16 research outputs found

    Nationwide Distribution of Per- and Polyfluoroalkyl Substances in Outdoor Dust in Mainland China From Eastern to Western Areas

    No full text
    From eastern to western areas, per- and polyfluoroalkyl substances (PFASs) were detected at substantial levels in the outdoor dust across mainland China. Urban samples generally showed higher levels compared with those of rural samples. Compared with neutral PFASs, ionizable PFASs (C4–C12 perfluoroalkyl carboxylic acids and C4/C8 perfluoroalkyl sulfonic acids) were more abundant, with the highest total concentration up to 1.6 × 10<sup>2</sup> ng/g and perfluorooctanoic acid (PFOA) being a predominant analogue. Fluorotelomer alcohols (FTOHs) and polyfluoroalkyl phosphoric acid diesters (DiPAPs) were both detected in most samples with total concentrations of 0.12–32 and 0.030–20 ng/g, respectively. Perfluorooctane sulfonamidoethanols/sulfonamides (FOSE/As) were detected at low frequencies (<30%). In addition to partitioning to organic moiety, specific adsorption onto mineral particles can be important for PFASs to bind onto outdoor dust, especially for short-chain ionizable PFASs. The eastern plain areas were characterized by a higher contribution of long-chain ionizable PFASs; whereas the western high plateau areas were characterized by the dominating contribution of short-chain analogues. The difference suggests that the long-range atmospheric transport potential of PFASs from source regions to the inland is probably limited by the increase in altitude, and different sources from adjacent regions may influence the western border area of China

    Large-Scale Manual Grinding Preparation of Ultrathin Porous Sulfur (S<sub>8</sub>)‑Anchored ScOOH Nanosheets for Photothermal Conversion and Dye Adsorption

    No full text
    Porous two-dimensional (2D) nanomaterials have attracted much attention in recent years and shown unique electronic and physicochemical properties by utilizing the advantages of both porous structure and 2D architecture. However, the low-cost, large-scale, and high-quality synthesis of porous 2D nanomaterials is still very challenging. Herein, for the first time, we develop a facile manual grinding strategy for the preparation of ultrathin porous sulfur (S8)-anchored ScOOH nanosheets (S8/ScOOH-NSs) by the mechanical stripping of S8-anchored ScOOH nanorods (S8/ScOOH-NRs). The formation of S8/ScOOH-NSs should be due to the intrinsic lamellar structure of S8/ScOOH-NRs. The obtained S8/ScOOH-NSs with rich mesopores have a high-quality crystal structure. Because of hydrophobic sulfur and carbon components on the surface, S8/ScOOH-NSs show good hydrophobicity. In addition, S8/ScOOH-NSs exhibit more excellent photothermal conversion efficiency and adsorption capacity compared with S8/ScOOH-NRs, which is directly attributed to the synergistic effect of sulfur-doping, porous structure, and 2D architecture. Therefore, the facile and large-scale synthesis strategy endows S8/ScOOH-NSs with multifunctional properties that have great application prospects in water cleaning and photothermal evaporators

    Per- and Polyfluoroalkyl Substances (PFASs) in Indoor Air and Dust from Homes and Various Microenvironments in China: Implications for Human Exposure

    No full text
    A newly developed solid-phase extraction cartridge composed of mixed sorbents was optimized for collection of both neutral and ionizable per- and polyfluoroalkyl substances (PFASs) in indoor air. Eighty-one indoor air samples and 29 indoor dust samples were collected from rooms of homes and hotels, textile shops, and cinemas in Tianjin, China. Fluorotelomer alcohols (FTOHs) were the predominant PFASs found in air (250–82 300 pg/m<sup>3</sup>) and hotel dust (24.8–678 ng/g). Polyfluoroalkyl phosphoric acid diesters were found at lower levels of nd–125 pg/m<sup>3</sup> in air and 0.32–183 ng/g in dust. Perfluoroalkyl carboxylic acids (PFCAs) were dominant ionizable PFASs in air samples (121–20 600 pg/m<sup>3</sup>) with C4–C7 PFCAs contributing to 54% ± 17% of the profiles, suggesting an ongoing shift to short-chain PFASs. Long-chain PFCAs (C > 7) were strongly correlated and the intermediate metabolite of FTOHs, fluorotelomer unsaturated carboxylic acids, occurred in all the air samples at concentrations up to 413 pg/m<sup>3</sup>, suggesting the transformation of precursors such as FTOHs in indoor environment. Daily intake of ∑PFASs via air inhalation and dust ingestion was estimated at 1.04–14.1 ng/kg bw/d and 0.10–8.17 ng/kg bw/d, respectively, demonstrating that inhalation of air with fine suspended particles was a more important direct exposure pathway than dust ingestion for PFASs to adults

    Occurrence and Phase Distribution of Neutral and Ionizable Per- and Polyfluoroalkyl Substances (PFASs) in the Atmosphere and Plant Leaves around Landfills: A Case Study in Tianjin, China

