Highly Dispersed Single Clusters Supported Porphyrinic Metal–Organic Frameworks for Synergetic CO2 Electroreduction to CH4

Abstract

The electrocatalytic CO₂ reduction is a promising path toward the carbon-neutral goal but remains a huge challenge due to the high activation barrier for CO₂ and poor selectivity. Herein, the highly dispersed triruthenium single cluster (Ru₃-SCs) is confined into the nanospace of pyrrole-3-carboxylic acid (PyrA)-modified nickel-porphyrin-based metal–organic framework (Ni-PCN-222-PyrA) to form the composite (Ru₃-SCs@Ni-PCN-222-PyrA) through the pre-coordination confinement strategy. The prepared Ru₃-SCs@Ni-PCN-222-PyrA can accelerate the selective reduction of CO₂ to CH₄ via electrocatalysis. Under −1.0 V versus reversible hydrogen electrode (RHE), Ru₃-SCs@Ni-PCN-222-PyrA affords CO₂ electroreduction to CH₄ with a high selectivity of 71.9% Faradaic efficiency. Mechanistic studies reveal that the superior reactivity can be attributed to the ensemble effect and synergistic catalysis of Ru₃-SCs, in which one Ru atom is responsible for CO₂ reduction to ^*CO and another Ru atom promotes the water splitting to generate ^*H, and then the two intermediates of ^*CO and ^*H coupled to form the key intermediate of ^*CHO in a thermodynamically favorable way.