Synthesis Of Bimetallic Catalyst On Carbon Matrix Toward Efficient Zinc-air Battery

Zinc-air battery has the advantages of environmental friendliness,low cost and high safety,which has opened up new ways to solve the energy crisis and environmental problems.However,the oxygen precipitation（OER）and oxygen reduction reaction（ORR）efficiency of the negative electrode is low,and the electrode material has become a key factor restricting the development of zinc-air batteries.In this paper,the study focuses on the design and preparation of cathode materials for zinc-air battery,mainly containing of the following two aspects.Cu-Zn nanoclusters on nitrogen-doped porous carbon are prepared,which are accompanied by Cu/Zn-N_x single atoms（named CuZn/NC）.The X-ray absorption fine structure test revealed the coexistence of M-N（N=Cu or Zn）bonds and M-M bonds in the catalyst.The CuZn/NC shows excellent oxygen reduction reaction performance in alkaline medium,with a half-wave potential of 0.884 V versus reversible hydrogen electrode（vs.RHE）.It reaches a kinetic current density of 36.42 m A cm^-2 and a Tafel slope of 45 m V dec^-1 at 0.85 V vs.RHE.In addition,when used as the air cathode of a zinc-air battery,it exhibits a higher open circuit voltage（1.444 V）and a higher peak power density(164.3 m W cm^-2).Based on the experimental and theoretical calculation results,the high activity of the catalyst can be attributed to the synergy between the Cu/Zn-N_x sites on the nitrogen-doped carbon and the CuZn clusters.Based on the inspiration of CuZn/NC,it was found that the replacement of carbon by nitrogen has a great influence on the ORR performance.In order to prepare a stable dual-functional catalyst,Fe Co alloy particles supported on nitrogen and phosphorus co-doped porous carbon（named Fe Co-P/PNC）were further prepared.Fe Co-P/PNC catalyst shows high oxygen evolution activity,and its overpotential is only 350 m V.In addition,Fe Co-P/PNC also has good oxygen reduction activity,exhibiting a half-wave potential of 0.86 V vs.RHE in alkaline media.Based on this,Fe Co-P/PNC can be used as an excellent air cathode to be assembled into water-based and flexible zinc-air batteries.The maximum power densities of the two device are 195.1 m W cm^-2 and 90.8m W cm^-2,respectively,and they show excellent charge-discharge performance and high stability.At the same time,flexible zinc-air batteries also exhibit high flexibility,and show huge application potential in a new generation of portable and even wearable high-efficiency rechargeable batteries.