Nanotechnology最新文献

The trend towards miniaturization of electronics and increasing transistor density in semiconductors requires more efficient cooling solutions. Vapor chambers are well established passive cooling devices that are used in a wide variety of electronics. Commercial vapor chambers are often made of high-density metals such as copper which can be a downside in lightweight applications such as laptops, smartphones, and tablets. In this study, different novel lightweight graphene-enhanced vapor chambers were built using graphene-assembled film with high thermal conductivity as envelope material. The thermal performance of the designed graphene-enhanced vapor chambers was characterized in a customized test rig and compared to a copper vapor chamber. One of the graphene-enhanced vapor chambers was shown to have 21.6% lower thermal resistance than that of a copper vapor chamber with the same design. A mass-based thermal resistance parameter was introduced as a figure of merit to account for the superior low density of the graphene-enhanced vapor chambers. The mass-based thermal resistance of the graphene-enhanced vapor chamber was seen to be 46.5% lower than that of the copper vapor chamber. The result of this study shows that replacing copper with graphene-assembled film as envelope in vapor chambers can both reduce thermal resistance and decrease the mass of the device. Hence, it is believed that graphene-enhanced vapor chambers have great potential for replacing conventional metal-based vapor chambers in lightweight and high-performance electronics and power module cooling applications in the future.

In this study, the mixture of zinc acetate dehydrates and boric acid was pyrolyzed in zeolite X to prepare novel B/ZnO/zeolite nanocomposites for the enhanced removal of tartrazine (TA) in aqueous environment. The composites are porous material with a relatively large pore size (35.3 nm). The surface area of the composite (19.72 m²g^-1) is smaller than that of zeolite (248.78 m²g^-1), but its adsorption capacity is quite high (q_maxof 97.6 mg g^-1). The factors influencing the adsorption process were investigated in detail. Under the optimal conditions (the initial dye concentration of 20 mg l^-1, the adsorbent content of 0.5 g l^-1, pH equal 6, and the temperature of 25°C), the removal efficiency (R_e) was 97.5%. The first and second-order equations were used to model the kinetic adsorption. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models were used to study isothermal adsorption. In addition, the thermodynamic of adsorption was also investigated. The ΔH^oof -52.423±2.306 kJ mol^-1indicates the exothermic process and the negative ΔG^oindicates a spontaneous process. At low temperatures, the adsorption of TA proceeds smoother and more effectively, and the negative ΔS^o(-129.638 7.376 J·mol^-1·K^-1) indicates a decrease in the degree of freedom of the adsorbed species. The adsorption mechanism was also proposed.

To advance the industrialization of flexible strain sensors, an innovative flexible sensing fiber was developed through a sophisticated wet spinning process. Silver trifluoroacetate and graphene oxide (GO) were combined with thermoplastic polyurethane (TPU) to prepare the fibers via wet spinning. Ascorbic acid was used toin situreduce the silver trifluoroacetate and graphene oxide within the polyurethane, causing the growth of silver nanoparticles to bond with reduced graphene oxide, forming a dual conductive pathway. This resulted in the creation of silver nanoparticles/reduced graphene oxide/polyurethane fibers (AgNPs-rGO-TPU sensing fibers). The tensile and sensing properties of AgNPs-rGO-TPU sensing fibers under different parameters were investigated. The results showed that with 25 wt% TPU as the matrix, 30 wt% silver trifluoroacetate, and 1 wt% graphene oxide, the fibers achieved an optimal balance of mechanical and sensing properties. The tensile strength was 7.69 MPa, the elongation at break was 370.75%, and the toughness modulus was 18.45 MJ m^-3. The AgNPs-rGO-TPU sensing fibers effectively detect external stimuli, exhibiting high sensitivity over a wide strain range (gauge factor is 4.25 below 5% strain, 24.79 in the 5%-25% strain range, 23.06 in the 25%-80% strain range, and 21.32 in the 80%-110% strain range), with a conductivity of 163.17 ms·cm^-1. They can stably recognize movements and physiological signals from various parts of the human body, showing good application prospects.

