The authors report first a new type of nitrogen‐triggered Zn single atom catalyst, demonstrating high catalytic activity and remarkable durability for the oxygen reduction reaction process. Both ...X‐ray absorption fine structure spectra and theoretical calculations suggest that the atomically dispersed Zn‐N4 site is the main, as well as the most active, component with O adsorption as the rate‐limiting step at a low overpotential of 1.70 V. This work opens a new field for the exploration of high‐performance Pt‐free electrochemical oxygen reduction catalysts for fuel cells.
The new nitrogen‐triggered Zn single‐atom catalyst shows high catalytic activity for the oxygen reduction reaction (ORR) process. The characterization and theoretical calculations suggest that the main active site is the dispersed Zn‐N4 moiety, with O adsorption as the rate‐limiting step at a low overpotential of 1.70 V. The single‐atom ZnNx/C catalyst is one of the most promising Pt alternatives for the ORR process.
Noble‐metal nanomaterials are attracting increasing research interest due to their promising applications in electrochemical catalysis, for example. Although great efforts have been devoted to the ...size‐, shape‐, and architecture‐controlled synthesis of noble‐metal nanomaterials, their crystal‐phase‐controlled synthesis is still in its infancy. Here, for the first time, this study reports high‐yield synthesis of Au nanorods (NRs) with alternating 4H/face‐centered cubic (fcc) crystal‐phase heterostructures via a one‐pot wet‐chemical method. The coexistence of 4H and fcc phases is relatively stable, and the 4H/fcc Au NRs can serve as templates for crystal‐phase‐controlled epitaxial growth of other metals. As an example, bimetallic 4H/fcc Au@Pd core–shell NRs are synthesized via the epitaxial growth of Pd on 4H/fcc Au NRs. Significantly, the 4H/fcc Au@Pd NRs show superior mass activity toward the ethanol oxidation reaction, i.e., 6.2 and 4.9 times those of commercial Pd black and Pt/C catalysts, respectively. It is believed that this new synthetic strategy can be used to prepare other novel catalysts for various promising applications.
High‐yield crystal‐phase‐heterostructured 4H/fcc Au@Pd core–shell nanorods are successfully synthesized via a one‐pot, facile, wet‐chemical method. By using the 4H/fcc Au nanorod as a template, a 4H/fcc Au@Pd nanorod with epitaxially grown Pd shell is prepared, which exhibits superior electrocatalytic performance toward the ethanol oxidation reaction.
Calcium ion (Ca
2+
) cycle plays a crucial role in the contraction and relaxation of cardiomyocytes. The sarcoplasmic reticulum (SR) acts as an organelle for storing Ca
2+
, which mediated the ...release and re-uptake of Ca
2+
during contraction and relaxation. Disorders of SR function lead to the dysfunction of Ca
2+
cycle and myocardial cell function. The sarcoplasmic/endoplasmic reticulum Ca
2+
ATPase 2a (SERCA2a) acts as a subtype of SERCA expressed in the heart, which mediates the contraction of cardiomyocytes and Ca
2+
in the cytoplasm to re-enter into the SR. The rate of uptake of Ca
2+
by the SR determines the rate of myocardial relaxation. The regulation of SERCA2a activity controls the contractility and relaxation of the heart, affecting cardiac function. The expression and activity of SERCA2a are reduced in failing hearts. Gene therapy by increasing the expression of SERCA2a in the heart has been proven effective. In addition, SERCA2a is regulated by a variety of factors, including transmembrane micropeptides, protein kinases, and post-translational modifications (PTMs). In this review, we discuss the regulatory factors of SERCA2a and provide new insights into future treatments and the direction of heart failure research. In addition, gene therapy for SERCA2a has recently emerged as therapeutic option and hence will be discussed in this review.
The applications of any two-dimensional (2D) semiconductor devices cannot bypass the control of metal-semiconductor interfaces, which can be severely affected by complex Fermi pinning effects and ...defect states. Here, we report a near-ideal rectifier in the all-2D Schottky junctions composed of the 2D metal 1 T'-MoTe
and the semiconducting monolayer MoS
. We show that the van der Waals integration of the two 2D materials can efficiently address the severe Fermi pinning effect generated by conventional metals, leading to increased Schottky barrier height. Furthermore, by healing original atom-vacancies and reducing the intrinsic defect doping in MoS
, the Schottky barrier width can be effectively enlarged by 59%. The 1 T'-MoTe
/healed-MoS
rectifier exhibits a near-unity ideality factor of ~1.6, a rectifying ratio of >5 × 10
, and high external quantum efficiency exceeding 20%. Finally, we generalize the barrier optimization strategy to other Schottky junctions, defining an alternative solution to enhance the performance of 2D-material-based electronic devices.
Similar to heterostructures composed of different materials, possessing unique properties due to the synergistic effect between different components, the crystal‐phase heterostructures, one variety ...of hetero‐phase structures, composed of different crystal phases in monometallic nanomaterials are herein developed, in order to explore crystal‐phase‐based applications. As novel hetero‐phase structures, amorphous/crystalline heterostructures are highly desired, since they often exhibit unique properties, and hold promise in various applications, but these structures have rarely been studied in noble metals. Herein, via a one‐pot wet‐chemical method, a series of amorphous/crystalline hetero‐phase Pd nanosheets is synthesized with different crystallinities for the catalytic 4‐nitrostyrene hydrogenation. The chemoselectivity and activity can be fine‐tuned by controlling the crystallinity of the as‐synthesized Pd nanosheets. This work might pave the way to preparing various hetero‐phase nanostructures for promising applications.
