Synthesis and electrochemical investigation of ligand-tuned antimony sulphide nanoparticles for persulfate-driven photocatalysis

Abstract

Ligand engineering offers a powerful approach for tuning the physicochemical and electronic properties of semiconductor nanomaterials, thereby optimising their photocatalytic and electrochemical performance. In this study, antimony sulphide (Sb₂S₃) nanoparticles were rationally designed using three surface-capping ligands, oleic acid (OAc), oleylamine (OAm) and octadecylamine (ODA) yielding Sb₂S₃ (1), Sb₂S₃ (2), and Sb₂S₃ (3), respectively. Systematic characterisation confirmed the successful formation of highly crystalline orthorhombic-phase Sb₂S₃ with ligand-dependent modulation of morphology and optical properties. Electrochemical behaviour was evaluated using cyclic voltammetry of screen-printed carbon electrodes (SPEs) modified with the nanoparticles. Among the series, SPE–Sb₂S₃ (1) exhibited superior anodic and cathodic current responses with minimal peak-to-peak separation, indicative of enhanced charge-transfer kinetics facilitated by the oleic acid ligand environment. The photocatalytic activity was investigated for the degradation of Safranine-O (Safsingle bondO) dye. Sb₂S₃ (1), Sb₂S₃ (2), and Sb₂S₃ (3) achieved degradation efficiencies of 51%, 46%, and 48%, respectively. Synergistic coupling of Sb₂S₃ (1) with persulfate (Sb₂S₃ (1))+PS) markedly enhanced the degradation efficiency to 94%, which was further optimized to 99.7% under 0.3 g L−1 catalyst loading, 0.4 g L−1 persulfate concentration, and pH 2. Kinetic analysis revealed that the apparent rate constant (kₐₚₚ) of the Sb₂S₃ (1) + PS system was ∼3.2 times higher than that of pristine Sb₂S₃ (1), confirming the ligand-assisted activation of persulfate and accelerated radical-mediated oxidation. Overall, the results demonstrate that ligand engineering profoundly influences the electronic conductivity, surface reactivity, and catalytic efficiency of Sb₂S₃ nanoparticles. The Sb₂S₃ (1)+PS system thus represents a highly efficient and tunable platform for persulfate-driven photocatalysis, with significant potential for advanced wastewater treatment and environmental remediation.

HIGHLIGHTS • Ligand engineering effectively tailored the properties of orthorhombic Sb₂S₃ nanoparticles. • Oleic-acid-capped Sb₂S₃ exhibited the best electrochemical performance on modified screen-printed electrodes. • Photo-degradation by the pristine Sb₂S₃ on Saf-O achieved efficiencies ranging from 46 to 51%. • Coupling of oleic-acid-capped Sb₂S₃ with persulfate (PS) boosted photocatalytic efficiency to 99.7%. • Ligand-assisted PS activation significantly enhanced the kinetics in Sb₂S₃ (1)+PS, enabling advanced wastewater treatment.