Pd Nanoparticles Versus Single Atoms on CuTi‐LDH: Reversing Photoinduced Charge Transfer to Switch Radical Generation Pathway for Selective Methane Photooxidation

ABSTRACT Photocatalytic methane conversion to liquid products offers a promising route for the efficient utilization of methane while enabling the generation of value‐added chemicals. However, the inherent complexity and uncontrollable nature of the reaction pathways make it extremely challenging to simultaneously achieve high C 1 product yield with high selectivity. In this study, we report a Pd nanoparticle‐supported CuTi layered double hydroxide (LDH) catalyst (Pd NPs ‐CuTi‐LDH), which achieves a high C 1 liquid‐oxygenates yield of 7220.7 µmol g −1 h −1 , exceeding that of Pd single atoms‐supported CuTi‐LDH (Pd 1 ‐CuTi‐LDH) by threefold, while maintaining an outstanding selectivity of 99.7%. Mechanistic investigations reveal the amounts of ·OH and ·OOH radicals as the key determinant of catalytic performance. Interestingly, in situ XAFS analyses indicate that Pd size modulation induces a spatial separation of photogenerated electrons and holes under light irradiation, directing them toward different metal species. Further radical kinetic evaluations demonstrate the distinct charge‐transfer behavior results in ·OH radicals mainly originating from H 2 O on Pd NPs ‐CuTi‐LDH, whereas they predominantly arise from O 2 on Pd 1 ‐CuTi‐LDH. Consistently, theoretical calculations reveal the Pd NPs ‐CuTi‐LDH possesses lower formation energies for both ·OH (Δ E = −0.86 eV) and ·OOH (Δ E = −0.27 eV), thereby promoting more efficient methane conversion.