Hierarchical Metal–Polymer Hybrids for Enhanced CO₂ Electroreduction

The design of catalysts with high activity, selectivity, and stability is key to the electroreduction of CO₂. Herein, we report the synthesis of 3D hierarchical metal/polymer–carbon paper (M/polymer-CP) electrodes by in situ electrosynthesis. The 3D polymer layer on CP (polymer-CP) was first prepared by in situ electropolymerization, then a 3D metal layer was decorated on the polymer-CP to produce the M/polymer-CP electrode. Electrodes with different metals (e.g. Cu, Pd, Zn, Sn) and various polymers could be prepared by this method. The electrodes could efficiently reduce CO₂ to desired products, such as C₂H₄, CO, and HCOOH, depending on the metal used. For example, C₂H₄ could be formed with a Faradaic efficiency of 59.4 % and a current density of 30.2 mA cm⁻² by using a very stable Cu/PANI-CP electrode in an H-type cell. Control experiments and theoretical calculations showed that the 3D hierarchical structure of the metals and in situ formation of the electrodes are critical for the excellent performance.