Tailoring Cu ⁺ –O _v –Ti Ensembles with Electrophilic O ^– Species for Enhanced Catalytic Toluene Oxidation

The acceleration of industrialization has driven the increased emission of volatile organic compounds (VOCs), posing significant threats to both the ecological environment and public health. The deficiency of reactive oxygen species fundamentally restricts the low-temperature catalytic toluene combustion in transition-metal oxide catalysts. Herein, we report a strategy for intelligently designing active Cu⁺-O_v-Ti ensembles by coupling isolated Cu with adjacent oxygen vacancy, which can synergistically activate chemisorbed O₂ into reactive superoxide species (O₂^-). The defective Cu/TiO_2-<i>x</i> catalyst exhibited remarkable catalytic performance for toluene oxidation, achieving a <i>T</i>₉₀ of 225 °C, significantly 100 °C lower than that of the pristine Cu/TiO₂ catalyst. The low coordination geometry and electron transfer within Cu⁺-O_v-Ti ensembles synergistically activated O₂ to form the Cu-(O-O)_ad-Ti bridged superoxide O₂^- intermediate with an elongated O═O bond. In addition, the distinctive Cu-(O-O)_ad-Ti bridging structure with localized electrons facilitated the chemisorbed O₂ dissociation into electrophilic monatomic O^- species, which subsequently nucleophilically attack the methyl C-H of toluene. These benzyl alcohol-derived Ph-CH₂-O^- intermediates can be readily and flexibly converted into reactive benzaldehyde and benzoic acid species, which were available for subsequent aromatic ring-opening reactions. This study not only advances mechanistic insights into the Cu⁺-O_v-Ti ensembles and electrophilic O^- species in toluene catalytic oxidation but also establishes a design Cu⁺-O_v-Ti principle for engineering efficient VOC elimination catalysts.