Ru single atoms in Mn2O3 efficiently promote the catalytic oxidation of 5-hydroxymethylfurfural through dual activation of lattice and molecular oxygen

Concurrent activation of lattice oxygen (O L ) and molecular oxygen (O 2 ) is crucial for the efficient catalytic oxidation of biomass-derived molecules over metal oxides. Herein, we report that the introduction of ultralow-loading of Ru single atoms (0.42 wt%) into Mn 2 O 3 matrix (0.4%Ru-Mn 2 O 3 ) greatly boosts its catalytic activity for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The FDCA productivity over the 0.4%Ru-Mn 2 O 3 (5.4 mmol FDCA ‧g cat -1 ‧h -1 ) is 4.9 times higher than the Mn 2 O 3 . Especially, this FDCA productivity is also significantly higher than that of existing Ru and Mn-based catalysts. Experimental and theoretical investigations discovered that the Ru single atom facilitated the formation of oxygen vacancy (O v ) in the catalyst, which synergistically weakened the Mn-O bond and promoted the activation of O L . The co-presence of Ru single atoms and O v also promote the adsorption and activation of both O 2 and HMF. Consequently, the dehydrogenation reaction energy barrier of the rate-determining step was reduced via both the O L and chemisorbed O 2 dehydrogenation pathways, thus boosting the catalytic oxidation reactions.