Watery Hydrogen-Bonding Ag–Organic Coordination Polymers with Proton–Electron Dual Conductivity for CO₂ Electroreduction

Two novel single-phase proton–electron dual-conductivity Ag–organic coordination polymers, FJU-223-Dpe and FJU-223-Bpy, were synthesized for electrochemical CO2 reduction (ECR). These polymers exhibit distinct coordination environments and have watery hydrogen-bonding network structures. FJU-223-Dpe, with Ag–N coordination, demonstrates higher electronegativity and richer water molecules than FJU-223-Bpy, which possesses mixed Ag–N, O coordination. The proton conductivity of FJU-223-Dpe is 3.40 × 10–8 S·cm–1 (76 times higher than FJU-223-Bpy’s 4.50 × 10–10 S·cm–1) at 25 °C and 98% RH. Additionally, the electron conductivity of FJU-223-Dpe (4.82 × 10–10 S cm–1) surpasses that of FJU-223-Bpy (1.17 × 10–11 S cm–1) by a factor of 41 at 25 °C. Furthermore, FJU-223-Dpe achieved superior ECR performance with a faradaic efficiency for CO of 77.3% (vs 72.1% for FJU-223-Bpy). Theoretical calculations indicated that FJU-223-Dpe facilitates the *COOH intermediate formation, enhancing its activity. This work presents a strategic approach to augmenting the efficacy of ECR by modulating the metal coordination environment of single-phase dual conductivity architectures.