The development of a convenient method for the discrimination of typically quenching metal ions such as Cu2+, Co2+, Ni2+, and Fe3+ is of great interest but still a challenge. By simultaneously ...incorporating Eu3+ and organic dye 3,3′‐diethyloxacarbocyanine iodide (DOC) into a metal‐organic framework, MOF‐253, a luminescent sensor array MOF‐253⊃Eu3++DOC with three emission centers is generated. Utilizing the diversity of quenching responses of metal ions to the different emission centers, five metal ions including Ag+, Cu2+, Fe3+, Co2+ and Ni2+ can be well distinguished with a discrimination accuracy of 100% at a concentration as low as 60 µm. Subsequently, the binary and ternary mixtures of three metal ions (Fe3+, Co2+, and Ni2+) can also be discriminated successfully. Furthermore, taking Cu2+ and Ag+ as examples, this MOF‐based sensor array can quantify the ion concentration at a low range from 0 to 15 µm. Most probably, this is the first case of simultaneous recognition and quantitation of metal ions in an aqueous solution using an MOF‐based luminescent sensor array. Since a variety of luminescent species including organic dyes and lanthanide ions can be introduced into MOFs to generate multiple‐dimensional luminescence, such strategy will open a new avenue for luminescent sensor assays.
By simultaneously incorporating Eu3+ and organic dye 3,3′‐diethyloxacarbocyanine iodide (DOC) into a metal‐organic framework, MOF‐253, a luminescent sensor array MOF‐253⊃Eu3++DOC with three emission centers is generated. Utilizing the diversity of quenching responses of metal ions to the different emission centers, five metal ions including Ag+, Cu2+, Fe3+, Co2+ and Ni2+ can be well distinguished and quantified.
Silicon/carbon (Si/C) composites have rightfully earned the attention as anode candidates for high-energy-density lithium-ion batteries (LIBs) owing to their advantageous capacity and superior ...cycling stability, yet their practical application remains a significant challenge. In this study, we report the large-scale synthesis of an intriguing micro/nanostructured pore-rich Si/C microsphere consisting of Si nanoparticles tightly immobilized onto a micron-sized cross-linked C matrix that is coated by a thin C layer (denoted P-Si/C@C) using a low-cost spray-drying approach and a chemical vapor deposition process with inorganic salts as pore-forming agents. The as-obtained P-Si/C@C composite has high porosity that provides sufficient inner voids to alleviate the huge volume expansion of Si. The outer smooth and robust C shells strengthen the stability of the entire structure and the solid–electrolyte interphase. Si nanoparticles embedded in a microsized cross-linked C matrix show excellent electrical conductivity and superior structural stability. By virtue of structural advantages, the as-fabricated P-Si/C@C anode displays a high initial Coulombic efficiency of 89.8%, a high reversible capacity of 1269.6 mAh g–1 at 100 mA g–1, and excellent cycle performance with a capacity of 708.6 mAh g–1 and 87.1% capacity retention after 820 cycles at 1000 mA g–1, outperforming the reported results of Si/C composite anodes. Furthermore, a low electrode swelling of 18.1% at a high areal capacity of 3.8 mAh cm–2 can be obtained. When assembled into a practical 3.2 Ah cylindrical cell, extraordinary long cycling life with a capacity retention of 81.4% even after 1200 cycles at 1C (3.2 A) and excellent rate performance are achieved, indicating significant advantages for long-life power batteries in electric vehicles.
Optically stimulated synaptic devices are critical to the development of neuromorphic computing with broad bandwidth and efficient interconnect. Although a few interesting materials have been ...employed to fabricate optically stimulated synaptic devices, the use of silicon (Si) that is the material of choice for very large-scale integration circuits in the conventional von Neumann computing has not been explored for optically stimulated synaptic devices. Here we take advantage of one of the most important nanostructures of Si — Si nanocrystals (NCs) to make synaptic devices, which can be effectively stimulated by light in the unprecedented broad spectral region from the ultraviolet to near-infrared, approaching the wavelength of ∼ 2 µm. These optically stimulated Si-NC-based synaptic devices demonstrate a series of important synaptic functionalities, well mimicking biological synapses. The plasticity of Si-NC-based synaptic devices originates from the dynamic trapping and release of photogenerated carriers at defects such as dangling bonds at the NC surface. The current facile use of Si NCs in broadband optoelectronic synaptic devices with low energy consumption has important implication for the large-scale deployment of Si in the emerging neuromorphic computing.
