Single-Atom Ru Alloyed with Ni Nanoparticles Boosts CO₂ Methanation

Designing catalysts to proceed with catalytic reactions along the desired reaction pathways, e.g., CO2 methanation, has received much attention but remains a huge challenge. This work reports one Ru1Ni single-atom alloy (SAA) catalyst (Ru1Ni/SiO2) prepared via a galvanic replacement reaction between RuCl3 and Ni nanoparticles (NPs) derived from the reduction of Ni phyllosilicate (Ni-ph). Ru1Ni/SiO2 achieved much improved selectivity toward hydrogenation of CO2 to CH4 and catalytic activity (Turnover frequency (TOF) value: 40.00 x 10(-3) s(-1)), much higher than those of Ni/SiO2 (TOF value: 4.40 x 10(-3) s(-1)) and most reported Ni-based catalysts (TOF value: 1.03 x 10(-3)-11.00 x 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 Ru1 to Ni. Both in situ experiments and theoretical calculations confirm that the interface sites of Ru1Ni-SAA are the intrinsic active sites, which promote the direct dissociation of CO2 and lower the energy barrier for the hydrogenation of CO* intermediate, thereby directing and enhancing the CO2 hydrogenation to CH4.