Capping ligand initiated CuInS2 quantum dots decoration on, ZnIn2S4 microspheres surface under different alkalinity levels resulting in different hydrogen evolution performance

Abstract

Surface distribution of quantum dots (QDs) at the semiconductor matrix caused by synthesis condition (e.g. pH of solution during coupling) could lead to different photocatalytic activity. Thus, achieving an optimal covering of semiconductor matrix by QDs has been challenging. Herein, the influence of the alkalinity level of aqueous decoration medium for the coupling of mercaptoundecanoic acid (MUA) capped CuInS2 quantum dots (CIS) and ZnIn2S4 microspheres (ZIS) on photocatalytic hydrogen evolution (PHE) performance was investigated. Aqueous decoration medium with different alkalinity levels for the formation of ZIS/CIS photocatalytic system resulted in significantly different PHE performances in the presence of (0.5 wt%) Pt co-catalyst deposition without any change in crystal structure of ZIS matrix up to pH 12.5. The photocatalytic system obtained at pH 10.5 possessed the highest performance followed by the decrease at pH 11.5 and again the remarkable increase was detected at pH 12.5 that was the pH level for uniform dispersion of CIS in aqueous medium. This work remarks the importance of the nanoparticle’s aggregates on PHE performance over non-toxic ZnIn2S4/CuInS2 photocatalytic system.