Sensor arrays are a powerful tool for multianalyte sensing and the development of an efficient sensor array has become one of the most intriguing problems. However, sensor arrays often employ lots of ...receptors which need large amounts of work to synthesise. This study describes an efficient method for the fabrication of a simple sensor array based on the competitive binding in supramolecular gels. By rationally introducing various well-designed competitive binding interactions into the supramolecular gel, which is self-assembled from a naphthylhydrazone-based organogelator, a supramolecular gel-based twenty-two-member sensor array has been created. Interestingly, the sensor array has been shown to accurately identify fourteen kinds of important ions (F
, Cl
, I
, CN
, HSO
, SCN
, S
, OH
, Al
, Fe
, Zn
, Hg
, Pb
and H
) in water. It's important to note that this sensor array needs only one synthesized receptor. Moreover, using this method, we also obtained a series of ion response fluorescent supramolecular materials, which could act as security display materials. Therefore, it's a novel and facile way for the design of a simple sensor array as well as ion response fluorescent supramolecular materials.
Efficient oxygen evolution reaction catalysts based on earth-abundant and low-cost elements are urgently required for water splitting devices and metal-air batteries. Herein, for the first time we ...report a novel and promising MOx (M = Mn, Fe, Co and Ni) nanosheets catalyst for oxygen evolution reaction based on the MnFeCoNi high entropy alloy. By an electrochemical cyclic voltammetry scan activation, the MOx nanosheets can grow directly on the MnFeCoNi high entropy alloy particle surfaces forming a core-shell structure. The core-shell structure exhibits a low overpotential of 302 mV to achieve current density of 10 mA cm−2, a small Tafel slope of 83.7 mV dec−1 and exceptional long-term stability of electrolysis for over 20 h in 1 M KOH alkaline solution, which is comparable to the state-of-the-art oxygen evolution reaction electrocatalyst RuO2. We make an investigation of the MnFeCoNi high entropy alloy before and after cyclic voltammetry scan activation on their morphologies, chemical states and elements composition to understand the materials evolution. The present work not only provides a promising electrocatalyst but also broadens the application areas of high entropy alloys.
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•A novel and promising electrocatalyst for OER based on the MnFeCoNi HEA is reported.•There are substantial MOx nanosheets formed after electrochemical CV-activation.•The MOx nanosheets can offer more active sites and bigger specific surface area.•The OER performance is comparable to the state-of-the-art RuO2 catalyst.
Mixed transition metal oxides (MTMOs) have enormous potential applications in energy and environment. Their use as catalysts for the treatment of environmental pollution requires further enhancement ...in activity and stability. This work presents a new synthesis approach that is both convenient and effective in preparing binary metal oxide catalysts (CeCuOx) with excellent activity by achieving molecular‐level mixing to promote aliovalent substitution. It also allows a single, pure MTMO to be prepared for enhanced stability under reaction by using a bimetallic metal–organic framework (MOF) as the catalyst precursor. This approach also enables the direct manipulation of the shape and form of the MTMO catalyst by controlling the crystallization and growth of the MOF precursor. A 2D CeCuOx catalyst is investigated for the oxidation reactions of methanol, acetone, toluene, and o‐xylene. The catalyst can catalyze the complete reactions of these molecules into CO2 at temperatures below 200 °C, representing a significant improvement in performance. Furthermore, the catalyst can tolerate high moisture content without deactivation.
A mixed transition metal oxide catalyst is prepared via the thermal transformation of a bimetallic metal–organic framework precursor. The as‐synthesized CeCuOx catalyst exhibits unique properties with high aliovalent substitution, abundant oxygen vacancies, and exposed active crystal planes, leading to high reactivity and moisture tolerance for the complete oxidation of various volatile organic compounds (i.e., toluene, o‐xylene, acetone, and methanol).
Sensitivity and pressure range are two significant parameters of pressure sensors. Existing pressure sensors have difficulty achieving both high sensitivity and a wide pressure range. Therefore, we ...propose a new pressure sensor with a ternary nanocomposite Fe
O
/C@SnO
. The sea urchin-like Fe
O
structure promotes signal transduction and protects Fe
O
needles from mechanical breaking, while the acetylene carbon black improves the conductivity of Fe
O
. Moreover, one part of the SnO
nanoparticles adheres to the surfaces of Fe
O
needles and forms Fe
O
/SnO
heterostructures, while its other part disperses into the carbon layer to form SnO
@C structure. Collectively, the synergistic effects of the three structures (Fe
O
/C, Fe
O
/SnO
and SnO
@C) improves on the limited pressure response range of a single structure. The experimental results demonstrate that the Fe
O
/C@SnO
pressure sensor exhibits high sensitivity (680 kPa
), fast response (10 ms), broad range (up to 150 kPa), and good reproducibility (over 3500 cycles under a pressure of 110 kPa), implying that the new pressure sensor has wide application prospects especially in wearable electronic devices and health monitoring.
