Cooperative Electronic Programming by Phenanthroline Pockets, Ethynyl Bridges, and Pyrene Cores in a One-Dimensional Covalent Organic Framework for Chemoselective Nitrate-to-Ammonia Electrosynthesis
Year: 2026
Type: preprint
Abstract: Covalent organic frameworks (COFs) offer molecular precision, yet their catalytic function is often treated as though the metal center operates independently of the scaffold that surrounds it. Here, we introduce TU-24, a one-dimensional COF in which phenanthroline pockets, ethynyl bridges, and pyrene cores are deliberately integrated to co-program coordination geometry, frontier electronic structure, and reaction progression for nitrate-to-ammonia electrosynthesis. Molecular deconstruction reveals noninterchangeable functions: the pyrene core supplies frontier-accessible π states, the ethynyl linkage preserves electronic communication, and the phenanthroline motif tunes the near-Fermi-level manifold while creating an accessible N,N coordination pocket. Postsynthetic Cu incorporation preserves the crystalline architecture while generating spatially dispersed, approximately four-coordinate Cu–N/O sites electronically distinct from metallic Cu and bulk copper oxides. TU-24-Cu delivers 92.0% NH3 Faradaic efficiency at −0.7 V versus RHE and an areal NH3 yield of 1.71 mg h-1 cm-2 at −0.8 V, while strongly suppressing nitrite release. Operando ATR-SEIRAS and density functional theory converge on a deep-reduction pathway involving hydrogenated N–O intermediates, with the framework favoring the lower-energy *NHO channel and adaptively weakening Cu–N binding as hydrogenation advances. These findings establish a broader design principle: COF electrocatalysis can be programmed not merely by installing an active site, but by electronically wiring that site to a framework that governs intermediate retention, pathway branching, and forward continuity across a multielectron reaction network.
Source: ChemRxiv
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Awards: Elucidation of electrocatalytic activity of atomically precise metal clusters for the creation of highly active energy and environmental catalysts, G1875653562, Construction of Functional Chemistry SystemUsing Precision Metal Nanoclusters as a Compositional Unit, G4620625083, G714438845, G725513421, G8445925457
OpenAlex ID: W7213969167