Low photoluminescence quantum yield (PLQY) and spectra instability, the two most difficult challenges in blue‐emitting CsPbBrxCl3−x NCs, have not yet been solved. Quickly controlling the reaction ...thermodynamics is crucial to enhance crystallinity, thus PLQY and spectra stability, but it has been ignored until now. An ultrafast thermodynamic control (UTC) strategy is designed by utilizing liquid nitrogen to instantaneously freeze the superior crystal lattices of CsPbBrxCl3−x NCs formed at high temperature. The average cooling rate exhibits a 33‐fold increase compared to conventional ice‐water cooling (from 1.5 to 50 K s−1). This UTC can make the reaction thermodynamic energy of the system lower than the threshold very quickly. Therefore, abrupt termination of further crystal growth can be achieved, which also avoids additional nucleation at low temperature. With the assist of defect passivation, the final blue‐emitting CsPbBrxCl3−x NCs exhibit an absolute PLQY of 98%, representing the highest value in Pb‐based blue perovskites to date. More importantly, they exhibit superior spectra instability. This UTC strategy not only represents a new avenue to synthesize perovskite NCs with excellent crystal quality and ultrahigh PLQY, but also provides a good reference to deal with the recognized bottleneck of spectra instability.
Liquid nitrogen is employed to reduce the reaction thermodynamic energy of a halide perovskite nanocrystal system to below the threshold very quickly, thus instantaneously freezing superior crystal lattices of CsPbBrxCl3−x NCs formed at high temperature. Crystal quality and grain size uniformity is thus improved, leading to a significant increase in luminous efficiency and spectra stability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In order to understand the degradation of different residual pesticides of white clover silage and their influence on silage quality, three commonly used orchard pesticides with different ...concentrations were added to the white clover and fermented for 90 days. The results showed that the degradation rate of cypermethrin and its toxic degradation product 3-phenoxybenzoic acid (3-PBA) was the highest after silage, at different concentrations, both were 100%. The degradation rate of Tebuconazole and chloropyridine was 72.47–80.27% and 47.76–64.82%, of which 3,5,6-trichloro-2-pyridinol (TCP) content, poisonous toxic degradation product, increased 0.0525–0.253 mg·kg−1. The residues of beta-cypermethrin and tebuconazole had reached safety standards after silage. As compared with the control, the contents of lactic acid, acetic acid, and propionic acid increased in the treated samples. The higher concentrations of three pesticides all significantly reduced the lactic acid content of silage (p<0.05). Pesticides had different effects on the nutritional components of white clover silage. Conclusively, silage is a potential way to expand the utilization of covering plants in orchards.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Understanding excitonic behavior in light absorption and recombination process is urgently needed to regulate luminescent properties of two-dimensional (2D) perovskite; however, such information is ...still unexplored. Here, first, we demonstrate that pure phenethylamine lead bromine (PEA2PbBr4) nanosheets (NSs) possess strong exciton absorption and emission spectrum with high exciton binding energy (up to 310 meV) and prove that free excitons (FEs) play a decisive role in the optical transition process. Then, we design Cd-doped PEA2PbBr4 NSs to induce self-trapped excitons (STEs). Doping with isoelectric Cd naturally induces an impurity-driven lattice distortion and a strong exciton–phonon coupling, resulting in the STEs broadband extrinsic luminescence spectra. Further, the corresponding exciton fluorescent components of FEs and STEs can be effectively distinguished from the emission spectrum through spectral line-shape analysis, revealing the synergistic effect of exciton states in the recombination process. Unambiguously, this work will provide a deeper understanding of the exciton behavior and look forward to regulating exciton composition to obtain ideal luminescence properties.
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IJS, KILJ, NUK, PNG, UL, UM
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•Natural orange peel powder with nano-size were firstly extracted and processed.•A memory device with Ag/Orange peel/FTO sandwich structure was prepared.•The device exhibits superior ...bipolar resistive switching memory characteristics.•This work reveals that orange peel can fabricate novel organic memory devices.
The memory device based on biomaterials is of great value in future applications because the biomaterials are environment-friendly, renewable and pollution-free. In this work, natural biomaterials, which were firstly extracted and processed from orange peel, were used as an active layer for fabricating an environment-friendly and sustainable nonvolatile memory device with Ag/Orange peel/FTO sandwich structure. An obvious memory behavior with reproducible bipolar resistive switching memory performance and large resistive storage window has been observed. This work reveals that the orange peel is a promising material for fabricating an environment-friendly and sustainable memory device in nonvolatile memory applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Two-dimensional (2D) Ruddlesden-Popper hybrid organic-inorganic perovskites are the most promising candidates for highly efficient optoelectronic devices due to their remarkable exciton ...characteristics, adjustable band structure and long-term environmental stability. However, excitons emission behavior of 2D Ruddlesden-Popper perovskites is still unclear. Here we theoretically-experimentally decoupled the excitons behavior in 2D Ruddlesden-Popper PEA2PbI4 nanosheets. Theoretically, the Elliott theory was used to separate exciton and band edge absorptions of PEA2PbI4 nanosheets and determine an exciton binding energy of about 274 meV. Experimentally, spectral-dependent photoluminescence lifetime and excitation powder density-dependent photoluminescence spectra revealed that a distinct photoluminescence tail emission should be derived from localized excitons with lower emission energy than free excitons. Further, the luminescent component of the free excitons and localized excitons with their corresponding densities of states was theoretically decoupled by line-shape analysis of PEA2PbI4 nanosheets photoluminescence spectra, which is consistent with the experimental results demonstrating the existence of localized excitons. Hence, our work provides understanding on the exciton behavior and luminescence mechanism of 2D Ruddlesden-Popper perovskites, which would benefit the prediction of high-performance excitonic devices based on 2D Ruddlesden-Popper perovskites.
