Hierarchical carbon coated vertically aligned α-MoO₃ nanoblades anode materials for supercapacitor application

Abstract

Molybdenum oxide (MoO3) is an appropriate electrode material for vast applications such as gas sensing, catalyst, and energy storage devices. Its high oxidation states provide the possibility for ion intercalation and de-intercalation to the electrode material, which is truly advantageous for supercapacitor application. Herein, we report about reduced vertically aligned α-MoO3 nanoblades on conducting substrates via a post-treatment in reduced gas environments (H2, N2 and vacuum) to tune their conductivity by introducing oxygen vacancies. These α-MoO3 nanoblades were further carbonized through decomposition of glucose as a carbohydrate material to obtain binder-free carbon coated vertically aligned α-MoO3 electrode. As a binder-free supercapacitor negative electrode, the vacuum treated α-MoO3 electrode showed the highest specific capacitance (39.8 mF cm−2), as compared to that achieved by N2 and H2 treated samples (29.2 mF cm−2 and 24.5 mF cm−2, respectively). Besides, the vacuum annealed electrode also maintained around 76.4% of its initial specific capacitance value after 10,000 cycles indicating a more stable electrochemical performance of such electrode. An asymmetric device 3D-MnO2//α-MoO3 was assembled and it attained maximum specific capacitance value of 37.5 mF/cm2 at current density value 1.5 mA cm− 2 and maximum energy density value of 16.875 µWh cm-2 at power density value of 675 µW cm-2. The results demonstrate that the proposed hybrid synthesis approach is very promising for preparation of binder-free materials for high-performance supercapacitors.