Increase In Electrical Conductivity Research Articles

Enhancing Effect of Fullerene Guest and Counterion on the Structural Stability and Electrical Conductivity of Octahedral Metallo‐Supramolecular Cages

Metallo‐supramolecular cages have garnered tremendous attention for their diverse yet molecular‐level precision structures. However, physical properties of these supramolecular ensembles, which are of potential significance in molecular electronics, remain largely unexplored. We herein constructed a series of octahedral metallo‐cages and cage‐fullerene complexes with notably enhanced structural stability. As such, we could systematically evaluate the electrical conductivity of these ensembles at both single‐molecule level and aggregated bulk state (as well‐defined films). Our findings reveal that counteranions and fullerene guests play a pivotal role in determining the electrical conductivity of aggregated state, while such effects are less significant for single‐molecule conductance. Both counteranions and fullerenes effectively tune the electronic structures and packing density of metallo‐supramolecular assemblies, and facilitate efficient charge transfer between the cage hosts and fullerenes, resulting in a notable one order of magnitude increase in electrical conductivity of the aggregated state.

Photoconductivity of explosive percolation in conductive polymer/graphene oxide nanocomposite films

AbstractIn this study, we explored the behavior of protonated polyaniline/graphene oxide (PANI‐CSA/GO) nanocomposite films with varying GO concentrations, focusing on the novel phenomenon of explosive percolation. We observed a significant increase in electrical conductivity at the explosive percolation threshold, attributed to the emergence of a percolating metallic pathway. This discovery positions PANI‐CSA/GO films as promising materials for various electronic and electrical engineering applications. Additionally, the films demonstrated consistent and repeatable photoconductivity, showing potential for use in high‐performance UV‐photodetectors, photoactive layers in solar cells, light‐emitting diodes, and energy storage devices. Structural analyses using fourier transform infrared spectroscopy (FTIR) and x‐ray diffraction (XRD) confirmed successful GO incorporation within the PANI‐CSA matrix. Different morphological features were observed depending on the GO volume fraction, with increased GO enhancing thermal stability in the conductive zone. Our findings highlight the immense potential of PANI‐CSA/GO nanocomposite films in advanced electronic applications, emphasizing their novel conductive and photoconductive properties and improved thermal stability.

Assessing the Impact of Brackish Water on Soil Salinization with Time-Lapse Inversion of Electromagnetic Induction Data

Over the last decade, electromagnetic induction (EMI) measurements have been increasingly used for investigating soil salinization caused by the use of brackish or saline water as an irrigation source. EMI measurements proved to be a powerful tool for providing spatial information on the investigated soil because of the correlation between the output geophysical parameter, i.e., the electrical conductivity, to soil moisture and salinity. In addition, their non-invasive nature and their capability to collect a high amount of data over broad areas and in a relatively short time makes these measurements attractive for monitoring flow and transport dynamics, which are otherwise undetectable with conventional measurements. In an experimental field, EMI measurements were collected during the growth season of tomatoes and irrigated with three different irrigation strategies. Time-lapse data were collected over three months in order to visualize changes in electrical conductivity associated with soil salinity. A rigorous time-lapse inversion procedure was set for modeling the soil salinization induced by brackish irrigation water. A clear soil response in terms of an increase in electrical conductivity (EC) in the upper soil layer confirmed the reliability of the geophysical tool to predict soil salinization trends.

Changes in the Properties of Soils Contaminated with Oil Production Water Before and Af ter Treatment with CaO

In the Mexican southeast, hydrocarbon spills and their residues af fect various agricultural sites. A specific case is spills of oil production or congenital waters that cause soil salinization. When soil is contaminated, restorations are regularly carried out based on regulatory limits, but many regions still do not consider the pedological classification, so restorations are not entirely ef fective and, in the case of agricultural soils, reduce your productivity. For these reasons, this study evaluated the cation exchange with CaO applied to four soils contaminated with congenital waters and determined if there are dif ferences in the treatment behavior according to the properties of each soil. It will be found that sandy soils require less treatment time, but have greater ef fects on their properties compared to clay soils, mainly in field capacity, pH, and porosity. Furthermore, it was found that contaminant removal times vary with respect to the type of soil and that this could be related to the amount and type of clay. In the case of congenital water spills, clay soils show a greater increase in electrical conductivity (EC) compared to sandy soils. When remediated with CaO, clay soils needed longer treatment times to reduce EC, but presented fewer changes in their physical and chemical properties. In addition, it was found that, although washing with drinking water is carried out, the treatment with CaO adds alkalinity to the soils, so they must be managed according to the crop to be developed. It is concluded that soils have dif ferent physical and chemical properties, this influences the response they have to an external agent, both when contaminated and when remediated.

