Atomic insights for Ag Interstitial/Substitutional doping into ZnIn2S4 nanoplates and intimate coupling with reduced graphene oxide for enhanced photocatalytic hydrogen production by water splitting

For the purpose of realizing effective visible-light-driven photocatalysis, Ag-doped ZnIn2S4 nanoplates were synthesized in situ onto reduced graphene oxide (RGO) sheets (denoted as Ag:ZnIn2S4/RGO). The high photocatalytic activity is predominantly attributed to the doping effect of Ag+ ions into ZnIn2S4 crystal structure. Interstitial and substitutional doping modes help introduce both acceptor and donor states, as supported by our calculations. Such a doping greatly increases the carrier density and charge transport efficiency. Meanwhile, there is a well-contacted interface between Ag:ZnIn2S4 nanoplates and RGO that renders RGO an electron collector and transporter to effectively lengthen the lifetime of the photogenerated charge carriers. As expected, the optimum nanocomposite exhibits a high H-2 -production rate of 6343.86 mu mol g(-1) h(-1), about 10.3 and 4.0 times higher than that of pure ZnIn2S4 and 0.15 wt% Ag:ZnIn2S4 samples, respectively. Similarly importantly, the photocatalysts exhibit long-term stability (>= 100 h) under visible light irradiation.