Enhanced photo/electrocatalytic efficiency of Zn-decorated TiO2 nanostructures for sustainable hydrogen evolution

Abstract

Monophasic 1, 2.5, and 5 % Zn-decorated TiO₂ nanocatalysts have been fabricated by environmentally benign hydrothermal synthesis by avoiding expensive chemicals. As- prepared nanostructures have been investigated utilizing various sophisticated instruments like XRD, scanning and transmission electron microscopy, EDAX, Raman, optoelectronics as well as BET Surface Area studies. 2.5 % Zn- decorated TiO₂ was found to have superior photocatalytic performance, exhibiting an H₂ formation of 25.55 mmol$g_{\mathrm{cat}}^{-1}$ in 8 hours and average H₂ generation of 3.15 mmol$g_{\mathrm{cat}}^{-1}$h⁻¹ at 170 W light intensity. Additionally, electrochemical investigations showed that 5 % and 2.5 % Zn-doped TiO₂ had a higher cathodic and anodic current density of 10 mA/cm² at −0.95, indicating that it has a higher HER catalytic activity, respectively. The synergistic impact of pristine TiO₂ and Zn-incorporated TiO₂ nanocatalysts is responsible for the increased kinetics of H₂ evolution, as it increases the separation and transfer of photo-charged (e^-/h⁺ pair) carriers and decreases redox potential for HER.