Controlled Synthesis of Porous Hollow Fe–N/C Nanoshells as High‐Performance Oxygen Reduction Reaction Electrocatalysts for Zn–Air Battery

Abstract

The development of high‐performance non‐noble oxygen reduction reaction (ORR) electrocatalysts is of significant importance for fuel cells and zinc–air batteries. Herein, a dual‐template‐assisted polymerization process is designed using both silica submicrospheres and ultrafine nanoparticles as hard templates, generating permeable hollow benzoxazine resin nanoshells with well‐controlled morphology and size; such resin nanoshells impregnated with urea and iron precursor salt are then calcined under different atmospheres and temperatures to produce a series of porous hollow Fe–N/C thin nanoshells with differentiated pore structures and various N compositions. The effects of the calcination atmosphere and temperature on the structure and composition of the Fe–N/C materials are also evaluated. Owing to its compositional and structural merits, the optimal porous Fe–N/C nanoshell with a specific surface area as high as 998.0 m2 g−1 exhibits a half‐wave potential E1/2 of 0.919 V (vs reversible hydrogen electrode (RHE)) in 0.1 m KOH, 37 mV more positive than that of the commercial Pt/C; when used as a cathode in a Zn–air battery, it displays a power density and specific energy density of 93.5 mW cm−2 and 779.7 mAh gZn−1, respectively. This work provides a straightforward method for the size‐ and shape‐controllable synthesis of Fe–N–C‐based ORR electrocatalysts.