Pentachlorophenol (PCP), as one of the common pesticide and preservatives, is easily accumulated in living organisms. Considering the high toxicity of PCP, the development of an effective and sensitive inspection method to determine the residual trace amounts of PCP continues to be a significant challenge. Herein, a convenient and sensitive electrochemical sensor is constructed by modifying glassy carbon electrode with cerium dioxide ( CeO2) nanoparticles anchored graphene ( CeO2-GR) to detect trace PCP. Benefiting from the two-dimensional lamellar structural advantages, the extraordinary electron-transfer properties, as well as the intensive coupling effect between CeO2 nanoparticles and graphene, the afforded CeO2- GR electrode nanomaterial possesses excellent electrocatalytic activity for the oxidation of PCP. Under the optimum synthetic conditions, the PCP oxidation peak currents of developed CeO2– GR sample exhibit a wide linear range of 5–150 μM. Moreover, the corresponding detection limit of PCP on the CeO2– GR electrode is as low as 0.5 μM. Apart from providing a promising electrochemical sensor, this work, most importantly, promotes an efficient route for the construction of highly active sensing electrode materials.

A composite photocatalyst of zinc oxide (ZnO) nanoparticles decorated with different content of reduced graphene oxide (rGO) was prepared via a simple and facile one-step method in this paper. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra, and UV–Vis diffuse reflection spectroscopy (UV–Vis DRS) were used to characterize the crystal structure, morphology and optical properties of the rGO–ZnO composite photocatalyst. The photocatalytic properties of the composites were investigated using methyl orange (MO), a typical orange compound, as a test pollutant. The results showed that rGO–ZnO composites displayed significantly enhanced photocatalytic activity in MO degradation than pure ZnO, and the pseudo-first-order kinetic constant on the optimal rGO–ZnO composite was 14 times as great as that on pure ZnO. The enhanced photocatalytic ability of the rGO-ZnO composites was mainly benefited from the high specific surface area and high conductivity of rGO, which facilitated efficient charge separation in the rGO-ZnO nanocomposite.

With the aim to fabricate flexible, mobile, and low-energy powered electronics, laser treatment of paper-based materials from carbon, cellulose, and natural products may be viable as one of the strategies to achieve this objective as it potentially provides a sustainable and precise patterning of a graphene-based circuit for various emerging electronic applications, such as sensor, robot, energy, and memory devices. Irradiation of high-energy beam for induction of porous-rich graphene or reduction of graphene oxide is easily accomplished from a commercially available laser machine with various laser sources, power, and pulse number setting. Moreover, the process itself can easily be adapted in the various manufacturing sectors due to the technology’s maturity status and its ability to be computer programmed. In comparison to environmental-benign polymer, the selection of paper as a substrate for electronics may introduce a new idea into the design possibility of electronic devices since the paper is not only thin, lightweight, biodegradable, and mechanically stable, but is also able to be assembled into another form and shape simply by traditional origami and kirigami technique for many applications. Here, in this work, recent laser processing strategies for the preparation of graphene either from graphitization of cellulose or deoxygenation of graphene oxide for green electronics are reviewed with brief coverage of the deposition technique of graphene oxide paper prior to laser annealing and discussion on the emerging relevant electronics field that benefitted greatly from the laser-assisted fabrication. To conclude the literature study, a remaining challenge, and prospective outlooks of laser writing of graphene on paper are also highlighted.

The hybridization of graphene with magnetic nanoparticles has endowed graphene with increasing interest as the adsorbent for wastewater treatment. However, its fabrication often involves a multi-stepped chemical synthesis process. In this work, we demonstrate a facile, one-step, and solvent-free approach to fabricate Fe3O4 nanoparticle-anchored Laser-Induced Graphene ( Fe3O4@LIG) as an efficient adsorbent by direct laser irradiation on a ferric acetylacetonate containing polybenzoxazine film. Raman and X-ray diffraction analysis confirm the graphene component in the adsorbent, and the morphology characterizations show that Fe3O4 nanoparticles are distributed uniformly on LIG with hierarchical meso- and macro-porous structures. Adsorption experiments indicate that Fe3O4@ LIG can adsorb methylene blue (MB) from aqueous solutions in a fast and effective manner, with a maximum adsorption capacity up to 350.9 mg/g. The adsorption kinetics and isotherms are also investigated, which are well-described by the pseudo-second-order model and Langmuir model, respectively. Additionally, Fe3O4@ LIG is also demonstrated with the efficient removal of a variety of organic solvents from water. The favorable adsorption behavior of Fe3O4@ LIG is attributed to its unique porous structure and the molecular interactions with adsorbates. On the other hand, Fe3O4@ LIG has high magnetic property, and therefore, it could be easily recovered from water and well regenerated for repeated use. With the efficient adsorption of organic pollutants, magnetic separability, and good

