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Single-step, single-precursor synthesis of nitrogen-doped graphene oxide (N-GO) was demonstrated in this work. By choosing aniline as the sole source of carbon and nitrogen, N-GO films were fabricated using microwave plasma at a power as low as 80 W in atmospheric conditions. The aniline vapor dissociated under plasma formed islands of N-GO nanosheets on the substrates or walls of the quartz deposition chamber. The interplanar spacing in the pristine N-GO films was observed to be lower than that of GO films, which indicated a lower concentration of oxygen and other species present in the space between the N-GO layers. The as-fabricated N-GO demonstrated superior antiscaling and algicidal properties that are deemed imperative for water purification applications.

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Graphene is a highly sought-after material for a wide range of applications, particularly in areas such as energy harvesting and storage, electronics, electrochemical sensors, biomedical, composites, and coatings. The synthesis of high-quality graphene is a precondition for its real-time application. However, conventional synthesis methods have certain drawbacks including laborious procedures and structural defects in graphene nanosheets. Plasma-based synthesis techniques such as plasma-enhanced chemical vapor deposition and atmospheric pressure microwave plasma are high-tech synthesis practices that can produce graphene without any solvents in a few seconds. This article reviews these state-of-the-art techniques emphasizing mainly their process parameters for the synthesis of high-grade graphene, which is defect-free, and comprises mono to few layers, great carrier mobility, and high purity. The applications of as-synthesized graphene in various fields are also provided. Moreover, the potential breakthroughs and the prospect of these techniques are also discussed in this work.

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Friction stir welding (FSW) of polymers is relatively a new concept among modern polymer joining techniques. This study demonstrates the applicability of FSW on 16mm thick nylon-6 plates at constant welding rate of 25mm/min and varying rotational speed between 300 to 1000RPM. A special designed tool was fabricated which has double shoulder and right-hand threaded pin profile. It has shown excellent results at relatively lower rotation speeds. Visual inspection and microstructural examination of cross sections showed that the cavities and tunnel defects appeared only at higher rotational speeds. A linear relationship was observed between temperature and rotation speed.

Developing applications for the by-products obtained from waste processing is vital for resource recovery. The synthesis of ZnCl2-activated biochar with high electrocatalytic activity was carried out by the microwave-assisted pyrolysis of pineapple peel and subsequent chemical activation process. Activated biochar is employed in the electrochemical sensing of nitrite by drop casting in a glassy carbon electrode (GCE). The activated biochar exhibited a stacked carbon sheet, 254 m2 g−1 Brunauer, Emmett and Teller (BET) surface area, 0.076 cm3 g−1 pore volume, 189.53 m2 g−1 micropore area and oxygen-containing functional groups. The electrochemical impedance spectroscopy of the modified GCE showed a reduced charge transfer resistance of  61%. This is crucial to determine the electrochemical properties of biochar. The sensor showed a significant current response and an excellent limit of detection of 0.97 µmol L−1. The modified-activated biochar electrochemical sensor demonstrated high selectivity, reproducibility (RSD=2.4%), and stability (RSD=2.6%). Graphical abstract