Search

BiVO4/Mn1-xZnxFe2O4 was prepared by the impregnation roasting method. XRD (X-ray Diffractometer) tests showed that the prepared BiVO4 is monoclinic crystal, and the introduction of Mn1-xZnxFe2O4 does not change the crystal structure of BiVO4. The introduction of a soft-magnetic material, Mn1-xZnxFe2O4, was beneficial to the composite photocatalyst's separation from the liquid solution using an extra magnet after use. UV-vis spectra analysis indicated that Mn1-xZnxFe2O4 enhanced the absorption intensity of visible light for BiVO4. EIS (electrochemical impedance spectroscopy) investigation revealed that the introduction of Mn1-xZnxFe2O4 enhanced the conductivity of BiVO4, further decreasing its electron transfer impedance. The photocatalytic efficiency of BiVO4/ Mn1-xZnxFe2O4 was higher than that of pure BiVO4. In other words, Mn1-xZnxFe2O4 could enhance the photocatalytic reaction rate. [ABSTRACT FROM AUTHOR]

BiVO4/Mn1-xZnxFe2O4 was prepared by the impregnation roasting method. XRD (X-ray Diffractometer) tests showed that the prepared BiVO4 is monoclinic crystal, and the introduction of Mn1-xZnxFe2O4 does not change the crystal structure of BiVO4. The introduction of a soft-magnetic material, Mn1-xZnxFe2O4, was beneficial to the composite photocatalyst's separation from the liquid solution using an extra magnet after use. UV-vis spectra analysis indicated that Mn1-xZnxFe2O4 enhanced the absorption intensity of visible light for BiVO4. EIS (electrochemical impedance spectroscopy) investigation revealed that the introduction of Mn1-xZnxFe2O4 enhanced the conductivity of BiVO4, further decreasing its electron transfer impedance. The photocatalytic efficiency of BiVO4/ Mn1-xZnxFe2O4 was higher than that of pure BiVO4. In other words, Mn1-xZnxFe2O4 could enhance the photocatalytic reaction rate. [ABSTRACT FROM AUTHOR]

The method of dividing the "three zones" of spontaneous combustion in goaf by oxygen volume fraction is the most widely used and effective method at present. However, the oxygen volume fraction method does not consider the influence of methane concentration in goaf, which is only applicable to low-gas goaf, not high-gassy goaf. In this work, the oxidation behavior and kinetics parameters of a lean coal at low temperatures under five different oxygen concentrations, including methane and its kinetics during low-temperature oxidation, were studied using temperature programming tests and thermogravimetric tests. The results showed that the decrease of oxygen content improves the adsorption capacity of coal to absorb different atmospheres at the initial stage. In the whole reaction process, there is a negative correlation between the strong-to-weak order of exothermicity and adsorption capacity, with a significant increase in apparent activation energy E. A marked hysteresis of the precipitation time of CO and CO2 and a decrease in their precipitation amount and a rise in the initial temperature for the generation of CO and CO2 were found. [ABSTRACT FROM AUTHOR]

The effects of electron beam irradiation on ethylene-tetrafluoroethylene copolymer (ETFE) were studied. Samples were irradiated in air at room temperature by a universal electron beam accelerator for various doses. The effect of irradiation on samples and the cross-linked ETFE after aging were investigated with respect to thermal characteristics, crystallinity, mechanical properties, and volume resistivity using thermo-gravimetric analysis (TGA), differential scanning calorimeter (DSC), universal mechanical tester, and high resistance meter. TGA showed that thermal stability of irradiated ETFE is considerably lower than that of unirradiated ETFE. DSC indicates that crystallinity is altered greatly by cross-link. The analysis of mechanical properties, fracture surface morphology, visco-elastic properties and volume resistivity certify radiation-induced cross-linking is vital to aging properties. [ABSTRACT FROM AUTHOR]

It is of great significance to thoroughly explore the interface charge extraction and migration in heterojunction systems, which could guide us to synthesize higher-efficiency photocatalytic materials. A novel noble-metal-free doped Z-scheme NiO@BiOCl heterojunction was found in this work. The corresponding heterostructure, interface electron extraction, and electron migration were investigated via first-principles calculation. 5,5′-dimethyl-1-pyrroline-N-oxide (DMPO) spin-trapping electron spin resonance (ESR) and time-resolved photoluminescence (TRPL) tests were implemented to confirm the calculation results, which showed that electrons and holes stayed in the NiO (100) facet and BiOCl (110) facet, respectively. Owing to the large chemical potential of 2.40 V (vs ENHE) for the BiOCl valence-band hole, it possessed super activity to oxidize water into hydroxyl radicals or molecular oxygen. We hope this promising multifunctional photocatalytic material, therefore, NiO@BiOCl can be applied in advanced treatment of organic wastewater and oxygen production from photolysis water. [ABSTRACT FROM AUTHOR]

