Defect-Tuned Carbon Layer Thickness Modulates Intermediate Confinement for Enhanced Carbon-Carbon Coupling in CO<sub>2</sub> Electroreduction to Ethanol.

Lu, Jun; Hou, Jing-Jing; Xu, Ke; Liang, Jing; Liang, Xiao-Long; Ge, Xu; Zou, Lie; Guo, Ji-Yuan et al. · ACS Nano · 2025

basic_science · Level V

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Abstract

The carbon-layer-induced intermediate escape confinement effect improves electrocatalytic C-C coupling by reducing the diffusion of <i>C</i><sub>1</sub> intermediates, thereby maintaining a high local concentration of these intermediates. Guided by finite element analysis simulations, CuSn(OH)<sub>6</sub>@C was synthesized with varying carbon layer thicknesses. The findings demonstrate that the thickness of the carbon layer significantly influences the diffusion behavior of C<sub>1</sub> intermediates within the catalyst's internal space during the CO<sub>2</sub> electroreduction reaction (CO<sub>2</sub>RR). A catalyst with a defective carbon layer measuring 21 nm achieved a Faradaic efficiency of 65.8% for ethanol in a flow cell operating at a current density of 300 mA cm<sup>-2</sup>. <i>In situ</i> FTIR, EIS, and time-relaxation distribution analyses revealed that the carbon layer suppresses CO* escape, enhancing the coverage of CO* within the catalyst and limiting early-stage reaction kinetics. This study provides valuable insights for the design of efficient catalysts to promote C-C coupling.