Carboxylated Carbon Nanotube‐Supported Copper‐Indium Bimetallic Catalysts for Electroreduction of CO ₂ to Dimethyl Carbonate via Membrane‐Free Cascade Electrosynthesis

ABSTRACT Under the background of the dual carbon strategy, upgrading CO 2 electroreduction from C 1 products to high‐value C 3 esters is an important direction for realizing its resource utilization and valorization. In this work, Cu 100 In 50 bimetallic catalysts supported on carboxylated carbon nanotubes were prepared, and a membrane‐free paired electrolytic cell cascade system was constructed to achieve the directional conversion of CO 2 →CO→dimethyl carbonate (DMC). The catalyst exhibits enhanced CO supply and interfacial mass transfer capability, with the number of CO adsorption sites increased by 1.8 times and the methanol contact angle reduced from 22° to 8°. Electrochemical measurements show that the catalyst achieves a CO Faraday efficiency (FE CO ) of 60.9% at −1.8 V versus Ag/AgCl, whereas the FE H2 remains as low as 2.1%. In the cascade reaction, the FE DMC reaches 52.3% at −2.2 V and remains at 49.6% after 5 cycles. The system can also be extended to the electrosynthesis of diethyl carbonate (DEC), giving a FE DEC of 27.8%. In situ Raman spectroscopy combined with DFT calculations reveals that In doping shifts the d‐band center of Cu by 0.38 eV, regulates the adsorption behavior of key intermediates, and suppresses HER, whereas carboxyl groups optimize the interfacial electronic structure and mass transfer behavior. This work provides an efficient catalytic strategy and mechanistic insight for the cascade valorization of CO 2 into high‐value carbonates.