CoFe alloy nanoparticles embedded in N-doped carbon supported on highly defective ketjenblack for rechargeable Zn-air battery

초록

we fabricated a CoFe alloy nanoparticles embedded in N-doped carbon supported on highly defective ketjenblack (FeCoNC/D) via simple hydrothermal and impregnation method, followed by high temperature annealing process. First, the defect-rich ketjenblack (D-KB) was prepared by partial oxidation and etching of carbon atoms in ketjenblack during hydrothermal procedure using H2O2, thereby introducing abundant carbon vacancies and nanopores. After that, metal ions and dicyandiamide (DCD) which has a high content of nitrogen were mixed and adsorbed on the D-KB. Finally, DCD was transformed to N-doped carbon matrix with homogeneously embedded CoFe alloy nanoparticles on D-KB via in-situ thermal polymerization into g-C3N4, followed by the high temperature carbonization process. The synthesized FeCoNC/D exhibits superior bifunctional electrocatalytic activity with a half-wave potential of 901 mV (vs. RHE) for ORR and an overpotential of 362 mV at a current density of 10 mA cm-2 for OER. Moreover, the FeCoNC/D showed outstanding long-term durability for both of ORR and OER compared to comercial Pt/C and RuO2. The excellent bifunctional oxygen electrocatalytic activity of FeCoNC/D encouraged us to assess its potential for air-cathode in rechargeable ZABs. The ZABs with FeCoNC/D display narrow discharge/charge gap of 0.7 V, higher power density of 157 mW cm-2 at 240 mA cm-2, and superior stability than Pt/C-RuO2. The improved electrocatalytic performances toward ORR, OER, and ZABs of FeCoNC/D can be attributed to these advantages