Coupling Oxygen Ion Conduction to Photocatalysis in Mesoporous Nanorod-like Ceria Significantly Improves Photocatalytic Efficiency

The mesoporous nanorod-like ceria with high BET surface area of 121 m 2 /g is prepared by a facile method, microwave-assisted hydrolysis of Ce(NO 3 ) 3 ·6H 2 O in presence of urea. As compared to bulk ceria, its absorption edge significantly shifts to the visible region with a band gap of as low as 2.75 eV due to the presence of Ce 3+ . A novel strategy of significantly improving its photocatalytic efficiency is developed by coupling oxygen ion conduction to photocatalysis in the mesoporous nanorod-like ceria, in which UV–visible photons and thermal energy from a Hg lamp were integrated. Under such photothermocatalytic oxidation conditions, the mesoporous nanorod-like ceria exhibits much higher photothermocatalytic activity for the gas-phase minerlization of organic contaminants than corresponding alone thermocatalytic and photocatalytic activity and good photothermocatalytic stability. The significantly enhanced mobility of oxygen ions with increasing temperature raised by thermal energy from the Hg lamp greatly improves the separation efficiency of photogenerated electrons and holes by UV–vis photons in the mesoporous nanorod-like ceria. Moreover, the hole-trapped lattice oxygen ion generated by UV–vis irradiation is more active than the lattice oxygen ion for benzene oxidation. These beneficial effects promote catalytic efficiency for gas-phase purification of organic contaminants such as benzene, hexane, and actone.