TiOxNy Modified TiO2 Powders Prepared by Plasma Enhanced Atomic Layer Deposition for Highly Visible Light Photocatalysis

In this work, TiN film deposited by plasma enhanced atomic layer deposition (PEALD) is adopted to modify the commercial anatase TiO2 powders. A series of analyses indicate that the surface modification of 20, 50 and 100 cycles of TiN by PEALD does not change the morphology, crystal size, lattice parameters, and surface area of TiO2 nano powders, but forms an ultrathin amorphous layer of nitrogen doped TiO2 (TiOxNy) on the powder surfaces. This ultrathin TiOxNy can facilitate the absorption of TiO2 in visible light spectrum. As a result, TiOxNy coated TiO2 powders exhibit excellent photocatalytic degradation towards methyl orange under the visible light with good photocatalytic stability compared to pristine TiO2 powders. TiOxNy (100 cycles PEALD TiN) coated TiO2 powders exhibit the excellent photocatalytic activity with the degradation efficiency of 96.5% in 2 hours, much higher than that of pristine TiO2 powder of only 4.4%. These results clearly demonstrate that only an ultrathin surface modification layer can dramatically improve the visible light photocatalytic activity of commercial TiO2 powders. Therefore, this surface modification using ALD is an extremely promising route to prepare visible light active photocatalysts.