Hydrothermally Derived Mg-Doped TiO2 Nanostructures for Enhanced H2 Evolution Using Photo- and Electro-Catalytic Water Splitting

Mg-doped TiO2 nano-structures in different compositions (1, 2.5 and 5%) were successfully synthesized by low-temperature hydrothermal route. X-ray diffraction and electron microscopic studies were used to investigate the crystal structure, surface morphology and particle size of the as-synthesized materials. Raman studies were carried out to elucidate the phase identification and the modes of vibrations to determine the impact of dopant ion on the crystal structures. The band gap was estimated using UV-DRS studies whereas, BET surface area analysis revealed an increase in the surface area of increasing Mg2+ ions concentration in TiO2 nanostructures. Among the synthesized various composition of nano-structures, 5% Mg-doped TiO2 photocatalyst showed maximum hydrogen evolution activity (38.96 mmol gcat−1) in an 8-hour (h) analysis cycle. Moreover, the 2.5% Mg-doped TiO2 nanocatalyst with tafel slopes of 123.5 and 126.7 mV/dec showed strong activity for both HER in 0.5N H2SO4 and 0.1N KOH, with an onset potential of 0.96 V (at 10 mA/cm2) and −1.38 V (at 1 mA/cm2) for HER, respectively. Experimental investigations deduced that the incorporation of Mg2+ ions in the TiO2 resulted in the increase of hydrogen generation catalytic activity of titanium dioxide owing to the synergistic effect provided by the remarkable surface area and the presence of defects introduced by doping.