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Superior anti-corrosion performance on Cu substrate achieved by dense polypropylene coating with ultrahigh inhibition efficiency deposited via the environmental-friendly method
No full textIn this work, an environmental-friendly and one-step synthetic method are adopted for the protective coating for electronic devices. A polypropylene (PP-V) coating has been deposited on Cu substrate by plasma enhanced chemical vapor deposition (PECVD). Compared with the solvent-based methods, the PECVD method enables the transition from gaseous feedstock to solid coating, and the process does not involve polluting organic solvents. Moreover, the PP-V coating prepared by the PECVD method possesses an excellent protective effect, which is determined by the high denseness of the coating. PP-V coating delivers 99.96% ultra-high corrosion inhibition efficiency and can increase the low-frequency impedance modulus of the substrate by 3 orders of magnitude, while providing good protection after 24 h of saltwater immersion as well, which displays a good application prospect in the protection of electronic devices
In situ TEM investigation of hexagonal WO3 irreversible transformation to Li2WO4
No full textLithium-ion migration at the WO3/electrolyte interface is governed by the phase transformation mechanism by which metastable states are replaced from one phase to another. Herein, an in situ single nanowire-based cell is constructed to investigate the dynamic phase transformation and morphology evolution of h-WO3 nanowire in real-time during its deep lithiation. One of the most significant features of h-WO3 lithiation is the irreversible transformation from h-WO3 to Li2WO4. There are a large number of deep ion-trapping sites composed of 4 O atoms in Li2WO4 crystal structure, that is, inserted lithium ions are irreversibly bound in these traps and nearly cannot be deintercalated. A mechanism on irreversible WO3-to-Li2WO4 transformation in deep lithiation reaction is demonstrated. With the aid of in situ transmission electron microscopy, we controllably triggered lithium-ion migration at the WO3/electrolyte interface and directly visualized the nanoscale lithium-ion migration as a stop motion movie. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
Fluorescent carbon dots with excellent moisture retention capability for moisturizing lipstick
No full textLong-lasting moisture retention is a huge challenge to humectants, and effective methods or additives for promote these functions are limited, especially nano-additives. Carbon dots (CDs) have attracted increasing research interest due to its ultra-small size, excellent optical properties and low toxicity, etc. However, most of researches have been focused on the photoexcited CDs and its subsequent photophysical and chemical processes, such as photoluminescence, photodynamic, photothermal and photocatalytic behavior. The intrinsic chemo-physical properties of the pristine CDs are not fully explored. Here, we report an excellent moisture retention capability of a new carmine cochineal-derived CDs (Car-CDs) for the first time. The relationship between the structure of Car-CDs and its moisture retention capability is revealed. More interestingly, the effective applications of Car-CDs in moisturizing lipstick are demonstrated. This work expands the research and application of CDs into a broad, new area, potentially in skin care
Understanding degradation mechanisms of perovskite solar cells due to electrochemical metallization effect
No full textOperational stability is becoming one of the most crucial parameters for commercialization of perovskite solar cells (PSCs). However the stability issue of PSCs is currently far from being resolved due to complicated and still unclear degradations. In this work, we systematically demonstrate the degradation of metal cathode PSCs under operation conditions. Discussions about influence of intrinsic factors i.e. light illumination, voltage and current, on device degradation are conducted. It is concluded that metal cathode stripping/plating behavior (electrochemical metallization effect) due to current together with perovskite degradation could dominate the device degradation. It is deduced that electrochemical cell in the PSC system could be formed by metal/counter electrodes and perovskite electrolyte. Both cells accelerate degradation of metal electrode and perovskite in working conditions, hence device degradation. These insights into the degradation and mechanisms can help further understand the working principle and solve the instability problem of perovskite-based optoelectronic devices
Research Progress on Evaluating the Effects of Nanomaterial-Based Development of Latent Fingerprints
