Bimetallic oxide/carbon nanomaterials hybrids were chemically synthesized and fully characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The elemental data analysis confirmed the successful formation of MnCo2O4/carbon nanomaterials. The fingerprint area of FTIR showed the incorporation of the metal oxides onto CNTs and GO surfaces. Morphological investigations of the nanocomposites, using FESEM and HRTEM, revealed the uniform distribution of bimetallic oxide nanostructures over the surface of carbon nanomaterials. Furthermore, electrochemical characteristics were explored using the CV and EIS. The obtained electrochemical results demonstrated significant improvements in the electrocatalytic properties, in addition to the direct and fast electron transfer provided by the modified surfaces whereas MnCo2O4/CNTs were exploited for the nano-enzymatic detection of hydrogen peroxide as an example to show the promising applications of such materials in designing non-enzymatic sensors and biosensors.

Electrochemical alongside the electro-catalytic properties of graphene and multi-walled carbon nanotubes have been improved via doping with manganese oxide nanostructures. Structural, morphological, and electrochemical properties of the as-synthesized nanocomposites were identified using XRD, FTIR, SEM, and electrochemical methods including cyclic voltammetry, and electrochemical impedance spectroscopy. The SEM images showed flower-like microsphere structures, while the conjugation of MnO2 with the carbon nanomaterials was confirmed by the FTIR and XRD analysis. All MnO2-based nanocomposites provided great enhancement in their electrochemical activities with a larger value of specific capacitance than the individual constituents of carbon nanomaterials. Accordingly, hydrogen peroxide-directed detection was evaluated, whereas the nanocomposites exhibited direct electron transfer, fast and linear responses in the range from 1.0 to 210 µM. Thus, the significant enhancements in the electrochemical features acquired by the nanocomposites could suggest these nanomaterials for energy storage and hydrogen peroxide sensing applications.

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The light scribe (LS) technique has been applied to reduce graphene oxide (LSGO) over a flexible substrate to be used as a humidity sensor. Graphene oxide (GO) suspension was drop casted over Polyethylene terephthalate (PET) substrate and then reduced inside a conventional light scribe digital video disc (DVD). Interdigitated electrode was precisely fabricated with dimensions of the finger length of 450 μm and width of 20 μm. The prepared material was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Raman spectroscopy. The results confirm the reduction process of GO using the LS technique. Moreover, the humidity sensing properties of the LSGO was evaluated. Results showed that the present light-scribed humidity sensor has many advantages including rapid response, highly precise due to light scribe technique, and more importantly sensors can be fabricated directly on flexible substrates which are highly favorable for future wearable smart electronics.

In the present contribution, the 3D hollow structure of manganese cobalt oxide/carbon nanotubes (MnCo2O4/CNTs) nanocomposite was successfully synthesized through a co-precipitation procedure followed by post-heat treatment. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). Based on the obtained results, the surface of carbon nanotubes was coated uniformly in radial directions by manganese oxide (MnO2) nanosheets forming a flower-shaped structure. In the next step, cobalt oxide precursor was introduced to form MnCo2O4/CNTs nanocomposite. The XRD data confirms the formation of MnCo2O4/CNTs. The estimated values of the strain and the crystallite size based on the Williamson-Hall (W-H) method are calculated as 5.326×10-4 and 16 nm respectively. The fingerprint area of FTIR suggests the successful incorporation of MnO2 and cobalt oxide onto CNTs’ surfaces. The flower-shaped structure in the nanoscale is verified by the FESEM and TEM devices. Furthermore, the magnetic specifications revealed the paramagnetic with a small ferromagnetic component of the aforementioned MnCo2O4/CNTs nanocomposite.