Regulation of oxygen reduction reaction performance cobalt-based nitrogen-doped carbon catalysts by vanadium

Abstract

BackgroundTransition metal nitrogen doped carbon materials are promising to replace precious metal platinum-based materials as an important electrocatalyst for oxygen reduction, and have attracted extensive attention in the research fields of energy storage materials and energy conversion devices.PurposeThis study aims to develop new vanadium doped transition metal carbon materials with excellent catalytic performance, and clarify the role of the introduced of vanadium.MethodsThe vanadium doped cobalt-nitrogen-carbon catalyst was designed by two-step pyrolysis method and impregnation method. The catalytic performance of the oxygen reduction reaction (ORR) was evaluated by a three electrode system using rotating disk electrode. The morphology and microstructure of catalysts were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray diffraction (XRD) was employed to examine crystal orientation structure of catalyst whilst the element types and distribution of materials was analyzed by X-ray photoelectron spectroscopy. Finally, Co K-edge and V K-edge X-ray absorption fine structure (XAFS) spectroscopy were used to determine the local atomic configuration and electronic structure.ResultsThe experimental results show that vanadium doped cobalt-nitrogen-carbon catalyst exhibits superior ORR performance than the traditional cobalt‒nitrogen‒carbon catalyst. XAFS spectra clarifies that the electronic state of cobalt is changed by the introduction of vanadium, and the catalytic performance is further enhanced.ConclusionThe performance of Co‒N‒C catalyst is regulated by the high-valence state V doping, which provides an idea for the design of high-efficiency oxygen reduction catalyst.

Keywords

• oxygen reduction reaction
• non-precious metal catalysts
• x-ray absorption fine structure
• metal doping