Metal Single Atom Strategy Greatly Boosts Photocatalytic Methyl Activation and C–C Coupling for the Coproduction of High-Value-Added Multicarbon Compounds and Hydrogen

Photocatalytic reforming of renewable and low-cost biomass is an alternative approach to synthesize high-value-added multicarbon compounds and hydrogen. However, the difficulty in activating the methyl group of biomass and simultaneously promoting the C–C coupling makes photocatalytic reforming still a great challenge. Herein, through the first-principles simulation calculation of the energy barrier of acetone dehydrogenation and conversion over a series of noble metal single atom (Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au)-loaded TiO 2 (MSA-TiO 2 ) photocatalysts, we predict a Pt single atom-loaded TiO 2 (PtSA-TiO 2 ) photocatalyst that can enable methyl activation, CH 3 COCH 2 • radical formation, and hydrogen production most effectively from acetone, which is very significant for the synthesis of high-value-added multicarbon compounds by C–C coupling. This is well confirmed by our photocatalytic experiments, revealing that PtSA-loaded commercial P25-TiO 2 exhibits the best photocatalytic activity of 3.87 mmol g –1 h –1 for the direct coproduction of high-value-added 2,5-hexanedione (HDN) and hydrogen from acetone with a selectivity of 93%, at least 13-fold higher activity than other noble metal (Ru, Rh, and Ir) single atoms or Pt nanoparticle-loaded ones. In situ attenuated total reflection infrared spectroscopy reveals that the PtSAs contribute to the effective methyl activation and simultaneously promote the formation of more intermediate CH 3 COCH 2 • radicals, which are further confirmed by in situ electron spin resonance spectroscopy.