The effect of treatment in nitrogen plasma on the properties of partially reduced graphene oxide (rGO) was studied. A comparison is made between two different sample locations in the reaction chamber. It is shown that in the case when rGO films were turned towards the inductor of the plasma system, the etching rate is much higher. Effective nitrogen functionalization of rGO was established in the second position, when the rGO films were turned in the opposite direction. In this case, the nitrogen content increases to 5 at% of the initial value. The change in the current–voltage characteristics is observed under illumination, which is independent of the wavelength. On and off daylight changes the resistance to 30% of the initial value. The magnitude of the photocurrent increases depending on the applied voltage. The effect is most noticeable for thin rGO films 10–15 nm in thickness.

In the work, the properties of graphene oxide processed in methane plasma and plasma of a mixture of methane and nitrogen and subjected to subsequent annealing at T = 650 ° C in an argon atmosphere are investigated. It is shown that during plasma treatment, the hydrogenated amorphous carbon film is deposited on the surface of the exhaust gas. During heat treatment, a significant part of this film is removed, another part of the carbon atoms participates in the formation of bonds with the structure of the exhaust gas. This process leads to a decrease in the density of defects introduced by the plasma. The inclusion of nitrogen in methane plasma leads to n or p doping depending on the plasma power level. This effect is explained by the predominant formation of graphite and pyridine nitrogen configurations, which are donor centers in structures with fewer defects. At a high density of defects, pyrrole nitrogen structures, which are acceptor centers, are mainly introduced.

Представлены результаты синтеза и исследования графенсодержащих порошков из пластиковых отходов методом быстрого джоулева нагрева. Процессы проводились на разработанной на основе предыдущей итерации макета установке быстрого джоулева нагрева. Эксперименты проводились на смеси полипропилена с техническим углем, которая подвергалась высокотемпературному воздействию при различных напряжениях разряда (100 В, 200 В, 300 В). Полученные углеродные порошки были исследованы методами спектроскопии комбинационного рассеяния света, рентгеноструктурного анализа, сканирующей электронной микроскопии с элементным анализом. Результаты показали, что при напряжении разряда 300 В формируется турбостратный графен (turbostratic graphene) с высокой степенью упорядоченности кристаллической структуры, что подтверждается наличием характерных пиков в спектрах комбинационного рассеяния света и рентгеноструктурного анализа. При более низких напряжениях разряда также образуются графеновые чешуйки, но с большим содержанием аморфного углерода. Электрические свойства сформированных пленок на основе полученных углеродных порошков демонстрируют низкое слоевое сопротивление, что делает их перспективными для использования в качестве электропроводящих покрытий и электродов для суперконденсаторов. Предлагаемый метод быстрого джоулева нагрева в перспективе может позволить эффективно перерабатывать пластиковые отходы в ценные углеродные материалы, что может позволить решить экологические проблемы и способствовать развитию «зеленых» технологий.

The rapid development of electric vehicles, unmanned aerial vehicles, and wearable electronic devices has led to great interest in research related to the synthesis of graphene with a high specific surface area for energy applications. However, the problem of graphene synthesis scalability, as well as the lengthy duration and high energy intensity of the activation processes of carbon materials, are significant disadvantages. In this study, a novel reactor was developed for the green, simple, and scalable electrochemical synthesis of graphene oxide with a low oxygen content of 14.1%. The resulting material was activated using the fast joule heating method. The processing of mildly oxidized graphene with a high-energy short electrical pulse (32 ms) made it possible to obtain a graphene-based porous carbon material with a specific surface area of up to 1984.5 m²/g. The increase in the specific surface area was attributed to the rupture of the original graphene flakes into smaller particles due to the explosive release of gaseous products. In addition, joule heating was able to instantly reduce the oxidized graphene and decrease its electrical resistance from >10 MΩ/sq to 20 Ω/sq due to sp² carbon structure regeneration, as confirmed by Raman spectroscopy. The low energy intensity, simplicity, and use of environment-friendly chemicals rendered the proposed method scalable. The resulting graphene material with a high surface area and conductivity can be used in various energy applications, such as Li-ion batteries and supercapacitors.

The effect of the two-step process on the properties of graphene oxide (GO) is studied. At the first stage, CH₄ (or CH₂+N₂) plasma treatment was performed. The second one was heat treated at a temperature of 650° C. The formation of thin polycrystalline carbon films on the surface of graphene oxide was detected. The ratio of carbon to oxygen concentration corresponds to graphene oxide. Smooth surfaces of the films were detected by an atomic force microscope. Films have lower sheet resistance and higher carrier mobility than reduced GO (rGO) during the same heat treatment. An analysis of the Raman spectra shows that the formed films have larger graphene domains than the rGO. The presence of nitrogen in methane plasma leads to a decrease in the resistance and mobility of carriers in the carbon film.