Hollow Metal–Organic-Framework-Mediated In Situ Architecture of Copper Dendrites for Enhanced CO₂ Electroreduction

Electrocatalytic reduction of CO₂ to a single product at high current densities and efficiencies remains a challenge. However, the conventional electrode preparation methods, such as drop-casting, usually suffer from low intrinsic activity. Herein, we report a synthesis strategy for preparing heterogeneous electrocatalyst composed of 3D hierarchical Cu dendrites that derived from an in situ electrosynthesized hollow copper metal–organic framework (MOF), for which the preparation of the Cu-MOF film took only 5 min. The synthesis strategy preferentially exposes active sites, which favor's the reduction of CO₂ to formate. The current density could be as high as 102.1 mA cm⁻² with a selectivity of 98.2 % in ionic-liquid-based electrolyte and a commonly used H-type cell.