Abstract Two‐dimensional (2D) tellurene (Te) has shown its great potential in nanoelectronics for its high carrier mobility and air stability. However, the high‐resistance electrical contact and relatively thick Te channel hinder its ultimate scaling and device performance. Here, the transport property of Te field‐effect transistors using platinum (Pt) contact with high work function is studied, which facilitates the effective hole injection in the p‐type Te channel. The electrical contact to Te using the Y‐function method (YFM) and the transmission line method (TLM) is investigated. The Te transistors with Pt contact show a low contact resistance of 400 Ωµm, a short transfer length of 80 nm, and low specific contact resistivity of 3.2 × 10 −7 Ωcm 2 , resulting from the low Schottky barrier height (SBH) of Pt/Te interface. The Pt electrode also can work as an efficient catalyst that allows reduction of the Te channel thickness with a controllable thinning process in water under white light illumination. This self‐aligned catalytic thinning process enables the construction of the transistors with a thin Te channel and thick Te contact with Pt metal electrodes, which provides a device configuration with both effective electrostatic control and low contact resistance.
Electrochemical ammonia (NH3) synthesis from nitrate (NO3-) reduction offers an intriguing approach for both sustainable ammonia synthesis and environmental denitrification, yet it remains hindered by a complicated reaction pathway with various intermediates. Here we present that the interlayer strain compression in bismuth (Bi) nanocrystals can contribute to both activity and selectivity improvement toward NH3 electrosynthesis from NO3- reduction. By virtue of comprehensive spectroscopic studies and theoretical calculations, we untangle that the interlayer lattice compression shortens Bi-Bi bond to broaden the 6p bandwidth for electron delocalization, promoting the chemical affinities of nitrogen intermediates. Such a manipulation facilitates NO3- activation to reduce the energy barrier for activity improvement, and also alleviates *NO2 desorption to suppress nitrite generation. As a result, a strain-compressive Bi electrocatalyst yields a maximal Faradaic efficiency of 90.6% and high generation rate of 46.5 g h-1 gcat-1 with industrially scalable partial current density up to 300 mA cm-2 for NH3 product at the optimized conditions, respectively.
Abstract Ammonia (NH 3 ) is vital in global production and energy cycles. Electrocatalytic nitrate reduction (e‐NO 3 RR) offers a promising route for nitrogen (N) conversion and NH 3 synthesis, yet it faces challenges like competing reactions and low catalyst activity. This study proposes a synergistic mechanism incorporating a proton donor to mediate O‐end e‐NO 3 RR, addressing these limitations. A novel method combining ultraviolet radiation reduction, confined synthesis, and microwave treatment was developed to create a model catalyst embedding Cu single atoms on La‐based nanoparticles ( p ‐CNCu s La n ‐m). DFT analysis emphasizes the critical role of La‐based clusters as proton donors in e‐NO 3 RR, while in situ characterization reveals an O‐end adsorption reduction mechanism. The catalyst achieves a remarkable Faraday efficiency (FE NH3 ) of 97.7%, producing 10.6 mol g metal −1 h −1 of NH 3 , surpassing most prior studies. In a flow cell, it demonstrated exceptional stability, with only a 9% decrease in current density after 111 hours and a NH 3 production rate of 1.57 mg NH3 /h/cm −2 . The proton donor mechanism's effectiveness highlights its potential for advancing electrocatalyst design. Beyond NH 3 production, the O‐end mechanism opens avenues for exploring molecular‐oriented coupling reactions in e‐NO 3 RR, paving the way for innovative electrochemical synthesis applications.
Conducting bridge random access memory (CBRAM) is one of the most promising candidates for future nonvolatile memories. It is important to understand the scalability and retention of CBRAM cells to realize better memory performance. Here, we directly observe the switching dynamics of Cu tip/SiO2/W cells with various active electrode sizes using in situ transmission electron microscopy. Conducting filaments (CFs) grow from the active electrode (Cu tip) to inert electrode (W) during the SET operations. The size of the Cu tip affects the electric-field distribution, the amount of the cation injection into electrolyte, and the dimension of the CF. This study provides helpful understanding on the relationship between power consumption and retention of CBRAM cells. We also construct a theoretical model to explain the electrode-size-dependent CF growth in SET operations, showing good agreement with our experimental results.
Abstract Conventional frame-based image sensors suffer greatly from high energy consumption and latency. Mimicking neurobiological structures and functionalities of the retina provides a promising way to build a neuromorphic vision sensor with highly efficient image processing. In this review article, we will start with a brief introduction to explain the working mechanism and the challenges of conventional frame-based image sensors, and introduce the structure and functions of biological retina. In the main section, we will overview recent developments in neuromorphic vision sensors, including the silicon retina based on conventional Si CMOS digital technologies, and the neuromorphic vision sensors with the implementation of emerging devices. Finally, we will provide a brief outline of the prospects and outlook for the development of this field.
