Preparation and enhanced supercapacitance performance of carbonized silk by feeding silkworms MoO2 nanoparticles

As a key building block to power flexible electronics, there is need for the development of flexible current collectors. Bombyx mori silk, a traditional textile, attracts increasing attention for its potential application in flexible electronics and is a promising raw material for flexible carbon electrodes in current collector fabrication. In this work, molybdenum dioxide nanoparticles (MoO2 NPs), which possess chemical stability and high mass specific capacitance, was used as a feed additive and combined with mulberry leaves to raise silkworms. It was found that the MoO2 NPs were embedded within the silk fibers, which endowed the resulting silk with favorable features for electrochemical energy storage in flexible electronics. After carbonization, the specific capacitance of electrodes prepared with silk from the MoO2 NPs feeding group, with a mass/volume ratio of 5 g/L, was enhanced from 100 F/g to 245 F/g at a current density of 0.2 A/g. Impressively, the electrodes show high coulombic efficiency with excellent stability. This work demonstrates the possibility of producing carbonized silk with superior properties for developing silk-based flexible electrodes for use in energy storage devices in a large-scale, green, low-cost way.