Gallium‐Based Eutectic Alloys as Liquid Electron Donors to Ruthenium Single‐Atom Catalysts for Selective Hydrogenation of Vanillin

Tuning the catalytic pathways of atomically dispersed single-atom catalysts (SAC) has emerged as an effective strategy to optimize their overall catalytic activity. Herein, we present Ru₁@m-tube, a hollow carbon nitride-supported Ru SAC, coated with eutectic galinstan (GaInSn), as a model catalyst, we demonstrate a performance inversion in vanillin conversion. Vanillin, as a biomass-derived compound with industrial relevance, presents challenges in catalytic hydrogenation, making it an ideal model reaction to test and compare the catalyst's selectivity and efficiency. The as-obtained Ru₁@m-tube(GaInSn) achieved nearly 100% vanillin conversion within 5 h and exhibited an impressive 93.8% selectivity for vanillyl alcohol. Electron spillover from gallium-based eutectic alloys to highly diluted ruthenium sites enhances the desorption of vanillyl alcohol, resulting in an exceptional performance shift between hydrogenation and hydrodeoxygenation. Our findings not only offer a novel approach for modulating SAC performance via liquid-metal interfaces but also expand the understanding of promoter screening for various challenging reactions.