Enhancing electrochemical performance of electrode material via combining defect and heterojunction engineering for supercapacitors

The poor conductivity and deficient active sites of transition metal oxides lead to low energy density of supercapacitors, which limits their wide application. In this work, double transition metal oxide heterojunctions with oxygen vacancy (V-o-ZnO/CoO) nanowires are prepared by effective hydrothermal and thermal treatments. The formation of the heterojunction results in the redistribution of interface charge between ZnO and CoO, generating an internal electric field to accelerate the electron transport. Meanwhile, oxygen vacancies can enhance the redox reaction activity to further improve the electrochemical kinetics of the electrode material. Therefore, the prepared V-o-ZnO/CoO can provide a superior specific capacity of 845 C g(-1) (1 A g(-1)). An asymmetric supercapacitor with the V-o-ZnO/CoO as positive electrode shows a higher energy density of 51.6 Wh kg(-1) when the power density reaches 799.9 W kg(-1). This work proposes a synergistic combination of defect and heterojunction engineering to improve the electrochemical properties of materials, providing an important guidance for material design in energy-storage field. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

In this study, double transition metal oxide heterojunction nanowires with oxygen vacancy were prepared to improve the electrochemical properties of materials, resulting in higher energy density and specific capacity of electrode materials.