SnS2 interfaced Li-Doped g-C3N4 heterojunctions with enhanced photocatalytic performances for organic pollutant decontamination: Performance and mechanistic analysis

Abstract

This study focuses on the synthesis of SnS₂-anchored Li-doped g-C₃N₄ photocatalysts, achieved through one-step thermal polymerization for doping and the precipitation method for anchoring SnS₂. These synthesized photocatalysts were characterized using XRD, FESEM, HRTEM, PL, UV-DRS, XPS, and zeta potential measurements to elucidate the structure properties pertaining to crystallinity, morphological, charge carrier dynamics, band gap energies, chemical compositions, and surface charges. These materials were highly active to degrade the antibiotic ciprofloxacin (CP) and the dye Rhodamine B (RhB). Among all the photocatalysts, LCSn-10 (10 wt% SnS₂ on 5 mmol Li-doped g-C₃N₄) demonstrated the highest removal efficiencies, achieving 99.75% degradation of RhB and 89.55% degradation of CP all in 120 min. The SnS₂ and Li-doped g-C₃N₄ interface formed a heterojunction with a reduced band gap to promote effective light absorption and charge carriers, leading to enhanced photocatalytic degradation activity. Electrochemical analyses, including Mott-Schottky plots and EIS, indicated increased donor density and reduced charge resistance due to the junction interface formation, which was also the rationale behind the improved performance of the synthesized composites. Scavenger studies revealed that superoxide radicals were chiefly responsible for the decomposition of both RhB and CP. Photocatalytic efficiency of LCSn-10 was assessed at various pH levels, demonstrating optimal removal performance of both pollutants at pH 7. The catalyst exhibited robust stability, with only a minimal decrease in removal efficiency observed after five cycles for each pollutant. The SnS₂/Li-doped/g-C₃N₄ photocatalyst provides highly effective materials-integrated technology that can be an energy- and cost-efficient method to purify polluted water.