Diatomic molecule catalysts toward synergistic electrocatalytic carbon dioxide reduction

Abstract

Synergistic catalysis with diatomic catalysts is an effective means to boost carbon dioxide (CO₂) electroreduction efficiency and product selectivity; studies in this field also contribute to an atomic-level understanding of the synergy mechanism. However, the precise design of atoms in diatomic active centers is extremely challenging. Herein, a diatomic-molecule catalyst (DMC), double Co-salophen (D-Co) with a precise Co–Co distance of 0.523 nm, was supported on carbon nanotubes using a non-covalent anchoring strategy. The catalyst exhibits excellent performance in the electrochemical CO₂ reduction reaction (CO₂RR) with a CO faradaic efficiency of 91.76% at −0.70 V versus a reversible hydrogen electrode (RHE), a turnover frequency of 2056.7 h⁻¹ at −0.90 V vs. RHE, and good stability. This excellent CO₂RR performance is attributed to the synergistic adsorption and activation of H₂O and CO₂ molecules on both Co atomic sites, which are connected by strong hydrogen bonds. Density functional theory calculations demonstrate that this type of hydrogen bond promotes CO₂ activation, stabilizes the intermediate, and decreases the energy barrier. The DMC developed in this study provides a new template and strategy for the precise and rational design and preparation of diatomic molecule catalysts.