Facile Synthesis of N‐doped TiO₂ and Its Enhanced Photocatalytic Activity for Degrading Colorless Pollutants

Abstract

N‐doped nanocrystalline TiO2 is synthesized successfully through a simple ammonia‐modified hydrolysis‐solvothermal process. It is demonstrated that the resulting TiO2 doped with an appropriate amount of N exhibits high visible photocatalytic activities for the degradation of gas‐phase acetaldehyde and liquid‐phase phenol, which is attributed to its increased visible adsorption, appropriate crystallinity, and good dispersibility, whereas its UV activity is decreased. On the basis of the atmosphere‐controlled surface photovoltage spectra, it is found that the doped N species can capture the photogenerated holes so as to be favorable for photogenerated charge separation, so it is suggested that its decreased UV activity results from its weak adsorption of O2 compared with that of undoped TiO2, as shown by the O2 temperature‐programed desorption curves. Interestingly, the photocatalytic activity of the resulting N‐doped TiO2 under visible or UV irradiation can be improved further by promoting O2 adsorption after modification with an appropriate amount of phosphoric acid.

Modification Strategies with Inorganic Acids for Efficient Photocatalysts by Promoting the Adsorption of O2

“…The theoretical results show that the adsorption-energy of O 2 with H in "-Ti:F-H" is -3.25 eV, much greater than that in "-Ti-O-H" (-0.53 eV) and that of O 2 with F in "-Ti:F" (-0.19 eV), suggesting that the "-Ti:F-H" form is much favorable for O 2 adsorption in comparison to the "-Ti-O-H" and "-Ti:F" ones. This is in good agreement with our previous work about phosphate modification (-Ti-O-P-OH or -Fe-O-P-OH) in which the attribute of surface H + is altered by the increased acidity [30][31][32][33]48. As highlighted in Chemical & Engineering News, it is hydrogen fluoride's unexpected role in photocatalysis 62.…”

Nanocomposite heterojunctions as sunlight-driven photocatalysts for hydrogen production from water splitting

“…Some researchers synthesized nanocomposites of TiO 2 and some metal oxides, which are activated in the visible light region. [58][59][60][61][62][63][64][65][66] Interestingly, some of them showed higher hydro-gen production in comparison to pristine TiO 2 due to visible light absorption and better charge separation. For instance, Martha et al tried to increase hydrogen production by combining doped TiO 2 with V 2 O 5 .…”

Modification strategies of TiO2 for potential applications in photocatalysis: a critical review

“…4%) greatly limits the practical applications of anatase TiO 2 . Further, at high temperature (500-600°C) treatment, anatase phase transforms into rutile phase and resulting in the decrease photocatalytic activities under normal conditions (14). To overcome the above-mentioned shortfalls, extensive research is underway to develop new routes to modify TiO 2 by doping metal and nonmetal elements, coupling other semiconductor materials and surface modification with inorganic acids (15)(16)(17).…”