Sunlight-driven photocatalytic degradation of Congo Red using hydrothermally-synthesized quaternary Cu2NiSnS4 nanoparticles for wastewater remediation

This study investigates the optoelectronic performance of quaternary Cu 2 NiSnS 4 (CNTS) nanoparticles for efficient solar-driven photocatalytic degradation of Congo Red, a persistent and toxic azo dye. The research addresses the critical need for efficient and low-cost materials for sustainable water treatment. The CNTS nanoparticles were synthesized via a facile hydrothermal route and characterized using X-ray diffraction (XRD), Scanning Electron Microscopy, Energy Dispersive X-Ray Spectroscopy (EDX) and UV-Visible spectroscopy. XRD confirmed a cubic crystal structure for the hydrothermally synthesized CNTS nanoparticles, SEM revealed a hierarchical morphology composed of interconnected plate-like and nanosheet structures while UV-Vis spectroscopy displayed a strong and broad absorption within the UV-Vis range. The band gap of 1.42 eV indicates semiconducting behavior and demonstrates its suitability for visible-light driven photocatalytic applications. Under natural solar irradiation, the CNTS catalyst demonstrated high photocatalytic activity, achieving 96% removal of Congo Red within 120 min. Total organic carbon (TOC) analysis revealed a mineralization efficiency of 63%, indicating substantial degradation of the dye beyond simple decolorization. Furthermore, the catalyst maintained a degradation efficiency of 85% after three consecutive cycles, showing good reusability and sustained photocatalytic performance, which are important considerations for practical wastewater treatment applications. Overall, these findings showcase CNTS as a promising photocatalyst for the removal of organic dye pollutants from wastewater under sunlight irradiation.