Efficient electrochemical CO2 conversion by cobalt-based metal organic frameworks modified by bimetallic gold–silver nanostructures

Abstract

The ongoing and rapid growth of atmospheric CO₂ levels causes a crucial worldwide concern. Herein, an efficient electrocatalyst has been introduced for electrochemical CO₂ reduction reaction (CO₂RR) to address the stability issue of ZIF-67. The catalyst consists of gold and silver nanostructures electrodeposited on the surface of a cobalt-based metal–organic framework (Au–Ag@ZIF-67). The uniform distribution of the Au–Ag alloy without any agglomeration on ZIF-67 was confirmed through microscopic observations. After 13.3 h of CO₂RR, the specific surface area of Au–Ag@ZIF-67 slightly decreased, whereas that of ZIF-67 declined drastically, indicating excellent structural stability of the Au–Ag alloy. Additionally, Au–Ag@ZIF-67/GCE revealed a faradaic efficiency of 53% and 38% for CO and H₂, respectively. The enhanced CO₂ absorption coupled with the effect of noble metal catalysts offered a current density of 16.4 mA cm⁻² at −1 V (vs. RHE) with 91% Faradaic efficiency. The results indicate that ZIF-67 enhanced the adsorption capacity of CO₂ molecules in comparison with the bare GCE. The combination of ZIF-67 with bimetallic Au–Ag nanostructures offers enhanced CO₂ absorption and reduced charge transfer resistance, leading to improved catalytic activity and selectivity toward CO gas. The results suggest that the use of Au–Ag nanostructures provides superior catalytic activity compared to traditional catalysts, making this approach a promising development for CO₂ gas elimination in the environment.