Charge Localization at Ce–O5 Sites Enables Efficient Photocatalytic Methane Oxidation to Methanol under Mild Conditions

Photocatalytic oxidation of methane (POM) to methanol under mild conditions remains challenging because of the difficulty in activating inert C–H bonds and the inevitable overoxidation of methanol. Herein, we simultaneously achieved high selectivity and productivity of CH3OH in POM by introducing Pd nanoclusters (NCs) on a Ce-doped TiO2 photocatalyst (Pdn/TiCeOx) at room temperature. Detailed mechanistic studies revealed that the construction of Ce–O5 sites could pre-activate the C–H bond by polarizing CH4 molecules. Furthermore, the introduced Pd NCs significantly altered the electronic structure of Ce atoms, inducing pronounced charge localization at Ce sites, thereby promoting CH4 adsorption and activation and, in turn, reducing the energy barrier for C–H cleavage by ∼0.65 eV. Meanwhile, the charge localization at Ce sites not only inhibited further dehydrogenation of the adsorbed *CH3 but also suppressed the overoxidation of *CH3OH by weakening the Ce–Om bond and strengthening the polarity of the O–H bond in CH3OH, thereby facilitating methanol desorption. As a result, Pdn/TiCeOx exhibits a CH3OH productivity of 11,620 μmol·g–1·h–1 with a selectivity of 98% in POM at ambient temperature and low pressure. This work underscores the efficacy of lanthanide-induced structural distortion and electronic engineering in oxide-based catalysts and offers a design principle for methane-to-methanol conversion.