Résumé
The CO2 electrochemical reduction (CO2RR) is a most promising technologies to mitigate CO2 emissions and generating value-added products. The formation of multi-carbon products involves a range of transient intermediates, the behavior of which critically influences the reaction pathway and product distribution [1]. Consequently, it is still a challenge to design a catalyst that can efficiently and rapidly reduce CO2 and obtain high-value products. Copper is the most promising key electrocatalyst, particularly in producing valuable hydrocarbons and alcohols, that hold substantial value in modern industries [2]. However, challenges such as weak *CO adsorption, high C–C coupling barriers, and competition with e.g hydrogen evolution reaction (HER) lead to complex product distributions [3]. To address these limitations, researchers have explored various strategies, including heteroatom doping, surface engineering, surface oxidation tuning, size control, and alloying. Among these, alloying stands out as it enhances active site diversity and enables electronic structure modulation via intermetallic interactions, offering a promising route to improve catalytic activity and selectivity.In the present work, we demonstrate that Cu–Al bimetallic electrocatalysts, fabricated via physical vapor deposition onto gas diffusion electrodes Cu90Al10, exhibit excellent performance in the electrocatalytic reduction of CO2 to C2+ products. Notably, the bimetallic catalysts achieved a C₂⁺ Faradaic efficiency exceeding 60% at elevated current densities above 450 mA cm⁻² in a flow cell configuration, significantly outperforming their monometallic Cu counterparts prepared under identical sputtering conditions. These results, supported by operando synchrotron-based spectroscopic analyses, online inductively coupled plasma mass spectrometry (ICP-MS) and advanced density functional theory (DFT) calculations, reveal the distinctive catalytic advantages of Cu–Al systems. Theoretical insights further demonstrate that incorporation of Al into the Cu matrix modulates the electronic structure of Cu, facilitating the C-C coupling in key intermediates shared by both ethylene and ethanol pathways. This electronic tuning preferentially accelerates the C2 formation pathway, highlighting the synergistic effect of alloying and electronic modulation in directing product selectivity during CO₂ electroreduction.1. Seh, Z.W., et al., Combining theory and experiment in electrocatalysis: Insights into materials design. Science, 2017. 355(6321).2. Wu, H., et al., Selective and energy-efficient electrosynthesis of ethylene from CO2 by tuning the valence of Cu catalysts through aryl diazonium functionalization. Nature Energy, 2024. 9(4): p. 422-433.3. Lei, H., W. Zhang, and J. Yang, Theoretical Insights into Enhancing Catalytic Performance of Al–Cu Alloy for CO2 Electroreduction toward Ethene Production. The Journal of Physical Chemistry Letters, 2024. 15(21): p. 5643-5653.