Facile synthesis of self-assembled WO3 nanorods for high-performance electrochemical capacitor

Abstract Hexagonal WO 3 nanorod thin films have been successfully synthesized by a simple hydrothermal method using ammonium sulfate ((NH 3 ) 2 SO 4 ) as a structure directing agent. The effect of structure directing agent on structural, morphological and electrochemical properties of WO 3 thin films is investigated. The nanorods with diameters of 50–200 nm and length up to several micrometers are obtained. The results demonstrate that the concentration of (NH 3 ) 2 SO 4 plays an important role in the growth direction and formation of self-assembled WO 3 nanorods. The electrochemical measurements show that WO 3 thin films demonstrate excellent electrochemical performance with a maximum specific capacitance of 538 F g −1 at 5 mV s −1 , high power performance and good cycling stability (85% over 2000 CV cycles). The present work may provide a facile and versatile approach to tune the morphology and capacitive performance of WO 3 thin films required for high-performance energy storage devices.