Structure and defect control are widely accepted effective strategies to manipulate the activity and stability of catalysts. On a freestanding hierarchically porous carbon microstructure, the tuning ...of oxygen vacancy in the embedded hollow cobaltosic oxide (Co3O4) nanoparticles is demonstrated through the regulation of nanoscale Kirkendall effect. Starting with the embedded cobalt nanoparticles, the concentration of oxygen‐vacancy defect can vary with the degree of Kirkendall oxidation, thus regulating the number of active sites and the catalytic performances. The optimized freestanding catalyst shows among the smallest reversible oxygen overpotential of 0.74 V for catalyzing oxygen reduction/evolution reactions in 0.1 m KOH. Moreover, the catalyst shows promise for substitution of noble metals to boost cathodic oxygen reactions in portable zinc–air batteries. This work provides a strategy to explore catalysts with controllable vacancy defects and desired nano‐/microstructures.
Controllable oxygen vacancy defects were introduced into the hollow Co3O4 nanoparticles through the regulation of the nanoscale Kirkendall effect. This dramatically enhanced the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities, leading to superior Zn–air battery performance.
Diseases such as cardiovascular problems and sleep apnea cause mass deaths annually due to a lack of timely and portable monitoring and alarm measures. Various wearable devices for health monitoring ...have been intensely researched to reduce mortality. However, these devices themselves can only detect physiological signals; they cannot sound an alarm. Therefore, they must rely on mobile phones or other peripheral devices such as speakers or vibration motors to sound an alarm, which may result in a patient missing the optimal treatment. It is valuable to develop a self‐alarm health monitoring device with the dual functions of physiological signal detection and sound alarm simultaneously. A one‐step laser‐induced graphene (LIG)‐based electronic skin (E‐skin) is fabricated to perform health monitoring and alarm at the same time, which benefit from its both excellent mechanical and acoustical performance. These customized shutter‐patterned E‐skins have an ultrahigh sensitivity of 316.3 and can detect various biosignals such as wrist pulse, respiratory, etc. They also have a self‐alarm function and can sound an alarm when detecting abnormal situations. This study addresses the multifunctional integration required for multisensors, which will open further applications in wearable sensors and health‐care devices.
The development of E‐skin with dual functionality, integrating strain detection and alarm into a single device, is crucial for health monitoring. A one‐step laser‐induced graphene (LIG)‐based E‐skin that can detect faint biosignals (respiration, pulse, etc.) and issue thermoacoustic sound to warn when detecting some abnormal conditions (sleep apnea, sudden cardiac arrest).
A crucial issue restricting the application of direct alcohol fuel cells (DAFCs) is the low activity of Pt‐based electrocatalysts for alcohol oxidation reaction caused by the reaction intermediate ...(CO*) poisoning. Herein, a new strategy is demonstrated for making a class of sub‐monolayer YOx/MoOx‐surface co‐decorated ultrathin platinum nanowires (YOx/MoOx–Pt NWs) to effectively eliminate the CO poisoning for enhancing methanol oxidation electrocatalysis. By adjusting the amounts of YOx and MoOx decorated on the surface of ultrathin Pt NWs, the optimized 22% YOx/MoOx–Pt NWs achieve a high specific activity of 3.35 mA cm−2 and a mass activity of 2.10 A mgPt−1, as well as the enhanced stability. In situ Fourier transform infrared (FTIR) spectroscopy and CO stripping studies confirm the contribution of YOx and MoOx to anti‐CO poisoning ability of the NWs. Density functional theory (DFT) calculations further reveal that the surface Y and Mo atoms with oxidation states allow COOH* to bind the surface through both the carbon and oxygen atoms, which can lower the free energy barriers for the oxidation of CO* into COOH*. The optimal NWs also show the superior activities toward the electro‐oxidation of ethanol, ethylene glycol, and glycerol.
A new class of sub‐monolayer YOx/MoOx‐surface‐co‐decorated ultrathin platinum (Pt) nanowires is demonstrated to effectively boost alcohol oxidation electrocatalysis. The surface Y and Mo atoms make the free energies of CO* and COOH* be decoupled on the nanowire surfaces, lowering the energy barriers for the oxidation of CO* into COOH*.
A novel anion sensor array based on supramolecular metallogels has been developed. It could accurately identify CN(-), SCN(-), S(2-) and I(-) in water. Interestingly, this sensor array is based on a ...novel design approach termed "competitive coordination control AIE mode" to develop anion-responsive gels which need only one synthesized gelator G1.
van der Waals (vdW) heterostructures, stacking different two-dimensional materials, have opened up unprecedented opportunities to explore new physics and device concepts. Especially interesting are ...recently discovered two-dimensional magnetic vdW materials, providing new paradigms for spintronic applications. Here, using density functional theory (DFT) calculations, we investigate the spin-dependent electronic transport across vdW magnetic tunnel junctions (MTJs) composed of Fe3GeTe2 ferromagnetic electrodes and a graphene or hexagonal boron nitride (h-BN) spacer layer. For both types of junctions, we find that the junction resistance changes by thousands of percent when the magnetization of the electrodes is switched from parallel to antiparallel. Such a giant tunneling magnetoresistance (TMR) effect is driven by dissimilar electronic structure of the two spin-conducting channels in Fe3GeTe2, resulting in a mismatch between the incoming and outgoing Bloch states in the electrodes and thus suppressed transmission for an antiparallel-aligned MTJ. The vdW bonding between electrodes and a spacer layer makes this result virtually independent of the type of the spacer layer, making the predicted giant TMR effect robust with respect to strain, interface distance, and other parameters, which may vary in the experiment. We hope that our results will further stimulate experimental studies of vdW MTJs and pave the way for their applications in spintronics.
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