Halogen/Nitrogen Codoped Carbon Encapsulated Ni Nanoparticles for Efficient CO2 Electroreduction and High-Performance Zn-CO2 Batteries.

Electroreduction of CO2 (ECR) to CO or syngas is an effective approach to alleviating greenhouse gas emissions. Herein, nickel nanoparticles coated with halogen/nitrogen codoped carbon were prepared (X-Ni/NC-a). Cl-Ni/NC-a can obtain three important syngas compositions (CO:H2) under different voltages, such as 0.97, 0.51, and 0.32, which are the ratios for hydroformylation, methanol, and ethanol synthesis, respectively. For Br-Ni/NC-a, the CO Faraday efficiency (FEco) can exceed 96%, with a CO partial current density (jco) of 48 mA cm-2. Additionally, Br-Ni/NC-a is used in a Zn-CO2 battery (ZCB); the power density can reach 2.6 mW cm-2, and the charge-discharge stability can reach 110 h. DFT calculations revealed that the strong interaction between nickel nanoparticles and halogen/nitrogen codoped carbon regulates the electronic structure of the catalyst, affecting the adsorption/desorption of intermediates. This study provides a feasible scheme for halogen doping to modulate the selectivity of ECR and the potential application of catalysts in ZCB.