Proton-electron coupling and mixed conductivity in a hydrogen-bonded coordination polymer.

Park, Minju; Ju, Huiyeong; Oh, Joohee; Park, Kwangmin; Lim, Hyunseob; Yoon, Seok Min; Song, Intek · Nat Commun · 2025

basic_science · Level V

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Abstract

The fundamental understanding of coupled proton-electron transport in mixed protonic-electronic conductors (MPECs) remains unexplored in materials science, despite its potential significance within the broader context of mixed ionic-electronic conductors (MIECs) and the possibility of controlled diffusion of protons using hydrogen-bond networks. To address these limitations, we present a hydrogen-bonded coordination polymer Ni-BAND ({[Ni(bpy)(H<sub>2</sub>O)<sub>2</sub>(DMF)<sub>2</sub>](NO<sub>3</sub>)<sub>2</sub>·2DMF}<sub>n</sub>), which demonstrates high mixed protonic-electronic conductivity at room temperature. Through detailed analysis, we unravel the coupled transport mechanism, offering insights for the rational design of high-performance MPECs. We demonstrate the practical implications of this mechanism by examining the humidity-dependent synaptic plasticity of Ni-BAND, showcasing how MPECs can expand into traditional MIEC applications while leveraging their unique proton-mediated advantages.