Organic-free hydrothermal synthesis of chalcopyrite CuInS2 and its photocatalytic activity for nitrate ions reduction

Abstract We performed a facile and organic-free hydrothermal method (thiourea-oxalic acid co-molten system) to prepare chalcopyrite CuInS2 nano-crystallite. Its intrinsic photocatalytic activities to nitrate reduction in aqueous solutions were investigated in comparison to bulk CuInS2 prepared by annealing Cu2S and In2S3 at 600–750 °C under vacuum. All samples show good and similar photocatalytic activities for nitrate reduction, for example, the conversion rate is about two times of that in a blank experiment. All CuInS2 catalysts were stable after the photocatalytic reactions, indicated by the identical XRD patterns before and after the reaction.