Highly-efficient RuNi single-atom alloy catalysts toward chemoselective hydrogenation of nitroarenes

The design and exploitation of high-performance catalysts as well as understanding the structure-property correlation have gained considerable attention in selective hydrogenation reactions, but remain a huge challenge. Herein, we report a RuNi single atom alloy (SAA) in which Ru single atoms are anchored onto Ni nanoparticle surface via Ru–Ni coordination accompanied with electron transfer from sub-surface Ni to Ru. The optimal catalyst 0.4% RuNi SAA exhibits simultaneously improved activity (TOF value: 4293 h^{− 1}) and chemoselectivity toward selective hydrogenation of 4-nitrostyrene to 4-aminostyrene (yield: >99%), which is, to the best of our knowledge, the highest level compared with reported heterogeneous catalysts. In situ experimental researches based on XAFS, FT-IR measurements and theoretical calculations reveal that the Ru–Ni interfacial sites as intrinsic active centers facilitate the preferential cleavage of N–O bond in nitro group with a decreased energy barrier by 0.35 eV. In addition, the Ru–Ni synergistic catalysis promotes the formation of intermediates (C₈H₇NO* and C₈H₇NOH*) and accelerates the rate-determining step (hydrogenation of C₈H₇NOH*), resulting in the extraordinary activity and chemoselectivity toward nitroarenes hydrogenation.