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•Monodisperse CsPbBr3@SiO2 NCs are prepared by one-pot route in nonpolar solvents.•These NCs exhibit high photoluminescence quantum yield of 87%.•The core@shell NCs exhibit evidently ...improved stability compared to bare QDs.•LEDs with high CRI and efficiency are constructed with these CsPbX3@SiO2 NCs.
Currently, unsatisfactory optical stability and toxicity of all-inorganic lead halide perovskite (CsPbX3, X = Cl, Br, and I) quantum dots (QDs) with excellent photoelectric properties is a major obstacle for their practical application. In this work, the CsPbBr3 QDs were assembled into SiO2 shell via nonpolar solvent synthesis, and monodisperse CsPbBr3@SiO2 nanocomposites (NCs) with high photoluminescence quantum yield (PLQY) of ~87% were successfully prepared. Moreover, the introduced hydrophobic and multibranched trioctylphosphine oxide (TOPO) effectively suppressed the hydrolysis rate of tetraethoxysilane (TEOS), resulting in the formation of core@shell NCs at a nanoscale-particle level. Benefiting from the protection of TOPO and SiO2 shell, the CsPbBr3@SiO2 NCs exhibit remarkably improved stability against thermal treatment, UV irradiation and water compared to the bare perovskite-QDs. Notably, the anion-exchange reaction among different perovskite-QDs was completely inhibited. To improve stability of iodide-substituted perovskite-QDs and expand emission wavelength, the CsPbBr0.6I2.4@SiO2 NCs with PLQY of 75% were also successfully prepared by similar strategy. White light-emitting-diodes (WLEDs) were designed by combining CsPbBr3@SiO2 NCs with CsPbBr0.6I2.4@SiO2 NCs onto blue GaN chips. Bright white-light with high color-rendering index of 90 and luminous efficiency of 80 lm W−1 were achieved from these WLEDs, indicating the synthesized perovskite NCs possess huge potentiality in displays and solid-state lighting.
The number of lithium‐ion batteries (LIBs) is steadily increasing in order to meet the ever‐growing demand for sustainable energy and a high quality of life for humankind. At the same time, the ...resulting large number of LIB waste certainly poses safety hazards if it is not properly disposed of and will seriously harm the environment due to its inherent toxicity due to the use of toxic substances. Moreover, the consumption of many scarce precious metal resources is behind the mass production of batteries. In the light of severe environmental, resources, safety and recycling problems, recycling spent LIBs have become an essential urgently needed action to achieve sustainable social development. This review therefore critically analyses the value and the need for recycling of spent LIBs from a variety of resources and the environment. A range of existing technologies for recycling and reusing spent LIBs, such as pretreatment, pyrometallurgy, hydrometallurgy, and direct recycled methods, is subsequently summarized exclusively. In addition, the benefits and problems of the methods described above are analyzed in detail. It also introduces recycling progress of other LIB components, such as anodes, separators, and electrolytes, as well as the high‐value cathode. Finally, the prospects for recycling LIBs are addressed in four ways (government, users, battery manufacturers, and recyclers). This review should contribute to the development of the recycling of used LIBs, particularly in support of industrialization and recycling processes.
Spent lithium‐ion batteries (LIBs) recovery is quite urgent due to the pressure from environmental, resources, and economic. Spent LIBs are turned into treasures through a series of recycling methods, which reflects the real meaning of recycling.
•Oxygen reduction reaction (ORR) in photocatalysis process is focused.•Multi-electron transfer ORR is reviewed.•This review provides a guide to access to enhanced photocatalysis via multi-electron ...transfer.
