Undercoordinated Site-Abundant and Tensile-Strained Nickel for Low-Temperature COx Methanation

Abstract

By means of the rapid quenching (RQ) technique, we fabricate RQ Ni with peculiar undercoordinated site (UCS) abundant and tensile-strained structural characteristics. In liquid-phase CO methanation at 473 K, RQ Ni displays markedly higher specific activity and CH4 selectivity in comparison to Raney Ni, supported Ni, and Al2O3-supported Pd and Pt. RQ Ni shows comparable activity but higher CH4 selectivity in comparison to Ru/Al2O3, with Ru being documented as the most active metal for CO methanation. Density functional theory (DFT) calculations confirm that the UCSs are the active centers and reveal that the tensile-strain effect can further accelerate the rate-limiting CO dissociation step. Attractively, RQ Ni is also powerful in converting the greenhouse gas CO2 to CH4 at 473 K with an unprecedentedly high TOF of CO2 of 86.9 × 10–3 s–1 and impressively high selectivity of >99%.