Summary In this work, flexible carbon nanotubes (CNTs)/manganese oxide (MnO2) composite electrode was fabricated by direct deposition of MnO2 nanoparticles on CNTs sheet by RF magnetron sputtering. The surface morphology and microstructure of the CNTs and CNTs/MnO2 composite electrodes were characterized by X‐ray diffraction (XRD), scanning electron microscope‐energy dispersive spectroscopy (SEM‐EDS), X‐ray photoelectron spectroscopy (XPS), and Raman spectroscopy. It was found that 1‐μm thick MnO2 film covered the surface of CNTs sheet with MnO2 mass loading of 0.125 mg/cm2. CNTs/MnO2 composite was tested as electrode materials for supercapacitors in sulfate media (1‐M H2SO4 and Na2SO4) by cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). The results obtained showed that CNTs/MnO2 composite electrode displayed good electrochemical performance in 1‐M Na2SO4, while the chemical stability of MnO2 film was highly affected due its dissolution in acidic medium. A specific capacitance of 940 F/g was retained (with a capacitance retention of about 80%) after 3000 GCD cycles. CNTs/MnO2 all‐solid symmetric supercapacitor using PVA/H3PO4 gel electrolyte exhibited an initial specific capacitance 80 F/g and decreased by 25% after 3000 cycles.

A great part of interest has been paid for fabricating new materials with novel mechanical, optical, and electrical properties. Boron carbon nitride (BCN) ternary system was applied for variable bandgap semiconductors and systems with extreme hardness. The purpose of this literature review is to provide a brief historical overview of B 4 C and BN, to review recent research trends in the BCN synthesizes, and to summarize the fabrication of BCN thin films by plasma sputtering technique from B 4 C and BN targets in different gas atmospheres. Pre-set criteria are used to discuss the processing parameters affecting BCN performance which includes the gasses flow ratio and effect of temperature. Moreover, many characterization studies such as mechanical, etching, optical, photoluminescence, XPS, and corrosion studies of the RF sputtered BCN thin films are also covered. We further mentioned the application of BCN thin films to enhance the electrical properties of metal-insulator-metal (MIM) devices according to a previous report of Prakash et al. (Opt. Lett. 41, 4249, 2016).

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Qatar is one of the major natural gas (NG) producing countries, which has the world’s third-largest NG reserves besides the largest supplier of liquefied natural gas (LNG). Since the produced water (PW) generated in the oil and gas industry is considered as the largest waste stream, cost-effective PW management becomes fundamentally essential. The oil/gas industries in Qatar produce large amounts of PW daily, hence the key challenges facing these industries reducing the volume of PW injected in disposal wells by a level of 50% for ensuring the long-term sustainability of the reservoir. Moreover, it is important to study the characteristics of PW to determine the appropriate method to treat it and then use it for various applications such as irrigation, or dispose of it without harming the environment. This review paper targets to highlight the generation of PW in Qatar, as well as discuss the characteristics of chemical, physical, and biological treatment techniques in detail. These processes and methods discussed are not only applied by Qatari companies, but also by other companies associated or in collaboration with those in Qatar. Finally, case studies from different companies in Qatar and the challenges of treating the PW are discussed. From the different studies analyzed, various techniques as well as sequencing of different techniques were noted to be employed for the effective treatment of PW.