Facile fabrication of electroactive microporous Co3O4 through microwave plasma etching for supercapacitors

The large volume expansion-contraction and low conductivity of Co3O4 leads to electrode pulverisation, capacity loss and poor cycling stability in the application of a capacitor. Herein, an effective and low cost strategy for microwave plasma chemical vapour deposition (CVD) equipment with a modified household microwave oven was implemented to handle micro-porous Co3O4 powder and get high O vacancy electrode active materials. The results show that the morphology, crystal structure and elemental composition of the sample are strongly affected by H-2 plasma. The capacity of the etched micro-porous Co3O4 powder is about 128 Fg(-1) after 4000 cycles, which is 3.5 times larger than that of the origin powder. The performance improvement mechanism of the plasma etch was also confirmed. The results show that microwave plasma etching can effectively improve the performance of Co3O4 capacitor materials due to O vacancy increasing and the ratio of Co2+/Co3+ changing, which will benefit other kinds of oxide semiconductor electrode materials. (C) 2018 Elsevier B.V. All rights reserved.