麻豆淫院

Catalytic conversion of waste CO₂ into value-added fuels and chemicals offers unprecedented opportunities for both environmental protection and economic development. Electrocatalytic CO₂ reduction reaction (CO₂RR) has garnered significant attention for its ability to efficiently convert CO₂ into clean chemical energy under mild conditions. However, the relatively high energy barrier for *COOH intermediate formation often becomes the determining step in CO₂RR, significantly limiting reaction efficiency.

Inspired by enzyme catalysis, a team led by Prof. Jiang Hai-Long and Prof. Jiao Long from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) developed a novel strategy to stabilize *COOH intermediate and enhance electrochemical CO₂ reduction by constructing and modulating the hydrogen-bonding microenvironment around catalytic sites. Their work is in the Proceedings of the National Academy of Sciences.

In this work, the team co-grafted catalytically active Co(salen) units and proximal pyridyl-substituted alkyl carboxylic acids (X-PyC_n) onto Hf-based MOF nanosheets (MOFNs) via a post decoration route, affording Co&X-PyC_n/MOFNs (X = o, m or p representing the ortho-, meta-, or para- position of pyridine N relative to alkyl chain; n = 1 or 3 representing the carbon atom number of alkyl chains) materials.

The Co&X-PyC_n/MOFNs achieve precise control over the spatial positioning of the N atoms in pyridine groups relative to the Co(salen), which provides a novel and facile approach to microenvironment modulation around catalytic sites at atomic scale.

Among the catalysts, the optimized Co&p-PyC₃/MOFNs exhibits significantly enhanced catalytic activity and selectivity in electrochemical CO₂ reduction, superior to Co/MOFNs without pyridine unit and other Co&X-PyC_n/MOFNs counterparts.

Furthermore, the in situ reduction of pyridine to pyridinyl radical (PyrH鈥�) is observed during electrochemical CO₂ reduction and the in situ formed PyrH鈥� species are confirmed to be the real microenvironment around Co(salen) for enhanced performance.

Mechanism investigations reveal that PyrH鈥� can collaborate with trifluoroethanol (TFE) molecules in electrolyte to stabilize the *COOH intermediate by generating *COOH路路路TFE路路路PyrH鈥� triad intermediate via hydrogen-bonding interaction, greatly minimizing reaction energy barrier. This provides a clear picture on the working mode of microenvironment for performance optimization during the catalysis.

This work unambiguously demonstrates the significance of microenvironment modulation around catalytic sites for enhancing catalysis, paving a new way for understanding the mechanism in future catalysis studies.