One-Step Synthesis of Graphene−Cobalt Hydroxide Nanocomposites and Their Electrochemical Properties

The well-documented novel performances of graphene make it a potential candidate for a wide range of utilizations, driving research into exploiting unusual properties of this wonder material. This paper reports a facile soft chemical approach to fabricate graphene−Co(OH)2 nanocomposites in a water−isopropanol system. Generally the depositing agent (OH−) and some reducing agents (such as HS− and H2S) could be produced from the hydrolyzation of Na2S in aqueous solution. Therefore utilizing Na2S as a precursor could enable the occurrence of the deposition of Co2+ and the deoxygenation of graphite oxide (GO) at the same time. Remarkably the electrochemical specific capacitance of the graphene−Co(OH)2 nanocomposite reaches a value as high as 972.5 F·g−1, leading to a significant improvement in relation to each individual counterpart (137.6 and 726.1 F·g−1 for graphene and Co(OH)2, respectively). The feeding ratios between Co(OH)2 and graphene oxide have a pronounced effect on their electrochemical activities.