Quaternary Cu2ZnSnS4 and Cu2ZnSnS4-WS2 composite for enhanced antioxidant, antibacterial, and photocatalyst for degradation of sulfamethoxazole

Abstract

Antibiotic contamination possesses several adverse effects including antibiotic resistance, ecological impact, and human health concern etc. Hence there is need to find ways in mitigation of this environmental issue. In this study, Cu₂ZnSnS₄ (CZTS) nanoparticles (NPs) and CZTS-WS₂ composite were synthesized and explored its photocatalytic efficiency in degrading sulfamethoxazole, an antibiotic. In addition, the antioxidant and antibacterial capabilities of CZTS NPs and CZTS-WS₂ composites were also investigated. The CZTS NPs and CZTS-WS₂ composites were synthesized by a modified hydrothermal method, and the physical properties were explored. The p-type pristine CZTS NPs semiconductor with a direct bandgap (1.49–1.51 eV) is non-toxic and has a remarkable photostability making it extremely valuable in light-harvesting and photocatalyst applications. Quaternary CZTS NPs loaded with 10 % WS₂ exhibits good photocatalytic activity for the breakdown of sulfamethoxazole. The Fenton procedure was used to extract sulfamethoxazole from an aqueous solution. When compared to CZTS NPs (0.088 min⁻¹), the apparent rate constant for CZTS-WS₂ composite (0.223 min⁻¹) is almost two and a half times higher. Reactive quenching studies showed that OH, O²⁻, and ¹O² all contributed to SMX deterioration, with ¹O² outperforming O²⁻ and OH. An SMX transformation pathway in the CZTS-WS₂ composite process was postulated based on the identified intermediates by LC/MS. Finally, the composite’s reusability and stability were assessed during five separate runs. CZTS-WS₂ composite demonstrated more than 80 % radical scavenging efficiency. CZTS NPs and CZTS-WS₂ composite also demonstrate antibacterial capabilities against E. coli, S. aureus, M. luteus, and C. albicans. This is the first paper on the photocatalytic study of the degradation of sulfamethoxazole using CZTS NPs and CZTS-WS₂ composite as catalysts. The current CZTS-WS₂ composite’s outstanding catalytic efficacy in the absence of severe oxidizing/reducing agents and pricey noble metals has been ascribed to its size, surface area, and electronic effect. Hence this work describes a novel approach to developing efficient materials for antioxidant, antibacterial, and photocatalysts for the degradation of sulfamethoxazole.