Cobalt Single Atoms in Hexagonal Boron Nitride Host for Efficient Electrochemical Nitrate Reduction.

Authors

Kanhai Kumar, Arpan Chakraborty, Omeshwari Yadorao Bisen, Chandrani Nayak, Ashok Kumar Yadav, Rajashri R Urkude, Dibyendu Bhattacharyya, Demudu Babu Gorle, Abhishek Kumar Singh, Karuna Kar Nanda

Published in

Small (Weinheim an der Bergstrasse, Germany). Pages e74585. Jul 13, 2026. Epub Jul 13, 2026.

Abstract

Stabilizing transition-metal single atoms in chemically inert hexagonal boron nitride (hBN) remains a fundamental challenge due to the absence of intrinsic anchoring sites. Here, we report an in situ co-pyrolysis strategy that simultaneously constructs hBN nanosheets and anchors atomically dispersed Co single atoms. Our first experimental demonstration shows that nitrate-to-ammonia electroreduction (NO₃RR) performance of Co single atoms in hBN (Co₁/hBN) is far superior to Co single atoms in N-doped graphene (Co₁/NG), with over sixfold enhancement in per-site turnover frequency compared with carbon-supported Co single atoms. The Co₁/hBN catalyst delivers high Faradaic efficiency, yield rate, low Tafel slope, and definitive ¹⁵N isotopic validation. Importantly, the structural adaptability of the polar hBN lattice significantly enhances nitrate adsorption, lowers the adsorption free energy of NO₃ ^--derived intermediates, and strongly accelerates NO₃RR kinetics relative to Co₁/NG. Combined EXAFS and DFT analyses identify a Co-N₆ coordination environment, while DFT reveals that NO₃ ^- adsorption induces a support-driven Co-N₆ → distorted Co-N₄ transformation, lowering the rate-determining energy barrier to 0.43 eV. In contrast, Co₁/NG retains a rigid Co-N₄ configuration with slower kinetics (0.62 eV). These findings highlight host-induced coordination flexibility as a powerful design principle for high-performance single-atom electrocatalysts in nitrogen-conversion reactions.

PMID:
42439067
Bibliographic data and abstract were imported from PubMed on 13 Jul 2026.

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