Environmental impact and health risk assessment of volatile organic compound emissions during different seasons in Beijing.

Volatile organic compounds (VOCs) are major contributors to air pollution. Based on the emission characteristics of 99 VOCs that daily measured at 10 am in winter from 15 December 2015 to 17 January 2016 and in summer from 21 July to 25 August 2016 in Beijing, the environmental impact and health risk of VOC were assessed. In the winter polluted days, the secondary organic aerosol formation potential (SOAP) of VOC (199.70 ± 15.05 µg/m3) was significantly higher than that on other days. And aromatics were the primary contributor (98.03%) to the SOAP during the observation period. Additionally, the result of the ozone formation potential (OFP) showed that ethylene contributed the most to OFP in winter (26.00% and 27.64% on the normal and polluted days). In summer, however, acetaldehyde was the primary contributor to OFP (22.00% and 21.61% on the normal and polluted days). Simultaneously, study showed that hazard ratios and lifetime cancer risk values of acrolein, chloroform, benzene, 1,2-dichloroethane, acetaldehyde and 1,3-butadiene exceeded the thresholds established by USEPA, thereby presenting a health risk to the residents. Besides, the ratio of toluene-to-benzene indicated that vehicle exhausts were the main source of VOC pollution in Beijing. The ratio of m-/p-xylene-to-ethylbenzene demonstrated that there were more prominent atmospheric photochemical reactions in summer than that in winter. Finally, according to the potential source contribution function (PSCF) results, compared with local pollution sources, the spread of pollution from long-distance VOCs had a greater impact on Beijing.

Interfacial Engineered Polyaniline/Sulfur-Doped TiO2 Nanotube Arrays for Ultralong Cycle Lifetime Fiber-Shaped, Solid-State Supercapacitors.

Fiber-shaped supercapacitors (FSCs) have great promises in wearable electronics applications. However, the limited specific surface area and inadequate structural stability caused by the weak interfacial interactions of the electrodes result in relatively low specific capacitance and unsatisfactory cycle lifetime. Herein, solid-state FSCs with high energy density and ultralong cycle lifetime based on polyaniline (PANI)/sulfur-doped TiO2 nanotube arrays (PANI/S-TiO2) are fabricated by interfacial engineering. The experimental results and ab initio calculations reveal that S doping can effectively promote the conductivity of titania nanotubes and increase the binding energy of PANI anchored on the electrode surface, leading to a much stronger binding of PANI on the surface of the electrode and excellent electrode structure stability. As a result, the FSCs using the PANI/S-TiO2 electrodes deliver a high specific capacitance of 91.9 mF cm-2, a capacitance retention of 93.78% after 12 000 charge-discharge cycles, and an areal energy density of 3.2 µW h cm-2. Meanwhile, the all-solid-state FSC device retains its excellent flexibility and stable electrochemical capacitance even after bending 150 cycles. The enhanced performances of FSCs could be attributed to the large surface area, reduced ion diffusion path, improved electrical conductivity, and engineered interfacial interaction of the rationally designed electrodes.

Preparation and characterization of LiFe0.975Rh0.025PO4 nanorods using the hydrothermal method.

An effective method for the synthesis of LiFe(0.975)Rh(0.025)PO(4) nanorods to serve as a cathode material for lithium-ion batteries is described. During their preparation, L-lysine was used as the growth director of nanorods. The contribution from chloride ions to the formation of the unique nanorods was also investigated. The samples were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Mössbauer measurements, scanning electron microscopy, electronic conductivity measurements, and transmission electron microscopy. The pH of the solution played a key role in controlling the particle size of the samples. The sample prepared at a pH of 9.5 exhibited excellent electrochemical performance. It delivered an initial discharge capacity of 143.1 mA h g(-1), and a capacity fade of only 7.7% was observed after 200 cycles at 2.5 C over a voltage range of 2.0-4.2 V. Furthermore, its discharge capacity remained stable for values as high as 20 C. The excellent electrochemical performance of LiFe(0.975)Rh(0.025)PO(4) nanorods can be attributed their unique nanorod structure, which limits the distance of lithium ion diffusion in the electrode material to the radius of the nanorods and decreases the surface-film resistance for the charge-transfer process.