A Dual‐Gate MoS2 Photodetector Based on Interface Coupling Effect

2D transition metal dichalcogenides (TMDs) based photodetectors have shown great potential for the next generation optoelectronics. However, most of the reported MoS₂ photodetectors function under the photogating effect originated from the charge‐trap mechanism, which is difficult for quantitative control. Such devices generally suffer from a poor compromise between response speed and responsivity (R) and large dark current. Here, a dual‐gated (DG) MoS₂ phototransistor operating based on the interface coupling effect (ICE) is demonstrated. By simultaneously applying a negative top‐gate voltage (V_TG) and positive back‐gate voltage (V_BG) to the MoS₂ channel, the photogenerated holes can be effectively trapped in the depleted region under TG. An ultrahigh R of ≈10⁵ A W^?1 and detectivity (D*) of ≈10¹⁴ Jones are achieved in several devices with different thickness under P_in of 53 µW cm^?2 at V_TG = ?5 V. Moreover, the response time of the DG phototransistor can also be modulated based on the ICE. Based on these systematic measurements of MoS₂ DG phototransistors, the results show that the ICE plays an important role in the modulation of photoelectric performances. The results also pave the way for the future optoelectrical application of 2D TMDs materials and prompt for further investigation in the DG structured phototransistors.     

协同催化水解羰基硫和二硫化碳的低温催化剂的研究进展

钢厂副产煤气是钢铁企业产生的二次能源,但是由于其中含有化学稳定性高的COS和CS2,二次利用困难,部分钢铁企业会将其直接高空排放,这样不仅造成了能源浪费,还造成了环境污染.因此,研究者们开发了多种技术用于脱除COS和CS2,其中水解法脱除废气中的COS和CS2是应用较为广泛的脱硫技术.然而,目前水解催化剂的使用温度相对较高,而钢厂副产煤气具有温度低、热值低、二氧化碳及氧含量高等特点.因此,近十年来研究者们研发了多种低温水解催化剂,用于COS和CS2的单独催化水解,甚至两种气体的协同催化水解.这些催化剂的成功研发不仅使得水解催化剂的使用温度大幅度降低,而且保持了其较高的水解效率.COS和CS2单独低温水解催化剂主要包括金属氧化物基催化剂、活性炭基催化剂以及类水滑石基催化剂.其中,金属氧化物基水解催化剂主要以γ-Al2 O3和TiO2为载体,并且以TiO2作为载体能更好地抑制水解催化剂中毒;活性炭基水解催化剂可通过调控其活性成分与含量以及提高活性炭载体自身品质来增强其低温水解性能;而类水滑石基水解催化剂则是通过调整其层板金属的组成、制备方法及条件使得其具有优异的低温水解性能.此外,由于活性炭具有特殊的物理化学特性,COS和CS2的协同水解催化剂主要是以活性炭基低温水解催化剂为主.本文归纳了COS和CS2低温水解催化剂的研究进展,分别对COS和CS2的单独水解催化剂和协同水解催化剂及其催化水解机理进行了介绍,分析了低温水解催化剂研发所面临的问题并提出未来可尝试的研究方向,以期开发更多COS和CS2协同水解的低温催化剂,更重要的是,为今后钢铁行业副产煤气中COS和CS2协同水解低温催化剂的研究方向及工业化应用提供参考.     