Silicon nanocrystals (Si NCs) are used to fabricate optoelectronic synaptic devices whose energy consumption may be rather low. Essential synaptic functionalities have been realized in these devices by using broadband light to stimulate them. Display omitted
•Silicon nanocrystals (Si NCs) are used to fabricate optoelectronic synaptic devices.•Main functionalities of biological synapses are emulated by using broadband light.•The operation is basically governed by the electronic and optical behavior of Si NCs.
The novel diamond-wire sawing technology has been applied in the wafering of Czochralski (CZ) silicon. It is found that phase transformations take place on the wafer surfaces, associated with a ...smaller roughness. The wafers sliced by the diamond-wire saw have a greater mechanical strength than those by the conventional cutting process, beneficial for the preparation of thin wafers. With the decrease of silicon wafers, both the transmittance and the reflectance of sunlight increase in the long wavelength range. After fabricated into the solar cells by a standard process, their performances have been investigated. The short-circuit current significantly decreases with the wafer thickness, which is attributed to the reduction of effective light absorption. The open-circuit voltage also reduces to some extent since the surface recombination becomes more and more dominant in the minority carrier lifetime. For the ultrathin wafers with a thickness of 60μm, an average conversion efficiency of 16.8% can still be achieved for solar cells based on the standard fabrication process in photovoltaic industry.
► Surface states of diamond-wire sawn wafers have been characterized. ► Diamond-wire sawn wafers have a higher mechanical strength, beneficial for the preparation of thin wafers. ► Transmittance and reflectance of sunlight increase with a decrease of wafer thickness. ► Short-circuit current and open-circuit voltage of solar cells decrease with a decrease of wafer thickness. ► An average conversion efficiency of 16.8% has been achieved for a 60μm thick silicon solar cell.
High‐performance photocatalysts should have highly crystallized nanocrystals (NCs) with small sizes, high separation efficiency of photogenerated electron–hole pairs, fast transport and consumption ...of photon‐excited electrons from the surface of catalyst, high adsorption of organic pollutant, and suitable band gap for maximally utilizing sunlight energy. However, the design and synthesis of these versatile structures still remain a big challenge. Here, we report a novel strategy for the synthesis of ultrasmall and highly crystallized graphene–ZnFe2O4 photocatalyst through interface engineering by using interconnected graphene network as barrier for spatially confined growth of ZnFe2O4, as transport channels for photon‐excited electron from the surface of catalyst, as well as the electron reservoir for suppressing the recombination of photogenerated electron–hole pairs. As a result, about 20 nm ZnFe2O4 NCs with highly crystallized (311) plane confined in the graphene network exhibit an excellent visible‐light‐driven photocatalytic activity with an ultrafast degradation rate of 1.924 × 10−7 mol g−1 s−1 for methylene blue, much higher than those of previously reported photocatalysts such as spinel‐based photocatalysts (20 times), TiO2‐based photocatalysts (4 times), and other photocatalysts (4 times). Our strategy can be further extended to fabricate other catalysts and electrode materials for supercapacitors and Li‐ion batteries.
A novel strategy for the synthesis of ultra‐small and highly crystallized graphene–ZnFe2O4 photocatalysts through interface engineering is reported. As a result, ≈20 nm ZnFe2O4 with highly crystallized (311) plane confined in the graphene network exhibits an excellent visible‐light‐driven photocatalytic activity with an ultrafast degradation rate of 1.924 × 10−7 mol gcat−1 s−1 for methylene blue.
Low-cost upgraded metallurgical grade silicon (UMG-Si) with inherent boron (B) and phosphorus (P) compensation is a novel material for photovoltaic application. This paper presents the impact of ...solar irradiance intensity and temperature on the performance of compensated crystalline silicon solar cells. For the same rated output power, compensated crystalline silicon solar cells generate less electricity than the reference silicon solar cells at low irradiance intensity, owing to the strong injection dependence of the carrier lifetime due to high concentration of B–O complexes in compensated silicon. However, at high temperature, compensated crystalline silicon solar cells generate more electricity than the reference silicon solar cells, which mainly originates from the lower temperature-variation of the minority electron mobility in compensated silicon. It suggests that compensated silicon solar cells will be more appropriate for high irradiation application, which often contains high irradiance intensity and high temperature. These results are of great significance for understanding the actual outdoor performance of the solar cells based on the UMG-Si and their application in the photovoltaic (PV) industry.
•At low irradiance intensity, the compensated cells generate less electricity.•At high temperature, the compensated cells generate more electricity.•The compensated cells will be more appropriate for high irradiation application.
