Photocatalytic waste-to-renewable energy nexus using solar light induced quantum dots

Abstract

Modern green transition obligations support a circular economy to maximize the use of existing resources, where climate-neutral net-zero energy goals argue for a hydrogen economy to minimize the energy dependence on fossil fuels. In this study, the surface functionalized cadmium sulfide nanoparticles were used as a photocatalyst to efficiently demineralize the methylene violet (MV) and rhodamine B (RhB) for hydrogen evolution. The influence of sulfur vacancy on photocatalytic hydrogen production was systematically investigated. The sulfur vacancy in CdS quantum dots (QDs) surface demonstrated a viable strategy for improving charge separation and photocatalytic performance. The impact of vacancy formation on the QDs properties, including the band gap, crystallite size, average strain, photoluminescence, dislocation density, electrostatic repulsion, and texture coefficient were thoroughly examined. The growth kinetics of CdS in the presence of different capping agents was analyzed using UV–Vis, Fourier transform infrared, and photoluminescence spectra. The results of experiments and theoretical calculations were used to examine the interactions of the CdS-ligand and its structural and optoelectronic properties. The thioglycolic acid functionalization effectively passivates surfaces, which gives desirable optical and textural properties and potential circular applications. Optimized nanocluster geometry, stability, and band gap were examined by implementing density functional theory and time-dependent density functional theory. The solar light-driven mineralization of MV and RhB was done, further, the treated water was used for the generation of hydrogen making circular use of CdS quantum dots for a net-zero energy approach.