Capacitance Enhancement of Hydrothermally Reduced Graphene Oxide Nanofibers

Abstract

Nanocarbon materials present sp2-carbon domains skilled for electrochemical energy conversion or storage applications. In this work, we investigate graphene oxide nanofibers (GONFs) as a recent interesting carbon material class. This material combines the filamentous morphology of the starting carbon nanofibers (CNFs) and the interlayer spacing of graphene oxide, and exhibits a domain arrangement accessible for fast transport of electrons and ions. Reduced GONFs (RGONFs) present the partial removal of basal functional groups, resulting in higher mesoporosity, turbostratic stacking, and surface chemistry less restrictive for transport phenomena. Besides, the filament morphology minimizes the severe layer restacking shown in the reduction of conventional graphene oxide sheets. The influence of the reduction temperature (140–220 °C) on the electrochemical behaviour in aqueous 0.5 M H2SO4 of RGONFs is reported. RGONFs present an improved capacitance up to 16 times higher than GONFs, ascribed to the unique structure of RGONFs containing accessible turbostratic domains and restored electronic conductivity. Hydrothermal reduction at 140 °C results in the highest capacitance as evidenced by cyclic voltammetry and electrochemical impedance spectroscopy measurements (up to 137 F·g−1). Higher temperatures lead to the removal of sulphur groups and slightly thicker graphite domains, and consequently a decrease of the capacitance.

Electrocatalytic Behavior of Manganese and Cobalt Porphyrins Attached to Graphene Quantum Dots: Applied in the Oxidation of Hydrazine

“…Compared to GQDs alone CoTA 3 CPP–GQDs and ClMnTA 3 CPP–GQDs show slightly lower capacitance, in Figure 7. The decrease could be due to restacking of graphene sheets as reported in literature [51]. The peaks observed at the negative potentials between −0.30 V and −0.4 V were employed for the determination of surface coverage Eqn.…”

Oxidized Multiwalled Carbon Nanotubes as Components and Oxidant Agents in the Formation of Multiwalled Carbon Nanotube/Polyazulene Composites

“…9). Because thermal treatment of carbon nanomaterials changes their structure and porosity, [59][60][61][62] the observed increase in currents may be associated with the higher porosity of materials synthesized at higher temperatures. Moreover, a higher temperature In order to investigate the influence of composite synthesis temperature on the porosity of formed materials, the N 2 adsorption--desorption isotherm has been recorded.…”

Capacitance Properties of Chemically Prepared Carbon Nanostructure/Polyazulene Composites

“…It is well known that thermal treatment of carbon nanomaterials changes their structure and porosity. [40][41][42][43] The SLGO/ PAZ composite was heated at 150 °C at two different times. Figure 6 shows an exemplary N 2 adsorption-desorption isotherm of the asprepared SLGO/polyazulene composite.…”

“…Similar behavior was observed for graphene materials that were heat-treated at different temperatures. 40,41 The electrochemical behaviors of the as-prepared SLGO/PAZ composite and composite heated at 150 °C are shown in Fig. 8.…”