TiO2 Nanosheet Based Photocatalysts with Oxygen Vacancies for Enhanced Hydrogen Evolution Reaction Activity: Synthesis and DFT Calculations

Abstract

This work, we propose an efficient method for synthesizing TiO₂ nanosheets on titanium foil via plasma electrolytic oxidation (PEO) followed by hydrothermal growth of nanostructures. Density functional theory (DFT) calculations were conducted to optimize the material’s electronic properties and enhance its activity in the photocatalytic hydrogen evolution reaction (HER) through Mo doping. The PEO method forms a porous TiO₂ seed layer with strong adhesion to the substrate. On this basis, in a multi-stage process in situ nucleation of sodium titanate nanosheets occurs, followed by their transformation into TiO₂ nanosheets with a high specific surface area. Oxygen vacancies formed in the anatase phase play a key role in the adsorption of oxygen-containing ions and the activation of photocatalytic processes. Furthermore, DFT modeling confirmed that Mo doping and surface modification resulted in a decrease in the band gap (from 2.67 to 2.4 eV) , which contributed to the improvement of the photocatalytic activity and stability of the system. The proposed approach represents a promising strategy for scalable synthesis of monolithic, nanostructured TiO₂ photocatalysts with robust adhesion to titanium substrates.