Heterojunction engineering at ternary Cu2S/Ta2O5/CdS nanocomposite for enhanced visible light-driven photocatalytic hydrogen evolution

Abstract

Photocatalytic H2 production has been successfully achieved using a novel Cu2S/Ta2O5/CdS ternary nanocomposite fabricated by a solid-state approach. Initially, a solvent-assisted chemical approach was adopted for the synthesis of morphology controlled Cu2S (six petals) and CdS (nanorods) nanostructures. The known sol-gel method was used to synthesize the Ta2O5 nanoparticles, and then the composition was optimized for suitable engineering at the ternary heterojunction. The electron microscopic analysis evidenced the presence of ternary nanocomposite consists of Cu2S, CdS, and Ta2O5 with six-petals, nanorods, and random-spherical morphology, respectively. The effect of solution pH and optimization of the catalyst dosage over the photocatalytic H2 has been described. Photocatalytic experiments were carried out under standard conditions and rate of H2 generation in the following order of Lactic acid > Triethanolamine > Na2S/Na2SO3 in an aqueous solution. The optimized Cu2S/Ta2O5/CdS nanocomposite demonstrated a high rate of H2 evolution of 131 mmol.h−1.g−1cat that is significantly higher than the pristine CdS, Cu2S, CdS/Ta2O5, and Cu2S/CdS composites. The appropriate conduction band position of selected materials with multistep charge transfer setbacks the charge recombination process and resulted in durable enhanced efficiency with the visible light to the H2 conversion efficiency of 5.6%. Moreover, the stability of the spent catalyst was analyzed chemically as well as structurally.