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

In this study, we constructed alpha-NiS/CdS and 13-NiS/CdS nanocomposites through loading alpha-NiS or 13-NiS cocatalysts onto the CdS nanosheets surface, and characterized them using different experimental techniqiues. Both alpha-NiS and 13-NiS improved the CdS photocatalytic hydrogen evolution capacity in a NiS crystal phase-dependent manner. The hydrogen production rates of 10wt%-alpha-NiS/CdS and 10wt%-13-NiS/CdS were 5501.9 and 3793.1 mu mol & sdot;g- 1 & sdot;h- 1, 6.2 and 4.3 folds higher than pure CdS, separately. Moreover, 10wt%-alpha-NiS/CdS and 10wt %-13-NiS/CdS showed the hydrogen production rates of 5638.7 and 3423.4 mu mol & sdot;g(- 1)& sdot;h(- 1) in simulated seawater, separately. Based on our characterization results and photocatalytic activity, we proposed a photocatalytic mechanism for the alpha-NiS/CdS nanocomposite. Ohmic heterojunction was formed between alpha-NiS and CdS, which facilitated the photogenerated electron and hole transfer and separation, thus enhancing the photocatalytic hydrogen production.