Origin of photoactivity of oxygen-deficient TiO2 under visible light

Abstract

As it is now well established that oxygen vacancies are spontaneously introduced during nitrogen doping of anatase TiO2, there is a lively debate on whether nitrogen dopant or oxygen vacancy contributes to the visible light photoactivity of the doped catalyst. We showed that the coordinately unsaturated Ti site is integral to the visible light photoactivity in anatase oxygen-deficient TiO2 catalyst. Accordingly, oxygen vacancies may contribute to the visible light photoactivities in N-doped TiO2 and other nonmetallic ion-doped TiO2 as well. A redox active visible light photocatalyst has been developed based on oxygen-deficient structure in anatase TiO2.

CNT-TiO2−δ Composites for Improved Co-Catalyst Dispersion and Stabilized Photocatalytic Hydrogen Production

“…Nevertheless, a nearly linear accumulation of H2 was achieved over all of the photocatalysts, indicating more stable photocatalytic performance. As compared to the pristine TiO2, TiO2−δ still demonstrated a higher activity, implying the importance of oxygen deficiency in this reaction [4,5]. Most importantly, CNT-TiO2−δ-15 and CNT-TiO2−δ-60 showed even higher H2 productivity than TiO2−δ.…”

“…One of the commonly observed and applied features for TiO2 is that its activity can be significantly enhanced by surface and/or bulk defects resulting from, for example, the introduction of heteroatoms or the removal of lattice oxygen [3,4,6]. Doping with metallic (Nb, Ag, Pt, W, Mn, etc.)…”

“…One of the key issues in solar water-splitting is the development of efficient and stable systems for light-driven reduction of protons to hydrogen. Among other materials, titanium dioxide (TiO2) is comprehensively studied as a photocatalyst for hydrogen production due to its relatively negative position in the conduction band edge allowing for proton reduction, low cost, high stability and the possibility of further functionalization [3][4][5][6][7][8].…”

Facile synthesis of mesoporous N doped zirconium titanium mixed oxide nanomaterial with enhanced photocatalytic activity under visible light

“…Recently it was reported that oxygen vacancies can enhance the visible light mediated catalytic activity to a very high level. 34 Therefore the enhanced photocatalytic reduction and oxidation activity of TiZr-6N-400 under visible light can be attributed to the synergistic effect of high surface area, oxygen vacancy and substantial N doping. So it is important to study the exact contribution of the oxygen vacancy as well as the non-metal doping separately for better understanding of the photocatalyst.…”

“…More recently, it was observed that the same peak is observed in a titania material having oxygen vacancy. 34 Due to the creation of oxygen vacancies the adjacent oxygen atom experiences less electron density in comparison to other lattice oxygen atoms. Hence the peak due to these oxygen atoms shifts towards the higher binding energy.…”