Enhanced photocatalytic and electrochemical properties of green synthesized strontium doped titanium dioxide nanoparticles for dye removal and supercapacitor applications

The development of multifunctional nanomaterials for environmental remediation and energy storage is critical for sustainable technologies. In this study, we synthesized strontium-doped titanium dioxide (Sr-TiO₂) nanoparticles (NPs) via a green method and investigated their structural, optical, and electrochemical properties to enhance photocatalytic and supercapacitive performance. Characterization results confirmed successful Sr incorporation into the TiO₂ lattice. X-ray diffraction (XRD) analysis revealed a slight shift in peak positions, indicating lattice distortion due to Sr doping. Scanning electron microscopy (SEM) showed uniform, well-dispersed nanoparticles, while energy-dispersive X-ray (EDX) spectra confirmed elemental composition. UV-visible spectroscopy (UV-Vis) demonstrated a redshift in absorption, reducing the bandgap and enhancing visible-light absorption. Fourier transform infrared (FTIR) spectroscopy identified characteristic functional groups, and Brunauer-Emmett-Teller (BET) analysis indicated increased surface area, favoring photocatalytic and electrochemical activity. The photocatalytic performance of Sr-TiO₂ NPs was assessed through Methylene Orange (MO) and Congo Red (Con-R) degradation under visible light at different pH levels. Under optimized conditions, Sr-TiO₂ NPs achieved 94.48% MO removal in 100 min and 97.89% Con-R removal in 70 min, following pseudo-first-order kinetics, demonstrating their efficiency as visible-light-driven photocatalysts for wastewater treatment. Electrochemical studies, including cyclic voltammetry (CV), charge-discharge tests, and electrochemical impedance spectroscopy (EIS), revealed improved charge storage and lower charge transfer resistance compared to bare TiO₂. The Sr-TiO₂ NPs exhibited enhanced specific capacitance and good electrochemical stability, underscoring their potential as high-performance electrode materials for supercapacitors. These findings highlight a sustainable approach to environmental remediation and energy storage by leveraging Sr-doped TiO₂ nanomaterials for dual-functional applications.