Molecular Level Study of Graphene Networks Functionalized with Phenylenediamine Monomers for Supercapacitor Electrodes

Abstract

Three phenylenediamine (PD) monomers, o-phenylenediamine (OPD), m-phenylenediamine (MPD), and p-phenylenediamine (PPD), were used to prepare the functionalized graphene (PD/rGO) networks. The results obtained from a series of chemical, thermal, and rheological analyses elucidated the mechanism of the covalent bonding and the existence of cross-linked graphene networks. The measured XRD patterns and molecular dynamic calculations discovered that those PPD and MPD molecules could enlarge graphene interlayer spacing to 1.41 and 1.30 nm, respectively, while OPD molecules were disorderly bonded or nonbonded to the basal planes of graphene layers, resulting in small and variable interlayer distances. The loadings of PD monomers were optimized to achieve superior supercapacitor performance. Electrochemical study showed that PPD/rGO exhibited the largest specific capacitance of 422 F/g with excellent cycling stability and low charge transfer resistance. The large variations in the capacitance values among PD/rGO networks with different PD monomers were explained by the difference in the graphene nanostructures, reversible redox transitions, and charge transfer characteristics. Particularly, density function theory calculations were adopted to compare electronic properties of the PD/rGO composites, including formation energy, electron density distribution, HOMO energy levels, and electron density of states near the Fermi level.

Adjusting the band structure and defects of ZnO quantum dots via tin doping

“…All the data were corrected with respect to the standard peak of C 1s at 284.6 eV. [27][28][29][30] As shown in Fig. 4, for all the samples, both Sn and Zn peaks could be found in the XPS spectra.…”

Hydrothermal Synthesis of Humate‐Layer‐Based Bimetal Organic Framework Composites as High Rate‐Capability and Enery‐Density Electrode Materials for Supercapacitors

“…Supercapacitors are a new generation of energy storage device that not only has high charge‐discharge efficiency, power density, reliability and long cycle lifetime similar to traditional capacitors, but also has high energy density close to batteries . In supercapacitor assemblies, electrode materials are a critical component affecting device performances.…”

Graphene/Polymer Nanocomposites for Supercapacitors

“…Alongside the above‐discussed commonly used polymers, other polymers have been also combined with graphene as electrodes for supercapacitor devices …”

“…The above discussed preparation methods can be extended to new interesting polymer candidates combined with graphene as electrodes for supercapacitors. The most widely used method is the noncovalent approach, while few examples of using covalently linked graphene/polymer nanocomposites in supercapacitors have been reported . This is reasonable, as supercapacitor cells require electrode materials with a high electrical conductivity, and the noncovalent method can largely reserve the intrinsic properties of graphene therefore leading to a high electrical conductivity of the formed nanocomposites.…”