Synergistic PtAg Dual‐Atom Sites Boost Photocatalytic Nonoxidative Methyl Activation for Coproduction of 1,2‐Diphenylethane and Hydrogen From Toluene

Photocatalytic nonoxidative methyl activation and subsequent C─C coupling in the methyl group of arenes offer an attractive strategy for the coproduction of value-added polycyclic aromatics and hydrogen with 100% atom economy and positive delta Gibbs free energy. However, its application remains constrained by the limited availability of highly active redox sites capable of simultaneously facilitating efficient dehydrogenation oxidation and proton reduction. Herein, a platinum-silver dual-atom catalyst (PtAg DAC) anchored on CdS is designed to enable a water-assisted photocatalytic nonoxidative conversion of toluene to 1,2-diphenylethane with hydrogen evolution. In situ infrared, ESR, and DFT analyses unveil an atomic-scale synergy within the PtAg-S_bridge unit that facilitates C(sp³)-H cleavage of methyl and formation of key C₇H₇· radical via a water-assisted pathway, lowering the overall energy barrier from 3.02 to 1.31 eV. Consequently, the PtAg DAC yields 1,2-diphenylethane at 32.8 µmol g^-1 h^-1 with 77.35% selectivity, outperforming monometallic counterparts by up to 3.1-fold. Simultaneously, a hydrogen evolution rate of 89.8 µmol g^-1 h^-1 was achieved over PtAg DAC, which was 2.1- and 6.5-fold higher than Pt and Ag single-atom catalysts, respectively, resulting in a solar-to-chemical energy conversion due to positive ΔG.