Tunable oxygen vacancy engineering via electron beam irradiation in TiO2/MXene: A combined experimental and DFT study on photocatalytic performance and hydrogen adsorption energetics

Defect engineering is a powerful strategy for enhancing catalytic activity, charge-carrier mobility, and structural stability through the controlled introduction of defects such as oxygen vacancies (O v ). Electron beam (EB) irradiation offers a precise route for generating vacancies and lattice disorders, enabling tailored modulation of electronic and surface states for photocatalytic applications. In this work, a 1D/2D TiO 2 /MXene (TMX) was synthesized via electrostatic self-assembly method, where TiO 2 serves as the primary light-absorbing semiconductor and MXene acts as a co-catalyst to promote charge separation and surface redox reactions. High-energy EB irradiation was employed to induce O v and Ti 3+ species within TiO 2 , markedly improving the photocatalytic hydrogen production of TMX. The optimally irradiated sample (TMX3-500) achieved a hydrogen evolution rate of 691 ± 9.54 μmol g -1 h -1 , 5.25 times higher compared to sample before irradiation. Such enhancement was ascribed to improved light absorption, efficient charge carrier separation by the generation of O v , confirmed by different spectroscopic characterizations. DFT calculations further showed that O v generate defect states within TiO 2 bandgap that interact with adsorbed hydrogen, while interfacial charge transfer from TiO 2 to MXene optimizes ΔG H⁎ towards thermoneutrality. The findings highlight the role of EB-induced defect engineering in designing efficient photocatalysts for solar-driven hydrogen production.