Semiconductor photocatalysis has attracted significant interest for solar light induced environmental remediation and solar fuel generation. As is well known, photocatalytic performance is determined by three steps: photoexcitation, separation and transport of photogenerated charge carriers, and surface reactions. To achieve higher efficiency, significant efforts have been made on improvement of efficiency of above first two steps, which have been well documented in recent review articles. In contrast, this review intends to focus on strategies moving onto the third step of improvement for enhanced photocatalysis wherein active oxygen species including superoxide radical, hydrogen peroxide, hydroxyl radical are in situ detected. Particularly, surface electron-transfer reduction of oxygen over single component photocatalysts is reviewed and systems enabling multi-electron transfer induced oxygen reduction reaction (ORR) are highlighted. It is expected this review could provide a guideline for readers to better understand the critical role of ORR over photocatalyst in charge carrier separation and transfer and obtain reliable results for enhanced aerobic photocatalysis.
Transient electronics that can physically vanish in solution can offer opportunities to address the ecological challenges for dealing with the rapidly growing electronic waste. As one important ...component, it is desirable that memory devices combined with the transient feature can also be developed as secrecy information storage systems besides the above advantage. Resistive switching (RS) memory is one of the most promising technologies for next‐generation memory. Herein, the biocompatible pectin extracted from natural orange peel is introduced to fabricate RS memory devices (Ag/pectin/indium tin oxides (ITO)), which exhibit excellent RS characteristics, such as forming free characteristic, low operating voltages (≈1.1 V), fast switching speed (<70 ns), long retention time (>104 s), and multilevel RS behaviors. The device performance is not degraded after 104 bending cycles, which will be beneficial for flexible memory applications. Additionally, instead of using acid solution, the Ag/pectin/ITO memory device can be dissolved rapidly in deionized water within 10 min thanks to the good solubility arising from ionization of its carboxylic groups, which shows promising application for green electronics. The present biocompatible memory devices based on natural pectin suggest promising material candidates toward enabling high‐density secure information storage systems applications, flexible electronics, and green electronics.
Biocompatible pectin extracted from natural orange peel is introduced to fabricate flexible multilevel resistive switching (RS) memory devices (Ag/pectin/indium tin oxides). The device exhibits excellent RS characteristics and it can be dissolved in deionized water rapidly thanks to the good solubility of pectin arising from ionization of its carboxylic groups.
The close replication of synaptic functions is an important objective for achieving a highly realistic memristor-based cognitive computation. The emulation of neurobiological learning rules may allow ...the development of neuromorphic systems that continuously learn without supervision. In this work, the Bienenstock-Cooper-Munro learning rule, as a typical case of spike-rate-dependent plasticity, is mimicked using a generalized triplet-spike-timing-dependent plasticity scheme in a WO
memristive synapse. It demonstrates both presynaptic and postsynaptic activities and remedies the absence of the enhanced depression effect in the depression region, allowing a better description of the biological counterpart. The threshold sliding effect of Bienenstock-Cooper-Munro rule is realized using a history-dependent property of the second-order memristor. Rate-based orientation selectivity is demonstrated in a simulated feedforward memristive network with this generalized Bienenstock-Cooper-Munro framework. These findings provide a feasible approach for mimicking Bienenstock-Cooper-Munro learning rules in memristors, and support the applications of spatiotemporal coding and learning using memristive networks.
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Constructing heterostructures can facilitate photoinduced charge separation, leading to enhanced photocatalytic performance. However, spatial separation of charge carriers in ...traditional type II heterojunctions is at the expense of their redox ability. In this paper, well-designed direct Z-scheme systems (ZSS) of p-CuAl2O4/n-Bi2WO6 composite nanofibers with uniform non-woven web nanostructure was built by electrospinning technique and solvothermal reactions. The formation mechanism of the ZSS and the charge migration pathway is investigated in detail. Results show that as-prepared composite nanofibers exhibit desirable photocatalytic performance for overall water splitting due to its stronger redox power and efficient charge separation. Meantime, it shows great activity for photodegradation of various organic pollutant models (RhB, MO, 4-NP), which is 1 order of magnitude higher than the single-component CuAl2O4 and Bi2WO6. Furthermore, the composite nanofibers exhibit well separable properties by natural sedimentation because of its ultra-long and non-woven web nanostructure. The paper explores CuAl2O4 and its Z-scheme heterostructures in water splitting for the first time, which may highlight its new applications.
