In situ synthesis of Co <sub>3</sub> O <sub>4</sub> nanoparticles confined in 3D nitrogen‐doped porous carbon as an efficient bifunctional oxygen electrocatalyst
Zhiyuan Wang, Shunda Jiang, Chanqin Duan, Dan Wang, Shaohua Luo, Yanguo Liu
Abstract
Abstract The rational exploitation of non‐precious metal catalyst with high activity, strong durability and low cost for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of vital importance for metal–air batteries. Herein, a composite of Co 3 O 4 nanoparticles confined in three‐dimensional (3D) N‐doped porous carbon (Co‐NpCs) was prepared by a simple freeze‐drying and in situ pyrolysis method. The effect of different dosages of Co(NO 3 ) 2 on the catalytic performance was discussed. The Co‐NpC‐12% exhibits the best catalytic performance ( E 1/2 = 0.78 V, better stability than 20% Pt/C) in ORR and in OER among all the as‐synthesized samples. Furthermore, it also exhibits the best bifunctional activity (Δ E = 0.849 V). The excellent properties of Co‐NpCs are mainly due to the synergy between Co 3 O 4 and carbon. Firstly, a high Co 3 O 4 loading amount can boost the defect level of the N‐doped hierarchical porous carbon and expose more active sites. Secondly, the unique in situ pyrolysis guarantees a large‐area contact between Co 3 O 4 and carbon as well as a strong C–O–Co bonding, which promotes charge transfer, avoids the peeling of Co 3 O 4 nanoparticles and effectively improves the stability of the material. This work is expected to offer a feasible strategy to produce metal oxide/carbon nanocomposite and push forward the development of bifunctional electrocatalyst with high activity and stability.