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

In this work, cobalt oxide decorated on carbon cloth (Co3O4/CC) is fabricated by the elec-trodeposition 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 elec-trochemical 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 elec-trocatalytic performance with the lowest overpotentials for both hydrogen evolution re-action (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.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.