Synthetic Metals最新文献

This study focuses on the rheological and tribological effects of the addition of graphene (GR) and functionalised multi-wall carbon nanotubes (FMWCNTs) as mono and hybrid nanoparticles in a polyester lubricant. We conduct a rheological study of viscosity in the range 30–100°C, following the ASTM D2270 standard. We also carry out a tribological study based on a four-ball test following the ASTM D4172 and ASTM D2783 standards for both wear and extreme pressure sample analysis. These studies reveal that FMWCNT has a higher degree of shear-thinning flow behaviour compared to GR nanolubricant samples. Samples with a higher GR ratio with added CTAB surfactant gave higher compared to samples with a lower GR ratio. The CTAB surfactant is found to enhance the dispersion and stability of the hybrid nanolubricant, and the hybrid nanoparticle system helps in preserving the complexity of the system, even at higher temperatures. The tribological findings show that the samples with GR tend to have a reduced coefficient of friction (COF) and increased wear scar diameter (WSD), while the samples with FMWCNTs tend to have increased COF and reduced WSD. This is due to the presence of the GR ball, which consists of nanoplatelets that have a spherical form and function as a nano ball bearing. This study explores the properties of a unique hybrid material that has promise as a lubricant additive to reduce friction and wear.

The Ni-Co nanoparticles with various Ni/Co ratios are immobilized on a Ni foam (NF) template, coated with reduced graphene oxides (rGO), and used as a novel noble-metal-free anode electrocatalyst for enhanced performance direct borohydride fuel cells. The electrochemical active surface area (EASA) of Ni₅₀Co₅₀ /rGO/NF (1515 cm²) catalyst is 45.5 times larger than NF (33.3 cm²). A comprehensive study of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) by Pt/C (0.5 mg cm⁻²) as a cathode and Ni₅₀-Co₅₀/rGO/NF as an anode is accomplished, so an open-circuit potential (OCP) of 1.90 V and the maximum power density of 309 mW cm⁻² is obtained at 60 ^◦C. These results show that electrocatalyst Ni₅₀Co₅₀/rGO/NF is a suitable candidate for use as an electrocatalyst in DBHPFC due to its low cost, ease of synthesis, excellent structural stability, and high catalytic performance.

The effect of graphite nanoflakes (GNFs)/modified barium titanate (MBT) hybrid fillers on the mechanical, electrical, and thermal properties of ethylene-propylene-diene monomer (EPDM) was extensively investigated in the current study. Moreover, the effect of gamma irradiation on the different properties of the prepared nanocomposites was investigated. To accomplish this goal, EPDM/MBT composites with various GNFs contents (0, 2, 4, 6, and 8 phr) were fabricated using a conventional roll mill. Graphite was expanded by heating and subsequently modified using tween 80 surfactant, resulting in the formation of GNFs. The presence of various functional groups on the surface of the modified BaTiO₃ particles was verified by Fourier transform infrared spectroscopy (FTIR). The scanning electron microscopy (SEM) analysis revealed a uniform dispersion of GNFs in EPDM/MBT composites, with a concentration up to 6 phr. The study revealed that the mechanical properties of the nanocomposites were reinforced by the inclusion of GNFs up to 6 phr. The irradiated EPDM/MBT/6 phr GNFs nanocomposite exhibited the maximum elastic modulus value of 4.8 MPa, which was approximately 32 % higher than that of the corresponding unirradiated nanocomposite. The thermal conductivity of the irradiated EPDM/MBT/8 phr GNFs nanocomposite increased from 0.213 W/m.K to 0.260 W/m.K (22 %), while the dielectric constant increased from 4.475 to 5.551 (24 % increase) at 10³ Hz as compared to the pure EPDM/MBT composite. The enhanced electric and thermal performance of GNFs can be attributed to the mobility of their π-electrons.

