Preferential Formation of Ethylene via Electrocatalytic CO₂ Reduction on Mesoporous Cu₂O Nanoparticles: Synergistic Effects of Pore Structure Confinement and Surface Amine

Comprehensive Summary We present a facile synthetic strategy to create mesoporous Cu 2 O nanocrystals with tunable pore structures and surface functional groups of amine derivatives for efficient and preferable electrochemical conversion of CO 2 into ethylene. The structural characteristics of these Cu 2 O nanocrystals can be manipulated using a set of amine derivatives, such as pyridine, 4,4'‐bipyridine, and hexamethylenetetramine, during the oxidative etching process of Cu nanocrystals by bubbling gaseous oxygen in N , N ‐dimethylformamide solution. These amine derivatives not only serve as surface functional groups but also significantly affect the resulting pore structures. The synergistic effect of pore structure confinement and surface amine functionalization leads to the superb Faradaic efficiency (FE) of 51.9% for C 2 H 4 , respectively, together with the C 2 H 4 partial current density of –209.4 mA·cm −2 at –0.8 V vs. reversible hydrogen electrode (RHE). The relatively high selectivity towards C 2 H 4 was investigated using DFT simulations, where 4,4'‐bipyridine functionalized Cu 2 O seemed to favor the C 2 H 4 formation with the low free energy of the intermediates. This study provides a feasible strategy to manipulate the pore structure and surface functionalization of mesoporous Cu 2 O nanocrystals by regulating the oxidative etching process, which sheds light on the rational preparation of high‐performance CO 2 RR electrocatalysts.