Low-1oading Ir decorated cobalt encapsulated N-doped carbon nanotubes/porous carbon sheet implements efficient hydrogen/oxygen trifunctional electrocatalysis

摘要

Development of cost-efficeint and high activity muli-functional catalysts for gas-involved reactions such as Oxygen reduction evolution(ORR),oxygen evolution reaction(OER)and hydrogen evolution recation reaction(HER)is desirable but challenging.Herein,low-1oading of Iridium(Ir)(≈2.3 wt)decorated cobalt nano-particles embedded in nitrogen-doped carbon nanotube/porous carbon sheets(IrCo@NCNT/PC)is prepared to serve as the OER/HER/ORR trifunctional electrocatalyst.The resulting composites demonstrate excellent OER and HER activity in both acidic and alkaline electrolytes,including low overpotentials at 10 mA cm~(-2)(η_(10))for OER(about 291 and 240 mV)and HER(about 26.8 and 37 mV),respectively,which are superior to the benchmarking Pt/C and IrO2 catalysts.Hence,low cell voltages of 1.51 and 1.45 V are required at;= 10 mA cm~(-2)(j_(10))for overall water splitting(OWS)in the acidic and alkaline electrolytes,respectively.In addition,the as-prepared IrCo@NCNT/PC also shows efficient ORR performance with a high half-wave potential(E_(1/2))of 0.83 V vs.RHE.It is then used as the air cathode for rechargeable Zn-air battery(r-ZAB),and exhibits an outstanding specific capacity(810 mAh g~(-1)),low charge-discharge polarization(ΔE = 0.896 V at j = 50 mA cm~(-2))and long cycling performance(increased only 0.15 V after 195 cycles).