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

Abstract

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 TiO2 (MSA-TiO2) photocatalysts, we predict a Pt single atom-loaded TiO2 (PtSA-TiO2) photocatalyst that can enable methyl activation, CH3COCH2• 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-TiO2 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 CH3COCH2• radicals, which are further confirmed by in situ electron spin resonance spectroscopy.