The effect of surface characteristics of reduced graphene oxide on the performance of a pseudocapacitor

In this research, we have analyzed the electrochemical characteristics of the different rGO/Co3O4 composites prepared by controlling the rGO surface characteristics and its relationship between the growth of Co3O4 nanoparticles and the performance of the pseudocapacitor. Reduced graphene oxide/cobalt oxide (rGO/Co3O4) nanocomposites of different morphologies were prepared through the simple hydrothermal method. First, different kinds of graphite precursors, crumpled and planar with different properties, were used to determine the most suitable substrate to grow Co3O4 nanoparticles. As a result, rGO/Co3O4 composite synthesized from planar graphite shows a higher specific capacitance of 207.2, 170.1, and 141.5 Fg?1 at 1, 2, and 5 Ag?1 than the one prepared from crumpled graphite. In the second part, planar graphite, confirmed to be the most suitable substrate from the previous part, was oxidized under various oxidation conditions to increase the oxygen functional groups attached on the GO surfaces and observed to see how it affects the growth of Co3O4 nanoparticles and its influence on the electrochemical performance of the rGO/Co3O4 pseudocapacitor. As a result, the one with the largest amount of functional groups had the Co3O4 nanoparticles well dispersed and grown on the rGO substrate in small nanoparticle sizes, as small as 5.9 nm, leading to an improved electrochemical performance. Thus, the specific capacitance with the least amount of oxygen functional groups are 207.2, 170.1, and 141.5 Fg?1 and for the largest amount of functional groups are 411.5, 371.4, and 292.7 Fg?1, at 1, 2, and 5 Ag?1 respectively. This approach could become a guideline for the ideal fabrication of rGO/metal oxide composite for further research involving rGO based pseudocapacitors.