As frontier materials, graphene oxide (GO) and graphene have penetrated almost all research areas and advanced numerous technologies in sensing, electronics, energy storage, catalysis, water treatment, advanced composites, biomedical, and more. However, the affordable large-scale synthesis of high-quality GO and graphene remains a significant challenge that negatively affects its commercialisation. In this article, firstly, a simple, scalable approach was demonstrated to synthesise high-quality, high yield GO by modifying the improved Hummers method. The advantages of the optimised process are reduced oxidation time, straightforward washing steps without using coagulation step, reduction in cost as eliminating the use of phosphoric acid, use of minimum chemical reagents, and increased production of GO per batch (~ 62 g). Subsequently, the produced GO was reduced to reduced graphene oxide (rGO) using three different approaches: green reduction using ascorbic acid, hydrothermal and thermal reduction techniques. The GO and rGO samples were characterised using various microscopy and spectroscopy techniques such as XRD, Raman, SEM, TEM, XPS and TGA. The rGO prepared using different methods were compared thoroughly, and it was noticed that rGO produced by ascorbic acid reduction has high quality and high yield. Furthermore, surface (surface wettability, zeta potential and surface area) and electrical properties of GO and different rGO were evaluated. The presented synthesis processes might be potentially scaled up for large-scale production of GO and rGO.

Due to its capacity to manufacture low-cost 3D-printed structures, 3D-printing technology offers a unique opportunity for the fast epitome of various applications. Using a typical fused deposition modeling 3D printer along with a Discovery extruder, a graphene-ink can be 3D printed to produce an interdigitated electrode (IDE) arrangement. This work fabricated a 3D-printed planar supercapacitor from pristine graphene-ink without using high-temperature processing or functional additives. The printable ink (89%) is formulated from pristine graphene without the addition of any functional additives. The symmetric flexible supercapacitor is demonstrated with an excellent specific capacitance of 137.50 F/g at 0.5 A/g and an energy density of 12.23 Wh/kg. The obtained gravimetric energy density beats reported earlier carbon-based supercapacitors that are 3D or inkjet printed. The flexibility and robustness of 3D-printed devices are achieved up to 150° folding angles. This work demonstrates an efficient and easy method for fabricating practical energy storage devices featuring a customizable shape and excellent flexibility.

Abstract Biosensors are a group of measurement systems and their design is based on the selective identification of analyses based on biological components and physical and chemical detectors. Biosensors consist of three components: biological element, detector, and converter. The design of biosensors in various fields of biological sciences, medicine has expanded significantly. Biosensor technology actually represents a combination of biochemistry, molecular biology, chemistry, physics, electronics, and telecommunications. A biosensor actually consists of a small sensor and biological material fixed on it. Because biosensors are a powerful tool for identifying biological molecules, today they are used in various medical sciences, chemical industry, food industry, environmental monitoring, pharmaceutical production, health, etc. In fact, these sensors are a powerful tool to identify biological molecules. In fact, biosensors are analytical tools that can use biological intelligence to detect and react with a compound or compounds, and thus create a chemical, optical, or electrical message. The basis of a biosensor is to convert a biological response into a message. In this category, the use of telecommunication engineering technology and electromagnetic waves and frequency and radio spectrum is growing more and more to detect, measure, and determine the desired parameters in microbiology and laboratory sciences. The use of radio, optical, electromagnetic, ultrasonic, and infrared wave detection technology is part of the applications of telecommunication science in this field. Even image and audio processing systems have been instrumental in the discussion of biosensors in microbiology. The science of using fiber optics and waveguides, micro-strip antennas, and microelectromechanical technology is also very efficient in the construction and design of these biosensors.