In this letter, we investigated the impact of percolation transport mechanisms on ferroelectric field effect transistor (FeFET) multi-value storage with Kinetic Monte-Carlo (KMC) simulation considering aspect ratio and temperature dependencies. It is found that the portion of the ferroelectric polarization, which dominated the threshold voltage shift of the FeFET, increases when aspect ratio of device decreases. Moreover, randomness of percolation path formation and variations of equivalent conductance can be suppressed, indicating mitigation of device-to-device variations and enhancement of separation of individual states. Besides, to further investigate an amorphous channel promising in multi-bit applications, disorder effects in channel contribute to intrinsic percolation transport, coupling with multi-domain dynamics in Fe-layer, are studied by the high temperature characterization. On this basis, the KMC scheme is further modified to predict multi-value distribution from 300 K to 400 K. To tackle with such critical reliability issues induced inaccuracy for in-memory computing (CIM), an efficient write-verify scheme is proposed to mitigate state overlapping and provides in-depth insights for co-design of device reliability and multi-bit CIM performances. .

We reported a novel strategy by the combination of two-step annealing treatment and ionic-liquid gating technology for effectively regulating the properties of g-C3N4, especially largely reducing the recombination rate of the electron-hole pairs, with evidenced by the remarkable reduction of photoluminescence (PL) intensity. Firstly, graphitic carbon nitrides with typical layered structure were obtained by annealing melamine with temperature above 500°C. Further annealing at 600°C with much longer time (from 2 hours to 12 hours) were found to effectively reduce the imperfections or defects, and thus the PL intensity (49% reduction). Secondly, by post-treating annealed sample with ionic liquid, the PL were found to be further reduced, mainly due to the passivation of charged defect centers by ionic liquid. Additionally, applying an external electric field in an ionic liquid (IL) environment significantly enhance charged defect passivation. The ionic liquid gating resulted in a larger bandgap and further reduced PL intensity. This study demonstrates a new approach for defect passivation, providing insights and strategies for modulating properties of advanced materials such as g-C3N4. .

Ciprofloxacin (CIP) is a widely used antibiotic, and its presence in water bodies poses a risk due to its resistance to conventional wastewater treatment processes. The accumulation of such pharmaceuticals can disrupt aquatic ecosystems, harm aquatic life, and contribute to ecological imbalances. Therefore, the degradation of CIP is of immense environmental significance. This study presents the microwave-assisted catalytic degradation of the antibiotic drug CIP using nanocomposites of carbazole copolymerized with pyrrole (PCz-co-PPy) and with thiophene (PCz-co-PTh). The PCz-co-PPy and PCz-co-PTh nanocomposites were synthesized through an ultrasound-assisted method. The resulting nanocomposites were characterized using spectral and morphological analyses. FT-IR and UV-Vis spectroscopy confirmed successful intercalation and copolymerization, while FESEM images revealed a chain-like morphology. These copolymer nanocomposites were employed as microwave-active catalysts for CIP degradation, achieving an optimal degradation efficiency of 95% within 21 min using PCz-co-PPy-50/50 and PCz-co-PTh-50/50 at 600 W microwave power. The degradation followed pseudo-first-order kinetics, with rate constants calculated as 0.031 min^-1, 0.020 min^-1, 0.030 min^-1, 0.056 min^-1, and 0.071 min^-1for PCz, PPy, PTh, PCz-co-PPy-50/50, and PCz-co-PTh-50/50 nanocomposites, respectively, for a 50 mg l^-1CIP solution. The catalytic efficiency is attributed to the formation of microwave-induced active species, including hot spots, electrons (e^-), holes (h⁺), superoxide radicals (•O₂^-), and hydroxyl radicals (•OH). Scavenger analysis verified that •OH and •O₂^-radicals play a crucial role in CIP degradation. A possible degradation mechanism and pathway for the nanocomposite system is proposed.

Developing effective and low-cost enzyme-like nanomaterials to kill bacteria is vital for human health. Herein, nanorod-assembled NiCo₂O₄microspheres were prepared though a facile hydrothermal method, andshowed highly enhanced peroxidase-like activity compared to pure Co₃O₄due to its large surface area and abundant active sites. The NiCo₂O₄possess the ability to catalyze H₂O₂to generate large amounts of •O^2-, which can be used for bacteriostatic applications. In particular, the antibacterial system combining the spiky NiCo₂O₄particles and a low concentration of H₂O₂(100μM) exhibits an excellent bacteriostatic efficiency against bothEscherichia coli(94.44%) andStaphylococcus aureus(93.45%).

