Bifunctional electrocatalytic activity of two-dimensional tetragonal metal-organic frameworks with the TM-N/C ₄ coordination

Abstract

The extensive structural tunability of metal-organic frameworks (MOFs) positions them as exceptional candidates for engineering multifunctional electrocatalysts. Motivated by recent experimental advancements and guided by first-principles simulations, we introduce a new class of two-dimensional (2D) MOFs, TM₂(TCNQ)₂ (TM = Cr, Mn, Fe, Co and Ni). These MOFs exhibit versatile and multifunctional catalytic activity for the hydrogen evolution (HER), oxygen evolution (OER), and oxygen reduction (ORR) reactions. Notably, in sharp contrast to the metal-centered activity observed in conventional TMN₄ catalysts, our findings reveal that the nonmetal site (specifically C) within the TCNQ linkers serve as the predominant active centers. This unique “ligand-centered” catalytic behavior is fundamentally rooted in the profound electronic coupling between the metallic centers and the π-conjugated organic components, which triggers a significant redistribution of electron density and local spin moments. Specifically, Mn₂(TCNQ)₂, Co₂(TCNQ)₂ and Ni₂(TCNQ)₂ monolayers serve as bifunctional catalysts for HER and OER, with overpotentials comparable to, or even surpassing, well-established noble-metal catalysts. These findings underscore the modular catalytic properties and the unconventional nonmetal-site-driven mechanism of the TM₂(TCNQ)₂ architecture, providing a strategic route toward cost-efficient, versatile catalysts for sustainable energy technologies.

Keywords

Density-functional theory / Metal-organic frameworks / Bifunctional catalyst / Exchange current / Dual volcano plots

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

CRediT authorship contribution statement

Kai Lei: Writing – original draft. Chenghao Yuan: Data curation. Longhua Ding: Visualization. Aizhu Wang: Writing – review & editing. Jingyang Peng: Visualization. Xin Yu: Visualization.

Acknowledgements

The work was supported by the Natural Science Foundation of Shandong Province (No. ZR2024MA030 and No. ZR2022JQ20), the Taishan Scholar Project of Shandong Province (tsqn202211168 and tspd20240813), the project funded by China Postdoctoral Science Foundation (No. 2022M712141).

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