Boosting C2H4 electrosynthesis from CO2 via Cu-nanoparticle-anchored carbon aerogels as tubular gas-flow-through electrodes

Abstract

The electrocatalytic CO₂ reduction reaction (CO₂RR) towards value-added C₂ products is often severely restricted by sluggish liquid-phase mass transfer and elusive control over C–C coupling pathways. In this study, novel Cu-decorated tubular carbon aerogels (Cu-TCA) were developed as gas-flow-through electrodes and integrated into a custom-designed coaxial reactor for high-rate CO₂RR. Finite element simulations revealed that the coaxial design established a uniform electric field, and the unique gas-flow-through configuration sustained a high local CO₂ concentration within the deep porous network, thereby circumventing liquid-phase diffusion limits and markedly enhancing CO₂ electroreduction kinetics. We precisely modulated the Cu species from isolated single atoms (SA) to crystalline nanoparticles (NP). Electrochemical investigations and in-situ spectroscopy revealed a distinct structure-sensitivity: the Cu-NP-TCA facilitated thermodynamically favorable C–C dimerization via dense ensemble sites, achieving a maximum C₂H₄ Faradaic efficiency of ~29% in the alkaline media, while the Cu-SA-TCA restricted the reaction into only C₁ products due to the "site-isolation" effect. Furthermore, the carbon encapsulation endowed the catalyst with superior structural and chemical robustness for long-term operation. This work not only alleviates the mass transport bottleneck but also provides a molecular-level blueprint for rationally designing C₂-selective electrocatalysts.