Broadband metamaterials absorbers with high absorption, ultrathin thickness and easy configurations are in great demand for many potential applications. In this paper, we first analyse the coupling ...resonances in a Ti/Ge/Ti three-layer absorber, which can realise broadband absorption from 8 to 12 μm. Then we experimentally demonstrate two types of absorbers based on the Ti/Ge/Si
N
/Ti configuration. By taking advantage of coupling surface plasmon resonances and intrinsic absorption of lossy material Si
N
, the average absorptions of two types of absorbers achieve almost 95% from 8 to 14 μm (experiment result: 78% from 6.5 to 13.5 μm). In order to expand the absorption bandwidth, we further propose two Ti/Si/SiO
/Ti absorbers which can absorb 92% and 87% of ultra-broadband light in the 14-30 μm and 8-30 μm spectral range, respectively. Our findings establish general and systematic strategies for guiding the design of metamaterial absorbers with excellent broadband absorption and pave the way for enhancing the optical performance in applications of infrared thermal emitters, imaging and photodetectors.
•p-CuO/n-ZnO nano-heterojunctions with controllable compositions and one dimensional hollow structure is constructed.•Hollow nanofibers were successfully synthesized by combining the electrospinning ...and atomic layer deposition method.•The ratios of Zn to Cu can be precisely controlled by adjusting the amounts of CuAc and the deposition cycles of ZnO.•The optimal response of the sensor was improved about 6-fold versus pure ZnO and 45-fold versus pure CuO.
In virtue of their fantastic sensing performance, heterojunction-based gas sensors has gained ascending attention and gradually become a new generation of high-performance gas sensors. However, due to the poor control on the element composition and distribution of heterostructure, it remains a great challenge to optimize and repeat the gas-sensing performance. In this paper, hollow p-CuO/n-ZnO nanofibers with controllable compositions were successfully synthesized by combining the electrospinning and atomic layer deposition (ALD) method, and the effect of compositions on the gas-sensing performance were systematically studied. The ratios of Zn to Cu (RZn/Cu) were well controlled by adjusting the amounts of raw materials and the deposition cycles of ALD in orthogonal experiments, which offers a good opportunity to optimize the gas sensing performances. Interestingly, with the increase of RZn/Cu, the gas responses to 100 ppm H2S at 250 °C first increased to 60.5 (RZn/Cu = 15.6) and then decreased gradually. The optimum response of these materials was improved about 6-fold versus the pure ZnO and 45-fold versus pure CuO. Meanwhile, the selectivity and stability of these H2S sensors were also got much optimized. The enhanced sensing performance is believed to be mainly attributed to the optimal ratio of p-CuO/n-ZnO and the mixed heterojunction with radial concentration gradient.
Carbon nanofibers/silver nanoparticles (CNFs/AgNPs) composite nanofibers were fabricated by two steps consisting of the preparation of the CNFs by electrospinning and the hydrothermal growth of the ...AgNPs on the CNFs. The as-prepared nanofibers were characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, resonant Raman spectra, thermal gravimetric and differential thermal analysis, and X-ray photoelectron spectroscopy, respectively. The results indicated that not only were AgNPs (25-50 nm) successfully grown on the CNFs but also the AgNPs were distributed without aggregation on the CNFs. Further more, by adjusting the parameters in hydrothermal processing, the content of silver supported on the CNFs could be easily controlled. The catalytic activities of the CNFs/AgNPs composite nanofibers to the reduction of 4-nitrophenol (4-NP) with NaBH(4) were tracked by UV-visible spectroscopy. It was suggested that the CNFs/AgNPs composite nanofibers exhibited high catalytic activity in the reduction of 4-NP, which might be attributed to the high surface areas of AgNPs and synergistic effect on delivery of electrons between CNFs and AgNPs. And, the catalytic efficiency was enhanced with the increasing of the content of silver on the CNFs/AgNPs composite nanofibers. Notably, the CNFs/AgNPs composite nanofibers could be easily recycled due to their one-dimensional nanostructural property.
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