Tunable CO₂ enrichment on functionalized Au surface for enhanced CO₂ electroreduction

Electrochemical conversion of carbon dioxide (CO₂) to higher-value products provides a forward-looking way to solve the problems of environmental pollution and energy shortage. However, the low solubility of CO₂ in aqueous electrolytes, sluggish kinetics, and low selectivity hamper the efficient conversion of CO₂. Here, we report a Au-based hybrid nanomaterial by modifying Au nanoparticles (NPs) with the macrocyclic molecule cucurbit[6]uril (Au@CB[6]). Au@CB[6] displays the optimal selectivity of CO, with the highest CO Faraday efficiency (FE_CO) reaching 99.50% at −0.6 V vs. reversible hydrogen electrode (RHE). The partial current density of CO formed by Au@CB[6] increases dramatically, as 3.18 mA/cm² at −0.6 V, which is more than ten times as that of oleylamine-coated Au NPs (Au@OAm, 0.31 mA/cm²). Operando electrochemical measurement combined with density functional theory (DFT) calculations reveals that CB[6] can gather CO₂ and lead the increased local CO₂ concentration near metal interface, which realizes significantly enhanced electrochemical CO₂ reduction reaction (CO₂RR) performance.