Amorphous/crystalline heterophase Pd nanosheets exhibit crystallinity‐dependent chemoselectivity and catalytic activity.
Developing high-performance film dielectrics for capacitive energy storage has been a great challenge for modern electrical devices. Despite good results obtained in lead titanate-based dielectrics, ...lead-free alternatives are strongly desirable due to environmental concerns. Here we demonstrate that giant energy densities of ~70 J cm
, together with high efficiency as well as excellent cycling and thermal stability, can be achieved in lead-free bismuth ferrite-strontium titanate solid-solution films through domain engineering. It is revealed that the incorporation of strontium titanate transforms the ferroelectric micro-domains of bismuth ferrite into highly-dynamic polar nano-regions, resulting in a ferroelectric to relaxor-ferroelectric transition with concurrently improved energy density and efficiency. Additionally, the introduction of strontium titanate greatly improves the electrical insulation and breakdown strength of the films by suppressing the formation of oxygen vacancies. This work opens up a feasible and propagable route, i.e., domain engineering, to systematically develop new lead-free dielectrics for energy storage.
Abstract
We establish a powerful poly(4-styrenesulfonate) (PSS)-treated strategy for sulfur vacancy healing in monolayer MoS
2
to precisely and steadily tune its electronic state. The self-healing ...mechanism, in which the sulfur vacancies are healed spontaneously by the sulfur adatom clusters on the MoS
2
surface through a PSS-induced hydrogenation process, is proposed and demonstrated systematically. The electron concentration of the self-healed MoS
2
dramatically decreased by 643 times, leading to a work function enhancement of ∼150 meV. This strategy is employed to fabricate a high performance lateral monolayer MoS
2
homojunction which presents a perfect rectifying behaviour, excellent photoresponsivity of ∼308 mA W
−1
and outstanding air-stability after two months. Unlike previous chemical doping, the lattice defect-induced local fields are eliminated during the process of the sulfur vacancy self-healing to largely improve the homojunction performance. Our findings demonstrate a promising and facile strategy in 2D material electronic state modulation for the development of next-generation electronics and optoelectronics.
Electrochemical reduction of carbon monoxide to high-value multi-carbon (C
) products offers an appealing route to store sustainable energy and make use of the chief greenhouse gas leading to climate ...change, i.e., CO
. Among potential products, C
liquid products such as ethanol are of particular interest owing to their high energy density and industrial relevance. In this work, we demonstrate that Ag-modified oxide-derive Cu catalysts prepared via high-energy ball milling exhibit near 80% Faradaic efficiencies for C
liquid products at commercially relevant current densities (>100 mA cm
) in the CO electroreduction in a microfluidic flow cell. Such performance is retained in an over 100-hour electrolysis in a 100 cm
membrane electrode assembly (MEA) electrolyzer. A method based on surface-enhanced infrared absorption spectroscopy is developed to characterize the CO binding strength on the catalyst surface. The lower C and O affinities of the Cu-Ag interfacial sites in the prepared catalysts are proposed to be responsible for the enhanced selectivity for C
oxygenates, which is the experimental verification of recent computational predictions.
As key equipment in modern industry, it is important to diagnose and predict the health status of bearings. Data-driven methods for remaining useful life (RUL) prognostics have achieved excellent ...performance in recent years compared to traditional methods based on physical models. In this paper, we propose a novel data-driven method for predicting the remaining useful life of bearings based on a deep graph convolutional neural network with spatiotemporal domain convolution. This network uses the average sliding root mean square (ASRMS) as the health factor to identify the healthy and degraded states, and then uses correlation coefficient analysis on the hybrid features of the degraded data to construct a spatial graph according to the strength of the correlation between the obtained features. In the time domain, we introduce historical data as the input to the temporal convolution. After the data are processed by the spatial map and the temporal dimension, we perform the prediction of the remaining useful life. The experimental results show the accuracy of the method.
Ultrathin molybdenum disulfide (MoS2) presents ideal properties for building next‐generation atomically thin circuitry. However, it is difficult to construct logic units of MoS2 monolayer using ...traditional silicon‐based doping schemes, such as atomic substitution and ion implantation, as they cause lattice disruption and doping instability. An accurate and feasible electronic structure modulation strategy from defect engineering is proposed to construct homogeneous electronics for MoS2 monolayer logic inverters. By utilizing the energy‐matched electron induction of the solution process, numerous pure and lattice‐stable monosulfur vacancies (Vmonos) are introduced to modulate the electronic structure of monolayer MoS2 via a shallow trapping effect. The resulting modulation effectively reduces the electronic concentration of MoS2 and improves the work function by 100 meV. Under modulation of Vmonos, an atomically thin homogenous monolayer MoS2 logic inverter with a voltage gain of 4 is successfully constructed. A brand‐new and practical design route of defect modulation for 2D‐based circuit development is provided.
Accurate and facile solution‐processable defect engineering is proposed for constructing atomic‐thin MoS2 homogeneous electronics. By utilizing the energy‐matched relationship between the formation energy of monosulfur vacancies (Vmonos) and the electron induction energy of H2O2 aqueous solution, numerous pure and lattice‐stable Vmonos are introduced for modulating electronic structure to construct homogeneous electronics including a logic inverter via the shallow trapping effect.
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