ESR study on the visible photocatalytic mechanism of nitrogen-doped novel TiO2: Synergistic effect of two kinds of oxygen vacancies

The visible photocatalytic mechanism of nitrogen-doped novel TiO2 was studied by means of electron spin resonance spectroscopy (ESR). It was found that, under visible light irradiation, the concentration of single-electron-trapped oxygen vacancy (SETOV, Vo
• ) of novel TiO2 remained unchanged, but that of nitrogen-doped novel TiO2 increased and returned to original state when the light was turned off. This implies that, aside from Vo
• in bulk of nitrogen-doped novel TiO2, oxygen vacancy without trapped electron (Vo
•
• ) was formed on its surface. Vo
•
• as a surface electron trap captured photogenerated electron from the bulk to generate extra Vo
• , carrying out photocatalytic reaction on the surface. At the same time, nitrogen doping product NO was chemically adsorbed on the vicinity of Vo
•
• and inhibited the attack of oxygen, allowing Vo
•
• to remain stable in air. The synergistic action of the two kinds of active structures, i.e., bulk Vo
• –NO–Ti and surface Vo
•
• –NO–Ti, accounted for the visible photocatalytic activity of N-doped novel TiO2.

Synergistic action is realized between (Vo
• )bulk and (Vo
•
• )surf in the presence of active structures (Vo
• )bulk–NO–Ti and (Vo
•
• )surf –NO–Ti.Figure optionsDownload as PowerPoint slideResearch highlights
► The origin of visible photocatalytic activity of the N-TiO2 was studied by ESR.
► (Vo
• )bulk and (Vo
•
• )surf formed in N-TiO2.
► (Vo
• )bulk and (Vo
•
• )surf show a synergistic effect in visible photocatalytic.
► TiO2 did not contain (Vo
•
• )surf, so no visible photocatalytic activity.