X-ray photoelectron spectroscopy of surface-treated TiO₂ mesoporous film by 500 eV argon ion beam

The surface sensitivity profiling feature of x-ray photoelectron spectroscopy (XPS) regularly calls for sample surface treatment through irradiation with beam of argon ion. The beam potentially ensures surface cleanliness against contaminations under ultra-high vacuum conditions for elemental identification. This work systematically and elegantly employs an argon ion (Ar⁺) beam to create oxygen vacancies in TiO₂ mesoporous film at different time of radiation exposure. Survey spectra acquired from XPS compositionally indicates the presence of oxygen (O 1s), titanium (Ti 2p) and carbon (C 1s). Three peaks were detected in the spectra of O 1s at high-resolution XPS which can be linked to oxygen vacancy, lattice oxygen and adsorbed oxygen while increase in radiation exposure time leads to increase in oxygen vacancy concentration. The presence of Ti³⁺ was observed in Ti 2p spectra analysis and indicates the creation of oxygen vacancies due to Ti⁴⁺ reduction. The potential of Ar⁺ to induce oxygen vacancies in TiO₂ mesoporous film as demonstrated in this work would facilitate photocatalytic activity enhancement of TiO₂ semiconductor films for different applications.