ABSTRACT
Supported nanostructured photocatalysis is considered to be a sustainable and promising method for water pollution photodegradation applications due to its fascinating features, including a high surface area, stability against aggregation, and easy handling and recovery. However, the preparation and morphological control of the supported nanostructured photocatalyst remains a challenge. Herein, a one-step hydrothermal method is proposed to fabricate the supported vertically aligned ZnO nanosheet arrays based on aluminum foil. The morphologically controlled growth of the supported ZnO nanosheet arrays on a large scale was achieved, and the effects of hydrothermal temperature on morphologic, structural, optical, and photocatalytic properties were observed. The results reveal that the surface area and thickness of the nanosheet increase simultaneously with the increase in the hydrothermal temperature. The increase in the surface area enhances the photocatalytic activity by providing more active sites, while the increase in the thickness reduces the charge transfer and thus decreases the photocatalytic activity. The influence competition between the area increasing and thickness increasing of the ZnO nanosheet results in the nonlinear dependence between photocatalytic activity and hydrothermal temperature. By optimizing the hydrothermal growth temperature, as fabricated and supported ZnO nanosheet arrays grown at 110 °C have struck a balance between the increase in surface area and thickness, it exhibits efficient photodegradation, facile fabrication, high recyclability, and improved durability. The RhB photodegradation efficiency of optimized and grown ZnO nanosheet arrays increased by more than four times that of the unoptimized structure. With 10 cm2 of as-fabricated ZnO nanosheet arrays, the degradation ratio of 10 mg/L MO, MB, OFL, and NOR was 85%, 51%, 58%, and 71% under UV irradiation (365 nm, 20 mW/cm2) for 60 min. All the target pollutant solutions were almost completely degraded under UV irradiation for 180 min. This work offers a facile way for the fabrication and morphological control of the supported nanostructured photocatalyst with excellent photodegradation properties and has significant implications in the practical application of the supported nanostructured photocatalyst for water pollution photodegradation.
ABSTRACT
In this work, localized surface plasmon resonance (LSPR) mediated by aluminum nanoparticles (Al NPs) was investigated to enhance the ultraviolet (UV) response of the zinc oxide nanorods (ZnO NRs) grown by the hydrothermal method. The ZnO NRs were characterized by scanning electron microscope, energy dispersive spectroscopy, X-ray diffractometer, Raman spectrometer, ultraviolet-visible spectrophotometer and fluorescence spectrometer. The results show that the morphology and crystalline structure of the ZnO NRs could not be changed before and after decoration with Al NPs, but the absorption rates in the UV range and the photoluminescence (PL) properties were improved. The photo-to-dark current ratio of ZnO NRs with Al NPs was about 447 for 325 nm UV light (5 mW/cm2) at 3.0 V bias, with the sensitivity increasing from 9.5 to 47.8, and the responsivity increasing from 53 to 267 mA/W.
ABSTRACT
Study of nonlinear laser-matter interactions in 2D materials has promoted development of photonics applications. As a typical MXene material, molybdenum carbide (Mo2C) has attracted much attention because of its graphene-like structure. Here, a type of D-shaped fiber (DF)-buried Mo2C saturable absorber (SA) fabricated by magnetron-sputtering deposition (MSD) and sol-gel technique is reported. The Mo2C material was buried between the bottom DF and the upper amorphous silica fabricated by sol-gel technology. Therefore, the DF-based SA effectively solves the problem of material shedding and aging, thus improving the stability and damage threshold of the fiber laser. Application of the SA in erbium-doped fiber laser and stable passive Q-switched operation with a maximum pulse energy of 430.47 nJ is realized. By adjusting the polarization state and pump power, high-power mode-locked pulses are generated with a pulse duration and output power of 199 fs and 54.13 mW, respectively. Further, bound-state soliton pulses are obtained with a pulse width of 312 fs and soliton interval of 1.26 ps for the first time based on MXene materials. Moreover, by application of the SA in ytterbium-doped fiber lasers, a stable dissipative soliton mode-locked pulse is obtained with a pulse width of 23 ps. These results indicate that the DF-based buried Mo2C as a novel SA provides a reliable method for all-fiber and multifunctional high-power ultrafast laser.
ABSTRACT
Pure WO3 and Ag-WO3 (mixed solid solutions Ag with WO3) have been successfully synthesized by sol-gel method and the influences of calcination temperature on the particle size, morphology of the WO3 and Ag-WO3 nanoparticles were investigated. Powder X-ray diffraction results show that the hexagonal to monoclinic phase transition occurs at calcination temperature varying from 300°C to 500°C. SEM images show that calcination temperature plays an important role in controlling the particle size and morphology of the as-prepared WO3 and Ag-WO3 nanoparticles. The NO2 gas sensing properties of the sensors based on WO3 and Ag-WO3 nanoparticles calcined at different temperatures were investigated and the experimental results exhibit that the gas sensing properties of the Ag-WO3 sensors were superior to those of the pure WO3. Especially, the sensor based on Ag-WO3 calcined at 500°C possessed larger response, better selectivity, faster response/recovery and better longer-term stability to NO2 than the others at relatively low operating temperature (150°C).
