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A string of AgCl/Bi3TaO7 two-component composite was synthesized by hydrothermal and deposition-precipitation process initially. The photocatalytic activities of mixed-phase AgCl/Bi3TaO7 were evaluated toward the decomposition of tetracycline (TC). Among these as-prepared materials, AgCl/Bi3TaO7 nanocomposites when the molar ratio of baked materials between AgCl and Bi3TaO7 was 1:5 presented the optimal photocatalytic quantum efficiency for TC dissociation (86.82%) with visible-light exposure, which was 1.69 and 2.38 folders higher than that of single Bi3TaO7 and AgCl, respectively. What is more, it illustrated that the photo-generated carriers were markedly isolated on account of the formation of heterojunction confirmed by EIS analysis. Meanwhile, radical trapping experiments implied that the photo-induced holes (h+), hydroxyl radical (·OH), and superoxide radical (·O2−) were the major active species. The escalated photocatalytic activity could be ascribed to the unique construction of Z-scheme AgCl/Bi3TaO7 heterojunction, which could expedite charge separation and transmission, cement light absorption capability and retain the strong redox ability of photo-generated electrons and holes. Our finding suggests that AgCl/Bi3TaO7 nanocomposites possess great potential for photocatalytic oxidation of residual TC in the wastewater effluents and the reported strategy can contribute to the development of novel high-performance photocatalyst. [ABSTRACT FROM AUTHOR]

The ability to rationally design a copper oxide anode with superior rate performance that possesses an ultra-small particle size is highly desirable for lithium-ion batteries (LIBs). Herein, the rapid and effective thermal expansion exfoliation technology was employed to synthesize ultra-small CuOx nanoparticles (∼2.7 nm) uniformly dispersed on graphite oxide after popping (CuOx/Li-PGO), in which the addition of lithium promoted the exfoliation process to obtain an enlarged specific surface area and efficient transfer ability of PGO. The CuOx/Li-PGO electrode achieved a reversible capacity as high as 512.1 mA h g−1 under 2.0 A g−1 after 1000 cycles, demonstrating superior rate performance and cycling stability. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides have been the most attractive two-dimensional layered materials for electrocatalytic hydrogen evolution due to their unique structure and multi-phase electronic states. However, the enhancement of the WSe2 electrocatalytic hydrogen evolution reaction (HER) performance by bimetal co-doping has been rarely reported. Herein, the NiMo–WSe2 catalyst has been synthesized by a one-step hydrothermal reaction, with lower overpotentials of 177 and 188 mV at a current density of 10 mA cm−2 in 0.5 M H2SO4 and 1 M KOH, respectively. The large specific surface area and thinner edge morphology provide more active sites for hydrogen production, thereby significantly improving the charge transfer kinetics. Density functional theory calculation results show that under acidic conditions the ΔGH* values of NiMo–WSe2 with different structures and hydrogen adsorption sites are also different, when the hydrogen adsorption site was located at the top of the Se–Ni bond, the meta NiMo–WSe2 has a ΔGH* value (−0.04 eV) that is closest to 0. Meanwhile, NiMo–WSe2 (meta) also has a minimum of ΔGH* under alkaline conditions. DOS confirmed that Ni doping has a large impact on the electronic states at the WSe2 Fermi level, while NiMo co-doping greatly reduces the potential energy barrier of the HER reaction, jointly increasing the current density, and thus improving the HER performance. [ABSTRACT FROM AUTHOR]

