Work

From Rim to Core: Nitrile Coordination Creates an Electronic Gradient across Cu12 Nanocluster Nodes for CO2-to-Formate Electrosynthesis

Year: 2026

Type: preprint

Abstract: Atomically precise copper nanoclusters offer an opportunity to program catalysis across individual metal positions, yet reticulation has largely been used to stabilize clusters rather than differentiate them electronically. Here, nitrile coordination converts a Cu12S9 nanocluster node into a radially polarized catalytic ensemble in Cu12TPN MOF. Single-crystal analysis resolves a thiolate-supported Cu12 architecture whose four terephthalonitrile linkers selectively address peripheral Cu sites. Bader analysis reveals an electronic gradient from electron-deficient nitrile-bound rim sites (~+0.57 |e|) to an electron-rich Cu–S/Cu interior (~+0.32–0.37 |e|). This coordination-encoded asymmetry translates directly into CO2 reduction, delivering 63.32% Faradaic efficiency for HCOOH with negligible CO formation. Density functional theory identifies a 0.91 eV energetic separation favoring O-bound *OCOH over *COOH at the pathway bifurcation, while H adsorption remains unfavorable. Post-electrolysis spectroscopy confirms persistence of the cluster-derived environment. These results establish reticulation as an electronic programming strategy within, rather than merely around, atomically precise nanocluster nodes. Atomically precise metal nanoclusters (NCs) occupy an unusual catalytic regime in which composition, metalmetal connectivity, ligand coordination, and individual surface sites can all be resolved at the atomic level.1-24 Unlike nanoparticles with distributed surface sites, NCs provide finite multinuclear ensembles in which structural and electronic perturbations can be traced from specific coordination events to catalytic consequences. Copper nanoclusters are especially attractive in this regard because the adaptable coordination chemistry of Cu(I), flexible Cu–S bonding, and short Cu···Cu contacts permit substantial redistribution of geometry and electron density within a single cluster.25-42 Yet this same adaptability makes it difficult to preserve atomically defined Cu ensembles under catalytic conditions.

Source: ChemRxiv

DOI: 10.26434/chemrxiv.15009115/v1

Authors: Sreelakshmi, Tsukasa Irie, Tokuhisa Kawawaki, Milan Kumar Jena, Saikat Das, Yuichi Negishi

Institutions: Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University

Language: English

Topic: CO2 Reduction Techniques and Catalysts

Subfield: Renewable Energy, Sustainability and the Environment

Field: Energy

Domain: Physical Sciences

SDG: Climate action

Open Access status: green