Pristine TiO₂ and Sr-Doped TiO₂ Nanostructures for Enhanced Photocatalytic and Electrocatalytic Water Splitting Applications

Pristine TiO₂ and Sr-doped TiO₂ (1%, 2.5% and 5%) nanoparticles were synthesized at low temperatures via an eco-friendly hydrothermal route for water-splitting applications. XRD, EDAX and Raman analysis were performed to analyze the crystallinity, purity and structure of the as-synthesized materials. TEM, SEM, BET and UV-DRS studies were carried out to elucidate the size, morphology, surface area and optoelectronic properties of the nanoparticles. High surface areas of 169, 182, 178 and 141.16 m² g⁻¹ for pristine TiO₂ (12 ± 0.6 nm) and 1% (11.1 ± 0.6 nm), 2.5% (12.1 ± 0.6 nm) and 5% (13 ± 0.7 nm) Sr-doped TiO₂ nanoparticles were obtained, respectively. One-percent Sr-doped TiO₂ nanoparticles were found to be active photocatalysts, as they showed higher hydrogen production (26.30 mmol$g_{cat}^{-1}$). Furthermore, electrocatalysis was investigated for HER and OER in 0.5 N H₂SO₄ and 0.1 N KOH electrolytic solutions using calomel as a reference electrode, revealing that 1% and 5% Sr-doped TiO₂ showed maximum current density for both HER (≈10 mA/cm²) and OER (≈2.49 mA/cm²), with an onset potential of 0.96 V for HER and 1.55 V for OER, and Tafel slopes of 84.09 and 91.60 mV/dec, respectively.