Nitrogen-doped hierarchically porous carbons for non-alkaline Zn-air battery cathodes

Non-alkaline Zn-air batteries (ZABs) attract great attention because they can potentially combine high energy density, safety, and low cost. However, cathodes for non-alkaline ZABs are underdeveloped and suffer from poor charge-discharge kinetics. Here we study N-doped hierarchically porous carbons, which are synthesized using a self-templating approach, as catalytic scaffolds for oxygen reduction and oxygen evolution reactions (ORR and OER) in near-neutral media. Interestingly, although nitrogen doping does not improve the OER performance or carbon corrosion rate during the OER, it leads to a significant boost of the ORR kinetics in non-alkaline ZABs. Specifically, the reported N-doped hierarchically porous carbons outperform their nitrogen-free hierarchically porous analog, as well as the best commercially available nitrogen-free carbons. These results show that N-doped carbons can serve as promising support materials for non-alkaline ZABs.