No full textResearches on latent fingerprint development using novel nanomaterials including quantum dots, metal and metal oxide nanomaterials, rare-earth doped up- and down-conversion luminescent nanomaterials, carbon dots, metal-organic frameworks, and aggregation-induced emission materials have mushroomed in recent years, resulting in the emergence of nanomaterial-based development of latent fingerprints. Fingerprint development employing nanomaterials has some outstanding advantages such as simple operation, flexible approach, remarkable effect, and wide applicability, which can be served as an important supplement to the traditional techniques. So far, most studies have focused on discovering new nanomaterials and the advancement of new methods for latent fingerprint development. However, research on the influence factors and the comprehensive evaluations for the effects of fingerprint development still remains scattered and unsystematic. The accurate evaluation of fingerprint development effects is of great significance to the reasonable selection of developing methods and the objective assessment of physical evidence. In this review, we systematically summarized the evaluation methodologies on the effects of nanomaterialbased development of latent fingerprints from four aspects, namely, contrast, sensitivity, selectivity, and toxicity. In addition, the influence factors on the effects of latent fingerprint development were discussed in detail. It was summarized that the optical property of the nanomaterials had great effects on the developing contrast, the morphology and size of the nanomaterials had great effects on the developing sensitivity, and the adsorption performance and surface characteristic of the nanomaterials had great effects on the developing selectivity. At the end of this review, we also put forward some prospects for the nanomaterialbased development of latent fingerprints. From the perspective of developing materials, the nanomaterials should be involved in the transition from single luminescent property to multiple luminescent properties, from direct use of available nanomaterials to elaborate control of particle morphology and size, from simple surface treatment to targeted molecule modification, from toxic materials to non-toxic materials. From the perspective of developing strategies, the methods should be involved in the transition from strong background noise to weak fluorescent interference, from clear visualization of minutiae to distinct development of sweat pores, from physical adsorption mechanism to targeted molecule recognition, from effective development of trace evidence to nondestructive detection of biological evidence. While only focusing on improving the effects of fingerprint development, we also suggest researchers pay more attention to the evaluation of development effects, which will greatly promote fingerprint development techniques to play an important role in forensic sciences
Controlled lithium plating in three-dimensional hosts through nucleation overpotential regulation toward high-areal-capacity lithium metal anode
No full textThree-dimensional (3D) porous hosts with abundant space inside can accommodate volume variation during lithium (Li) plating/stripping and promote reversibility of Li anode; however, the porous structure in 3D hosts usually induces uneven Li-ion/electron migration, giving rise to undesirable surface preferential Li nucleation and growth. A feasible coating strategy is developed herein to create gradient nucleation overpotentials on Cu mesh to realize the 'bottom-up' Li plating mode on 3D host. The ex-situ scanning electron microscopy (SEM) characterization confirms that this two-step coating strategy by coating Au and polymer blend (polyacrylonitrile and poly(vinylidene fluoride-co-hexafluoropropylene)) on the bottom and top sides of Cu mesh, respectively, successfully changes the nucleation overpotentials of this 3D host by altering Li affinity. As a result, stable Li plating/stripping and high coulombic efficiency of 97.3% can be achieved under high areal capacity of 5.0 mAh/cm(2). The full cell using the modified Cu mesh with predeposited Li as the anode and lithium iron phosphate as the cathode (N/P ratio of similar to 4) can cycle steadily at 2.0 C with a capacity retention ratio of 96.4% after 150 cycles. The modification strategy proposed in this work is considered as a promising approach for designing a 3D conductive host for long life and safe Li metal batteries. (C) 2021 Elsevier Ltd. All rights reserved
Lightweight thermal interface materials based on hierarchically structured graphene paper with superior through-plane thermal conductivity