Doping of 2,2′,7,7′-tetrakis(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene(Spiro-OMeTAD), which is the most common used hole transport material in perovskite solar cells, is widely studied. Especially, bis(trifluoromethane)sulfonamide (Li-TFSI) combined with 4-tert-butylpyridine (TBP) is the most studied dopant to improve the conductivity of Spiro-OMeTAD, with conductivity around 6×10⁻⁸ S/cm. In this study, we employed a new oxidizing agent NO₂ to dop the Spiro-OMeTAD simply by vapor exposure, showing efficient doping with conductivity up to 2.53×10⁻³ S/cm and excellent film quality. The doping mechanism was further analyzed by ultraviolet-visible-near infrared spectroscopy (UV-Vis-NIR), electron paramagnetic resonance spectroscopy (EPR), Fourier infrared absorption spectroscopy (TFIR), and X-ray photoelectron spectroscopy. Our findings highlight the potential of molecular doping with NO₂ to significantly improve the conductivity of Spiro-OMeTAD, providing a deep understanding of the doping effects on Spiro-OMeTAD.

The continuous search for novel materials to meet the requirements of modern technological applications has led to the widespread use of polyaniline (PANI) composites for sensing purposes. Although research has been carried out on both chemical sensors using PANI/polymer composites and chemical sensors with impedimetric/capacitive transduction using PANI composites, there is still a gap in the use of PANI/polymer composites in impedimetric and capacitive transduction platforms for pH sensing. In this study, the influence of composite thin films consisting of PANI and poly(methyl methacrylate) (PMMA) on the sensitivity and linearity of pH sensors based on electrochemical impedance and capacitance spectroscopy (EIS/ECS) was evaluated. The sensitivity and linearity of the devices showed a dependence on the polymer content. For PANI:PMMA equal to 30:70, the EIS and ECS sensitivity reached 12.6 ± 2.7 and 18.7 ± 4.9 %/pH, respectively, after reaching its minimum value for the 50:50 sample. Similarly, the linearity values for the 30:70 sample were 92.7 % and 99.8 % for EIS and ECS, respectively. We were able to encapsulate the PANI in the PMMA matrix, which improved the control of ion diffusion and analyte access to the active redox quinoid rings on the PANI. As a result, the saturation effect of the polymer was reduced. By adjusting the relative content of PANI and PMMA, the structure and properties of the composite can be controlled, directly affecting the sensor parameters. These materials have potential applications in sensors for various fields such as food, biomedical and environmental monitoring, with the ability to tailor their properties for optimal response.

PEDOT:PSS flexible thermoelectric materials are promising for future wearable continuous power support, but it remains challenging due to low power factor. Herein, we propose a “one-stone-two-birds” strategy using L-ascorbic acid as the reductant in synthesis of tellurium nanorods and separating agent in in-situ removing PSS chains. L-ascorbic acid reduces Te⁴⁺ to Te, supplying inorganic thermoelectric materials with high Seebeck coefficient as fillers to significantly increase the Seebeck coefficient value of PEDOT:PSS. Meanwhile, L-ascorbic acid separates PSS chains from PEDOT chains, resulting in the increase of electrical conductivity at room temperature by ∼360 % due to structure transformation from benzoid structure to the quinoid structure in PEDOT. As a result, the power factor of optimal PEDOT:PSS with Te fillers and L-ascorbic acid treatment is improved significantly by ∼100 times as compared to that of pristine PEDOT:PSS. Finally, a prototype wearable thermoelectric generator was assembled by 18 legs of Te/PEDOT:PSS composites, which demonstrates a high power density of 2.3 μW·cm⁻² with good mechanical stability, flexibility and durability. The present study offers a new strategy for rational design of high-performance flexible thermoelectric materials from PEDOT:PSS.

The discovery of transparent electrodes led to the development of optoelectronic devices such as touchscreens, infrared (IR) sensors, etc. Carbon nanotubes (CNTs) have been a potential replacement for ITO due to their exceptional properties, especially in the IR region. In this work, we present the development of a CNT-polymer composite thin film that exhibits outstanding transparency across visible and IR spectra prepared by layer-by-layer (LbL) technique. This approach ensures uniform integration and crosslinking of CNTs into lightweight matrices, and also represents a cost-effective method for producing transparent electrodes with remarkable properties. The produced films achieved a transparency above 80 % in the UV/VIS range and approximately 70 % in the mid-IR range. The sheet resistance of the fabricated thin films was measured at about 4 kΩ/sq, showing a tendency to decrease with the number of bilayers. In this work we have investigated electrical properties and transport mechanisms in more detail with computational analysis. Computational analysis was performed to better understand the electrical behavior of nanotube-polymer junctions in the interbundle structure. Based on all results, we propose that the transparent electrodes with 4 and 6 bilayers are the most optimal structures in terms of optical and electrical properties.

