Modulating the exposed facets of CeO₂ nanorods by MoO₄^2– inducing to promote low-temperature photothermocatalytic toluene combustion

Photothermocatalysis is a synergetic process with the participation of both thermal and light energies, and ceria is a promising candidate as photothermocatalysts for VOCs combustion. Nevertheless, how its exposed facets affect the photothermocatalytic activity remains dubious, since suitable facet control strategies are scarce. Herein, we exploit a “MoO₄^2– inducing” method to modulate the exposed facets of CeO₂ nanorods from (111) to (100) facet, and the effect of exposed facets on toluene combustion is systematically investigated. As compared to CeO₂ nanorods with only the (111) facet, CeO₂ nanorods with the (100) and (111) facets have more reducible Ce⁴⁺ and edge/corner defect-derived Ce³⁺ with stronger ability to capture O₂, thereby leading to the higher thermocatalytic activity for toluene combustion; The Ce–O bonds at the (100) facet are more easily photoactivated, which is responsible for the more significant activity enhancement upon participation of both thermal and light energies. Additionally, in situ FTIR analysis shows that photothermocatalytic toluene combustion over ceria probably follows the process: toluene→ benzyl alcohol → benzaldehyde, benzoic acid, aliphatic aldehyde/acid→ anhydride → carbonate →CO₂ and H₂O. The work supplies new insight into correlation between ceria exposed facets and photothermocatalytic activity.