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N-Heterocyclic Carbenes in Advanced Electrocatalysis: From Molecular Complexes to Hybrid Metal Nanostructures

  • Amalia Rapakousiou 1, 2

Received: 04 Aug 2025 | Revised: 26 Aug 2025 | Accepted: 27 Aug 2025 | Published: 02 Sep 2025

Abstract

N Heterocyclic carbenes (NHCs) have emerged as powerful and versatile ligands in electrocatalysis, offering a unique combination of strong σ-donor and π-acceptor properties, exceptional thermal and electrochemical stability, and broad structural tunability. This review surveys recent advances in NHC-based electrocatalytic systems across a spectrum of key energy-relevant transformations —including CO2 reduction (CO2RR), hydrogen evolution (HER), oxygen evolution (OER), oxygen reduction (ORR), ammonia oxidation, and urea electrosynthesis. From well-defined molecular complexes to nanostructured hybrids and surface-bound architectures, NHC ligands enable fine control over metal–ligand redox interplay, substrate activation, and reaction selectivity. Their covalent anchoring on conductive supports ensures strong metal–support coupling, maximized active-site exposure, and exceptional long-term durability. Mechanistic insights from operando studies and DFT simulations reveal how NHC coordination shapes charge-transfer steps, stabilizes high-valent intermediates, and enhances multielectron reactivity. Particular attention is paid to macrocyclic and redox-active NHC scaffolds, which offer new opportunities for stabilizing reactive intermediates and mediating proton-coupled electron transfer. Together, these findings highlight the broad utility of NHCs as molecular design elements bridging homogeneous and heterogeneous catalysis. We conclude by outlining emerging ligand architectures and materials integration strategies that will be key for advancing scalable, durable, and selective NHC-based electrocatalytic technologies.

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Rapakousiou, A. N-Heterocyclic Carbenes in Advanced Electrocatalysis: From Molecular Complexes to Hybrid Metal Nanostructures. Organometallic Science 2025, 1 (1), 2.
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