No full textGraphene-based papers have recently triggered considerable interests in developing the application as thermal interface materials (TIMs) for addressing the interfacial heat transfer issue, but their low through-plane thermal conductivity (kappa perpendicular to), resulting from the layer-by-layer stacked architecture, limits the direct use as TIMs. Although various hybrid graphene papers prepared by combining the graphene sheets and the thermally conductive insertions have been proposed to solve this problem, achieving a satisfactory kappa perpendicular to higher than that of commercial TIMs (>5 W m-1 K-1) remains challenging. Here, a strategy aimed at the construction of heat pathways along the through-plane direction inside the graphene paper for achieving a high kappa perpendicular to was demonstrated through the simultaneous filtration of graphene sheets with two different lateral sizes. The as-prepared graphene paper presented a hierarchical structure composed of loosely stacked horizontal layers formed by large graphene sheets, intercalated by a random arrangement of small graphene sheets. Due to the heat pathways formed by small graphene sheets along the through-plane direction, the hierarchically structured graphene paper exhibited an improved kappa perpendicular to as high as 12.6 W m-1 K-1 after a common graphitization post-treatment. In the practical test, our proposed paper as an all-graphene TIM achieved an enhancement in cooling efficiency of approximate to 2.2 times compared to that of the state-of-the-art TIM, demonstrating its superior performance to meet the ever-increasing heat dissipation requirement
The cutting process and damage mechanism of large thickness CFRP based on water jet guided laser processing
No full textCarbon fiber-reinforced polymer composites (CFRP) is a composite material with resin as matrix and carbon fiber as reinforcement. It has been widely used in aerospace, military products, and automotive industries. However, CFRP is prone to damage because of its complex anisotropy and low interlayer strength, so it is a typical difficultto-process material. Water jet guided laser processing technology is a combination of laser and water jet processing technology, which has the characteristics of no wear, no contact, flexible processing, and potential advantages of reducing HAZ and increasing cutting depth. In this paper, the water jet guided laser processing technology is used to perform cutting experiment for CFRP processing of low damage and large depth. In the experiment, the influencing law of the process parameters such as laser power, CFRP feed speed and water jet speed on the cutting results is obtained; then the cutting thickness of 1 mm, 2 mm, 4 mm and 10 mm CFRP is realized by adopting the parallel path layered scanning method. Moreover, the influences of carbon fiber arrangement direction and laser cutting path on the CFRP cutting damage mechanism are analyzed for the first time, and three damage mechanisms (exposing, falling-off and pulling-out) are summarized, which will provide the reference for the high precision cutting of large thickness CFRP
Highly thermal conductive red-emitting AlN-CaAlSiN3:Eu2(+) composite phosphor ceramics for high-power laser-driven lighting
No full textThermally robust red-emitting phosphor ceramics are urgently required for laser lighting and displays with high luminance and better color saturation. The most promising CaAlSiN3:Eu ceramics have a low thermal conductivity of 4.2 W m(-1) K-1 and a small luminance saturation of 0.5 W, making it hard to be used under high power laser irradiation. In this work, we incorporated AlN into the CaAlSiN3:Eu ceramic to produce red-emitting AlNCaAlSiN3:Eu composite phosphor ceramics by spark plasma sintering. The fully densified phosphor ceramics have the highest thermal conductivity reported so far (53.5 W m(-1) K-1), which is about 13 times higher than the reported one. The luminance saturation of the composite ceramics occurs at a high threshold of 4.2 W under blue laser excitation, enabling them to be used for high power laser lighting. This work provides an idea of tackling the microstructure of nitride phosphor ceramics and of preparing thermally robust red-emitting color converters
Non-covalent assembly of a super-tough, highly stretchable and environmentally adaptable self-healing material inspired by nacre
No full textDeveloping autonomous ambient temperature self-healing materials with excellent mechanical strength is extremely challenging. Herein, inspired by nacre and mussels, we utilize the T-shaped chain extender with quadruple hydrogen bonds on the side chain to extend the polyurethane (PU) prepolymer. Then by virtue of the high-density non-covalent bond interaction at the interface between the dopamine-modified graphene oxide and the PU matrix, we obtained an ultrarobust strong self-healing material. Relying on the rapid and dynamic reconstruction of side chain quadruple hydrogen bonds, the composite with an inverse artificial nacre structure and interwoven network exhibits excellent stretchability (596.2%), high ultimate tensile strength (10.3 MPa), toughness (37.8 MJ m(-3)), and Young's modulus (31.5 MPa), as well as unexpected ambient temperature rapid self-healing ability (90%, 25 degrees C for 1 h). Interestingly, graphene arranged in parallel in PU can significantly enhance the impermeability and long-term corrosion resistance of the coating. This bionic strategy provides a potential pathway to develop ultrarobust self-healing materials used in marine harsh environment equipment, various flexible functional devices and even medical materials