A graphene oxide (GO)/poly 3-methyl aniline (P3MA) photodetector has been developed for light detection in a broad optical region: UV, Vis, and IR. The 3-methyl aniline was initially synthesized via radical polymerization using an acid medium, i.e., K2S2O8 oxidant. Consequently, the GO/P3MA composite was obtained through the adsorption of GO into the surface of P3MA. The chemical structure and optical properties of the prepared materials have been illustrated via XRD, FTIR, SEM, and TEM analysis. The absorbance measurements demonstrate good optical properties in the UV, Vis, and near-IR regions, although a decrease in the bandgap from 2.4 to 1.6 eV after the composite formation was located. The current density (Jph) varies between 0.29 and 0.68 mA·cm−2 (at 2.0 V) under dark and light, respectively. The photodetector has been tested using on/off chopped light at a low potential, in which the produced Jph values decrease from 0.14 to 0.04 µA·cm−2, respectively. The GO/P3MA photodetector exhibits excellent R (and D) values of 4 and 2.7 mA·W−1 (0.90 × 109 and 0.60 × 109 Jones) in the UV (340 nm) and IR (730 nm) regions, respectively. The R and D values obtained here make the prepared photodetector a promising candidate for future light detection instruments.

A fractal, flower petal-like CuS-CuO/G-C3N4 nanocomposite is prepared and applied in a symmetric two-electrode supercapacitor. The preparation of CuS-CuO/G-C3N4 is carried out through the hydrothermal method, in which salts of copper are dissolved and mixed with a suspension of G-C3N4 nanoparticles. A symmetric two-electrode supercapacitor, formed from CuS-CuO/G-C3N4 paste on Au-plates is investigated. The measurements are carried out in diluted 0.5 M HCl, and Whatman filter paper is used as a separator. The supercapacitor electric properties are determined by measuring the charge/discharge, cyclic voltammetry, impedance, and lifetime parameters. An enhancement in the charge/discharge time from 65 to 420 s was recorded while decreasing the current density (J) from 1.0 to 0.3 A/g. The cyclic voltammetry behavior is studied from 50 to 300 mV·s−1, causing a direct increase in the produced J values. The specific capacitance (CS) and energy density (E) values are 370 F/g and 37 W·h·kg−1, respectively. The magnificent properties of the prepared supercapacitor qualify it for industrial applications as an alternative to batteries.

Rolled graphene oxide (roll-GO) with anew morphological properties than normal graphene is synthesized using modified Hummer. Then, the roll-GO/PANI composite is prepared through the adsorption of roll-GO on the surface of the PANI film, that performed through the oxidative polymerization method. The developed composite displays a small bandgap of 1.9 eV and shows a high optical property extends through a wide optical region from UV to IR regions. The chemical structure and function groups are confirmed using the XRD and FTIR. The roll-GO/PANI composite was investigated as a photodetector. The effects of different irradiation light conditions and the monochromatic wavelengths were tested through the measurements of the produced current density, Jph. The optical photon response exhibited excellent light sensitivity of the photodetector. The Jph enhanced highly under light (0.34 mA·cm−2) compared to dark conditions (0.007 mA·cm−2). Jph reached 0.24, 0.23, 0.14, and 0.09 mA·cm−2 under 340, 440, 540, and 730 nm, respectively. The photodetector detectivity (D) and photoresponsivity (R) are found to equal 0.45 × 109 Jones and 2.25 mA·W−1, respectively.

The discovery of twisted bilayer graphene with tunable superconductivity has diverted great focus at the world of twisted van der Waals heterostructures. Here we propose a paradigm for bilayer materials, where covalent bonding replaces the van der Waals interaction between the layers. On the example of germanene-stanene bilayer, we show that such systems demonstrate fascinating topological properties and manifest giant capacitance effects of the order of C = 102μ F as well as dipole-like charge densities of q = 1 − 2 × 10−4μ C cm−2, showing promise for 2D ferroelectricity. The observed unique behaviour is closely linked to transverse strain-induced buckling deformations at the bilayer/substrate interface. In alternative GeSn bilayer structures with low twist angles the strain distortions trigger rich topological defect physics. We propose that the GeSn bilayer topology may be switched locally by a substrate-strain-induced electric fields. We demonstrate an approach to fabricate covalent bilayer materials, holding vast possibilities to transform applications technologies across solar, energy and optoelectronic sectors.