Single-Atom Ru Alloyed with Ni Nanoparticles Boosts CO2 Methanation

Abstract

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 × 10−3 s−1), much higher than those of Ni/SiO2 (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 Ru1–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.