Fabrication of nitrogen-doped mesoporous TiO2 layer with higher visible photocatalytic activity by plasma-based ion implantation

Nitrogen-doped porous TiO2 layers were fabricated on the titanium substrate by plasma-based ion implantation sequentially using He, O-2 or N-2 atmospheres. Post implantation annealing at 570 degrees C generates a mixture of anatase with a small fraction of rutile in the implanted layer. In order to enlarge the specific surface area, a mesoporous surface structure was produced by exposing the helium bubbles at the subsurface after removing the surface compact layer using argon ion sputtering. Nitrogen doping extends the photoresponse into the visible light region. Moreover, a lower dose of 4 x 10(15) N/cm(2) induces a stronger visible light absorption. The photodegradation of Rhodamine B solution with visible light sources indicates that the mesopores at the fresh surfaces and nitrogen doping, both individually and in combination, contribute to an apparent increase in the photodegradation rate. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.