Carbon Supported Metal Oxide Nanoparticles: Hierarchical Porous Structure and Electrochemical Properties

Abstract

Energy storage devices made from nanostructured electrodes are reported to be lightweight and possess promising performance. Interest is growing in new energy storage devices that are low cost, lightweight, and deliver high energy and power densities. Supercapacitors are important energy storage devices that can deliver high power during short periods of time, making them attractive for electric vehicle applications.Porous carbon supported metal oxide materials have been successfully used as electrode in supercapacitors. The efficiency of the electrochemical properties can be improved by using novel electrode with controlled nanostructure, nanoparticle size and electrochemical performance. In this work, hierarchically porous carbon supported metal oxides, including cobalt oxide and molybdenum oxide nanoparticles are designed, aiming to improve metal loading and dispersion with uniform nanoparticles, which in-turn enhances eletrochemical performance.The hierarchically porous carbon matrix synthesized has bimodal porous structure with 300-400 nm macropores and ~ 20 nm mesopores with a BET surface area of ~370 m2/g. Cobalt oxides and molybdenium oxides were loaded by a wet impregnation method. The electrochemical properties of the synthesized hybrid materials will be demonstrated.Current results demonstrate that cobalt oxide particles in the synthesized composites can be tuned from < 5 nm to 10 nm and are dispersed uniformly across the carbon matrix with loading as high as 15 wt%. Molybdenum oxide particles also can be well dispersed in the carbon matrix with a high loading up to 40 wt% and the valence of molybdenum can be tuned. We also demonstrate the network of meso- and macro- pores and high surface area offered by this type of carbon materials is promising to achieve high metal loadings and dispersion for better activity and mass transport.