Preparation of a visible light-responsive photocatalyst from a complex of Ti4+ with a nitrogen-containing ligand

An anatase type of TiO2 photocatalyst containing N atoms was synthesized by a new technique using a complex of Ti4+ with a nitrogen-containing ligand as a precursor. The TiO2-like photocatalyst prepared by calcination of a Ti4+-bipyridine complex exhibited high photocatalytic activity for NOx removal under both ultraviolet and visible-light (lambda < 645 nm) illumination. The doping of the N atom into the anatase lattice, which is expected from UV-VIS spectroscopy, XRD, and XPS, is inferred as an important factor for the visible light absorption and NOx removal activity under a wide range of visible light illumination. The bipyridine ligand acted as the source of N and C atoms and additionally inhibited sintering of the photocatalyst during heat treatment.