Notched-Polyoxometalate Strategy to Fabricate Atomically Dispersed Ru Catalysts for Biomass Conversion

The development of the synthesis methods of single-atom catalysts (SACs) is of great significance for the study of the specificity of SACs. Herein, we report a strategy to immobilize Ru atom using notched-polyoxometalate (N-POM) to prevent Ru from aggregation during pyrolysis and obtain a Ru catalyst with atomically dispersed Ru anchored on uniform subsupporter WO x clusters on carbon–nitrogen (Ru1@WO x /CN). Interestingly, the as-synthesized Ru1@WO x /CN catalyst exhibits an outstanding catalytic activity for the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in solvent-free condition (conversion of over 99% and selectivity of ∼100%). According to experimental analysis and density functional theory (DFT) calculations, both the regulation of the electronic structure of Ru active center through the subsupporter WO x clusters as well as the CN substrate and the catalysis of the acidifying WO x in the reaction for the dehydrogenation of 4-hydroxypentanoic acid intermediate are correlated with the enhancement of the enhanced catalytic activity. This N-POM strategy is also demonstrated to be impressive in preparing a series of atomically dispersed noble-metal atoms, which provides an opportunity of discovering SACs.