Engineering of Sn-O-Sn Sites in CuMOF via Atomic Layer Infiltration for Efficient CO₂RR in Neutral Aqueous Media

Developing copper-based catalysts that suppress HER, ensure high selectivity, and activate CO₂ is vital for efficient neutral aqueous CO₂ electroreduction (CO₂RR). However, due to electronic complexity and the adsorption energy-selectivity paradox, the precise microstructural design of copper-based catalysts remains challenging. Herein, we use a gas-phase atomic layer infiltration (ALI) strategy to precisely control the copper microenvironment in CuBDC, enabling the uniform distribution of Cu-O-Sn-O-Sn-O-Cu active sites while maintaining structural integrity. Electrochemical characterization reveals that atomic-level engineering simultaneously enhances the number of active sites and optimizes charge transfer dynamics, while in situ Raman spectroscopy confirms the formation of Sn-CO intermediates. This multifaceted synergy drives a significant improvement in catalytic performance: CO selectivity increases from 15% to 99%, while H₂ selectivity is effectively suppressed from 85% to 1% in an aqueous CO₂RR system. Density functional theory calculations reveal that the presence of Sn-O-Sn sites enhances CO₂ adsorption stability, lowers the formation energy barrier of the key intermediate COOH^*, and creates a HER-inert region. This study establishes a new paradigm for designing highly efficient neutral aqueous CO₂RR electrocatalysts by synergistically regulating reaction pathways and charge transfer through atomic-level optimization of electronic, geometric, and structural properties of CuMOF.