This paper presents a straightforward and easily scalable method for producing buckypapers. These thin films consist of single-walled carbon nanotubes (SWCNTs) dispersed on a PET substrate using an airbrushing technique, followed by solvent evaporation. Notably, this process requires minimal equipment complexity. The study investigates the electrical properties of buckypapers made from both purified and unpurified SWCNTs, as well as chemical vapor deposition graphene. Specifically, we focus on their electromagnetic interference (EMI) shielding effectiveness in theS-band of microwaves (2-4 GHz). To evaluate this, we installed buckypaper and graphene plates within a waveguide cross section. The results show that these buckypapers exhibit high overall shielding effectiveness. It is found that buckypapers based on purified carbon nanotubes have higher shielding parameters (due higher electrical conductivity measured by TRL method) than those based on unpurified CNTs. In summary, our approach offers a practical route for manufacturing effective EMI shielding materials, with potential applications in various technological domains.

This paper presents the synthesis of mixed metal oxide (BaTiO₃: ZnO) (B: Z) sensors with various molar ratios using a low-temperature hydrothermal method for dual sensing applications (gas and acceleration). The sensor developed with an equal molar ratio of 1B:1Z, showcases superior performance compared to unmixed and alternative mixed metal oxide sensors. This equilibrium in ratios optimally enhances synergistic effects between elements B and Z, resulting in improved sensing properties. Furthermore, it contributes to structural stability, enhancing performance in gas and acceleration sensing. A decreased band gap of 2.82 eV and a rapid turn-on voltage of 0.18 V were achieved. The acceleration performance of 1B:1Z sensor exhibits a maximum voltage of 2.62 V at a 10 Hz resonant frequency and an output voltage of 2.52 V at 1 g acceleration, achieving an improved sensitivity of 3.889 V g^-1. In addition, the proposed gas shows a notable sensor response of ∼63.45% (CO) and 58.29% (CH₄) at 10 ppm with a quick response time of 1.19 s (CO) and 8.69 s (CH₄) and recovery time of 2.09 s (CO) and 8.69 s (CH₄). Challenges in selectivity are addressed using machine learning, employing various classification algorithms. Linear discriminant analysis achieves superior accuracy in differentiating between CO and CH_4,reaching 96.6% for CO and 74.6% for CH₄at 10 ppm. Understanding these concentration-dependent trends can guide the optimal use of the sensors in different current applications.

Nanomaterials stand out for their exceptional properties and innovative potential, especially in applications that protect against space radiation. They offer an innovative approach to this challenge, demonstrating notable properties of radiation absorption and scattering, as well as flexibility and lightness for the development of protective clothing and equipment. This review details the use of polymeric materials, such as polyimides (PIs), which are efficient at attenuating ultraviolet (UV) radiation and atomic oxygen (AO). For example, polyimides show a decrease in elongation at break by 10% after exposure to VUV radiation of 2000 equivalent solar hours (ESH). The thermal stability under vacuum ultraviolet (VUV) irradiation shows that colorless polyimides like CPI-T/Al exhibit an onset degradation temperature of 451°C, while CPI-L/Al shows a degradation onset of 439° C. Additionally, advancements in composite materials for gamma and neutron radiation shielding are covered. Materials such as fluorinated hyperbranched polyimides (FHBPI) display a decomposition temperature of approximately 450°C, which ensures structural integrity during space missions involving radiation. Radiation absorption and scattering properties of these composites are assessed, with materials such as W-Bi2O3 demonstrating a high linear attenuation coefficient (LAC) of 2.5 MeV, enhancing their efficiency in protecting against gamma radiation. Mechanical and optical changes, such as a 15% increase in solar absorbance after exposure to VUV, are critical for prolonged space missions. Moreover, the integration of nanoparticles like graphene and carbon nanotubes into polymers has proven to be an efficient strategy for improving the shielding properties and stability of materials. Nanocomposites like BNTT-Ti display a neutron transmission reduction of 20%, further validating their potential for space applications. Future investigations will focus on optimizing the functionality, manufacturing, and compatibility of composite materials, as well as validating their performance under actual space mission conditions. Collaboration among material scientists, aerospace engineers, and space agencies is vital to transforming laboratory discoveries into viable solutions for radiation protection in space.