Shape controlled synthesis of CeO2 nanostructures for high performance supercapacitor electrodes

Abstract

We report CeO₂ nanostructures with the desired shape synthesized via a simple hydrothermal approach without any specific structure directing agent for supercapacitor applications. Well-distributed hexagonal nanoplates and nanorods were designed with large exposed surfaces under controlled hydrothermal conditions. As an advantage of this favorable shape and structural features, both of these nanostructures exhibit large specific capacitance values and excellent rate capabilities. Unique carbon supported CeO₂ nanorod microstructures have shown a high capacitance of 644 F g⁻¹ at 0.5 A g⁻¹. Furthermore, they can deliver up to 400 F g⁻¹ at a high current density of 20 A g⁻¹. This is the first report of a CeO₂ nanostructure for use as a supercapacitor electrode with a high rate capability. The notable electrochemical performance can be attributed to its large exposed surface, reasonable electronic conductivity, and the carbon support which increases the electrode/electrolyte contact significantly. The observed specific capacitance values are much higher and comparable with the other transition metal oxide electrodes. The present study suggests that the shape controlled CeO₂ nanostructure will be an alternative high performance electrode for next generation supercapacitors.