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Dual-mode bioanalysis integrating photoelectrochemical (PEC) and other modes is emerging and allows signal cross-checking for more reliable results. Metal-organic frameworks (MOFs) have been shown to be attractive materials in various biological applications. This work presents the utilization of MOF encapsulation and stimuli-responsive decapsulation for dual-mode PEC and fluorescence (FL) bioanalysis. Photoactive dye methylene violet (MV) was encapsulated in zeolitic imidazolate framework-90 (ZIF-90) to form an MV@ZIF-90 hybrid material, and MV could be released by adenosine triphosphate (ATP)-induced ZIF-90 disintegration. The released MV not only had FL emission but also had a sensitization effect on the ZnIn

Defect states dominate the performance of low-dimensional nanoelectronics, which deteriorate the serviceability of devices in most cases. But in recent years, some intriguing functionalities are discovered by defect engineering. In this work, we demonstrate a bifunctional memory device of a MoS2/BiFeO3/SrTiO3 van der Waals heterostructure, which can be programmed and erased by solely one kind of external stimuli (light or electrical-gate pulse) via engineering of oxygen-vacancy-based solid-ionic gating. The device shows multibit electrical memory capability (>22 bits) with a large linearly tunable dynamic range of 7.1 × 106 (137 dB). Furthermore, the device can be programmed by green- and red-light illuminations and then erased by UV light pulses. Besides, the photoresponse under red-light illumination reaches a high photoresponsivity (6.7 × 104 A/W) and photodetectivity (2.12 × 1013 Jones). These results highlighted solid-ionic memory for building up multifunctional electronic and optoelectronic devices. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version This research was supported by National Research Foundation Singapore Grants NRF-CRP22-2019-0007 and NRF-CRP21- 2018-0007, Singapore Ministry of Education via AcRF Tier 3 Programme “Geometrical Quantum Materials” (Grant MOE2018-T3-1-002), AcRF Tier 2 (Grant MOE2016-T2-1- 131), and AcRF Tier 1 Grants RG4/17 and RG7/18. This research is also supported by A*STAR under its AME IRG Grant (Project A2083c0052). This work was also financially supported by the National Key R&D Program of China (Grant 2020YFA0309200), the National Natural Science Foundation of China (Grant 62074025), Applied Basic Research Program of Sichuan Province (Grant 2020ZYD014), and Sichuan Province Key Laboratory of Display Science and Technology.

Recently, new states of matter like superconducting or topological quantum states were found in transition metal dichalcogenides (TMDs) and manifested themselves in a series of exotic physical behaviors. Such phenomena have been demonstrated to exist in a series of transition metal tellurides including MoTe2, WTe2, and alloyed MoxW1-xTe2. However, the behaviors in the alloy system have been rarely addressed due to their difficulty in obtaining atomic layers with controlled composition, albeit the alloy offers a great platform to tune the quantum states. Here, we report a facile CVD method to synthesize the MoxW1-xTe2 with controllable thickness and chemical composition ratios. The atomic structure of a monolayer MoxW1-xTe2 alloy was experimentally confirmed by scanning transmission electron microscopy. Importantly, two different transport behaviors including superconducting and Weyl semimetal states were observed in Mo-rich Mo0.8W0.2Te2 and W-rich Mo0.2W0.8Te2 samples, respectively. Our results show that the electrical properties of MoxW1-xTe2 can be tuned by controlling the chemical composition, demonstrating our controllable CVD growth method is an efficient strategy to manipulate the physical properties of TMDCs. Meanwhile, it provides a perspective on further comprehension and sheds light on the design of devices with topological multicomponent TMDC materials.

A carbon microtube aerogel (CMA) with hydrophobicity, strong adsorption capacity, and superb recyclability was obtained by a feasible approach with economical raw material, such as kapok fiber. The CMA possesses a great adsorption capacity of 78-348 times its weight. Attributed to its outstanding thermal stability and excellent mechanical properties, the CMA can be used for many cycles of distillation, squeezing, and combustion without degradation, which suggests a potential practical application in oil-water separation. In addition, the adsorption capacity still retained 98% by distillation, 97% by squeezing, and 90% by combustion after 10 cycles. Therefore, the obtained CMA has a broad prospect as an economical, efficient, and environmentally friendly adsorbent. National Research Foundation (NRF) This work was financially supported by Singapore National Research Foundation under NRF RF Award No. MOE2016- T2-1-131, Tier 1 2017-T1-001-075.

