Maximizing CO₂ Reduction Efficiency: Surface‐Regulated Highly Porous Ag‐Cu Alloy Aerogel Inserted With Multi‐Wall Carbon Nanotube Achieving Nearly Complete CO Selectivity

Abstract

Abstract The electrochemical reduction of CO 2 (eCO 2 RR) holds promise in mitigating atmospheric greenhouse gas levels but is hindered by low reaction kinetics, high energy barriers, and poor selectivity. To address these challenges, we developed a novel series of cost‐effective AgCu‐containing metal‐aerogel catalysts with high electrochemical surface areas (ECSA) using a top‐down reduction approach. The Ag 85 Cu 15 aerogel, with an ECSA of 27.41 cm 2 , achieved a Faraday efficiency (FE%) of 89.3 % for CO production at −0.9 V vs. RHE. Increasing the Cu content to over 50 % in the aerogel matrix produced small amounts of C 2 H 4 , with a maximum FE% of 12.9 % at −1.0 V vs. RHE. To further enhance CO 2 reduction efficiency, multi‐walled carbon nanotubes (CNT) were incorporated into the Ag 85 Cu 15 alloy aerogel via a hydrothermal treatment. The highly dispersed CNTs within the aerogel matrix increased the ECSA to 57.00 cm 2 by forming a well‐defined porous structure through van‐der Waals interactions, improving CO selectivity, and achieving a FE% of 98.6 % at −0.7 V vs . RHE and a partial current density of 9.6 mA/cm 2 in an H‐cell. 86 % of the initial FE CO % was maintained during an 18 h test with continuous electrolysis.