Nitrogen doped porous carbon-based bifunctional oxygen electrocatalyst with controllable phosphorus content for zinc-air battery

The controllable construction of non-noble metal based bifunctional catalysts with high activities towards oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is of great significance,but remains a challenge.Herein,we reported an effective method to synthesize cobalt-nitrogen doped mesoporous carbon-based bifunctional oxygen electrocatalyst with controllable phosphorus content(Co-N-P_(X)-MC,X=0.5,1.0,1.5,2.0).The mesoporous carbon substrate endowed the asprepared samples with more exposed active surface(236.50 m^(2)·g^(−1))and the most appropriate doping ratio of phosphorus had been investigated to be 1.5(Co-N-P1.5-MC).For ORR,Co-N-P1.5-MC exhibited excellent catalytic activity with more positive onset potential(1.01 V)and half-wave potential(0.84 V)than the other samples.For OER,Co-N-P1.5-MC also showed a low overpotential of 415 mV.Combining experimental results and density-functional theory(DFT)calculations,the outstanding bifunctional catalytic performance of Co-N-P1.5-MC was due to the synergistic cooperation between the P and N dopants,which could reduce the reaction barriers and was favorable for ORR and OER.Moreover,the Zn-air battery using Co-N-P1.5-MC as the cathode showed remarkable battery performance with high stability(could operate stably for over 160 h at 10 mA·cm^(−2))and maximum power density(119 mW·cm^(−2)),demonstrating its potential for practical applications.This work could provide significant enlightenment towards the design and construction of bifunctional oxygen electrocatalyst for next-generation electrochemical devices.