Preparation and Characterization of PANI@NiO Visible Light Photocatalyst for Wastewater Treatment

Unsupported Copper Nanoparticles in the Arylation of Amines

Commercially available copper and copper (II) oxide nanoparticles (CuNPs and CuO NPs) were characterized using TEM and electronography methods to elucidate their true average size and composition. The catalytic amine arylation using unsupported copper nanoparticles differing in their size and copper oxidation state was investigated. The reaction of the model iodobenzene with n-octylamine was shown to be successfully catalyzed by CuNPs of average size 25 and 10/80 nm in the presence of the ligands such as 2-isobutyrylcyclohexanone (L1) and rac-1,1′-bi-2-naphthol (BINOL, L2), giving high yields (up to 95%) of the target N-octylaniline. CuO in bulk and nano forms was shown to be almost equally efficient in this process. Studies on the Cu-catalyzed amination of substituted iodobenzenes and 2-iodopyridine, as well as the arylation of different aliphatic amines and NH-heterocycles, verified that CuNPs (25 or 10/80 nm) with L1 and L2 are the most versatile and efficient nanocatalysts for a variety of substrates. Investigation of copper leaching under different conditions was carried out.

Nanoengineering of NiO/MnO2/GO Ternary Composite for Use in High-Energy Storage Asymmetric Supercapacitor and Oxygen Evolution Reaction (OER)

Designing multifunctional nanomaterials for high performing electrochemical energy conversion and storage devices has been very challenging. A number of strategies have been reported to introduce multifunctionality in electrode/catalyst materials including alloying, doping, nanostructuring, compositing, etc. Here, we report the fabrication of a reduced graphene oxide (rGO)-based ternary composite NiO/MnO₂/rGO (NMGO) having a range of active sites for enhanced electrochemical activity. The resultant sandwich structure consisted of a mesoporous backbone with NiO and MnO₂ nanoparticles encapsulated between successive rGO layers, having different active sites in the form of Ni-, Mn-, and C-based species. The modified structure exhibited high conductivity owing to the presence of rGO, excellent charge storage capacity of 402 F·g^-1 at a current density of 1 A·g^-1, and stability with a capacitance retention of ~93% after 14,000 cycles. Moreover, the NMGO//MWCNT asymmetric device, assembled with NMGO and multi-wall carbon nanotubes (MWCNTs) as positive and negative electrodes, respectively, exhibited good energy density (28 Wh·kg^-1), excellent power density (750 W·kg^-1), and capacitance retention (88%) after 6000 cycles. To evaluate the multifunctionality of the modified nanostructure, the NMGO was also tested for its oxygen evolution reaction (OER) activity. The NMGO delivered a current density of 10 mA·cm^-2 at the potential of 1.59 V versus RHE. These results clearly demonstrate high activity of the modified electrode with strong future potential.

Aluminum Doping Effects on Interface Depletion Width of Low Temperature Processed ZnO Electron Transport Layer-Based Perovskite Solar Cells

Rapid improvement in efficiency and stabilities of perovskite solar cells (PSCs) is an indication of its prime role for future energy demands. Various research has been carried out to improve efficiency including reducing the exciton recombination and enhancement of electron mobilities within cells by using electron transport material (ETM). In the present research, electrical, optical, and depletion width reduction properties of low temperature processed ZnO electron transport layer-based perovskite solar cells are studied. The ZnO thin films vary with the concentration of Al doping, and improvement of optical transmission percentage up to 80% for doped samples is confirmed by optical analysis. Reduction in electrical resistance for 1% Al concentration and maximum conductivity 11,697.41 (1/Ω-cm) among the prepared samples and carrier concentration 1.06×10²² cm⁻³ were corroborated by Hall effect measurements. Systematic impedance spectroscopy of perovskite devices with synthesized ETM is presented in the study, while the depletion width reduction is observed by Mott Schottky curves. IV measurements of the device and the interfacial charge transfer between the absorber layer of methylammonium lead iodide and ETM have also been elaborated on interface electronic characteristics.

In Situ Synthesis of a Polyaniline/ Fe-Ni Codoped Co3O4 Composite for the Electrode Material of Supercapacitors with Improved Cyclic Stability

Conductive polymers have become a remarkable candidate for electrode materials of supercapacitors. Polyaniline (PANI) is the most promising contender for supercapacitors because of its easy method of synthesis, low cost, and higher choice in the improvement of energy storage applications. The main issue in the use of PANI in supercapacitors is its lower stability. In this work, PANI@Fe-Ni codoped Co₃O₄ (PANI@FNCO) nanocomposite has been prepared by in situ addition of 10 wt % FNCO as fillers in the PANI matrix. The nanocomposites were then characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry to observe the morphology, crystal structure, functional groups, and thermal stability of samples, respectively. SEM results showed that FNCO was fairly dispersed in the PANI matrix, while XRD results showed a broad peak for nanocomposites because of the semicrystalline nature of polymers. The electrochemical properties of the samples were analyzed via cyclic voltammetry, galvanostatic charge and discharge, and electrochemical impedance spectroscopy. PANI@FNCO nanowires are found to overcome the shortcomings in electrochemical energy storage devices by exhibiting a higher value of specific capacitance of 1171 F g^-1 and energy density of 144 W h kg^-1 at a current density of 1 A g^-1. Moreover, the FNCO nanowires also showed a cyclic charge/discharge stability of 84% for 2000 cycles.