To evaluate air pollution and the public health burden of heavy metals in PM2.5 in a campus with a population of approximately 40,000 in a typical suburb area of Taiyuan, North China, PM2.5 measurements were conducted during the spring and winter of 2016. The average concentrations of PM2.5 in spring and winter were 97.3 ± 35.2 μg m-3 and 205.9 ± 91.3 μg m-3, respectively. The order of concentration of heavy metals in PM2.5 was as follows: Zn > Pb > Mn > Cu > Cr > Ni > Cd > As, in both spring and winter. The concentrations of Cd and Pb in winter and the concentrations of Cr in both spring and winter in this study were significantly higher than the corresponding air quality standard values. Road/soil dust, industrial emissions/coal combustion, and vehicle emissions/oil combustion and coal combustion/industrial emissions, road/soil dust, and vehicle emissions/oil combustion were identified by principal component analysis to be the major sources of heavy metals for spring and winter, respectively. The carcinogenic risks posed by Cr via the three exposure pathways (except for inhalation exposure to children) and by Pb via ingestion exposure exceeded the acceptable level for both children and adults. The non-carcinogenic risks posed by Mn via inhalation for both children and adults, and by Cr and Pb for children via ingestion exceeded the acceptable level. [ABSTRACT FROM AUTHOR]

PM2.5 samples were collected in the rural and urban areas of Taiyuan, China during a typical haze episode and the heavy metals (Cr, Mn, Ni, Cu, Zn, As, Cd and Pb) in PM2.5 were analyzed. The haze was characterized by start-up stage with a daily mean PM2.5 of 149.34 ± 52.33 and 146.73 ± 18.96 μg m-3 in the rural and urban sites, respectively, a peak stage (288.20 ± 12.43 and 323.44 ± 5.23 μg m-3), and a weakening stage (226.59 ± 12.43 and 195.60 ± 2.93 μg m-3). The concentrations of PM2.5 in the rural and urban sites in the peak stage were 5.9 and 5.5 times higher than those in the normal stage, respectively. The order of concentrations of heavy metals in PM2.5 at the rural and urban sites were the same and are listed as follows: Zn > Pb > Mn > Cr > Cu > Ni > Cd > As. Pb at the rural site, As at the urban site, and Cd at the both sites failed to meet the air quality standard. The concentrations of Pb and Zn were higher at the rural site than those at the urban site. Principal component analysis indicated that the main sources of heavy metals for the rural area were raw coal combustion and soil/road dust, and for the urban area were coal combustion/industrial emissions, road/soil dust, and vehicle emissions/oil combustion. [ABSTRACT FROM AUTHOR]

The ability to rationally design a copper oxide anode with superior rate performance that possesses an ultra-small particle size is highly desirable for lithium-ion batteries (LIBs). Herein, the rapid and effective thermal expansion exfoliation technology was employed to synthesize ultra-small CuO x nanoparticles (∼2.7 nm) uniformly dispersed on graphite oxide after popping (CuO x /Li-PGO), in which the addition of lithium promoted the exfoliation process to obtain an enlarged specific surface area and efficient transfer ability of PGO. The CuO x /Li-PGO electrode achieved a reversible capacity as high as 512.1 mA h g -1 under 2.0 A g -1 after 1000 cycles, demonstrating superior rate performance and cycling stability.

Transition metal dichalcogenides have been the most attractive two-dimensional layered materials for electrocatalytic hydrogen evolution due to their unique structure and multi-phase electronic states. However, the enhancement of the WSe 2 electrocatalytic hydrogen evolution reaction (HER) performance by bimetal co-doping has been rarely reported. Herein, the NiMo-WSe 2 catalyst has been synthesized by a one-step hydrothermal reaction, with lower overpotentials of 177 and 188 mV at a current density of 10 mA cm -2 in 0.5 M H 2 SO 4 and 1 M KOH, respectively. The large specific surface area and thinner edge morphology provide more active sites for hydrogen production, thereby significantly improving the charge transfer kinetics. Density functional theory calculation results show that under acidic conditions the Δ G H* values of NiMo-WSe 2 with different structures and hydrogen adsorption sites are also different, when the hydrogen adsorption site was located at the top of the Se-Ni bond, the meta NiMo-WSe 2 has a Δ G H* value (-0.04 eV) that is closest to 0. Meanwhile, NiMo-WSe 2 ( meta ) also has a minimum of Δ G H* under alkaline conditions. DOS confirmed that Ni doping has a large impact on the electronic states at the WSe 2 Fermi level, while NiMo co-doping greatly reduces the potential energy barrier of the HER reaction, jointly increasing the current density, and thus improving the HER performance.