CrN supported by carbon nanosheets as efficient catalysts toward oxygen reduction reaction and Zn-air batteries

Exploring non-precious efficient oxygen reduction reaction （ORR） catalysts is of great significance to fuel cells and Zn-air batteries （ZABs）.CrN is a theoretically promising ORR catalyst,but its potential needs to be unlocked by proper supports that provide high conductivity and high exposure of active sites.In this work,we introduce a novel synthesis of carbon nanosheets-supported CrN nanoparticles （CrN/C） by annealing the mixture of CrCl3,1,10-phenanthroline and melamine via a two-step pyrolysis.The prepared CrN/C materials show good ORR activity and stability in acidic and alkaline media.The optimal CrN/C material has an ORR half-wave potential of 0.73 and 0.72 V （vs.reversible hydrogen electrode） in acidic and alkaline media,respectively.And it retains 82% and 78% of ORR current density in acidic and alkaline media after durability tests,respectively.Furthermore,the optimal CrN/C material-based self-breathing ZABs deliver a maximum power density of 168 mW·cm-2,which is one of the highest among transition metal nitrides-based ZABs It is found that the ORR activity of CrN/C materials is highly related to the Cr–N valence state.This work highlights the good potential of CrN as robust ORR catalyst and verifies its promising application in ZABs.