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Design and synthesis of HFCA-based plasticizers with asymmetrical alkyl chains for poly(vinyl chloride)
No full textA series of bio-based diester plasticizers with various alkyl chain asymmetry and the same molecular weight were designed and synthesized, using renewable 5-hydroxymethyl-2-furancarboxylic acid (HFCA) as the raw material. The chemical structures of the HFCA-based plasticizers were characterized by Fourier transform infrared and nuclear magnetic resonance (H-1 NMR and C-13 NMR). Besides, the influence of alkyl chain asymmetry on plasticization properties of the HFCA-based plasticizers in poly(vinyl chloride) (PVC) blends was also investigated. It was found that increasing the alkyl chain asymmetry of the diester plasticizer and keeping the molecular weight unchanged simultaneously could further improve its plasticizing efficiency, without sacrificing its volatility resistance and exudation resistance. The results showed that this study provided a new approach for further optimizing the overall properties of the asymmetric diester plasticizers
Introducing a self-improving catalyst for hydrogen evolution and efficient catalyst for oxygen evolution reaction
No full textHerein, MoS2/Ni3S2 nano-cubic rods (NCR) is fabricated on Ni foam via a two-step process including modified solution method and thiourea phosphate-assisted strategy. The resultant material serves as a selfimproving high intrinsic catalyst for hydrogen evolution reaction (HER), and exhibits desirable activity for oxygen evolution reaction (OER) in alkaline media. Results demonstrated that two different phases of MoS2 and Ni3S2 along with the presence of abundant active sulfur edge sites and particular structure lead to the enhanced electrocatalytic activity. The most interesting point is the self-improving behavior of MoS2/Ni3S2 NCR by proceeding the HER. It means by time and catalyzing the hydrogen evolution reaction the performance of catalyst improved, so that after long time HER the catalyst reaches 10 and 20 mA cm(-2) at overpotential of 40 and 85 mV, respectively. It is found that the improvement in catalytic performance can be assigned to the charge transfer enhancement and increasing in active surface area as HER proceeds. Further, characterization investigations show that thiourea phosphate-assisted strategy plays a key role to attain the nano-cubic rods structure. Indeed, the generated MoS2 nanolayers act as a substrate for anchoring and growing of Ni3S2 nano-cubic particles and consequently lead to preparation of cubic nano rods structures. Besides, low onset potential with the overpotential of 200 mV was obtained for OER using MoS2/Ni3S2 NCR. (C) 2021 Elsevier B.V. All rights reserved
Plasmomechanical Systems: Principles and Applications
No full textExtreme confinement of electromagnetic waves and mechanical displacement fields to nanometer dimensions through plasmonic nanostructures offers unprecedented opportunities for greatly enhanced interaction strength, increased bandwidth, lower power consumption, chip-scale fabrication, and efficient actuation of mechanical systems at the nanoscale. Conversely, coupling mechanical oscillators to plasmonic nanostructures introduces mechanical degrees of freedom to otherwise static plasmonic structures thus giving rise to the generation of extremely large resonance shifts even for minor position changes. This nanoscale marriage of plasmonics and mechanics has led to the emergence of a new field of study called plasmomechanics that explores the fundamental principles underneath the coupling between light and plasmomechanical nanoresonators. In this review, both the fundamental concepts and applications of plasmomechanics as an emerging field of study are discussed. After an overview of the basic principles of plasmomechanics, the active tuning mechanisms of plasmonic nano-mechanical systems are extensively analyzed. Moreover, the recent developments on the practical implications of plasmomechanic systems for such applications as biosensing and infrared detection are highlighted. Finally, an outlook on the implications of the plasmomechanical nanosystems for development of point-of-care diagnostic devices that can help early and rapid detection of fatal diseases are forwarded
Sequentially Bridged Graphene Sheets for High-Performance Anticorrosion
No full textGraphene has been widely studied in metal protection due to its complete impermeability and ultrathin properties. However, it is still a huge challenge to fully use the unparalleled features to design and construct graphene-based coatings with long-term anticorrosion properties. Herein, a facile and scalable approach to design an ultrathin bioinspired graphene-based (B-G-WEP) composite coating through sequential bridging of interfacial interactions and ordered graphene layers, is described. The combination of covalent bonding and pi-pi stacking greatly increases the graphene sheet ordered alignment and compatibility with epoxy matrix. This optimizes physical barrier effect, penetration resistance to sea water, and resistance to localized galvanic corrosion deterioration. The resultant B-G-WEP coating has a 190-times reduced corrosion rate as well as a three-orders increased impedance modulus, and keeps a high protection efficiency of 99.5% after 60 days of immersion tests. Furthermore, the coating damage function and coating damage index also decline by 2.8- and 10.7-fold, respectively. This work provides overall consideration to facile, scalable, practical, high barrier and anticorrosion properties, showing great potential applications for high-efficiency and durable metal protection
Integrated sensing array of the perovskite-type LnFeO(3) (Ln(=)La, Pr, Nd, Sm) to discriminate detection of volatile sulfur compounds
