Fe-doped SrTiO3 perovskites: exploring their applications in photocatalytic dye degradation and supercapacitors

Fe-doped SrTiO₃, SrTi_1−xFe_xO₃ (STFO, x = 0.3, 0.5, 0.7), were prepared using the solid-state reaction method and their performances in photocatalytic dye degradation and supercapacitor applications were tested. STFO samples were characterized using XRD, EDX, and XPS to confirm its cubic perovskite structure and chemical compositions. The morphology and particle size were analyzed via SEM. UV–Vis spectroscopy reveal that Fe³⁺ could tune the bandgap and an optimized bandgap of 2.15 eV was found in STFO (x = 0.5), which is suitable for visible photocatalysts. Raman spectra could characterize the longitudinal and transverse optical modes (LO and TO), which revealed the phonon vibration of STFOs. The decolorization efficiency of the MB dye is found to be 87.71% at 220 min under visible light. The decolorization kinetics was found to be of the pseudo-first-order type with the R² value of 0.66 and the degradation rate constant of 0.02 min⁻¹. STFO (x = 0.7) was found to be the optimized supercapacitor material with the specific capacitance of 1028.45 F·g⁻¹, energy density of 0.0073 W·h·kg⁻¹, and power density of 22.74 W·kg⁻¹ at the current density of 0.22 A·g⁻¹. This study is anticipated to encourage exploring more potential lead-free perovskite materials with high dielectricity and low cost for photocatalytic and energy storage applications.