Development of Co3O4 nanomaterials on flexible carbon cloth substrates for hydrogen and oxygen evolution reactions

Abstract

In this work, cobalt oxide decorated on carbon cloth (Co3O4/CC) is fabricated by the electrodeposition method by optimizing two factors: (i) the electrodeposition time; (ii) the volume ratio between ethylene glycol (EG) and deionized water (DI) in deposition solution. Results indicate that 5 min of electrodeposition is the most effective interval to acquire the sample with the most homogeneous in size and distribution. Furthermore, the addition of EG has a significant effect on the surface morphology of Co3O4/CC, causing the formation of the mesoporous Co3O4 layers on the substrate's surface. Due to the porous and rough structure of Co3O4/CC, its specific surface area reaches 111.3 m2g-1 as opposed to pure CC (37.2 m2g-1). Additionally, the coverage of Co3O4 on the cloth helps to enhance the electrochemical surface area up to 10 times and improve strongly the conductivity of the whole system. In the electrochemical water splitting (EWS) application, the Co3O4/CC sample prepared in precisely 5 min with the existence of EG at 40 %vol. possesses the best electrocatalytic performance with the lowest overpotentials for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with 291 mV and 357 mV at a current density of 10 mA cm−2 for each. This material also exhibits good stability to maintain a stable voltage at 10 mA cm−2 for 30 h.