•Excitons behavior in 2D Ruddlesden-Popper PEA2PbI4 nanosheets was decoupled.•A band tail state emission derived from localized excitons.•The luminescent component of the free excitons and localized excitons was separated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
It is the consensus of researchers that the reuse of natural resources is an effective way to solve the problems of environmental pollution, waste and overcapacity. Moreover, compared with the case ...of inorganic materials, the renewability of natural biomaterials has great prominent advantages. In this study, keratin, which was first extracted from hair due to its high content in hair, was chosen as a functional layer for the fabrication of a resistance switching device with the Ag/keratin/ITO structure; in this device, a stable resistive switching memory behavior with good retention characteristic was observed.
Via
mechanism analysis, it is expected that there is hopping conduction at low biases, and the formation of a conductive filament occurs at high biases. Furthermore, our device exhibited a stable switching behavior with different conductive materials (Ti and FTO) as bottom electrodes, and the influence of Ag and graphite conductive nanoparticles (NPs) doped into the keratin layer on the switching performance of the device was also investigated. This study not only suggests that keratin is a potential biomaterial for the preparation of memory devices, but also provides a promising route for the fabrication of bio-electronic devices with non-toxicity, degradability, sustainability
etc.
This study suggests that keratin is a potential biomaterial for the preparation of memory devices with non-toxicity, degradability and sustainability.
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IJS, KILJ, NUK, UL, UM, UPUK
NiO nanostructures and film were deposited on Cu foil using radiofrequency (RF) magnetron sputtering with oblique and glancing angle deposition technology. The modified CU foil was used as an anode ...material for a Li ion battery without binder or conductive additives. The electrochemical properties of the NiO electrodes depended on their porosity, which varied with the angle of incidence of the target with respect to the normal substrate surface. The NiO electrodes showed a well aligned nanorod structure when deposited at a glancing angle of 85°. The optimal NiO nanorod electrodes exhibited a reversible lithium capacity of 710 mAh g−1 at a current rate of 0.5C and 270 mAh g−1 at a current rate of 20 C. Furthermore, after 1000 ultra-long cycles at 2.0C, the capacity of the NiO nanorod electrode was retained at about 500 mAh g−1, which was ~ 70% of theoretical capacity. The high performance and ultra-long life cycle of the NiO nanorod electrodes was attributed to super-structures with macroporosity.
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•NiO nanorods array were deposited on Cu foil using RF magnetron sputtering.•NiO nanorods are used as anodes without binder and conductive additive.•The optimal NiO nanorods electrodes exhibit a reversible high capacity.•The ultra-long life over 1000 cycles should be attributed to the macroporosity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
CO oxidative coupling to dimethyl oxalate (DMO) is an important approach for the product of ethylene glycol and CO elimination. In this work, the Co doped Pd/Al2O3 nanocatalyst was highly effective ...for CO oxidative coupling and enhanced remarkably CO conversion and the formation of DMO. The maximum DMO STY reached 1082 g L−1 h−1 over the Pd/Al2O3@1/20Co catalyst at 130 °C for 2 h under the space velocity of 3000 h−1, which is two times higher than that over the Pd/Al2O3 catalyst. The Co modification and its influence on the structure of the Pd/Al2O3 catalyst were also studied systematically by XRD, TEM, CO‐TPD, N2 physical adsorption and XPS techniques. An appropriate Co doing was confirmed to promote distinctly the generation of smaller Pd particles and the adjustment of the adsorption or activation of CO over the catalyst. A positive interaction between Pd nanoparticles and the modulated support with Co doping was demonstrated and favored the enhanced activity of the catalyst for the reaction.
An efficient Pd nanocatalyst with Co doping was synthesized by impregnation method with in situ reduction, and exhibited an excellent catalytic activity for CO oxidative coupling to dimethyl oxalate. Co doping facilitated distinctly CO conversion and the formation of dimethyl oxalate arising from the positive interaction between Co and the catalyst.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract CO oxidative coupling to dimethyl oxalate (DMO) is an important approach for the product of ethylene glycol and CO elimination. In this work, the Co doped Pd/Al 2 O 3 nanocatalyst was highly ...effective for CO oxidative coupling and enhanced remarkably CO conversion and the formation of DMO. The maximum DMO STY reached 1082 g L −1 h −1 over the Pd/Al 2 O 3 @1/20Co catalyst at 130 °C for 2 h under the space velocity of 3000 h −1 , which is two times higher than that over the Pd/Al 2 O 3 catalyst. The Co modification and its influence on the structure of the Pd/Al 2 O 3 catalyst were also studied systematically by XRD, TEM, CO‐TPD, N 2 physical adsorption and XPS techniques. An appropriate Co doing was confirmed to promote distinctly the generation of smaller Pd particles and the adjustment of the adsorption or activation of CO over the catalyst. A positive interaction between Pd nanoparticles and the modulated support with Co doping was demonstrated and favored the enhanced activity of the catalyst for the reaction.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The resistance change of an insulator or semiconductor under applied current or voltage is defined as resistive switching effect, which is a significative physical performance in the exploit of new ...concept nonvolatile resistance random access memory (RRAM). In our work, the g-C3N4 powder was firstly fabricated by calcination method, and continuously a device with Ag/g-C3N4/FTO structure was prepared using drop-coated g-C3N4 powder to form a film onto FTO. It can be observed that the as-prepared cell exhibits an excellent resistive switching memory characteristic (HRS/LRS resistance ratio can be reached to ~ 52) and good reliability under applied voltage window of 4.0 V. Finally, it is believed that the space charge limited conduction is appropriate to understanding such the memory behavior.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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