Large-area graphene of the order of centimeters was deposited on copper substrates by low-pressure chemical vapor deposition (LPCVD) using hexane as the carbon source. The effect of temperature and the carrier gas flowrates on the quality and uniformity of the as-deposited graphene was investigated using the Raman analysis. The film deposited at 870 °C with a total carrier gas flowrate of 50 sccm is predominantly single-layer with very low defects according to the Raman spectra. The 2D/G peak intensity ratios obtained from the Raman spectra of samples from three different locations of graphene deposited on a whole copper catalyst was used to calculate the large-area uniformity. Based on the results, a very high uniformity of 89.6% was calculated for the graphene deposited at 870 °C. The uniformity was observed to decrease with increasing temperature. Similar to the thickness uniformity, the electrical conductivity values obtained as a result of I–V measurements and water contact angle measurements were found to be close to each other for the graphene deposited under the same deposition conditions.

Graphene, the wonder material has brought a revolutionary change in the field of nanotechnology owing to its tremendous properties. Though different methods for the synthesis of graphene have been reported, the chemical synthesis route offers a scalable and high-volume production of graphene. The unreliability of graphite and hydrocarbon resources to serve as steady supplies of carbon resources and further in the synthesis of graphene has led to the exploration and use of alternative low-cost carbon-rich resources (coal, graphite, rice husk, sugarcane bagasse, peanut shells, waste tyres, etc.) as precursors for graphene synthesis. The use of untraditional carbon resources reduces dependence on traditional resources (coal, graphite), reduced cost, increased reliability, and provides a way for the management of waste biomass. This review hence focuses on the synthesis of graphene by the most common approachable method, oxidation–reduction of graphite, along with the various other chemical methods of synthesis from varied carbon resources.

The feasibility study of synthesizing graphene quantum dots from spent resin, which is used in nuclear power plants to purify the liquid radioactive waste, was conducted. Owing to radiation safety and regulatory issues, an uncontaminated ion-exchange resin, IRN150 H/OH, prior to its use in a nuclear power plant, was used as the material of experiment on synthesis of graphene quantum dots. Since the major radionuclides in spent resin are treated by thermal decomposition, prior to conducting the experiment, carbonization of ion-exchange resin was performed. The experiment on synthesis of graphene quantum dots was conducted according to the general hydrothermal/solvothermal synthesis method as follows. The carbonized ion-exchange resin was added to a solution, which is a mixture of sulfuric acid and nitric acid in ratio of 3:1, and graphene quantum dots were synthesized at 115°C for 48 hours. After synthesizing, procedure, such as purifying, filtering, evaporating were conducted to remove residual acid from the graphene quantum dots. After freeze-drying which is the last procedure, the graphene quantum dots were obtained. The obtained graphene quantum dots were characterized using atomic force microscopy (AFM), Fourier-transform infrared (FT-IR) spectroscopy and Raman spectroscopy. The AFM image demonstrates the topographic morphology of obtained graphene quantum dots, the heights of which range from 0.4 to 3 nm, corresponding to 1–4 graphene layers, and the step height is approximately 2–2.5 nm. Using FT-IR, the functional groups in obtained graphene quantum dots were detected. The stretching vibrations of hydroxyl group at 3,420 cm−1, carboxylic acid (C=O) at 1,751 cm−1, C-OH at 1,445 cm−1, and C-O at 1,054 cm−1. The identified functional groups of obtained graphene quantum dots matched the functional groups which are present if it is a graphene quantum dot. In Raman spectrum, the D and G peaks, which are the characteristics of graphene quantum dots, were detected at wavenumbers of 1,380 cm−1 and 1,580 cm−1, respectively. Thus, it was verified that the graphene quantum dots could be successfully synthesized from the ionexchange resin.

