Phase‑controlled Sb₂O₃ nanostructures enabling visible‑light photocatalysis and high‑retention supercapacitor performance

Optimizing multifunctional semiconductor nanomaterials for simultaneous environmental remediation and electrochemical energy storage remains a significant challenge, as their functional properties are strongly dependent on thermal processing conditions. In this study, orthorhombic antimony trioxide (Sb₂O₃) nanoparticles were synthesized via a sol–gel route and systematically calcined at 600 °C for varying durations (30–150 min) to investigate the influence of calcination time on structural evolution, optical behavior, photocatalytic activity, and electrochemical performance. X-ray diffraction (XRD) confirmed phase-pure orthorhombic Sb₂O₃ with enhanced crystallinity and reduced lattice strain upon prolonged calcination. Scanning electron microscopy (SEM) revealed progressive morphological ordering and grain densification. FTIR analysis identified characteristic Sb–O–Sb vibrational bands in the 450–700 cm⁻¹ region, while Raman spectroscopy exhibited prominent phonon modes at 264, 403, and 465 cm⁻¹ , confirming phase stability and improved lattice ordering of orthorhombic Sb₂O₃. UV–DRS analysis demonstrated a progressive reduction in band gap from 3.72 to 2.46 eV with increasing calcination time. TGA/DTA results confirmed the need for calcination at 600 °C for complete phase stabilization, while BET analysis revealed a maximum surface area of 276.8 m² g⁻¹ for the 150 min sample. The optimized sample exhibited enhanced Congo Red photodegradation efficiency (95%) and a specific capacitance of 144.37 F g⁻¹ with excellent cyclic stability. EIS analysis indicated reduced charge-transfer resistance and efficient charge transport, supporting enhanced photocatalytic and electrochemical behavior. The findings demonstrate that calcination-time engineering provides an effective strategy for tailoring Sb₂O₃ nanostructures toward multifunctional environmental and energy-storage applications.