Preparation and electrochemical performance of nitrogen-doped carbon-coated Cu S nanobox catalyst for hybrid Na−CO2 batteries

To promote CO 2 redox kinetics on the cathode of hybrid sodium−carbon dioxide (Na−CO 2 ) batteries, hollow cubic CuS nanoboxes were encapsulated in polypyrrole and polydopamine by in situ polymerization of pyrrole and dopamine monomers, respectively, and coupled with high-temperature heat treatment to obtain nitrogen−carbon encapsulated Cu x S@NC PPy and Cu x S@NC PDA catalysts. The results show that the encapsulation of nitrogen-doped carbon not only increases the specific surface area and improves the electron affinity but also promotes the synergistic interaction between the CuS-based active species and the defect carbon, thus providing abundant active sites for CO 2 conversion. The electrochemical performances of the carbon-coated modified samples were all improved, especially the hybrid Na−CO 2 battery based on Cu x S@NC PPy , which showed a low voltage gap of 0.74 V at 0.1 mA/cm 2 and a high power density of 3.42 mW/cm 2 .