Neuromorphic computing can potentially solve the von Neumann bottleneck of current mainstream computing because it excels at self‐adaptive learning and highly parallel computing and consumes much ...less energy. Synaptic devices that mimic biological synapses are critical building blocks for neuromorphic computing. Inspired by recent progress in optogenetics and visual sensing, light has been increasingly incorporated into synaptic devices. This paves the way to optoelectronic synaptic devices with a series of advantages such as wide bandwidth, negligible resistance–capacitance (RC) delay and power loss, and global regulation of multiple synaptic devices. Herein, the basic functionalities of synaptic devices are introduced. All kinds of optoelectronic synaptic devices are then discussed by categorizing them into optically stimulated synaptic devices, optically assisted synaptic devices, and synaptic devices with optical output. Existing practical scenarios for the application of optoelectronic synaptic devices are also presented. Finally, perspectives on the development of optoelectronic synaptic devices in the future are outlined.
Inspired by recent progress in optogenetics and visual sensing, optoelectronic synaptic devices having the advantages of wide bandwidth, facile global regulation, and negligible resistance–capacitance (RC) delay and power loss are intensely studied. Herein, optoelectronic synaptic devices with optical stimulation, optical assistance, or optical output are introduced. Practical scenarios for the application of optoelectronic synaptic devices and perspectives on the future development are presented.
Pt-based multimetallic core–shell nanoplates have received great attention as advanced catalysts, but the synthesis is still challenging. Here we report the synthesis of multimetallic Pd@PtM (M = Ni, ...Rh, Ru) nanoplates including Pd@Pt nanoplates, in which Pt or Pt alloy shells with controlled thickness epitaxially grow on plate-like Pd seeds. The key to achieve high-quality Pt-based multimetallic nanoplates is in situ generation of CO through interfacial catalytic reactions associated with Pd nanoplates and benzyl alcohol. In addition, the accurate control in a trace amount of CO is also of great importance for conformal growth of multimetallic core–shell nanoplates. The Pd@PtNi nanoplates exhibit substantially improved activity and stability for methanol oxidation reaction (MOR) compared to the Pd@Pt nanoplates and commercial Pt catalysts due to the advantages arising from plate-like, core–shell, and alloy structures.
The incorporation of augmentative functionalities into a single synaptic device is greatly desired to enhance the performance of neuromorphic computing, which has brain-like high intelligence and low ...energy consumption. This encourages the development of multi-functional synaptic devices with architectures that are capable of achieving demanded synaptic plasticity. Here we take advantage of the remarkable optical absorption of boron (B)-doped silicon nanocrystals (Si NCs) to make synaptic phototransistors, which can be stimulated by both optical and electrical spikes. The optical and electrical stimulations enable a series of important synaptic functionalities for the synaptic Si-NC phototransistors, well mimicking biological synapses. It is interesting that the synergy of the photogating and electrical gating of the synaptic Si-NC phototransistors leads to the implementation of aversion learning and logic functions. We show that a spiking neural network based on the synaptic Si-NC phototransistors may be trained for the recognition of handwritten digits in the modified national institute of standards and technology (MNIST) database with a recognition accuracy around 94%. The energy consumption of the synaptic Si-NC phototransistors may be rather low, which should help advance energy-efficient neuromorphic computing.
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•Synaptic phototransistors with optical and electrical stimulations are fabricated by using silicon nanocrystals (Si NCs).•The synergy of the photogating and electrical gating enables the emulation of aversion learning and logic functions.•A spiking neural network based on Si-NC phototransistors is proposed for pattern recognition with accuracy up to 94%.
•A uniform SiO2 layer was deposited on multi-walled carbon nanotube.•Synthesis of uniform (MWCNT)@Si nanocomposites via the magnesiothermic reduction.•The MWCNT@Si nanocomposites show high reversible ...capacity and good cyclability.•Enhanced performance is attributed to porous nanostructure, introduction of MWCNTs.
We demonstrate the synthesis of uniform multi-walled carbon nanotube (MWCNT)@Si nanocomposites via the magnesiothermic reduction of pre-synthesized MWCNT@SiO2 nanocables. At first, the acid vapor steaming is used to treat the surface, which can facilitate the uniform deposition of SiO2 layer via the TEOS hydrolysis. Then, the uniform MWCNT@Si nanocomposites are obtained on the basis of MWCNT@SiO2 nanocables via a simple magnesiothermic reduction. When used as an anode material for lithium-ion batteries, the as-synthesized MWCNT@Si nanocomposites show high reversible capacity and good cycling performance, which is better than bulk Si and bare MWCNTs. It is believed that the good electrochemical performance can be attributed to the novel porous nanostructure and the introduction of MWCNTs that can buffer the volume change, maintain the electrical conductive network, and enhance the electronic conductivity and lithium-ion transport.
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