Tuning the electrochemical properties of W18O49 by conjugating with reduced graphene oxide and cerium oxide
Zartasha Sarwar, Muhammad Umair, Sumara Ashraf, Yasir Javed, Sajad Hussain, Naveed Akhtar Shad, Asim Jilani, Muhammad Ramzan Khawar, Chungyeon Cho, Dongwhi Choi
Abstract
One of the interesting energy technologies is a hybrid (asymmetric) device, has an exceptional power density, a quick charging/discharging process, and outstanding cycle stability. Herein, tungsten oxide (W 18 O 49 ) and its nanocomposites with reduced graphene oxide (rGO) and cerium oxide (CeO 2 ) were hydrothermally synthesized. The phase stability and crystalline nature were confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was employed to analyze the morphological features of the synthesized materials, while UV–visible and photoluminescence techniques were used to evaluate their optical characteristics. The rGO/W 18 O 49 nanocomposites exhibit an improved specific capacity of 723 C/g at 1 A/g which is better than W 18 O 49 (519 C/g at 1 A/g) and CeO 2 /W 18 O 49 (385 C/g at 1 A/g). XPS assessment confirms that the rGO increases conductivity by lowering binding energies in W and O bondings. Due to the high specific capacity of rGO/W 18 O 49 , the material is employed as an anode material for hybrid supercapacitors. The fabricated device depicts an excellent energy density of 11.25 Wh/kg with 2250 W/kg power density at 3 mA/g current density. Moreover, the fabricated device showed a remarkable rate capability of ∼ 93.26 % with 88.29 % columbic efficiency.