Search

Detection of vector magnetic fields at nanoscale dimensions is critical in applications ranging from basic material science and fundamental physics to information storage and medical diagnostics. So far, nanoscale vector magnetic field sensing is achieved solely by exploiting a single nitrogen‐vacancy (NV) center in a diamond, by evaluating the Zeeman splitting of NV spin qubits by using the technique of an optically‐detected magnetic resonance. This protocol requires a complex optical setup and expensive detection systems to detect the photoluminescence light, which may limit miniaturization and scalability. Here, a simple approach with all‐electric operation to sensing a vector magnetic field at 200 × 200 nm2 dimensions is experimentally demonstrated, by monitoring a stochastic nanomagnet's transition probability from a metastable state, excited by a driving current due to spin‐orbit torque, to a settled state. [ABSTRACT FROM AUTHOR]

Converting extensive sugars into value‐added 2,5‐furandicarboxylic acid (FDCA) has been considered to be a promising approach to developing sustainable substitutes for chemicals from fossil resources. The complicated conversion processes involved multiple cascade reactions and intermediates, which made the design of efficient multifunction catalysts challenging. Herein, we developed a catalyst by introducing phosphotungstic acid (PW) and Co sites into the UiO‐66, which achieved a one‐pot cascade conversion of fructose‐to‐FDCA with high conversion (>99 %) and yield (94.6 %) based on the controllable Lewis/Brønsted acid sites and redox sites. Controlled experiments and detailed characterizations show that the multifunctional PW/UiO(Zr, Co) catalysts successfully affords the direct synthesis of FDCA from fructose via dehydration and selective oxidation in the one‐pot reaction. Additionally, the MOF catalysts could also efficiently convert various sugars into FDCA, which has broad application prospects. This study provides new strategies for designing multifunctional catalysts to achieve efficient production of FDCA from biomass in the one‐pot reaction. [ABSTRACT FROM AUTHOR]

As one of the most commonly bulky chemicals, chlorine is conventionally manufactured by electrolysis of NaCl solution in the chlor–alkali process, which requires a huge supply of electrical energy. The photocatalytic route to produce chlorine by using solar energy and NaCl solution offers a promising strategy to reduce energy consumption and bring economic benefits. Herein, it was found that the introduction of CO2 would enhance the productivity of Cl2 from 8.24 μmol⋅h−1 to 39.6 μmol⋅h−1 in NaCl solution over BiOCl. Experimental studies reveal that the CO2 species (CO32−) entered into the crystal texture of BiOCl and the interlayer space between [Bi2O2]2+ slabs were increased and distorted, accelerating the cycle of Cl species. Besides, the cycle of carbonate species also existed and accelerated the reaction efficiency of Cl− oxidation to Cl2. This work provides a new feasible method of using abundant CO2 resources to accelerate the process of chlorine production via photocatalysis. [ABSTRACT FROM AUTHOR]

Potentiostatic anodization was developed to synthesize copper oxide/copper (CuxO/Cu, x=1,2) electrode with nano structure for sensitive non‐enzymatic glucose detection. At a catalytic potential of 0.55 V, the CuO/Cu electrode presented a high sensitivity of 2954.38 μA mM−1 cm−2 to glucose and a linear range of 0.1 mM to 1.3 mM. The response time is less than 3 s with addition of 0.1 mM glucose. The CuO/Cu electrode above was anodized in 1M KOH solution at −100 mV and the morphology was compact nanoparticles and sparsely dispersed nanosheets, which enlarged the surface area and provided abundant electrocatalytic active sites. Compared the sensing property of electrodes with different morphologies, it indicated that nanostructure was significant to the efficient glucose catalytic oxidation process and it could be regulated by changing the potential and electrolyte concentration during anodization. [ABSTRACT FROM AUTHOR]

The conductivity and corrosion performance of metallic bipolar plates were crucial to the development of the proton exchange membrane fuel cell (PEMFC). In this study, polypyrrole (PPy) coatings doped with titanium nitride nanoparticles (TiN NPs) were deposited on 304 stainless steel (304SS) by constant potential polymerization. To improve dispersion and form a negative charge surface, TiN NPs were modified by anionic surfactants such as sodium dodecyl diphenyl ether disulfate (MADS). Through comparing potentiodynamic curves of the composite coatings in the simulated cathodic environment of PEMFC, the PPy‐0.1 TiN (0.1 g/L) coating presented a more positive corrosion potential (Ecorr = 293 mVAg/AgCl) and a lower corrosion current (Icorr = 0.841 μA cm−2). Furthermore, PPy‐0.1 TiN exhibited more stable corrosion resistance during long‐term immersion. Interfacial contact resistance (ICR) testing demonstrated that the addition of TiN NPs improved conductivity compared to a PPy coating. The results indicated that the PPy‐TiN‐coated 304SS could be used as a kind of promising bipolar plate material. [ABSTRACT FROM AUTHOR]

