A dopant-mediated recombination mechanism in Fe-doped TiO2 nanoparticles for the photocatalytic decomposition of nitric oxide

作者：Wu Qingping; Yang Chieh Chao; van de Krol Roel^*

来源：Catalysis Today, 2014, 225: 96-101.

DOI：10.1016/j.cattod.2013.09.026

• Photocatalysis
• TiO2
• Nanoparticles
• Fe-doping
• Nitric oxide
• IR spectroscopy

The photon-assisted adsorption and catalytic decomposition of nitric oxide (NO) over undoped and Fe-doped TiO2 nanoparticles have been investigated by in situ diffuse reflectance infrared Fourier transformed (DRIFT) spectroscopy, in situ X-ray photoelectron spectroscopy (XPS) and on-line NO analysis. The DRIFT spectra and on-line NO analysis reveal that the usual photo-oxidation of NO to NO2 is strongly suppressed by the Fe dopant. This is found to be caused by the photo-reduction of Fe3+ to Fe2+, which is an effective adsorption site for nitric oxide species. The DRIFT spectra indeed reveal a new band at 1805 cm(-1), which is assigned to the N=O stretch vibration in a Fe2+(NO)(2) complex. Instead of producing NO2, photo-generated hydroxyl radicals oxidize the Fe2+ back to Fe3+. This causes the NO to desorb again, effectively closing an NO-mediated recombination loop. These results support the recently proposed reaction mechanisms for the photocatalytic decomposition of NO over undoped and Fe-doped TiO2, and provide new insights for the development of highly selective photocatalysts based on doped metal oxides.

• 出版日期2014-4-15