Enhancing CO2 Electroreduction Precision to Ethylene and Ethanol: The Role of Additional Boron Catalytic Sites in Cu-Based Tandem Catalysts

The electrocatalytic conversion of carbon dioxide (CO₂) into valuable multicarbon (C₂₊) compounds offers a promising approach to mitigate CO₂ emissions and harness renewable energy resources. However, achieving precise selectivity for specific C₂₊ products, such as ethylene and ethanol, poses a formidable challenge. This investigation advances the concept that incorporating elemental boron (B) into copper (Cu) catalysts can serve as supplementary adsorption sites for *CO intermediates in subsequent reduction reactions, thereby enhancing the selectivity of desirable C₂₊ products. Furthermore, the utilization of a nickel single atom catalyst (Ni-SAC) as a *CO source component elevates local *CO concentration and mitigates the hydrogen evolution reaction. In-situ experiments and density functional theory (DFT) calculations reveal that surface-bound boron units adsorb and convert *CO more efficiently, promoting ethylene production, while B elements within the bulk phase of copper influence charge transfer and lattice alignment, facilitating ethanol generation. In a neutral electrolyte, the bias current density for ethylene production using the CuB₂-Ni_0.05SAC hybrid catalyst exceeded 300 mA cm^-2, and that for ethanol production with CuB₅-Ni_0.2SAC surpassed 250 mA cm^-2. This study underscores that elemental doping in Cu-based catalysts not only induces alterations in charge and crystalline phase arrangement at Cu sites but also serves as supplementary reduction sites for coupling reactions, enabling the efficient synthesis of distinct C₂₊ products.