Non-fused ring electron acceptors (NFREAs) have displayed promising candidates for practical application of organic solar cells (OSCs) owing to their short synthesis routes and cost effectiveness. The terminal groups halogenation have facilitated the optimization the physicochemical properties of NFREAs. In this work, we developed two NFREAs using a phenyl-substituted benzodithiophenedione unit as central core and electron-withdrawing groups 2-(3-oxo-2,3-dihydro-1 H-inden-1-ylidene) malononitrile (IC) or chlorinated IC (IC-2Cl) as the terminal groups. These NFREAs were designated as BDDPh-H and BDDPh-Cl, respectively. DFT calculations revealing that both NFREAs exhibited good backbone coplanarity due to S…O noncovalent interactions, and BDDPh-Cl exhibited red-shifted absorption compared with BDDPh-H owing to the stronger molecular stacking caused by chlorinated terminal groups. Moreover, BDDPh-Cl-based blended film demonstrated better nano-scale morphology, facilitating exciton dissociation and charge transport. Thus, PM6: BDDPh-Cl-based OSCs achieved a higher power conversion efficiency (PCE) of 12.69 %, outperforming BDDPh-H-based device (3.20 %) due to the enhanced short-circuit current and fill factor. Our findings indicate that combining phenyl-substituted benzodithiophenedione as central unit with chlorinated terminal groups showed great potential to construct highly efficient NFREAs.

Bismuth ferrite (BF) serves a potential electrode-active material due to its peculiar characteristics such as wide voltage window and high specific capacitance, excellent stability, facile synthesis routes, etc. to name a few. Herein we report the strategic design and facile synthesis of multiwalled carbon nanotubes (MWCNT)/BF/polyaniline (PANI) nanocomposites, particularly for application in advanced supercapacitors. The MWCNT/BF/PANI nanocomposite architecture is a strategic design in which the maximum available surface area is utilized for the electrode nanostructure with increased porosity that allows easy movement of electrolyte-ions through it. The uniform arrangement of BF on MWCNTs helps in mitigating the possible agglomeration, further augmenting the surface area for an enhanced charge storage. The strategic layout of PANI on BF-decorated MWCNTs has given a coral-like structure for the nanocomposite electrode which significantly increased the surface area, reduced ion pathways and facilitating better access to electrolytic K⁺ ions. The MWCNT/BF/PANI nanocomposite electrode exhibits a specific capacitance of 3640 F g⁻¹ at a current density of 5 A g⁻¹. The innovative design as well as the synergy between the individual components of the nanocomposite electrode play a pivotal role in attaining the enhanced electrochemical performance.

Considering the energy level cascade, introducing a hole transport layer (HTL) between the NiOx and perovskite layers has become a common and effective strategy to enhance the performance of inverted perovskite solar cells (PSCs). Herein, we designed and synthesized three hole-transporting interfacial layers (TPAD, TPAO, and TPAS) based on a dibenzofulvene-bridged triphenylamine (TPA) core to fabricate efficient and stable inverted NiO_x-based PSCs. Dibenzofulvene, known for its sp²-hybridized structure, offers superior planarity and molecular stacking, and it easily bonds with triphenylamine derivatives, resulting in unique light-harvesting and charge mobility properties for optoelectronic applications. Specifically, diphenylamine, dimethoxy diphenylamine, and dimethylthio diphenylamine were used as end-capping units for TPAD, TPAO, and TPAS, respectively. The NiO_x-based inverted PSC devices fabricated with TPAS as an interfacial layer effectively modified NiO_x to improve energy level alignment, enhance film quality and crystallinity, and improve carrier transport, leading to a high-quality perovskite layer and superior interface contact behavior. Consequently, this device yielded a highly efficient cell performance of 20.30 %, surpassing those using TPAD (19.29 %) and TPAO (18.78 %) as interfacial layers, and significantly outperforming devices using only NiO_x (17.69 %). Additionally, the champion cell exhibited negligible hysteresis and long-term stability. These findings demonstrate a facile approach to preparing multifunctional TPA-based hole transport materials and showcase the efficient performance of inverted cells based on a triphenylamine dibenzofulvene-based interfacial layer, contributing to the development of high-efficiency inverted PSCs.