No full textDistinguishing toxic gases among the various volatile sulfur compounds (VSCs) is of significant practical value for atmospheric and environmental pollution monitoring, industrial monitoring, and even for medical diagnostics (where VSCs are indicators of diseases). The particular challenge lies in the detection and discrimination of sulfur-containing gases such as dimethyl disulfide (DMDS), methyl sulfide (DMS), hydrogen sulfide (H2S), and carbon disulfide (CS2) is of value. Herein, single-phase perovskite-type LnFeO(3) nanoparticles were prepared by the citrate sol-gel method. Their gas sensing characteristics regard to the four typical VSCs were investigated. We found that the gas response of the p-type semiconductor LnFeO(3) gas sensors to the four typical VSCs are significantly different. In addition, the sensors offer high performance, good tolerance to environmental changes and long-term stability for detecting VSCs gas at an operating temperature of 210 degrees C. A new design of sensor array was realized by integrating a series of LnFeO(3) materials, which revealed excellent recognition ability for various VSCs, showing promise for real time monitoring
Ni3N-V2O3 enables highly efficient 5-(Hydroxymethyl) furfural oxidation enabling membrane free hydrogen production
No full textConventional water electrolyzers produce H-2 and O-2 simultaneously. The sluggish water oxidation reaction (WOR) results in low overall energy conversion efficiency; also the production of O-2 is not of economic value. Thus, replacing sluggish anodic water oxidation reaction with 5-(Hydroxymethyl) furfural oxidation reaction (HmfOR) has been considered as a more energy-efficient strategy to produce hydrogen. Here, Ni3N incorporated by V2O3 is synthesized via thermal ammonolysis, which shows excellent bifunctional electrocatalytic performance for hydrogen evolution reaction (HER) and HmfOR. The electrocatalyst has strong tolerance to Hmf, which avoids the use of membrane. The Ni3N-V2O3 hybrids shows a low overpotential of 53 mV for HER, and a low overpotential of 230 mV for HmfOR, which is below 140 mV for WOR at 10 mA cm(-2). When Ni3N-V2O3 is employed as a bifunctional electrode, it offers a cell voltage of only 1.40 V at 10 mA cm(-2) for continuously hydrogen production
Optical thermostability and weatherability of TiN/TiC-Ni/Mo cermet-based spectral selective absorbing coating by laser cladding
No full textIn the present work, a monolayer of micro-nano scale TiN/TiC-Ni/Mo ceramic solar spectral selective coating was deposited on the stainless steel substrate by laser cladding. The absorptance (alpha) and emittance (epsilon) of the coating prepared at the mixed scale of TiN/TiC-Ni/Mo were 80.1% and 2.24%, respectively. After annealing at 600 ?C for 24 h, the absorptance increased to 80.8% and the emittance was 1.9%. The ratio of absorptance to emittance is alpha/? = 42.52. This study showed that the thermal stability and optical properties of the ceramic coating was excellent under high temperature. It also provides a new idea for the preparation of solar absorbing coatings in the future
Structural and Magnetic Properties of P Microalloyed Fe76Cu0.8Nb2.2B9Si12 Alloys
No full textThe development of Fe-based nanocrystalline alloys with high saturation magnetization (B-s), excellent magnetic softness and good manufacturability is highly desirable. Here, the effect of substituting 1 at% P for B and Si on the thermal stability, microstructure and magnetic properties of Fe76Cu0.8Nb2.2B9Si12 alloy has been studied in detail. It was found that replacing B with P effectively reduces the coercivity (H-c) of the alloy without deteriorating the B-s and permeability (mu). However, replacing Si with P has little effect on the H-c and B-s, yet significantly reduces the mu. The variation in the magnetic properties can be well understood from the evolution of the microstructure and magnetic anisotropy induced by P microalloying. The Fe76Cu0.8Nb2.2B8Si12P1 alloy with a good processing window, a high B-s of 1.41 T, a great mu of 29,000 at 1 kHz and a low H-c of 0.6 A/m is suitable for high-power electronic devices
Small activation entropy bestows high-stability of nanoconfined D-mannitol*
No full textIt has been a long-standing puzzling problem that some glasses exhibit higher glass transition temperatures (denoting high stability) but lower activation energy for relaxations (denoting low stability). In this paper, the relaxation kinetics of the nanoconfined D-mannitol (DM) glass was studied systematically using a high-precision and high-rate nanocalorimeter. The nanoconfined DM exhibits enhanced thermal stability compared to the free DM. For example, the critical cooling rate for glass formation decreases from 200 K/s to below 1 K/s; the T (g) increases by about 20 K-50 K. The relaxation kinetics is analyzed based on the absolute reaction rate theory. It is found that, even though the activation energy E* decreases, the activation entropy S* decreases much more for the nanoconfined glass that yields a large activation free energy G* and higher thermal stability. These results suggest that the activation entropy may provide new insights in understanding the abnormal kinetics of nanoconfined glassy systems
Epitaxial Growth and Stoichiometry Control of Ultrawide Bandgap ZnGa2O4 Films by Pulsed Laser Deposition
No full textZnGa2O4 is a promising semiconductor for developing high-performance deep-ultraviolet photodetectors owing to a number of advantageous fundamental characteristics. However, Zn volatilization during the ZnGa2O4 growth is a widely recognized problem that seriously degrades the film quality and the device performance. In this study, we report the synthesis of epitaxial ZnGa2O4 thin films by pulsed laser deposition using a non-stoichiometric Zn1+xGa2O4 target. It is found that supplementing excessive Zn concentration from the target is highly effective to stabilize stochiometric ZnGa2O4 thin films during the PLD growth. The influence of various growth parameters on the phase formation, crystallinity and surface morphology is systematically investigated. The film growth behavior further impacts the resulting optical absorption and thermal conductivity. The optimized epitaxial ZnGa2O4 film exhibits a full width at half maximum value of 0.6 degree for a 120 nm thickness, a surface roughness of 0.223 nm, a band gap of 4.79 eV and a room-temperature thermal conductivity of 40.137 W/(m.K). This study provides insights into synthesizing epitaxial ZnGa2O4 films for high performance optoelectronic devices