    No full text
    A total of 23 per- and polyfluoroalkyl substances (PFASs) were investigated in the air, dry deposition, and plant leaves at two different landfills and one suburban reference site in Tianjin, China. The potential of landfills as sources of PFASs to the atmosphere and the phase distribution therein were evaluated. The maximum concentrations of ∑PFASs in the two landfills were up to 9.5 ng/m<sup>3</sup> in the air, 4.1 μg/g in dry deposition, and 48 μg/g lipid in leaves with trifluoroacetic acid and perfluoropropionic acid being dominant (71%–94%). Spatially, the distribution trend of ionizable and neutral PFASs in all three kinds of media consistently showed the central landfill > the downwind > the upwind > the reference sites, indicating that landfills are important sources to PFASs in the environment. Plant leaves were found effective in uptake of a variety of airborne PFASs including polyfluoroalkyl phosphoric acid diesters, thus capable of acting as a passive air sampling approach for air monitoring

    Template Synthesis of CuInS<sub>2</sub> Nanocrystals from In<sub>2</sub>S<sub>3</sub> Nanoplates and Their Application as Counter Electrodes in Dye-Sensitized Solar Cells

    No full text
    We report the room temperature template synthesis of CuInS<sub>2</sub> nanocrystals through incorporation of Cu<sup>+</sup> cations into In<sub>2</sub>S<sub>3</sub> nanoplates whose chemical composition has been controlled by varying the amount of copper ions in the reaction mixture. As a result, bandgaps of the resultant CuInS<sub>2</sub> nanoplates can be tuned from 1.45 to 1.19 eV with [Cu]/[In] molar ratios increasing from 0.7 to 2.9, which was demonstrated by the cyclic voltammetry. We explored the use of CuInS<sub>2</sub> nanocrystals as potential counter electrodes in dye-sensitized solar cells, and a power conversion efficiency of 6.83% was achieved without selenization and ligand exchange. The value is comparable with the performance of a control device using Pt as a counter electrode (power conversion efficiency: 7.08%) under the same device architecture

    Electronic Signatures of all Four DNA Nucleosides in a Tunneling Gap

    No full text
    Nucleosides diffusing through a 2 nm electron-tunneling junction generate current spikes of sub-millisecond duration with a broad distribution of peak currents. This distribution narrows 10-fold when one of the electrodes is functionalized with a reagent that traps nucleosides in a specific orientation with hydrogen bonds. Functionalizing the second electrode reduces contact resistance to the nucleosides, allowing them to be identified via their peak currents according to deoxyadenosine > deoxycytidine > deoxyguanosine > thymidine, in agreement with the order predicted by a density functional calculation

    Improving Pore Filling of Gel Electrolyte and Charge Transport in Photoanode for High-Efficiency Quasi-Solid-State Dye-Sensitized Solar Cells

    No full text
    We demonstrate the enhancement of pore-filling and wettability of gel electrolyte in quasi-solid-state dye-sensitized solar cells (DSSCs) by developing a kinetically driven electrolyte infiltration approach, in which the air purging provides the driving force. This method renders fast electrolyte diffusion throughout the three-dimensional TiO<sub>2</sub> nanoparticle network, promising for large-area device fabrication. In addition, for the first time we incorporate multiwalled carbon nanotubes into the anode of quasi-solid-state DSSCs to improve the charge transfer efficiency and fill factor. These advancements finally generate an efficiency exceeding 7.0%, much higher than the device efficiency of 5.5% fabricated by the conventional method

    Significant Improvement of Dye-Sensitized Solar Cell Performance Using Simple Phenothiazine-Based Dyes

    No full text
    A series of simple phenothiazine-based dyes have been synthesized, in which a cyanoacrylate acceptor directly attached to the C(3) position of phenothiazine, and an additional linear electron-rich (4-hexyloxy)­phenyl group at C(7) on the opposite side of the acceptor, and an alkyl chain with different length at N(10) of the phenothiazine periphery are presented. The dye molecules have a linear shape which is favorable for the formation of a compact dye layer on the TiO<sub>2</sub> surface, while their butterfly conformations can sufficiently inhibit molecular aggregation. Moreover, the structural features of (4-hexyloxy)­phenyl donor moiety at the C(7) position of phenothiazine extends the π-conjugation of the chromophore, thus enhancing the performance of dye-sensitized solar cells (DSSCs). Moreover, the alkyl substituents with different chain length at the N(10) atom of phenothiazine could further optimize the performance through completely shielding the surface of TiO<sub>2</sub> from the I<sup>–</sup>/I<sup>3‑</sup> electrolyte and subsequently reducing the leakage of dark current. Under simulated AM 1.5G irradiation, the PT-C6 based DSSC produces a short-circuit photocurrent of 15.32 mA cm<sup>–2</sup>, an open-circuit photovoltage of 0.78 V, a fill factor of 0.69, corresponding to a power conversion efficiency (PCE) of 8.18%, which exceeds the reference N719 (7.73%) under identical fabrication conditions. Notably, the designed molecular structure represents the highest photovoltaic conversion efficiency value when compared with other reported phenothiazine-derived dyes
    corecore