Enhanced effect of a plasma-irradiated titanium substrate on the photocatalytic activity of a TiO₂ film

To improve the photocatalytic activity of TiO₂ film, Ti substrates are irradiated by He ions with different incident ion energy, temperature, and fluence. Anatase TiO₂ films are then coated on the plasma-irradiated substrates via chemical vapor deposition followed by calcination. Photocurrent tests and photocatalytic oxidation (PCO) of formaldehyde are used to assess photocatalytic performance. The optimal plasma-irradiated samples showed a four times higher photocurrent and a three fold increase in the rate constant of the PCO reaction compared to the TiO₂ coated, untreated control sample. It is found that the enhanced photocatalytic activity and photocurrent are related to the changes of Ti crystal structure and surface morphology through plasma irradiation.