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Carbon-based materials are mostly used in supercapacitor due to control porosity, higher surface area, and easy processing for electrode production. However, it is still challenging to fabricate carbon/metal oxide-based nanocomposite electrodes with various structures and configurations for supercapacitors, particularly for miniaturized electronics. Here, in the present study, CeO2–Nd2O3/rGO ternary nanocomposite was synthesized by facial co-precipitation route, which evident enhanced capacitive performance than CeO2–Nd2O3 binary composite, bare CeO2, and Nd2O3. The rGO was homogeneously anchored on the surface of CeO2–Nd2O3 nanoparticles, forming a semi-spherical morphology. The electrochemical performance of all electrodes was investigated by different measurements. The ternary composite have a higher specific capacitance of 1265 F g−1 at 3 A g−1 current density and maintained 99% retention after 2000th cycles, showing excellent cycling performance and rate capability compared to other grown products. The excellent electrochemical pseudocapacitive performance of the ternary composite-based electrode could be ascribed due to rGO and its interfacial contact with CeO2–Nd2O3. The improved electrode conductivity generates plentiful active sites for charging and discharging and provides an easy path for the fast transportation of ions. These results open an innovative pathway for fabricating rGO and metal oxide-based composite in developing electrochemical energy storage devices for commercial production. [ABSTRACT FROM AUTHOR]

In the present work, pristine and transition metal (TM) (W, Ag, Zn)-doped SnO2 nanocrystals using a facile sol–gel approach were synthesized. The grown products were anchored on graphene oxide (GO) sheets via a simple ultrasonication technique to fabricate binary nanocomposites. The structural, optical, and morphological properties of as-synthesized samples were studied by XRD, FTIR, Raman, EDX, UV–Visible, PL, and FE-SEM. The charge transferability of graphene oxide-based samples was investigated by EIS. The XRD exhibited the TM doping in SnO2 and the development of GO-based nanocomposite. FTIR data evidenced the existence of the metal–oxygen bonds. Raman spectra presented the optical phonon modes of SnO2 and the existence of oxygen vacancy defects. FE-SEM images demonstrated the anchoring of particles on the GO sheet, and EDX further approved the existence of desired dopants. The integration of SnO2 with TM doping remarkably reduced optical bandgap (3.65–3.10 eV), which was further decreased (3.10–2.99 eV) by making composite with GO. The photodegradation results exhibited that GO-based nanocomposites have the higher potential to degrade synthetic dyes (methyl red (MR), and methyl orange (MO) and SnZnO2/GO have shown superb photocatalytic performance after 80-min sunlight illumination (99.9% MR and 95.0% MO dyes) with the higher rate constant and superior stability up to 6th cycle against MR dye. The grown samples were tested for bacterial disinfection, and SnZnO2/GO sample showed a higher zone of inhibition towards S. aureus and K. pneumoniae bacteria strains. The greater charge transfer rate and lower recombination of charge carriers in GO-based composites were also observed by EIS and PL analysis. Moreover, the present article ascribed that the photocatalytic and antibacterial properties of bare SnO2 could be improved by TM doping and fabricating their composite with GO. [ABSTRACT FROM AUTHOR]

In the present work, pristine anatase titanium oxide (TiO2), vanadium oxide (V2O5), and yttrium oxide (Y2O3) nanopowders (NPs), and tri-phase TiO2–Y2O3–V2O5 nanocomposite (NC) were prepared via a simple co-precipitation method. The grown products were characterized by employing a range of techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis. The XRD diffraction pattern confirmed the formation of NC having TiO2 tetragonal, Y2O3 cubic, and V2O5 orthorhombic phases. FTIR spectra evident the presence of metal–oxygen bond in NPs and NC. The energy bandgap (2.55 eV) of NC is found in the range of visible region specified its use as an efficient photocatalyst under sunlight illumination. EDX analysis confirmed the existence of Ti, Y, and V in the nanocomposite. The antibacterial studies against Staphylococcus aureus, Klebsiella pneumonia, and Proteus vulgaris bacteria by varying concentrations (10, 20, 30, and 40 mg ml−1) showed that the NC has higher antibacterial activity than individual oxides. The photocatalytic activity exhibited that NC has the highest degradation efficiency 99.29%, 90.69%, and 99.83% against methylene blue (MB), safranin-O (SO), and methyl orange (MO) dyes as compared to pristine TiO2, V2O5, and Y2O3 NPs under 80 min direct sunlight irradiation. Furthermore, the grown NC is a good candidate for treating organic pollutants and bacteria inactivation. [ABSTRACT FROM AUTHOR]

