Bimetallic Single Atoms for Mild Anaerobic Photocatalytic C(sp3)–H Activation in C–C Coupling Reaction

Achieving efficient activation of inert C(sp3)–H bonds while preserving the reactivity of intermediates remains a substantial challenge. Herein, we present bimetallic Pt and Pd single atoms on commercial P25-TiO2 (PtPdSA-TiO2) to produce active surface lattice oxygen species for effective and mild anaerobic activation of C(sp3)–H bonds and generation of targeted intermediates, facilitating the C–C coupling reaction of acetone into a high-value-added 2,5-hexanedione (HDN, C6 compound) and hydrogen. The in situ ESR, in situ ATR-IR and theoretical studies demonstrate that the surface oxygen species bridging Pt and Pd single atoms can effectively balance the activation energy of C(sp3)–H and the formation energy of free radical intermediates through bonding with the key −CH2COCH3 intermediate, contributing to a remarkable rate of 5.98 mmol gphotocatalyst–1 h–1 for the production of HDN with excellent selectivity (98.2%) on PtPdSA-TiO2 compared to previously reported PtSA-TiO2 (3.48 mmol gphotocatalyst–1 h–1) or PdSA-TiO2 (2.78 mmol gphotocatalyst–1 h–1). Additionally, the PtPdSA-TiO2 equipped in an outdoor solar-tracking reactor shows an HDN-production rate of 6.48 mmol gphotocatalyst–1 h–1 under the irradiation of concentrated sunlight (∼1800 mW cm–2), validating the feasibility of the system in real solar conditions.