Single-Atom Ru Alloyed with Ni Nanoparticles Boosts CO 2 Methanation.

Designing catalysts to proceed with catalytic reactions along the desired reaction pathways, e.g., CO 2 methanation, has received much attention but remains a huge challenge. This work reports one Ru 1 Ni single-atom alloy (SAA) catalyst (Ru 1 Ni/SiO 2 ) prepared via a galvanic replacement reaction between RuCl 3 and Ni nanoparticles (NPs) derived from the reduction of Ni phyllosilicate (Ni-ph). Ru 1 Ni/SiO 2 achieved much improved selectivity toward hydrogenation of CO 2 to CH 4 and catalytic activity (Turnover frequency (TOF) value: 40.00 × 10 -3  s -1 ), much higher than those of Ni/SiO 2 (TOF value: 4.40 × 10 -3  s -1 ) and most reported Ni-based catalysts (TOF value: 1.03 × 10 -3 -11.00 × 10 -3  s -1 ). Experimental studies verify that Ru single atoms are anchored onto the Ni NPs surface via the Ru 1 -Ni coordination accompanied by electron transfer from Ru 1 to Ni. Both in situ experiments and theoretical calculations confirm that the interface sites of Ru 1 Ni-SAA are the intrinsic active sites, which promote the direct dissociation of CO 2 and lower the energy barrier for the hydrogenation of CO* intermediate, thereby directing and enhancing the CO 2 hydrogenation to CH 4 .