Simultaneous electron and proton conduction in a stable metal organic material with highly selective electrocatalytic oxygen reduction reaction to water

Proton coupled electron transfer (PCET) is considered as the elementary step of several chemical, electrochemical and biological processes and thus the development of dual conducting materials has recently become a major focus in Chemical Science. Herein, we report the highly selective electrocatalytic oxygen reduction to water by the stable dual conducting metal-organic material (MOM) [Cu(INA)₂(H₂O)₄] (INA = isonicotinate). Structural analysis reveals the important role of both, hydrogen bonding and π-interactions, in the formation of a supramolecular 3D network. Theoretical calculations show that hydrogen bonding interactions among the coordinated water molecules and deprotonated carboxylate oxygen atoms induce proton transport (2.26 ± 0.10 × 10⁻⁵ S cm⁻¹ at 98% RH) while weak intermolecular π-interactions (π-π and anion-π) provide the pathway for electron transport (1.4 ± 0.1 × 10⁻⁷ S cm⁻¹ at 400 K). Such dual proton and electron conductivity leads to a selective oxygen reduction reaction (ORR) to water in an alkaline medium. To the best of our knowledge, this is the first report on electrocatalytic ORR by a dual-conducting metal-organic material.