Cathodic plasma–induced syntheses of graphene nanosheet/MnO2/WO3 architectures and their use in supercapacitors

Shih Yu Huang, Phuoc Anh Le, Po Jen Yen, Yi Chun Lu, Sumanta Kumar Sahoo, Hao Wen Cheng, Po Wen Chiu, Tseung Yuen Tseng*, Kung Hwa Wei*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

In this study, we synthesized new 0.01–2 μm graphene nanosheet/MnO2/WO3 (G/MnO2/WO3) architectures through an electrochemically induced cathodic plasma process in a single batch at a lower temperature (70 °C) and for a shorter time (2 h) than those required for the syntheses of similar structures when using a hydrothermal method. We first obtained 0.01–1 μm leaf-like graphene (G) nanosheets, then 0.1–0.3 μm long and approximately 10 nm diameter petiole-like MnO2 nanowires on the G nanosheets, and finally 0.20–2.0 μm petal-like WO3 on MnO2/G — thereby forming the G/MnO2/WO3 architectures — as evidenced using scanning electron microscopy and transmission electron microscopy. We deciphered the step-wise reaction mechanism behind the formation of the G/MnO2/WO3 architectures during the plasma process. The high surface area of 291 m2 g−1 in the G/MnO2/WO3 architecture was contributed mainly by the G nanosheets, providing a suitable surface area for diffusion of the charge carriers during the charging and discharging process. As a result, an electrode incorporating the G/MnO2/WO3 architectures exhibited an excellent specific capacitance of 620 F g−1 — 45 and 200% higher than those of G/MnO2 (421 F g−1) and G (189 F g−1) electrodes, respectively — at a current density of 0.5 A g−1. Moreover, the G/MnO2/WO3–incorporated electrode exhibited good electrochemical cycling stability, with 90% capacitance retention over 5000 cycles at 1 A g−1. Such new G/MnO2/WO3 heterojunction structures, not only provide high-performance electrode applications, but also suggest a potential approach toward fabricating other heterojunction structures having high surface areas for energy storage applications.

Original languageEnglish
Article number136043
JournalElectrochimica Acta
Volume342
DOIs
StatePublished - 10 May 2020

Keywords

  • Cathodic plasma process
  • G/MnO/WO architectures
  • Sequential syntheses
  • Supercapacitor

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