For the first time, we experimentally demonstrated the fully reconfigurable switching between selector and RRAM in one V/VO x /HfWO x /Pt device while with no electroforming or high-temperature annealing processes during fabrication. In the same device: (1) Ultra-high endurance (>10 12 ), high operation speed (<30ns) and excellent threshold stability (variation <5.7%) are demonstrated in the selector mode which is attributed to threshold switching (TS) characteristics of VO x ; (2) High on-off ratio (>10 3 ), high endurance (>10 10 ) and reduction of the leakage current with two orders of magnitude are achieved in the RRAM mode resulted from resistive switching (RS) characteristics of HfWO x . These reproducible volatile and non-volatile switching properties are further utilized to emulate electronic neurons and synapses, respectively, and in this way the V/VO x /HfWO x /Pt-based fully memristive spiking neural network can be realized at a dramatically reduced lentency (∼500 ns) and power consumption (∼10 fJ/per operation for one synapse).
The rapid development of machine vision applications demands hardware that can sense and process visual information in a single monolithic unit to avoid redundant data transfer. Here, we design and demonstrate a monolithic vision enhancement chip with light-sensing, memory, digital-to-analog conversion, and processing functions by implementing a 619-pixel with 8582 transistors and physical dimensions of 10 mm by 10 mm based on a wafer-scale two-dimensional (2D) monolayer molybdenum disulfide (MoS 2 ). The light-sensing function with analog MoS 2 transistor circuits offers low noise and high photosensitivity. Furthermore, we adopt a MoS 2 analog processing circuit to dynamically adjust the photocurrent of individual imaging sensor, which yields a high dynamic light-sensing range greater than 90 decibels. The vision chip allows the applications for contrast enhancement and noise reduction of image processing. This large-scale monolithic chip based on 2D semiconductors shows multiple functions with light sensing, memory, and processing for artificial machine vision applications, exhibiting the potentials of 2D semiconductors for future electronics.
Exploring the advanced oxygen evolution reaction (OER) electrocatalysts is highly desirable toward sustainable energy conversion and storage, yet improved efficiency in acidic media is largely hindered by its sluggish reaction kinetics. Herein, we rationally manipulate the electronic states of the strongly electron correlated pyrochlore ruthenate Y2Ru2O7 alternative through partial A-site substitution of Sr2+ for Y3+, efficiently improving its intrinsic OER activity. The optimized Y1.7Sr0.3Ru2O7 candidate observes a highly intrinsic mass activity of 1018 A gRu–1 at an overpotential of 300 mV with excellent durability in 0.5 M H2SO4 electrolyte. Combining synchrotron-radiation X-ray spectroscopic investigations with theoretical simulations, we reveal that the electron correlations in the Ru 4d band are weakened through coordinatively geometric regulation and charge redistribution by the exotic Sr2+ cation, enabling the delocalization of Ru 4d electrons via an insulator-to-metal transition. The induced Ru–O covalency promotion and band alignment rearrangement decreases the charge transfer energy to accelerate interfacial charge transfer kinetics. Meanwhile, the chemical affinity of oxygen intermediates is also rationalized to weaken the metal–oxygen binding strength, thus lowering the energy barrier of the overall reaction. This work offers fresh insights into designing advanced solid-state electrocatalysts and underlines the versatility of electronic structure manipulation in tuning catalytic activity.
A new design of a selective catalytic reduction (SCR) mixer called tornado was developed for a heavy-duty diesel engine to solve the urea deposition problem. A combination of CFD simulation and experimental studies was used to comprehensively evaluate the performance of the tornado mixer. According to the numerical simulations, this mixer can improve the front surface flow uniformity of the SCR carrier by 6.67% and the NH3 distribution uniformity by 3.19% compared to a traditional mixer. Similarly, steady state SCR conversion efficiency test results have shown that the tornado mixer can increase the average SCR conversion efficiency by 1.73% compared to a traditional mixer. Therefore, the tornado mixer outperforms traditional mixers in terms of mixing uniformity, resistance to deposition and impact on NOX emissions. In addition, a dimensionless parameter, the “limiting deviation rate”, is proposed in the present study to improve the mixing uniformity assessment method for SCR mixers (with the explicit intent to evaluate the mixing uniformity more accurately).
TGF-ß signaling is known to function during tooth formation. The authors’ study investigated the role of TGF-ß signaling during tooth root development and determined how the common mediator for TGF-ß signaling, Smad4, affected root formation in mice. Smad4 was specifically inactivated in all epidermal-derived tissues by using a two-component genetic system. The authors’ findings show that when Smad4 expression is eliminated in the dental epithelium, there is lack of root formation and severe crown defects.
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