Analog arithmetic operations are the most fundamental mathematical operations used in image and signal processing as well as artificial intelligence (AI). In‐memory computing (IMC) offers a high performance and energy‐efficient computing paradigm. To date, in‐memory analog arithmetic operations with emerging nonvolatile devices are usually implemented using discrete components, which limits the scalability and blocks large scale integration. Here, a prototypical implementation of in‐memory analog arithmetic operations (summation, subtraction and multiplication) is experimentally demonstrated, based on in‐memory electrical current sensing units using spin‐orbit torque (SOT) devices. The proposed structures for analog arithmetic operations are smaller than the state‐of‐the‐art complementary metal oxide semiconductor (CMOS) counterparts by several orders of magnitude. Moreover, data to be processed and computing results can be locally stored, or the analog computing can be done in the nonvolatile SOT devices, which are exploited to experimentally implement the image edge detection and signal amplitude modulation with a simple structure. Furthermore, an artificial neural network (ANN) with SOT devices based synapses is constructed to realize pattern recognition with high accuracy of ≈95%. [ABSTRACT FROM AUTHOR]

We have developed an intermolecular conjugate addition of 3a-pyrroloindoline/furoindoline radicals to α,β-unsaturated enones, through visible-light photoredox catalysis. Ir(ppy)2(dtbbpy) PF6 was found to be an effective promoter to initiate this reaction from readily available 3a-bromopyrroloindolines/furoindolines. This method was exploited to prepare a series of indole terpenoid-like compounds of potential biological interest. [ABSTRACT FROM AUTHOR]

Oh my darling, Drimentine: The first total synthesis of the pyrroloindoline alkaloids drimentines A, F, and G, and their congener, indotertine A, is reported. An intermolecular radical conjugate addition was key in the synthesis of the drimentine alkaloids, and a biologically inspired iminium–olefin cyclization converted drimentine F into indotertine A. [ABSTRACT FROM AUTHOR]

A domain wall can be driven back and forth in a continuous manner in a ferromagnetic (FM) layer by applying in‐plane positive or negative current pulses along the heavy‐metal (HM) layer, as reported by Long You and co‐workers in article number 1800782. Utilizing the spin‐orbit torque that the current exerts on the CoFeB magnetization results in memristive (synapse‐like) functions. [ABSTRACT FROM AUTHOR]

Memristors, demonstrated by solid‐state devices with continuously tunable resistance, have emerged as a new paradigm for self‐adaptive networks that require synapse‐like functions (artificial synapse, for example). Spin‐based memristors offer advantages over other types of memristors because of their significant endurance and high energy efficiency. Yet it remains a challenge to build dense and functional spintronic memristors with structures and materials that are compatible with existing ferromagnetic devices. Here, a memristive device based upon Ta/CoFeB/MgO heterostructures is demonstrated, which are commonly used in out‐of‐plane magnetized magnetic tunnel junctions (MTJ). To achieve the memristive function, a domain wall (DW) is driven back and forth in a continuous manner in the CoFeB layer by applying in‐plane positive or negative current pulses along the Ta layer, utilizing the spin–orbit torque (SOT) that the current exerts on the CoFeB magnetization. Hence, the magnetization and consequently the anomalous Hall effect (AHE) resistance are modulated in an analog manner, being controlled by the pulsed current characteristics including amplitude, duration, and repetition number. The quasi‐continuous AHE resistance variation is explained by the SOT‐induced DW creep motion. These results pave the way for developing SOT‐based energy‐efficient neuromorphic systems. A memristive device based on a Ta/CoFeB/MgO heterostructure is demonstrated, utilizing spin–orbit torque (SOT) to drive a domain wall back and forth in the creep region. The anomalous Hall effect resistance can be modulated in an analog manner by the pulsed current characteristics including amplitude, polarity, duration, and repetition number, paving a way for developing SOT‐based energy‐efficient neuromorphic systems. [ABSTRACT FROM AUTHOR]