Novel tri-phase CuO–MgO–ZnO nanocomposite was prepared using the co-precipitation technique and investigated its physical properties using characterization techniques including XRD, FTIR, Raman, IV, UV-vis, PL, and SEM. The application of grown CuO–MgO–ZnO nanocomposite for the degradation of various dyes under sunlight and antibacterial activity against different bacteria were studied. The XRD confirmed the existence of diffraction peaks related to CuO (monoclinic), MgO (cubic), and ZnO (hexagonal) with CuO phase 40%, MgO 24%, and ZnO 36%. The optical energy gap of nanocomposite was 2.9 eV, which made it an efficient catalyst under sunlight. Raman and FTIR spectra have further confirmed the formation of the nanocomposite. SEM images revealed agglomerated rod-shaped morphology. EDX results showed the atomic percentage of a constituent element in this order Cu>Zn>Mg. PL results demonstrate the presence of intrinsic defects. The photocatalytic activity against methylene blue (MB), methyl orange (MO), rhodamine-B (RhB), cresol red (CR), and P-nitroaniline (P-Nitro) dyes has shown the excellent degradation efficiencies 88.5%, 93.5%, 75.9%, 98.8%, and 98.6% at 5 ppm dye concentration and 82.6%, 83.6%, 64.3%, 93.1%, and 94.3% at 10 ppm dye concentration in 100 min, respectively, under sunlight illumination. The higher degradation is due to the generation of superoxide and hydroxyl radicals. The recyclability test showed the reusability of catalyst up to the 5th cycle. The antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Proteus Vulgaris, Staphylococcus aureus, and Pseudomonas aeruginosa bacteria with the zone of inhibition 30, 31, 30, 30, and 30 mm, respectively, was achieved. [ABSTRACT FROM AUTHOR]

The disposal of chromium (Cr) containing wastewater in surface water bodies without prior treatment is a serious threat to humans, animals, and plants. A novel nanocomposite (CSB/ZnO) of cotton stalks biochar (CSB) with ZnO nanoparticles was synthesized for the removal of Cr (VI) ions from contaminated water at batch scale. The impact of adsorbent dosage (1–4 g/L), initial Cr (VI) levels (25–200 mg/L), pH (2–8), and interaction time (0–180 min) was assessed for the removal of Cr (VI) from contaminated water. The Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and point of zero charge (PZC) characterization showed successful impregnation of ZnO particles on CSB with improved surface characteristics. The maximum adsorption (qmax) of CSB and CSB/ZnO was 54.95 and 107.53 mg Cr/g, respectively that is relatively higher than various previously studied adsorbents. The experimental isothermal data better fitted with the Freundlich model in comparison with other isotherm models while adsorption kinetics well corroborated with the pseudo-second-order model. The results revealed that doping of biochar with metallic nanoparticles (CSB/ZnO) proved very effective (99.6% at 50 mg/L) with high reusability (91%) after five adsorption/desorption cycles and seems a suitable strategy for the decontamination of Cr (VI) contaminated waters. [ABSTRACT FROM AUTHOR]

Binary NiO-Fe2O3, NiO-CdO nanocomposites, and ternary NiO-Fe2O3-CdO nanocomposite are synthesized using facile co-precipitation method, and their photocatalytic and antibacterial properties are studied. The as-obtained products are characterized using different analytical techniques. The microstructural parameters were calculated using X-ray diffraction data. UV–vis spectra technique was used to calculate the bandgap and listed 3.1, 2.7, and 2.5 eV for NiO-Fe2O3, NiO-CdO, and NiO-Fe2O3-CdO nanocomposite, respectively. The photocatalytic activity of as-obtained products was tested under visible light against methylene blue (MB) dye. The NiO-Fe2O3-CdO nanocomposite has shown higher degradation efficiency as compared to binary nanocomposites and revealed improve electron–hole separation efficiency. The photocatalytic performance of NiO-Fe2O3-CdO nanocomposite was also tested for other synthetic dyes such as rhodamine-B (RhB), methyl orange (MO), and cresol red (CR). The antibacterial performance of grown products was tested against E. coli bacteria. The ternary NiO-Fe2O3-CdO nanocomposite has shown higher antibacterial activity than binary NiO-Fe2O3 and NiO-CdO nanocomposites. [ABSTRACT FROM AUTHOR]