A Confined Cu_xO@Styrene Microreactor Achieves the Conversion of CO₂ to C₂₊ Products via Intermediate Trapping

The electrochemical reduction of carbon dioxide to multi-carbon (C₂₊) products is impeded by the instability and inefficient utilization of key reaction intermediates. To address this challenge, we developed a strategy based on geometric control of spatially confined microenvironments, enabling the rational design of programmable Cu_xO microreactors on Cu²⁺(111)/Cu⁺(200) substrates. Two distinct catalyst architectures-small-ordered (s-Cu_xO@styrene) and large-ordered (c-Cu_xO@styrene)-were systematically engineered to modulate CO intermediate behavior, thereby directing reaction selectivity toward ethylene and ethanol production. Faradaic efficiencies for C₂₊ products demonstrate pronounced dependence on microstructure: increasing from negligible values in the small-ordered s-Cu_xO@styrene (25.6% ethylene,12.4% ethanol, 3% propylene) to 78.8% in the large-ordered c-Cu_xO@styrene (55% ethylene, 23% ethanol, 1% propylene). In situ infrared spectroscopy reveals that the highly ordered configuration enhances CO adsorption, promoting the accumulation of critical *OCCOH and *OC₂H₅ intermediates. Moreover, synergistic interactions between Cu⁺ and Cu⁰ active sites accelerate C-C coupling kinetics, favoring selective formation of C₂₊ species. This work establishes a geometry-driven paradigm for controlling catalytic selectivity independent of compositional tuning, offering a promising avenue for the development of adaptive catalytic systems in renewable energy conversion.