Zeolites as Photoactive Scaffolds for Efficient Photooxidation

Zeolites are widely applied in thermal catalysis as highly efficient catalysts but show limited photocatalytic activities. In this work, we demonstrated zeolites as photoactive scaffolds for perovskite nanocrystals that triggered a hydroxyl radical (^•OH)-mediated reaction pathway for selective C(sp³)-H bond activation. The as-prepared Cs₂AgBiBr₆@ZSM-5 (CABB@ZSM-5) photocatalyst afforded efficient toluene oxidation to benzaldehyde at ambient conditions under visible light irradiation, with >98% selectivity and an exceptional reaction rate of 40.9 mmol g^-1 h^-1, surpassing those of previously reported photocatalytic systems under comparable conditions. The host-guest design of CABB@ZSM-5 favored the adsorption of toluene and oxygen molecules and preactivated the adsorbed toluene molecules by Lewis acidic sites within ZSM-5 to reinforce the oxidation process. Significantly, we discovered that the adsorbed water in zeolite channels promoted the ^•OH-mediated oxidation reaction pathway, offering thermodynamic advantages over the conventional superoxide radical (^•O₂^-)-dominated reaction pathway. The incorporation of Zn²⁺ into CABB@ZSM-5 further boosted benzaldehyde production by 2-fold. This work redefines the role of zeolites, transforming them from passive supports into multifunctional scaffolds with significant potential in advanced photochemical applications.