Extreme Reconfigurable Nanoelectronics at the CaZrO3/SrTiO3 Interface

Complex oxide heterostructures have fascinating emergent properties that originate from the properties of the bulk constituents as well as from dimensional confinement. The conductive behavior of the polar/nonpolar LaAlO₃/SrTiO₃ interface can be reversibly switched using conductive atomic force microscopy (c‐AFM) lithography, enabling a wide range of devices and physics to be explored. Here, extreme nanoscale control over the CaZrO₃/SrTiO₃ (CZO/STO) interface, which is formed from two materials that are both nonpolar, is reported. Nanowires with measured widths as narrow as 1.2 nm are realized at the CZO/STO interface at room temperature by c‐AFM lithography. These ultrathin nanostructures have spatial dimensions at room temperature that are comparable to single‐walled carbon nanotubes, and hold great promise for alternative oxide‐based nanoelectronics, as well as offer new opportunities to investigate the electronic structure of the complex oxide interfaces. The cryogenic properties of devices constructed from quasi‐1D channels, tunnel barriers, and planar gates exhibit gate‐tunable superconductivity, quantum oscillations, electron pairing outside of the superconducting regime, and quasi‐ballistic transport. This newly demonstrated ability to control the metal–insulator transition at nonpolar oxide interface greatly expands the class of materials whose behavior can be patterned and reconfigured at extreme nanoscale dimensions.     

Fe-Regulated Amorphous-Crystal Ni(Fe)P2 Nanosheets Coupled with Ru Powerfully Drive Seawater Splitting at Large Current Density

Water electrolysis is an ideal method for industrial green hydrogen production. However, due to increasing scarcity of freshwater, it is inevitable to develop advanced catalysts for electrolyzing seawater especially at large current density. This work reports a unique Ru nanocrystal coupled amorphous-crystal Ni(Fe)P₂ nanosheet bifunctional catalyst (Ru-Ni(Fe)P₂/NF), caused by partial substitution of Fe to Ni atoms in Ni(Fe)P₂, and explores its electrocatalytic mechanism by density functional theory (DFT) calculations. Owing to high electrical conductivity of crystalline phases, unsaturated coordination of amorphous phases, and couple of Ru species, Ru-Ni(Fe)P₂/NF only requires overpotentials of 375/295 and 520/361 mV to drive a large current density of 1 A cm⁻² for oxygen/hydrogen evolution reaction (OER/HER) in alkaline water/seawater, respectively, significantly outperforming commercial Pt/C/NF and RuO₂/NF catalysts. In addition, it maintains stable performance at large current density of 1 A cm⁻² and 600 mA cm⁻² for 50 h in alkaline water and seawater, respectively. This work provides a new way for design of catalysts toward industrial-level seawater splitting.     

Visualizing Thermally Activated Memristive Switching in Percolating Networks of Solution-Processed 2D Semiconductors

Memristive systems present a low-power alternative to silicon-based electronics for neuromorphic and in-memory computation. 2D materials have been increasingly explored for memristive applications due to their novel biomimetic functions, ultrathin geometry for ultimate scaling limits, and potential for fabricating large-area, flexible, and printed neuromorphic devices. While the switching mechanism in memristors based on single 2D nanosheets is similar to conventional oxide memristors, the switching mechanism in nanosheet composite films is complicated by the interplay of multiple physical processes and the inaccessibility of the active area in a two-terminal vertical geometry. Here, the authors report thermally activated memristors fabricated from percolating networks of diverse solution-processed 2D semiconductors including MoS₂, ReS₂, WS₂, and InSe. The mechanisms underlying threshold switching and negative differential resistance are elucidated by designing large-area lateral memristors that allow the direct observation of filament and dendrite formation using in situ spatially resolved optical, chemical, and thermal analyses. The high switching ratios (up to 10³) that are achieved at low fields (≈4 kV cm⁻¹) are explained by thermally assisted electrical discharge that preferentially occurs at the sharp edges of 2D nanosheets. Overall, this work establishes percolating networks of solution-processed 2D semiconductors as a platform for neuromorphic architectures.     

高速加工机床的设计与应用

本文通过对高速加工机床设计与应用的一些基本知识的介绍,提出了对设计技术方案和加工工艺方法进行综合分析与评估是设计和应用高速加工机床的关键。     

Ultralight and resilient Al2O3 nanotube aerogels with low thermal conductivity

This report describes a novel method to produce fluffy and resilient nanotube aerogels by combining solution blow spinning and Atom Layer Deposition (ALD). Polyvinylpyrrolidone (PVP) sponges obtained by blow spinning are used as templates and are deposited in ALD. After removal of template, semitransparent aerogels whose density can be as low as 0.68 mg/cm³ were obtained. The product is heat‐stable, with the ability to retain original shape and keep elastic after being kept at 900°C for 2 hours. It is also heat‐insulated, with a thermal conductivity of 0.022 W/K?m at room temperature. Additionally, when compressed to 60% of the original height for 100 cycles during in‐situ mechanical test, the sponges recovered to around 80% of the original shape, further indicating excellent mechanically elasticity of the aerogel.     

