Light assisted synthesis of hierarchically structured Cu/CdS nanorods with superior photocatalytic activity, stability and photocatalytic mechanism

Abstract

Abstract In the present study, we report a facile and green route for the synthesis of hierarchically structured novel Cu/CdS nanorods by photo deposition method for the first time. The morphology of the newly synthesized composite was confirmed as nanorods using transmission electron microscopy (TEM) and grew well crystallinity with hexagonal phase exhibiting a crystalline size of 24 nm. The doping of copper significantly altered the bandgap from 2.43 to 2.30 eV. For the very first time, the photodegradation of different class of dyes viz azo, triphenylmethane, anionic and cationic dyes using Cu/CdS nanorods as a photocatalyst was investigated under visible light illumination. The complete degradation of the dye solution was observed within 25 min and the condition for the effective degradation was optimized. Interestingly, the present photocatalytic system was very faster than that of other CdS based photocatalytic dye degradation. The roles of Cu doping, reaction kinetics, degradation mechanism as well as catalyst stability the in photoreaction were comprehensively studied. The prevention of the electron-hole pair recombination was strongly evidenced by photoluminescence studies which showed very low emission intensity for the Cu/CdS (0.75%) compared to that of CdS and other ratios of Cu/CdS. Importantly hydroxyl radical was actively involved in the photocatalytic degradation mechanism which was strongly supported by the trapping experiments using different scavengers. The crucial role of Cu doping for the improved photocatalytic activity was mainly attributed to the superior electron transfer ability, enhanced light harvesting and boosted catalytic active sites.