Integrating Mixed Metallic Selenides/Nitrogen-Doped Carbon Heterostructures in One-Dimensional Carbon Fibers for Efficient Oxygen Reduction Electrocatalysis
Li‐Ping Lv, Pingping Du, Pengbo Liu, Xiaopeng Li, Yong Wang
Abstract
Developing electrocatalysts for oxygen reduction reaction (ORR) with superior catalytic activity, long-period stability, and low price is extremely desirable but full of challenges. Hybrid nitrogen-doped carbon nanofibers encapsulated with mixed metallic selenides of ZnSe and CoSe2 (assigned as Co1–xZnxSe, x represents the molar ratio of Zn/Co) nanoparticles are successfully prepared and denoted as Co1–xZnxSe@NCF-y (y represents the carbonization temperature). By controlling the ratio of Zn to Co and the carbonization temperature, the obtained Co0.62Zn0.38Se@NCF-800 fibers with a large specific surface area (385 m2 g–1) and a high content of nitrogen species (8.39 wt %) exhibit outstanding ORR electrocatalytic activity with a half-wave potential of 0.83 V (vs reversible hydrogen electrode, RHE), a limiting current density of 5.05 mA cm–2, an excellent catalytic stability, and methanol tolerance. The superior ORR catalytic performances can be first explained by the hierarchical nanoparticles-in-fiber structure, which helps suppress the particle agglomeration, increase the structural stability, and promote the mass/electron transportation. The mixed metallic selenides are also believed to facilitate the electronic conductivity through redistribution of electrons from the metallic selenides to the nitrogen-doped carbon layers. Meanwhile, the highly nitrogen-doped carbon layers act as supports for metallic selenides to exhibit good electrocatalytic performances and electrochemical stability.