2019, Vol.29, No.2

Carbon Letters 2023 KCI Impact Factor : 1.35 KCI-WoS Impact Factor : 6.04

pISSN : 1976-4251 / eISSN : 2233-4998
https://journal.kci.go.kr/carbon

Herein, the edges in carbon materials were quantitatively evaluated by summing the amount of hydrogen and the amount of functional groups without hydrogen in the material. The amount of hydrogen in the carbon material was quantitated via temperature-programmed oxidation (TPO) under an oxygen atmosphere, whereas the amount of functional groups was determined via temperature-programmed desorption (TPD) of the sample under an inert atmosphere. Consequently, the amount of edges in exfoliated carbon fibers prepared from polyacrylonitrile (PAN) (referred to as PAN-1000) was 9.4 mmol g−1. In addition, Ketjen Black (KB) and activated carbon (AC) had edge content of 1.3 and 3.6 mmol g−1, respectively. Because the total amount of functional groups of PAN-1000, KB and AC were estimated to be 8.18, 0.082 and 1.02 mmol g−1 via TPD, the total amount of edges and oxygen-containing functional groups of each sample could be quantified. The difference between amount of edges and the amount of functional groups is speculated to correspond to the amount of edges terminated with hydrogen. This study revealed that detailed information about the edges such as their proportion terminated with oxygen-containing functional groups, the species and amount of oxygen-containing functional groups via a combination of TPO and TPD.

Low cost and scalable manufacturing of highly doped cellulose for enhanced multifunctional applications is still an issue. In this work, eco-friendly nanocomposites were fabricated by incorporating regenerated cellulose (RC) of 10, 30, and 50 wt% into an exfoliated graphene nanoplatelets (GNPs), resulting in the intercalation of GnPs. The thermal and electrical properties of hybrid nanocomposites were investigated. The structural property was conducted through scanning electron microscope and X-ray diffraction analyses. Strong frequency-dependent dielectric response was found due to the change of the permittivity and the loss tangent of nanocomposites by different content of RC, which is associated with the polarizations behavior. Non-elastic relaxation at the GNPs–RC chains interfacial areas in an alternating field was identified as the main cause of polarization losses among others. Detailed ferroelectric measurements provided the evidence of the ideal resistive behavior of the nanocomposites, which are confirmed by the resistivity measurements along the out-of-plane direction of the nanocomposite sheets.

We report a facile and versatile strategy to prepare multi-dimensional nanocarbons hybridized with mesoporous SiO2. Carbon nanoplatelets (CNPs, two-dimensional structure of nanocarbons) were combined with carbon nanotubes (CNTs, onedimensional nanocarbons) to form multi-dimensional carbons (2D–1D, CNP–CNTs). The CNP–CNTs were synthesized by directly growing CNTs on CNPs. A simple solution-based process using TEOS (tetraethyl orthosilicate) resulted in coating or hybridizing CNP–CNTs with mesoporous silica to produce CNP–CNTs@SiO2. The nanocarbons’ surface area significantly increased as the amount of TEOS increased. Electrochemical characterizations of CNP–CNTs@SiO2 as supercapactior electrodes including cyclic voltammetry and galvanostatic charge–discharge in 3 M KOH (aq) reveal excellent-specific capacitance of 23.84 mF cm−2 at 20 mV s−1, stable charge–discharge operation, and low internal resistance. Our work demonstrates mesoporous SiO2 on nanocarbons have great potential in electrochemical energy storage.