Porous nanosheet composite with multi-type active centers as an efficient and stable oxygen electrocatalyst in alkaline and acid conditions

The reversible oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are proton-coupled/decoupled four-electron reactions requiring multi-type active centers for catalysis. Herein, porous nanosheets codoped with a carbon-encapsulated FeNi alloy, metal-N species, and N defects (FeNi-N/PCN) were synthesized through a facile and environmentally friendly molten NaCl template method. The obtained FeNi-N/PCN achieved impressive performances as an oxygen electrocatalyst for the ORR and OER in alkaline (E-1/2 of 0.88 V-RHE, E-j=10 of 1.57 V-RHE) and acidic electrolytes (E-1/2 of 0.78 V-RHE, E-j=10 of 1.76 V-RHE). Furthermore, this FeNi-N/PCN catalyst achieved an impressive power density of 224 mW cm(-2) and a specific capacity of 691 mA h g(-1) in a Zn-air battery, which are 1.34- and 1.20-fold higher than that of the Pt and RuO2 catalysts, respectively. These outstanding performances are due to the layered carbon nanosheet with multi-type active sites, including a carbon-encapsulated FeNi alloy, N defects, and metal-N sites (M-N-x).

Automated summary

Porous nanosheets codoped with carbon-encapsulated FeNi alloy, metal-N species, and N defects (FeNi-N/PCN) were synthesized through a simple and environmentally friendly molten NaCl template method. The obtained FeNi-N/PCN showed impressive performances as an oxygen electrocatalyst for the ORR and OER in alkaline and acidic electrolytes. Furthermore, this FeNi-N/PCN catalyst exhibited outstanding power density and specific capacity in a Zn-air battery, surpassing the performance of Pt and RuO2 catalysts.