Carbonyl‐Anchoring Stabilized Copper Single Sites with Cavity‐Enhanced Mass Transport for Acetylene‐to‐Ethylene Electrosynthesis

Controlling mass transfer and adsorption in single-site catalysts is critical for the activity and selectivity of heterogeneous electrocatalytic hydrogenation, but structural fragility at large current densities (≥200 mA cm^-2) makes their practical application challenging. Here, taking acetylene (C₂H₂) hydrogenation to ethylene (C₂H₄) as an example, cucurbit[6]uril-coordinated copper (CB[6]-Cu) is theoretically predicted and experimentally proven to be the desired carbonyl-anchoring isolated Cu site with engineered mass transport. CB[6]-Cu demonstrates an outstanding Faradaic efficiency of 95.4% for C₂H₄, which significantly suppresses the competitive coupling and hydrogen evolution reactions at 300 mA cm^-2, with a turnover frequency of 2.91 s^-1 and 65 h of continuous stable operation. The distinctive C₂H₂ adsorption configuration and broken hydrogen bond network are revealed to result in optimal coverage and a sufficient supply of C₂H₂ feedstocks, accounting for the remarkable C₂H₄ performance. The extended CB[6]-Co also exhibits enhanced NO-to-NH₂OH electrosynthesis performance, highlighting its potential.