Discrimination and simultaneous quantification of poly(ethylene terephthalate) and poly(butylene terephthalate) microplastics in environmental samples via gas chromatography-tandem mass spectrometry.

A method has been developed to quantify PET and PBT microplastics (MPs) based on depolymerization and detection of depolymerization products by gas chromatography-tandem mass spectrometry (GC-MS/MS) without a complex separation process from environmental samples. Under the optimal depolymerization conditions, PET and PBT were efficiently converted to ethylene glycol (78%) and 1,4-butanediol (87%), respectively. Subsequently, the linear curves were constructed between signal intensities of depolymerization products and polymer masses by GC-MS/MS, and the correlation coefficients of PET and PBT were 0.996 and 0.997, respectively. The spiking and recovery experiments of PET and PBT in the environmental samples showed that the recovery was stable in the range 89-100%, and the limit of detection was 4.95 µg and 1.39 µg of PET and PBT, respectively. The method has been proven to be capable of simultaneous identification and quantification of PBT and PET MPs in real environmental water samples without complex separation process, which provided a scheme for the determination of microplastics.

Kármán Vortex Street Driven Membrane Triboelectric Nanogenerator for Enhanced Ultra-Low Speed Wind Energy Harvesting and Active Gas Flow Sensing.

Wind energy harvesting and sensing have a huge prospect in constructing self-powered sensor nodes, but the energy transducing efficiency at low and ultra-low wind speeds is still limited. Herein, we proposed a Kármán vortex street driven membrane triboelectric nanogenerator (KVSM-TENG) for ultra-low speed wind energy harvesting and flow sensing. By introducing Kármán vortex in the KVSM-TENG, the cut-in wind speed of the KVSM-TENG decreased from 1 to 0.52 m/s that is the lowest cut-in wind speed in current TENGs. The instantaneous output density of the KVSM-TENG significantly increased by 1000 times and 2.65 times at the inlet wind speeds of 1 and 2 m/s, respectively. In addition, with the excellent energy transducing performance at the ultra-low speed range, the KVSM-TENG was successfully demonstrated to detect a weak leakage of gas pipeline (∼0.6 m/s) for alarming with high sensitivity. The interaction mechanism between the vortex and KVSM-TENG was systematically investigated. Through the simulation and experimental validation, the enhancement mechanism of vortex dependence on the cylinder diameter and placement location of KVSM-TENG was investigated in detail. The influence of parameters such as membrane length, width, thickness, and electrode gap on the performance of the KVSM-TENG was systematically studied. This work not only provided an ingenious strategy for ultra-low speed wind energy harvesting but also demonstrates the promising prospects for monitoring the air flow in the natural gas exploitation and transportation.

A versatile logic detector and fluorescent film based on Eu-based MOF for swift detection of formaldehyde in solutions and gas phase.

Due to the huge threat of formaldehyde (FA) on human beings, the development of chemical sensors for swift detection of FA in solutions and gas phase is highly anticipated. In this paper, a versatile logic detector and a portable fluorescent film based on small-scaled Eu-based MOF were applied successfully to detect FA in solutions and gas phase, respectively. For FA in aqueous solution, the design of logic detector will efficiently identify FA in different concentration ranges: when the FA concentration are 0-500 ppb, 500-1000 ppb and >1000 ppb, the output signals of logic detector are the concentration level of FA ("L", "H" and "VH"), and accompanied by red, purple and blue signal lamps to remind, respectively. For FA in the air, the color of rigid film sensor will gradually change from red to blue with the increase of FA under UV lamp, and the detection limit of gaseous FA is 11.8 ppb. Through the preparation of logic devices and fluorescent films, Eu-based MOF realized swift detection of FA in solutions and gas phase, which will be very helpful to improve the human response level to FA from different emission sources.

Template-Free Synthesis of Nanoporous Nickel and Alloys as Binder-Free Current Collectors of Li Ion Batteries.

This paper reports a versatile template-free method based on the hydrogen reduction of metallic salts for the synthesis of nanoporous Ni and alloys. The approach involves thermal decomposition and reduction of metallic precursors followed with metal cluster nucleation and ligament growth. Topological disordered porous architectures of metals with a controllable distribution of pore size and ligament size ranging from tens of nanometers to micrometers are synthesized. The reduction processes are scrutinized through X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The formation mechanism of the nanoporous metal is qualitatively explained. The as-prepared nanoporous Ni was tested as binder-free current collectors for nickel oxalate anodes of lithium ion batteries. The nanoporous Ni electrodes deliver enhanced reversible capacities and cyclic performances compared with commercial Ni foam. It is confirmed that this synthesis method has versatility not only because it is suitable for different types of metallic salts precursors but also for various other metals and alloys.

Phosphorescence detection of manganese(VII) based on Mn-doped ZnS quantum dots.

The phosphorescent l-cysteine modified manganese-doped zinc sulfide quantum dots (l-cys-MnZnS QDs) was developed for a highly sensitive detection of permanganate anions (MnO4-). l-cys-MnZnS QDs, which were easily synthesized in aqueous media using safe and low-cost materials, can emit intense phosphorescence even though the solution was not deoxygenated. However, the phosphorescence of l-cys-Mn-ZnS QDs was strongly quenched by MnO4- ascribed to the oxidation of l-cys and the increase of surface defects on l-cys-MnZnS QDs. Under the optimal conditions, l-cys-MnZnS QDs offer high selectivity over other anions for MnO4- determination, and good linear Stern-Volmer equation was obtained for MnO4- in the range of 0.5-100µM with a detection limit down to 0.24µM. The developed method was finally applied to the detection of MnO4- in water samples, and the spike-recoveries fell in the range of 95-106%.

A silver nanoparticle based surface enhanced resonance Raman scattering (SERRS) probe for the ultrasensitive and selective detection of formaldehyde.

Here we report a silver nanoparticle based surface enhanced resonance Raman scattering (SERRS) probe for the ultrasensitive and selective detection of formaldehyde. The detection limit reaches as low as 10(-11) M.