Synthesis of nano-tube CoNi/N–C complex and its catalytic properties for highly efficient oxygen reduction

Abstract

Electrochemical energy storage systems such as fuel cells and metal air cells can be used as clean energy. In these systems, an essential reaction on the cathode is the oxygen reduction reaction (ORR). As ORR catalyst, non noble metal based catalyst is an important substitute for commercial Pt/C catalyst due to its rich reserves, low cost, good stability and high catalytic activity. Herein, CoNi alloy supported on nitrogen doped carbon, CoNi/N–C nanotubes, prepared by hydrothermal method and high-temperature pyrolysis method, shows excellent ORR catalytic activity and stability in 0.1 M KOH solution. In particular, the obtained CoNi/N-C-800 demonstrates the highest ORR activity of the prepared samples, with a half wave potential of 0.81V, which was equivalent to the commercially available Pt/C (0.82V). At the same time, it exhibits approximate 4e- pathway with a comparable electron transfer number to the commercial Pt/C, and is much higher tolerant in methanol than the latter. Co and Ni alloying can induce the internal electron interaction of the catalyst, thus exposing more active sites. Furthermore, nano-tube CoNi exhibits appropriate size and hollow geometry, and its large surface area and strong conductivity improve its catalytic activity. The results may possibly provide a new impetus to the rational design of non noble metal based nanocomposite catalysts. Moreover, it is also of great significance to improve the performance of electrocatalysis and energy storage applications.