Stable Co/N-Doped Carbon Nanotubes as Catalysts for Oxygen Reduction

Abstract

It is an urgent and difficult task to develop low-cost, high-performance catalysts for the oxygen reduction reaction (ORR) to overcome the inherent defects of platinum-based catalysts, including low abundance, high cost, poor stability, and poor methanol tolerance. In this study, N-doped carbon nanotubes (N-CNTs) and Co/N-CNT catalysts are synthesized by grinding and subsequent calcination, and the whole process does not require strict control of the reaction conditions, thus greatly simplifying the synthesis route of the catalysts. The unique structure, in which Co nanoparticles are evenly embedded in the tube and tip of CNTs, exhibits outstanding ORR performance and electrochemical stability as a result of the Co–CNT interactions. Furthermore, due to the catalytic graphitization ability of Co nanoparticles, a high graphitization degree, large specific surface area, and abundant pore structure are achieved by adjusting the calcination temperature, thus accelerating electron transfer and oxygen diffusion. The optimized catalyst, calcined at 750 °C (Co/N-CNT-750), exhibits better ORR activity and excellent methanol tolerance in alkaline media, indicating its great potential for large-scale application in storage technologies.