rates of 5638.7 and 3423.4 μmol·g−1·h−1 in simulated seawater, separately. Based on our characterization results and photocatalytic activity, we proposed a photocatalytic mechanism for the α-NiS/CdS nanocomposite. Ohmic heterojunction was formed between α-NiS and CdS, which facilitated the photogenerated electron and hole transfer and separation, thus enhancing the photocatalytic hydrogen production.