Cerium oxide decorated on nickel hydroxide anchored on reduced graphene oxide (Ce-Ni(OH)2/rGO) composite with hexagonal structures were synthesized by facile hydrothermal method. Fourier transform infrared spectroscopy (FT-IR), highresolution transmission electron microscopy with selected area diffraction (HRTEM-SAED), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer– Emmett–Teller (BET) surface area analysis and electrochemical technology were used to characterize the composite. Due to its unique two-dimensional structures and synergistic effect among Ce2O3, Ni(OH)2 and rGO components indicated twodimensional hexagonal nano Ce-Ni(OH)2/rGO composite is promising electrode material for improved electrochemical H2O2 sensing application. From 50 to 800 μM, the H2O2 concentration was linearly proportional to the oxidation current, with a lower detection of limit of 10.5 μM (S/N = 3). The sensor has a higher sensitivity of 0.625 μA μM−1 cm− 2. In addition, the sensor demonstrated high selectivity, repeatability and stability. These findings proved the viability of the synthetic method and the potential of the composites as a H2O2 sensing option.

The reduced graphene oxide (rGO) has attracted more and more attention in recent years. How to choose a suitable reduction method to prepare rGO is a critical problem in the preparation of graphene composites. In this work, the differences of rGO reduced by thermal, microwave, Ultraviolet (UV) and reducing agent were studied. The reduction degree and functional groups of rGO were compared by SEM, XPS, Raman, FTIR and TGA. Thermal can remove most of the oxygen-containing groups of graphene oxide (GO) and the thermal reduction is the most effective reduction method. UV light can directly act on the unstable oxygen-containing groups, and its reduction efficiency is second only to thermal reduction. The efficiency of chemical reduction is not as good as that of UV reduction, because the reducing agent only act on the surface of GO. Microwave reduction is a mild thermal reduction with the lowest efficiency, but the residual oxygen-containing groups increase the hydrophilicity of rGO. To sum up, this work studies that rGO prepared by different reduction methods has different characteristics, which provides a reference for selecting appropriate reduction methods to prepare graphene composites with better properties.

Silver/graphene core/shell nanocomposites were synthesized through a one-step electric explosion of wire method using only silver wires and ethanol. The morphology of the graphene shell structures can be easily formed by alternating the solvent from deionized water to ethanol. Transmission electron microscopy revealed that the size of the prepared silver/graphene core/ shell nanocomposites was in the 10–110 nm range. The Raman spectra showed the formation of graphene shells on silver. A possible formation mechanism of the silver/graphene core/shell nanocomposites is proposed in this study. The crystallinity of the nanoparticles was investigated via X-ray diffraction. The graphene on the surfaces of the nanocomposites containing functional groups was analyzed through Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses. Zeta potential and dynamic light scattering analyses were performed to determine the dispersion characteristics of the nanocomposites when redispersed in other solvents.

The mechanosynthesis route is a physical top–down strategy to produce different nanomaterials. Here, we report the formation of graphene nanoribbons (GNRs) through this route using carbon bars recovered from discarded alkaline batteries as raw material. The mechanosynthesis time (milling time) is shown to have an influence on different features of the GNRs such as their width and edges features. TEM revealed the presence of GNRs with widths of 15.26, 8.8, and 23.55 nm for the milling times of 6, 12, and 18 h, respectively. Additionally, the carbon bars evolved from poorly shaped GNRs for the shortest milling time (6 h) to well-shaped GNRs of oriented sheets forming for the longest milling time. Besides GNRs, graphene sheets (GNS) of different sizes were also observed. The Raman analysis of the 2D bands identified the GNS signal and confirmed the GNRs nature. ID/IG values of 0.21, 0.32, and 0.40 revealed the degree of disorder for each sample. The in-plane sp2 crystallite sizes ( La) of graphite decreased to 91, 60, and 48 nm with increasing peeling time. The RBLM band at 288 cm− 1 confirmed the formation of the GNRs. Mechanosynthesis is a complex process and the formation of the GNRs is discussed in terms of a mechanical exfoliation, formation of graphene sheets and its fragmentation to reach GNR-like shapes. It is shown that the synthesis of GNRs through the mechanosynthesis route, besides the use of recycled materials, is an alternative for obtaining self-sustaining materials.