  Commercial titanium dioxide is successfully plasma-treated under ambient
conditions for different time periods, leading to reduced crystallite size and
the creation of oxygen vacancies. Density functional theory-based calculations
reveal the emergence of additional localized states close to the conduction
band, primarily associated with under-coordinated titanium atoms in
non-stoichiometric titanium-oxide systems. The plasma-treated samples exhibit
improved photocatalytic performance in the degradation of methylene blue
compared to untreated samples. Moreover, the 4-hour plasma-treated
photocatalyst demonstrates commendable stability and reusability. This work
highlights the potential of cost-effective plasma treatment as a simple
modification technique to significantly enhance the photocatalytic capabilities
of titanium dioxide.