The charge density wave (CDW) in two-dimensional (2D) materials is attracting substantial interest because of its magnificent many-body collective phenomena. Various CDW phases have been observed in several 2D materials before they reach the phase of superconductivity. However, to date, the atomically thin CDW materials were mainly fabricated by mechanically exfoliating from their bulk counterparts, which leads to low production yield and small sample sizes. Here, we report the controlled synthesis of atomically thin 1T-TaS2, a typical CDW material, by a chemical vapor deposition (CVD) method. The high quality of as-grown 1T-TaS2 has been confirmed by complementary characterization technologies. Moreover, the thickness-dependent CDW phase transitions have been revealed in these ultrathin flakes by temperature-dependent Raman spectra. This work opens up a new window for the large-scale synthesis of ultrathin CDW materials and sheds light on the fabrication of next-generation electronic devices.

In this work, we have demonstrated the synthesis of high-quality monolayered α-In2Se3 using physical vapor deposition method under atmospheric pressure. The quality of the In2Se3 atomic layers has been confirmed by complementary characterization technologies such as Raman/photoluminescence spectroscopies and atomic force microscope. The atomically resolved images have been obtained by the annular dark-field scanning transmission electron microscope. The field-effect transistors have been fabricated using the atomically layered In2Se3 and exhibit p-type semiconducting behaviors with the mobility up to 2.5 cm(2)/ Vs. The In2Se3 layers also show a good photoresponsivity of 340A/W, as well as 6 ms response time for the rise and 12 ms for the fall. These results make In2Se3 atomic layers a promising candidate for the optoelectronic and photosensitive device applications.

High-quality yttrium oxide (Y(2)O(3)) is investigated as an ideal high-kappa gate dielectric for carbon-based electronics through a simple and cheap process. Utilizing the excellent wetting behavior of yttrium on sp(2) carbon framework, ultrathin (about few nm) and uniform Y(2)O(3) layers have been directly grown on the surfaces of carbon nanotube (CNT) and graphene without using noncovalent functionalization layers or introducing large structural distortion and damage. A top-gate CNT field-effect transistor (FET) adopting 5 nm Y(2)O(3) layer as its top-gate dielectric shows excellent device characteristics, including an ideal subthreshold swing of 60 mV/decade (up to the theoretical limit of an ideal FET at room temperature). The high electrical quality Y(2)O(3) dielectric layer has also been integrated into a graphene FET as its top-gate dielectric with a capacitance of up to 1200 nF/cm(2), showing an improvement on the gate efficiency and on state transconductance of over 100 times when compared with that of its back-gate counterpart.

While it has been shown that scandium (Sc) can be used for making high-quality Ohmic contact to the conduction band of a carbon nanotube (CNT) and thus for fabricating high-performance n-type CNT field effect transistors (FETs), the cost for metal Sc is currently five times more expensive than that for gold and one thousand times more expensive than for yttrium (Y) which in many ways resembles Sc. In this Letter we show that near perfect contacts can be fabricated on single-walled CNTs (SWCNTs) using Y, and the Y-contacted CNT FETs outperform the Sc-contacted CNT FETs in many important aspects. Low-temperature measurements on Y-contacted devices reveal that linear output characteristics persist down to 4.3 K, suggesting that Y makes a perfect Ohmic contact with the conduction band of the CNT. Self-aligned top-gate devices have been fabricated, showing high performance approaching the theoretical limit of CNT-based devices. In particular a room temperature conductance of about 0.55G(0) (with G(0) = 4e(2)/h being the quantum conductance limit of the SWCNT), threshold swing of 73 mV/decade, electron mobility of 5100 cm(2)/V.s, and mean free length of up to 0.639 mum have been achieved. Gate length scaling behavior of the Y-contacted CNT FETs is also investigated, revealing a more favorable energy consumption and faster intrinsic speed scaling than that of the Si-based devices.

Photovoltaic effects are studied for asymmetrically contacted single-walled carbon nanotube (SWCNT) barrier-free bipolar diode (BFBD) under infrared laser illumination. The BFBD is based on a SWCNT with a diameter d ∼ 1.5 nm and length L ∼ 800 nm, and the device shows a good open-circuit voltage of VOC = 0.23V and large photocurrent ISC of more than 15 nA.