Large-scale deforestation and abandoned planting will bring about the destruction of the ecological environment and the deterioration of the climate. In 1999, China initiated its "Grain for Green" Program (GGP) to improve the ecological environment, control soil erosion, and adjust the agricultural industrial structure to promote the sustainable development of the rural economy. In this paper, economic statistics, rainfall, and remote sensing data are used to analyze the impact of the GGP on agricultural and rural economic development and regional precipitation in the hilly and gully regions of the Loess Plateau. The results show that since the implementation of the program, the employment structure of the labor force has changed and the regional economic growth and farmers' income have increased. From 2000 to 2016, the total gross domestic product (GDP) and per capita GDP of the Yan River Basin increased. The conversion of large-scale sloping farmland to forestry and grassland resulted in the decrease of farmland area and the increase of forestry area. The maximum, minimum, and mean value of vegetation coverage increased year by year. With the increase of vegetation coverage, the surface roughness, soil water content, and evapotranspiration improved and annual average precipitation grew significantly after the implementation of the program (2000 to 2018). From 1970 to the implementation of the project (1999), the annual average rainfall decreased at the trough from 1988 to 1999, and there was an overall upward trend from 1970 to 2018. The GGP has an important impact on the economy and people's income in the Yan River Basin, and the vegetation change caused by the variation of land use types has a certain impact on regional rainfall. Under the background of global and regional climate change, it is of great significance to fully understand the impacts of vegetation conversion on climate and its mechanism for objective assessment of driving factors in regional and global climate, as well as for scientific planning of future land use. [ABSTRACT FROM AUTHOR]

Magnetic BiOBr/SrFe12O19 nanosheets were successfully synthesized using the hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and UV-visible diffused reflectance spectra (UV-DRS), and the magnetic properties were tested using a vibration sample magnetometer (VSM). The as-produced composite with an irregular flaky-shaped aggregate possesses a good anti-demagnetization ability (Hc = 861.04 G) and a high photocatalytic efficiency. Under visible light (λ > 420 nm) and UV light-emitting diode (LED) irradiation, the photodegradation rates of Rhodamine B (RhB) using BiOBr/SrFe12O19 (5 wt %) (BOB/SFO-5) after 30 min of reaction were 97% and 98%, respectively, which were higher than that using BiOBr (87%). The degradation rate of RhB using the recovered BiOBr/5 wt % SrFe12O19 (marked as BOB/SFO-5) was still more than 85% in the fifth cycle, indicating the high stability of the composite catalyst. Meanwhile, after five cycles, the magnetic properties were still as stable as before. The radical-capture experiments proved that superoxide radicals and holes were main active species in the photocatalytic degradation of RhB. [ABSTRACT FROM AUTHOR]

β-Bi2O3 decorated graphene nanosheets (β-Bi2O3/GN) were prepared by a facile solution mixing method. The crystal structure, surface morphology, and photo absorbance properties of the products were characterized by XRD, SEM, and UV-VIS diffuse reflection, respectively. Moreover, the effect of graphene content on photocatalytic activity was systematically investigated, and the results indicated that these composites possessed a high degradation rate of Rhodamine B (RhB), which was three times higher than that of bare β-Bi2O3 when graphene content was 1 wt %. This high photocatalytic activity was attributed predominantly to the presence of graphene, which served as an electron collector and transporter to efficiently lengthen the lifetime of the photogenerated charge carriers from β-Bi2O3. [ABSTRACT FROM AUTHOR]

