Effect of graphite oxide and exfoliated graphite oxide as a modifier for the voltametric determination of dopamine in presence of uric acid and folic acid

In the present work, exfoliated graphite oxide (E-GO) was prepared by sonicating graphite oxide (GO) (prepared by modified Hummer’s and Offemam methods). Prepared GO and E-GO were characterized using infrared absorption spectroscopy, X-ray diffraction, and scanning electron microscopy. The electrocatalytic properties of GO and E-GO towards detection of dopamine (DA), uric acid (UA), and folic acid (FA) were investigated using cyclic voltammetry and differential pulse voltammetry. Our results revealed that E-GO has a slighter advantage over the GO as an electrode modifier for detection DA, UA, and FA, which might be ascribed to the good conductivity of E-GO when compared to the GO.

Ultrasonic-Assisted Diels–Alder Reaction Exfoliation of Graphite into Graphene with High Resveratrol Adsorption Capacity

Scalable preparation of graphene with high adsorption capacity is an important prerequisite for fully realizing its commercial application. Herein, we propose an environmentally friendly route for exfoliation of graphene, which is established based on the Diels–Alder reaction. In our route, N-(4-hydroxyl phenyl) maleimide enters between the flakes as an intercalating agent and participates in the Diels–Alder reaction as a dienophile to increase the interlayer spacing of graphite. Then, graphite is exfoliated into graphene with the aid of ultrasound. The exfoliated product is hydroxyl phenyl functionalized graphene with a thickness of 0.5–1.5 nm and an average lateral size of about 500–800 nm. The exfoliation process does not involve any acid or catalyst and would be a safe and environmentally friendly approach. In addition, the exfoliated graphite shows high resveratrol adsorption capacity, which is ten times that of macroporous resins reported in the literature. Thus, the method proposed herein yields exfoliated graphite with high resveratrol adsorption capacity and is of great significance for the mass production of graphene for practical applications.

Influence of Electrochemically Exfoliated Graphite Addition on the Dielectric Properties of Epoxy/Montmorillonite Nanocomposites

The influence of hydrophilic electrochemically exfoliated graphite (EEG) and hydrophobic reduced EEG (rEEG) on the electrical conductivity, dielectric properties, and high-frequency dielectric losses of epoxy-based composites with montmorillonite was described. It was confirmed, that the addition of EEG changes the low-temperature conduction mechanism. The electrical conductivity in composite with EEG and montmorillonite was described by correlated barrier hopping model, whereas for composites with montmorillonite and rEEG two models were used: non-overlapping small polaron tunneling and correlated barrier hopping. The addition of EEG drastically changes the activation energy of charge carriers motions from 2.68 to 0.83 eV, whereas the addition of rEEG only to 2.43 eV. Also composite with EEG was characterized by highest high-frequency dielectric losses.