变焦电子腹腔镜物镜光学系统的设计

医用内窥镜在现代医学中的应用越来越广泛,为了使医生在临床检查的时候能够更好的观察病灶图像,设计一种可以实现变焦的电子腹腔镜物镜的光学系统,可以对病灶图像进行原位放大观察。以高斯变焦公式为基础,利用ZEMAX软件模拟设计了一个变焦物镜的光学系统,当视场范围在24°~64°,焦距在5mm~15mm三倍变焦,成像大小保持在6mm左右。传递函数设定在40线对时,其传递函数(MTF)要满足≥0.6,点列图弥散斑直径≤0.05mm。设计具有大视场,镜片数少,结构简单等特点,可以对病灶图像进行放大,具有较高的实际应用价值。     

Multi‐Atomic Layers of Metallic Aluminum for Ultralong Life Lithium Storage with High Volumetric Capacity

Metallic aluminum (Al) have been explored as potential anode materials for lithium storage because of its high theoretical capacity (993 mAh g^–1) and low voltage plateaus. Al possesses high electric conductivity, low cost and environmental friendliness. Unfortunately, Al suffers from huge volume change (>100%) during the lithiation/delithiation process, which inevitably results in the pulverization of electrode and rapid capacity decay during cycling processes. To circumvent above issues, a simple but efficient strategy is demonstrated to fabricate free‐standing multi‐atomic layers of metallic Al by harnessing the good ductility of Al under pressure. The resultant multi‐atomic Al layers are ultrathin, ≈3 nm, and have a large aspect ratio. Such unique features enable multi‐atomic Al nanosheets to construct uniform and compact films with graphene. Thus, the hybrid films with different ratios are achieved, in which the notorious volume change of metallic Al can be efficiently circumvented via the good flexibility of graphene, and the density of whole electrode can be significantly enhanced. As a consequence, the optimized multi‐atomic Al layers‐graphene (AlL‐G) film exhibits a very high volumetric capacity of 1089 mAh cm^–3, high‐rate capability and ultralong cycle life up to 20 000 cycles for lithium storage.     

Highly optical transparency and thermally stable polyimides containing pyridine and phenyl pendant

In order to obtain highly optical transparency polyimides, two novel aromatic diamine monomers containing pyridine and kinky structures, 1,1-bis[4-(5-amino-2-pyridinoxy)phenyl]diphenylmethane (BAPDBP) and 1,1-bis[4-(5-amino-2-pyridinoxy)phenyl]-1-phenylethane (BAPDAP), were designed and synthesized. Polyimides based on BAPDBP, BAPDAP, 2,2-bis[4-(5-amino-2-pyridinoxy)phenyl]propane (BAPDP) with various commercial dianhydrides were prepared for comparison and structure-property relationships study. The structures of the polyimides were characterized by Fourier transform infrared (FT-IR) spectrometer, wide-angle X-ray diffractograms (XRD) and elemental analysis. Film properties including solubility, optical transparency, water uptake, thermal and mechanical properties were also evaluated. The introduction of pyridine and kinky structure into the backbones that polyimides presented good optical properties with 91–97% transparent at 500 nm and a low cut-off wavelength at 353–398 nm. Moreover, phenyl pendant groups of the polyimides showed high glass transition temperatures (T_g) in the range of 257–281 °C. These results suggest that the incorporating pyridine, kinky and bulky substituents to polymer backbone can improve the optical transparency effectively without sacrificing the thermal properties.