The distribution of dopants in semiconductors can intrinsically determine the electronic structure and consequently the absorbance, redox potential, and charge-carrier mobility of the semiconductor photocatalysts. In contrast to most reported nitrogen-doped titania photocatalysts with some localized states in the intrinsic band gap and small visible light absorption shoulders induced by inhomogeneous nitrogen doping near the particle surface, we report here the homogeneous substitution of O by N in the whole particles of layered titanates. The resultant materials Cs 0.68 Ti 1.83 O 4-x N x exhibited extraordinary band-to-band excitation in the visible-light ranging up to blue light. From photoelectron spectroscopy and first-principles calculations, the upward shift of valence band maximum by N 2p states is concluded as the cause of the band-to-band visible light excitation. The holes generated upon visible light excitation in the newly formed valence bands of Cs 0.68 Ti 1.83 O 4-x N x and H 0.68 Ti 1.83 O 4-x N x had strong oxidation ability in oxidizing OHinto active •OH radicals in photocatalysis. These findings are the clear evidence for the substantial role of homogeneous nitrogen doping in obtaining band-to-band visible-light photon excitation in layered titanates. The new physical insights into the electronic structure of homogeneous substitutional N in layered titanates gained here may have important implications for developing other efficient visible light photocatalysts by nonmetal doping.

Two-dimensional (2D) layered materials have attracted intensive interests in the past decade. Their unique electronic, magnetic, optical, and mechanical properties render broad applications in various fields. Stability of these ultrathin materials has to be delicately considered because their structures and properties are subject to ambient conditions. In this work, we review the chemical and structural stabilities of versatile 2D layered materials, and summarize the ways to modify the materials for the enhancement of their stabilities. Our review not only provides deep understandings of the stability of 2D materials, but may inspire new ideas to improve the reliability and durability of related devices.

On‐chip microsupercapacitors (MSC) with facile fabrication procedures, high integration design, and superior performance are desired as an energy storage device for microelectronics. Hence, a novel procedure is proposed to fabricate an asymmetric microsupercapacitor (AMSC), employing interwoven nanowire (NW) network electrodes of poly(3,4‐ethylenedioxythiophene) coated titanium oxynitride (P‐TiON) and vanadium nitride (VN) NW as a cathode and an anode, respectively. The interwoven NWs with a high mass loading offer a sufficient electrochemical reaction area and rapid electron/ion transport pathway, delivering superior energy and power densities. With the LiCl/polyvinyl alcohol electrolyte, the assembled P‐TiON//VN AMSC can achieve a wide voltage window from 0 to 1.8 V with an excellent areal capacitance of 72 mF cm−2, a high areal energy density of 32.4 μWh cm−2 (at 0.9 mW cm−2), an outstanding power density of 45 mW cm−2 (at 21.9 μWh cm−2), and a good cycling performance. Furthermore, the substrate‐free electrodes exhibit outstanding integrability, and the system on one printed circuit board including two AMSCs in series and a LED demonstrates excellent practicability.

As essential units in an artificial neural network (ANN), artificial synapses have to adapt to various environments. In particular, the development of synaptic transistors that can work above 125 °C is desirable. However, it is challenging due to the failure of materials or mechanisms at high temperatures. Here, we report a synaptic transistor working at hundreds of degrees Celsius. It employs monolayer MoS 2 as the channel and Na + -diffused SiO 2 as the ionic gate medium. A large on/off ratio of 10 6 can be achieved at 350 °C, 5 orders of magnitude higher than that of a normal MoS 2 transistor in the same range of gate voltage. The short-term plasticity has a synaptic transistor function as an excellent low-pass dynamic filter. Long-term potentiation/depression and spike-timing-dependent plasticity are demonstrated at 150 °C. An ANN can be simulated, with the recognition accuracy reaching 90%. Our work provides promising strategies for high-temperature neuromorphic applications.

In this paper, the piezoelectric properties of laminated films made of polytetrafluoroethylene (PTFE) and tetrafluoroethylene-hexafluoropropylene (FEP) copolymer by an improved process and charged by a corona method are investigated by measurements of the pressure dependence of the piezoelectric d33 coefficents, the isothermal decay of d33 at various temperatures, and thermally stimulated discharge current spectra. The results show that the structure of the laminated films is mechanically stable. The quasistatic piezoelectric d33 coefficents can reach 400pC∕N and they are relatively independent of the static pressure in the range up to 16kPa. The decay of the d33 coefficients is primarily due to charge detrapping. Compared to polypropylene ferroelectrets, the thermal stability of the piezoelectric activity in such laminated films at 90°C is improved by a factor of 2 with respect to the percentage of the d33 values remaining. The dominant drift path of the detrapped charges at temperatures of about 130°C is most likely along the surface of the PTFE fibers, while charge drift through the solid layer of FEP is possibly prevailing at temperatures of around 210°C.

Positively charged conjugated polymer nanoparticles (CPNs) are emerging biomaterials exhibiting high levels of cellular entry. High rate of cellular entry efficiency is believed that the amphiphilic CPNs interact efficiently with the negatively charged hydrophobic cellular membranes. For the first time, the cell surface morphological changes of human cervical cancer cells treated with CPNs using a scanning probe microscopy technique, scanning ion conductance microscopy (SICM) are imaged. After 1 h of CPN incubation, distinct changes are observed in cell surface morphology such as interconnected protrusions and pits with sub-micrometer sizes, which are not observed from cells treated with positively charged polyethyleneimine (PEI) under the same treatment conditions. The change on cell surface morphology is quantified by surface roughness ratio, which is increased as CPN concentration increases, while the ratio first increases and then decreases as the incubation time increases. These results suggest that cells respond actively toward CPN with both positive charges on the side chain and the hydrophobicity from rigid aromatic backbone, which leads to subsequent endocytosis. In conclusion, it is demonstrated that SICM is a suitable imaging technique to reveal the dynamic alternations on the cell surface morphology at the early stage of nanoparticles endocytosis with high resolution.

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Due to the poor vanadium recovery of mineral processing, the extraction of vanadium from stone coal is directly carried out by metallurgical processes. Salt process, acid process and alkali process three types of stone coal leaching including nine technologies are introduced. However, all of these nine leaching technologies have serious disadvantages and up to now the stone coal has not been efficiently utilised. Chemical precipitation, ion exchange and solvent extraction all can be used to extract vanadium from stone coal leach solutions. Due to the low extraction of vanadium, Chemical precipitation method is rarely used. Ion exchange is only used for the extracting of V(V) from the leach solution. For the extraction of low valence, P204 is one of effective extraction agent. The lately developed technology, LTSRWL, is characterised by high recovery of vanadium, comprehensive recovery of other valuable elements and environmental friendliness, which make it become the best option.