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Our study investigated a large variety of per- and polyfluoroalkyl substances (PFASs) in house dust collected from Guangzhou, South China during 2015–2018. The perfluorobutane sulfonic acid (PFBS) exhibited the highest median concentration (17.6 ng/g), followed by linear perfluorooctanoic acid (L-PFOA; 4.8 ng/g), linear perfluorooctane sulfonic acid (L-PFOS; 4.2 ng/g), 6:2 fluorotelomer phosphate diester (6:2 diPAP; 3.4 ng/g), perfluorodecanoic acid (PFDA; 1.2 ng/g) and perfluoroundecanoic acid (PFUdA; 1.2 ng/g), and 6:2 chlorinated perfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA; 1.1 ng/g). Total concentrations of PFASs (median: 53 ng/g) were generally within the 25–50 percentile of the concentration range reported in global studies. However, our samples exhibited composition profiles different from those reported in many other regions. Analysis based on this and previous studies revealed that the compositions in house dust from East Asia, North America, and Europe exhibit a region-specific pattern. This may indicate region-specific market demands, application patterns, as well as associated human exposure risks. Exploration of dwelling characterizations suggested that renovation history appeared to be a significant factor influencing PFAS concentrations in house dust, although other factors may exist and play a role. Estimation of daily intakes via dust ingestion and dermal contact indicates low exposure risks from these two pathways. However, the PFAS chemical-specific biological effects, possible mixture effects, as well as additional exposure pathways, imply that the risk from indoor PFAS exposure should not be overlooked. • Our study investigated various PFAS chemicals in house dust collected from South China. • Dust compositions of PFASs from East Asia, North America and Europe exhibit a region-specific pattern. • Renovation history may be a significant factor influencing PFAS concentrations in house dust. • Estimation of daily intakes via dust ingestion and dermal contact indicates low exposure risks. [ABSTRACT FROM AUTHOR]

A simple strategy is developed for synthesis of PdCu nanoplates as efficient ORR electrocatalysts with simultaneously highly methanol tolerance. [Display omitted] The methanol-poisoning of electrocatalysts at the cathodic part of direct methanol fuel cells (DMFCs) can severely degrade the overall efficiency. Therefore, engineering cathodic catalysts with outstanding oxygen reduction activity, and simultaneously, superior methanol tolerance is greatly desired. Herein, bimetallic palladium-copper (PdCu) nanoplates with the optimized d-band center are designed as promising cathodic catalysts for DMFCs. It shows outstanding oxygen reduction activity with a mass activity (MA) of 0.522 A mg Pd −1 in alkaline electrolyte, overwhelming the benchmarked commercial Pt/C and Pd/C. Meanwhile, it has prominent stability with only 4.0 % loss in MA after continuous 20 K cycles. More importantly, the PdCu nanoplates are almost inert toward methanol oxidation and show excellent anti-methanol capability. The theoretical calculations reveal that the downshift of d-band center in PdCu nanoplates and the electronic interaction between Pd and Cu atoms could effectively lower the methanol adsorption energy, thus leading to enhanced methanol tolerance. This work highlights the important role of tuning the electronic structure and optimized geometry of electrocatalysts to simultaneously boost their oxygen reduction activity, stability, and methanol tolerance for their future application in DMFCs. [ABSTRACT FROM AUTHOR]

A simple strategy is developed for synthesis of PdCu nanoplates as efficient ORR electrocatalysts with simultaneously highly methanol tolerance. [Display omitted] The methanol-poisoning of electrocatalysts at the cathodic part of direct methanol fuel cells (DMFCs) can severely degrade the overall efficiency. Therefore, engineering cathodic catalysts with outstanding oxygen reduction activity, and simultaneously, superior methanol tolerance is greatly desired. Herein, bimetallic palladium-copper (PdCu) nanoplates with the optimized d-band center are designed as promising cathodic catalysts for DMFCs. It shows outstanding oxygen reduction activity with a mass activity (MA) of 0.522 A mg Pd −1 in alkaline electrolyte, overwhelming the benchmarked commercial Pt/C and Pd/C. Meanwhile, it has prominent stability with only 4.0 % loss in MA after continuous 20 K cycles. More importantly, the PdCu nanoplates are almost inert toward methanol oxidation and show excellent anti-methanol capability. The theoretical calculations reveal that the downshift of d-band center in PdCu nanoplates and the electronic interaction between Pd and Cu atoms could effectively lower the methanol adsorption energy, thus leading to enhanced methanol tolerance. This work highlights the important role of tuning the electronic structure and optimized geometry of electrocatalysts to simultaneously boost their oxygen reduction activity, stability, and methanol tolerance for their future application in DMFCs. [ABSTRACT FROM AUTHOR]

A Cu 9 S 5 @MoS 2 core–shell heterostructure with controlled layers were synthesized through the combination of electrospinning technology and a chemical vapor deposition method via an in situ S vapor-assisted strategy. [Display omitted] Binary transition metal chalcogenide core–shell nanocrystals are considered the most promising nonprecious metal catalysts for large-scale industrial hydrogen production. Herein, we report a one-dimensional, space-confined, solid-phase strategy for the growth of a Cu 9 S 5 @MoS 2 core–shell heterostructure by combining electrospinning and chemical vapor deposition methods. The Cu 9 S 5 @MoS 2 core–shell nanocrystals were synthesized in situ on carbon nanofibers (Cu 9 S 5 @MoS 2 /CNFs) by an S vapor graphitization process. Tuning of the MoS 2 shell numbers can be controlled by changing the mass ratio of the Cu and Mo precursors. We experimentally determined the effects of the thickness of the MoS 2 shell on the electrocatalytic activity for the hydrogen evolution reaction (HER) in acidic and alkaline solutions. When the mass ratio is 3:1, the Cu 9 S 5 @MoS 2 /CNFs show the fewest MoS 2 shells with just 1–2 layers each and exhibit the best HER performance with small overpotentials of 116 mV and 114 mV in acidic and alkaline solutions, respectively, at a current density of 10 mA cm−2. The core shell structures, with their unique Cu-S-Mo nanointerfaces, could enhance the electron transfer and surface area, thus increasing the performance of the HER. This work provides a facile method to design unique core shell assemblies in one-dimensional nanostructures. [ABSTRACT FROM AUTHOR]