Magnetic photocatalyst BiVO4/Mn-Zn ferrite (Mn1−xZnxFe2O4)/reduced graphene oxide (RGO) was synthesized by a simple calcination and reduction method. The magnetic photocatalyst held high visible light-absorption ability with low band gap energy and wide absorption wavelength range. Electrochemical impedance spectroscopies illustrated good electrical conductivity which indicated low charge-transfer resistance due to incorporation of Mn1−xZnxFe2O4 and RGO. The test of photocatalytic activity showed that the degradation ratio of rhodamine B (RhB) reached 96.0% under visible light irradiation after only 1.5 h reaction. The photocatalytic mechanism for the prepared photocatalyst was explained in detail. Here, the incorporation of RGO enhanced the specific surface area compared with BiVO4/Mn1−xZnxFe2O4.The larger specific surface area provided more active surface sites, more free space to improve the mobility of photo-induced electrons, and further facilitated the effective migration of charge carriers, leading to the remarkable improvement of photocatalytic performance. Meanwhile, RGO was the effective acceptor as well as transporter of photo-generated electron hole pairs. •O2− was the most active species in the photocatalytic reaction. BiVO4/Mn1−xZnxFe2O4/RGO had quite a wide application in organic contaminants removal or environmental pollution control. [ABSTRACT FROM AUTHOR]

Ag/BiVO4/Mn1−xZnxFe2O4 was synthesized with a dip-calcination in situ synthesis method. This work was hoped to provide a simple method to synthesis three-phase composite. The phase structure, optical properties and magnetic feature were confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometer (XPS), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectrophotometer (UV-vis DRS), and vibrating sample magnetometer (VSM). The photocatalytic activity was investigated by Rhodamine B (RhB) photo-degradation under visible light irradiation. The photo-degradation rate of RhB was 94.0~96.0% after only 60 min photocatalytic reaction under visible light irradiation, revealing that it had an excellent visible-light-induced photocatalytic activity. In the fifth recycle, the degradation rate of Ag/BiVO4/Mn1−xZnxFe2O4 still reached to 94.0%. Free radical tunnel experiments confirmed the dominant role of •O2− in the photocatalytic process for Ag/BiVO4/Mn1−xZnxFe2O4. Most importantly, the mechanism that multifunction Ag could enhance photocatalytic activity was explained in detail. [ABSTRACT FROM AUTHOR]

SrTiO3 and Ce4+ doped SrTiO3 were synthesized by a modified sol–gel process. The optimization synthesis parameters were obtained by a series of single factor experiments. Interesting phenomena are observable in Ce4+ doped SrTiO3 systems. Sr2+ in SrTiO3 system was replaced by Ce4+, which reduced the surface segregation of Ti4+, ameliorated agglomeration, increased specific surface area more than four times compared with pure SrTiO3, and enhanced quantum efficiency for SrTiO3. Results showed that Ce4+ doping increased the physical adsorption of H2O and adsorbed oxygen on the surface of SrTiO3, which produced additional catalytic active centers. Electrons on the 4f energy level for Ce4+ produced new energy states in the band gap of SrTiO3, which not only realized the use of visible light but also led to an easier separation between the photogenerated electrons and holes. Ce4+ repeatedly captured photoelectrons to produce Ce3+, which inhibited the recombination between photogenerated electrons and holes as well as prolonged their lifetime; it also enhanced quantum efficiency for SrTiO3. The methylene blue (MB) degradation efficiency reached 98.7% using 3 mol % Ce4+ doped SrTiO3 as a photocatalyst, indicating highly photocatalytic activity. [ABSTRACT FROM AUTHOR]

BiVO₄/Mn 1-x Zn x Fe₂O₄ was prepared by the impregnation roasting method. XRD (X-ray Diffractometer) tests showed that the prepared BiVO₄ is monoclinic crystal, and the introduction of Mn 1-x Zn x Fe₂O₄ does not change the crystal structure of BiVO₄. The introduction of a soft-magnetic material, Mn 1-x Zn x Fe₂O₄, was beneficial to the composite photocatalyst's separation from the liquid solution using an extra magnet after use. UV-vis spectra analysis indicated that Mn 1-x Zn x Fe₂O₄ enhanced the absorption intensity of visible light for BiVO₄. EIS (electrochemical impedance spectroscopy) investigation revealed that the introduction of Mn 1-x Zn x Fe₂O₄ enhanced the conductivity of BiVO₄, further decreasing its electron transfer impedance. The photocatalytic efficiency of BiVO₄/Mn 1-x Zn x Fe₂O₄ was higher than that of pure BiVO₄. In other words, Mn 1-x Zn x Fe₂O₄ could enhance the photocatalytic reaction rate., Competing Interests: The authors declare that they have no conflict of interest.