Study on Strategy to Incorporate Carbon and Nitrogen in Nanostructured TiO2: Modification of Low Bandgap Initiated by Broad Spectrum Response and Its Photoelectrochemical Properties

A material of nitrogen, carbon-codoped TiO2 (HITNC-1) with an unusual optical property in the near-infrared region is prepared at 800°C in NH3 and CO2 atmosphere. TEM results show semiconductor nanocrystals with grain size approximately in the range of 2~8 nm. HITNC-1 exhibits two strong absorption bands in near-infrared region, which is relative with the F-type color centers produced by the behaviors of Ti3+ trapping electrons and lies on the doping of N,C atoms into TiO2 lattices. The results of the surface photovoltage spectrum indicate that the intensity of positive photovoltage signal is 20 times than raw TiO2, and emerges a new signal in NIR region. The transient photovoltage results provide the investigation of dynamic behavior of photo-induced charge carriers in HITNC-1. Therefore, the photoelectrochemical properties clearly demonstrate that N,C-codoped TiO2 at high temperature could induce the separation of e- and h+ and harvest photons for optical property.