Visible-light driven noble metal (Au, Ag) permeated multicomponent Cu2ZnSnS4 nanocrystals: A potential low-cost photocatalyst for textile effluents and heavy metal removal.

ABSTRACT

An exemplary vision to understand the fundamental role of metal-doped multi-components system such as Au/Ag doped CZTS (Cu2ZnSnS4) nanocrystals encourages the non-vacuum approach for the best performing photocatalyst. Hydrophilic nanoparticles (Au/Ag and CZTS) are allowed to amalgamate under NTP atmosphere, eradicating the prerequisite for high-end equipment. The potential of Au and Ag-doped CZTS nanoparticles was speculated using various optical and structural characterizations. The absorption range of CZTS nanoparticles lies in the visible range, while Au/Ag doping slightly red-shifts the absorption range, considered the desirable state for photocatalysis. The synthesized nanoparticles are highly monodispersed with ∼15-35 nm particle size for Ag, Au, and CZTS. Photocatalysis is a discernible scheme for treating wastewater containing dyes, textile effluents, chemicals, and heavy metals. Here, we strive to use these ex-situ synthesized nanomaterials as photocatalysts, where the real textile waste (collected from industrial outlets), dyes, and heavy metal (chromium (VI)) have been photo-reduced after scrutinizing the finest combination of Ag or Au doped CZTS. Au-CZTS shows superior catalytic activity with an efficiency of 99.7% with a rate constant of 0.2 min-1 (while Ag-CZTS shows 90% efficiency with a rate constant of 0.07 min-1); hence, used for real textile waste and heavy metal (Chromium VI) photo-reduction. The maximum efficiency achieved for textile-1, textile-2, and Cr (VI) reductions is 80%, 70%, and 97%, respectively. The nanocrystals are highly stable and recyclable, tested for 15 repeated cycles. These studies pave the way for developing cost-effective, environmentally-friendly, durable, and selective semiconductor-metal (Au/Ag) hybrid heterostructures as visible-light-driven photocatalysts for wastewater remediation.