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Two-dimensional molybdenum disulfide (MoS2) with multilayer hierarchical structures is generally considered to be able to provide more active sites and shorter diffusion channels for electrolytes, which make them extremely suitable for supercapacitor applications. Nevertheless, the MoS2 poor conductivity and rare surface area are the major technical obstacles. Herein, we demonstrated a honeycomb basis using carbon nanotubes (CNTs). The honeycomb-shaped carbon skeleton provides a relatively larger surface area to store more ions with a more stable and stronger structure to maintain long-term electrochemical tests. During MoS2 fabrication, MoOx was also synthesized onto CNTs. MoOx influenced the electrochemical test results. Thermal annealing was conducted to remove the MoOx attachments to assure the optimal capacitance value. For the particular composite honeycomb structure (MoS2/CNTs) used in this research, the specific capacitance increased from 4.7 F/g (CNTs) to 75 F/g (MoS2 + MoOx/CNTs), measured using cyclic voltammetry measurements. The specific capacitance further reached 425 F/g using thermal annealing at optimal temperature, 700 °C. The designed electrode materials demonstrated excellent electrochemical characteristics and had great potential for future electrochemical applications. [ABSTRACT FROM AUTHOR]

Photoconductivities (PCs) with high responsivity in two-dimensional (2D) diindium triselenide (In2Se3) nanostructures with α-phase hexagonal structure were studied. The In2Se3 nanosheet photodetectors fabricated by focused-ion beam technique exhibit broad spectral response with wavelength range from 300 nm to 1000 nm. The In2Se3 nanosheets achieve optimal responsivity of 720 A W−1 in near-infrared region (808 nm), and detectivity of 2.2 × 1012 Jones, which were higher than several 2D material photodetectors. The physical origins that result in high photoresponse in In2Se3 nanosheets such as carrier lifetime and mobility were also characterized by time-resolved PC and field-effect transistor measurements. The fast (hundred microseconds to milliseconds) and slow (seconds and longer) current rise or decay processes were both observed during the photoresponse. The narrowing (or relaxation) of depletion region and oxygen-sensitized photoconduction mechanism were suggested to be the causes of the efficient photoresponse in the In2Se3 nanostructure detectors. All these observations suggest that α-In2Se3 nanosheets could be a promising candidate for photosensitive material applications. [ABSTRACT FROM AUTHOR]

Cu2O has been deposited on quartz substrates by reactive ion beam sputter deposition. Experimental results show that by controlling argon/oxygen flow rates, both n-type and p-type Cu2O samples can be achieved. The bandgap of n-type and p-type Cu2O were found to be 2.3 and 2.5 eV, respectively. The variable temperature photoluminescence study shows that the n-type conductivity is due to the presence of oxygen vacancy defects. Both samples show stable photocurrent response that photocurrent change of both samples after 1,000 seconds of operation is less than 5%. Carrier densities were found to be 1.90 × 1018 and 2.24 × 1016 cm−3 for n-type and p-type Cu2O, respectively. Fermi energies have been calculated, and simplified band structures are constructed. Our results show that Cu2O is a plausible candidate for both photoanodic and photocathodic electrode materials in photoelectrochemical application. [ABSTRACT FROM AUTHOR]

Zinc oxide nanodonuts have been synthesized using vapor-phase transport method. Zinc oxide powder, graphite powder, and erbium oxide powder were mixed with a molar ratio of 1:1:0.2 and heated at 1050 °C in a flowing argon environment. Perfectly donut-shaped nanostructures with outer diameters ranging from 450 to 850 nm were observed. The inner diameter of the zinc oxide donut varies from 75 to 95 nm and the vertical distance from the highest point to the lowest point vary from 85 to 130 nm. The composition of the nanodonut was analyzed using Auger electron spectroscopy and was found to be mainly of zinc oxide. Diffusion of silicon into the zinc oxide layer was confirmed by secondary ion mass spectroscopy. [ABSTRACT FROM AUTHOR]

Photoconductivities (PCs) with high responsivity in two-dimensional (2D) diindium triselenide (In 2 Se 3 ) nanostructures with α-phase hexagonal structure were studied. The In 2 Se 3 nanosheet photodetectors fabricated by focused-ion beam technique exhibit broad spectral response with wavelength range from 300 nm to 1000 nm. The In 2 Se 3 nanosheets achieve optimal responsivity of 720 A W -1 in near-infrared region (808 nm), and detectivity of 2.2 × 10 12 Jones, which were higher than several 2D material photodetectors. The physical origins that result in high photoresponse in In 2 Se 3 nanosheets such as carrier lifetime and mobility were also characterized by time-resolved PC and field-effect transistor measurements. The fast (hundred microseconds to milliseconds) and slow (seconds and longer) current rise or decay processes were both observed during the photoresponse. The narrowing (or relaxation) of depletion region and oxygen-sensitized photoconduction mechanism were suggested to be the causes of the efficient photoresponse in the In 2 Se 3 nanostructure detectors. All these observations suggest that α-In 2 Se 3 nanosheets could be a promising candidate for photosensitive material applications.