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The xylene isomers p-xylene, o-xylene, and m-xylene are aromatic hydrocarbons comprising with two methyl groups located at different positions on a benzene ring. The mixture originates from catalytic reforming of crude oil, and each individual isomer acts as a valuable intermediate; however, similar physicochemical properties make their separation difficult. This Review focuses on materials employed for their separation, such as metal−organic frameworks, molecular sieves, organics, and graphene quantum dots. Recent advances in separation of xylene isomers are summarized, including adsorption, membrane, and chromatographic separation techniques, and adsorption capacity and selectivity combined with mechanisms of separation are discussed.

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Perovskite ceramics and single crystals are commonly hard and brittle due to their small maximum elastic strain. Here, large-scale BaTi Co O (BTCO) film with a SrRuO (SRO) buffered layer on a 10 µm thick mica substrate is flexible with a small bending radius of 1.4 mm and semitransparent for visible light at wavelengths of 500-800 nm. Mica/SRO/BTCO/Au cells show bipolar resistive switching and the high/low resistance ratio is up to 50. The resistive-switching properties show no obvious changes after the 2.2 mm radius memory being written/erased for 360 000 cycles nor after the memory being bent to 3 mm radius for 10 000 times. Most importantly, the memory works properly at 25-180 °C or after being annealed at 500 °C. The flexible and transparent oxide resistive memory has good prospects for application in smart wearable devices and flexible display screens.

In polycrystalline bismuth telluride-based thermoelectric materials, mechanical-deformation-induced donor-like effects can introduce a high concentration of electrons to change the thermoelectric properties through the evolution of intrinsic point defects. However, the evolution law of these point defects during sample preparation remains elusive. Herein, we systematically investigate the evolution of intrinsic point defects in n-type Bi 2 Te 3 -based materials from the perspective of thermodynamics and kinetics, in combination with positron annihilation measurement. It is found that not only the mechanical deformation but also the sintering temperature is vital to the donor-like effect. The mechanical deformation can promote the formation of cation vacancies and facilitate the donor-like effect, and the sintering process can provide excess energy for Bi antisite atoms to surmount the diffusion potential barrier. This work provides us a better understanding of the evolution law of intrinsic point defects in Bi 2 Te 3 -based alloys and guides us to control the carrier concentration by manipulating intrinsic point defects.

An electroactive covalent organic framework (COF Thi−TFPB ) was prepared by a dehydration condensation reaction between 1,3,5-tris(p-formylphenyl)benzene (TFPB) and thionine (Thi) and wound with carbon nanotubes (CNTs) to design COF Thi−TFPB −CNT composites for electrochemical sensing of ascorbic acid (AA) and pH. COF Thi−TFPB was a highly ordered two-dimensional (2D) crystalline nanosheet, and its thickness was 0.75 nm. The loading of CNTs onto COF Thi−TFPB nanosheets could significantly improve the dispersibility, stability, and catalytic activity of the CNTs. Here CNTs could well catalyze the oxidation of AA, while COF Thi−TFPB had a pair of redox peaks that were inert for AA. Accordingly, a ratiometric electrochemical AA sensor was constructed by using the peak of COF Thi−TFPB as the reference signal. The ratiometric AA sensor showed a detection limit of 17.68 μM and linear ranges of 53.04 μM to 4.00 mM and 4.00−8.00 mM, revealing a good performance, together with satisfactory selectivity, reproducibility, and stability. The redox peak potential of COF Thi−TFPB was linearly shifted with the pH, so a pH sensor was constructed. The linear range and sensitivity of the pH sensor were 1−12 and 54 mV pH −1 , respectively. The electroactive COF Thi−TFPB −CNT might also be applied to construct other electrochemical sensors.

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The short-circuit photocurrent (ISC) that can be reversed by polarization switch enhances with temperature increasing to 130 °C in the epitaxial BiFeO3 thin film on SrTiO3 substrate. The La2/3Sr1/3MnO3/BiFeO3/indium tin oxide (In2O3:SnO2 = 9:1) junction shows the current rectifying characteristic and the photovoltaic effect at 20–130 °C. Importantly, the ISC can be reversed by the polarization switch in this temperature range. More charge carriers are activated and the density of free electrons enhances with the increase in the temperature, which results in the decrease in the depletion layer width. As a result, the open-circuit voltage decreases 50% and the ISC increases from 180 nA to 404 nA with the increase in the temperature from 20 °C to 130 °C. This suggests that the corresponding sensors and devices can be used at a relatively high temperature.