Interface Synergy of Exposed Oxygen Vacancy and Pd Lewis Acid Sites Enabling Superior Cooperative Photoredox Synthesis

Photo-driven cross-coupling of o-arylenediamines and alcohols has emerged as an alternative for the synthesis of bio-active benzimidazoles. However, tackling the key problem related to efficient adsorption and activation of both coupling partners over photocatalysts towards activity enhancement remains a challenge. Here, we demonstrate an efficient interface synergy strategy by coupling exposed oxygen vacancies (V_O) and Pd Lewis acid sites for benzimidazole and hydrogen (H₂) coproduction over Pd-loaded TiO₂ nanospheres with the highest photoredox activity compared to previous works so far. The results show that the introduction of V_O optimizes the energy band structure and supplies coordinatively unsaturated sites for adsorbing and activating ethanol molecules, affording acetaldehyde active intermediates. Pd acts as a Lewis acid site, enhancing the adsorption of alkaline amine molecules via Lewis acid-base pair interactions and driving the condensation process. Furthermore, V_O and Pd synergistically promote interfacial charge transfer and separation. This work offers new insightful guidance for the rational design of semiconductor-based photocatalysts with interface synergy at the molecular level towards the high-performance coproduction of renewable fuels and value-added feedstocks.