A powerful three-dimensional C–F–Bi cathode for Zn–CO2 batteries

Abstract

Mars could be the second home for humans but obtaining reliable energy is the primary issue that needs to be addressed. Metal–CO₂ batteries are considered a reliable method because the concentration of CO₂ in the Martian atmosphere exceeds 95%. Herein, we developed a three-dimensional self-supporting electrode fabricated using Bi₂O₃ composites and F-doped carbon fibers, in which the fluorine element, as an atom-bridge, was applied to construct a novel C–F–Bi active site to strengthen the interaction between C and Bi by orbital hybridization. This electrode was directly used as a cathode for Zn–CO₂ batteries. The strong electron-withdrawing effect of F allowed Bi to maintain a positive charge at negative potentials, thus endowing the bismuth active sites with both high activity and stability during CO₂ electroreduction. Remarkably, this cathode achieved a high faradaic efficiency of 97% towards formate with a high current density of −231 mA cm⁻² under a low potential of −1.1 V vs. RHE and offered a high-power density of 7.2 mW cm⁻² in the Zn–CO₂ battery. The self-supported C–F–Bi cathode, without any adhesives and ionomers, may bring a new era of Mars batteries.