Strategy for boosting Co-N_x content for oxygen reduction reaction in aqueous metal-air batteries

Electrocatalyst is the pivotal component promoting the kinetics of oxygen reduction reaction in aqueous metalair batteries. However, the content of increased bond as the active species is usually limited by the metal loading, tiny pore canal, insufficient nitrogen further restraining the electrocatalytic effectiveness of single-atom catalysts in oxygen reduction reaction (ORR). Herein, Co, N-dual doped carbon (Co/NNC) is prepared by a versatile strategy of the combination approach of SiO2 template with extra nitrogen source. Based on ZIF-67 prepared with the assistance of SiO2 template, the extra nitrogen source was introduced in the high-temperature pyrolysis procedure. The material characterizations of XRD, SEM, HRTEM, BET, Raman and XPS are conducted to synthetically analyze the functional role of extra nitrogen source. Moreover, the Co/NNC with increased Co-N-x active sites is employed into two aqueous metal-air batteries of Zn-air and Mg-air batteries, which exhibits excellent performances especially in the aspects of discharge specific capacity, discharge stability and power density.