Abstract
The production of vanillin from biomass offers a sustainable route for synthesizing daily-use chemicals. However, achieving sunlight-driven vanillin synthesis through H(2)O activation in an aqueous environment poses challenges due to the high barrier of H(2)O dissociation. In this study, we have successfully developed an efficient approach for gram-scale vanillin synthesis in an aqueous reaction, employing Mn-defected γ-MnO(2) as a photocatalyst at room temperature. Density functional theory calculations reveal that the presence of defective Mn species (Mn(3+)) significantly enhances the adsorption of vanillyl alcohol and H(2)O onto the surface of the γ-MnO(2) catalyst. Hydroxyl radical (˙OH) species are formed through H(2)O activation with the assistance of sunlight, playing a pivotal role as oxygen-reactive species in the oxidation of vanillyl alcohol into vanillin. The Mn-defected γ-MnO(2) catalyst exhibits exceptional performance, achieving up to 93.4% conversion of vanillyl alcohol and 95.7% selectivity of vanillin under sunlight. Notably, even in a laboratory setting during the daytime, the Mn-defected γ-MnO(2) catalyst demonstrates significantly higher catalytic performance compared to the dark environment. This work presents a highly effective and promising strategy for low-cost and environmentally benign vanillin synthesis.