Copper-Azolate Metal−Organic Framework as Cathode Material for Electrocatalytic CO ₂ Reduction within a Zero-Gap Electrolyzer

High Resolution Image Download MS PowerPoint Slide Electrochemical CO 2 reduction (eCO 2 R) is a sustainable strategy for converting CO 2 into value-added chemicals. Here, we report the Cu-azolate metal−organic framework (MOF) CuBBTA (Cu 2 Cl 2 -bbta, MAF-X29) as a stable electrocatalyst for eCO 2 R in a zero-gap electrolyzer. CuBBTA was spray-coated onto carbon paper using either PTFE or Nafion binders to form gas diffusion electrodes that achieved Faradaic efficiencies of up to 50% for carbon-containing products (CH 4, C 2 H 4, and CO) at current densities as high as 100 mA cm −2 under a flow of CO 2 . Post-electrolysis studies confirmed retention of the MOF structure. DFT calculations reveal that CO 2 reduction proceeds via COOH* and CO* intermediates, with a thermodynamically favourable and kinetically accessible CO*−CO* dimerization pathway for ethylene formation. Importantly, polymer binder selection significantly influences product selectivity. While PTFE favours methane formation, Nafion shifts selectivity toward CO, highlighting the critical yet underexplored role of electrode environment in MOF-based eCO 2 R catalysis.