Defect and dopant complex mediated high power factor in transparent selenium-doped copper iodide thin films

Copper iodide (CuI) is a promising p-type transparent thermoelectric material for near-room temperature energy harvesting. We report a high-power factor for selenium (Se)-doped CuI films. Ion beam-sputtered CuI films were doped using 30 keV 80Se+ implantation with Se concentration varying between 0.50% and 6.50%. Hall effect measurements showed a ∼34% increase in electrical conductivity (σ ≈ 36.1 Ω−1cm−1) due to a ∼54% increase in carrier density (pH ≈ 5.4 × 1019 cm−3) in the p-type γ-CuI film implanted with 5.0 × 1014 Se.cm−2. A high Seebeck coefficient, α ≈ 388.9 μVK−1−1, and moderate electrical conductivity, σ ≈ 29.1 Ω−1cm−1, yield a nearly 85% increase in the power factor, α2σ ≈ 439.7 μWm−1K−2, for a 1.0 × 1015 Se.cm−2 implanted film compared to the unimplanted film (α2σ ≈ 236.4 μWm−1K−2). Monte Carlo simulation and ab initio density functional theory calculations revealed that the increased displacement per atom values and the {SeI−VCu} defect complex-induced shallow acceptor could be attributed to the observed increase in hole density. Our results highlight that native defects and defect complexes are beneficial for enhancing the power factor in transparent CuI for thermoelectric applications.

SODIUM, MONOETHANOLAMMONIUM AND POLYETHYLENE POLYAMMONIUM CITRATES AQUEOUS SOLUTIONS ELECTROCHEMICAL PROPERTIES

pH and conductometric study of aqueous (0.1 ÷ 9.0)⋅10-3 mol/l solutions of sodium (Na3Cit), monoethanolammonium (H3Cit⋅3MEA) and polyethylenepolyammonium (kH3Cit⋅3PEPA) citrates was carried out. Features of the electrochemical behavior of monoethanolamine and polyethylenepolamine ammonium citrates aqueous solutions were revealed in comparison with Na3Cit. As the temperature increases from 293 to 303 K, the pH values and Na3Cit solutions molar electrical conductivity increase. Due to hydrolytic processes, when diluting H3Cit⋅3MEA solutions, a change in pH is observed from slightly acidic to slightly alkaline, in contrast to Na3Cit. An increase in temperature (in the region of 293–308 K) leads to an increase in the medium acidity, in contrast to sodium citrate solutions, which is accompanied by an atypical decrease in molar electrical conductivity at the same H3Cit⋅3MEA content. It has been shown that an increase in temperature in the range of 293-308 K leads to a decrease in H3Cit⋅3MEA aqueous solutions pH, in contrast to Na3Cit and kH3Cit⋅3PEPA solutions, which is accompanied by an atypical decrease in molar electrical conductivity at the same H3Cit⋅3MEA content. The component composition of Na3Cit, H3Cit⋅3MEA and kH3Cit⋅3PEPA aqueous solutions was calculated. The probability of the existence of negatively charged ion-molecular complexes in H3Cit⋅3MEA and kH3Cit⋅3PEPA aqueous solutions is shown. The concentration and temperature dependence of citrate ions hydrolysis constant was obtained. The concentration and temperature dependence of these complexes was assessed. The atypical negative effect of heating on H3Cit⋅3MEA aqueous solutions molar electrical conductivity is associated with a change in the radius of the ion-molecular complex and its stability. The value of the limiting molar electrical conductivity of sodium, monoethanolammonium and polyethylenepolyammonium citrates aqueous solutions in the range of 293–313 K was estimated. Correlations were revealed between the values of the limiting electrical conductivity and ion-molecular complexes formation constants in H3Cit⋅PEPA aqueous solutions. The values of energy, enthalpy and entropy of activation of molar electrical conductivities of aqueous solutions were calculated. For the solutions studied, compensation effects were noted in the activation parameters of molar electrical conductivity.

Electromagnetic wave absorption value of iron-rich steel slag for application in foam concrete

In this study, iron-rich steel slag (IRSS) and carbon fiber (CF) were incorporated into foam concrete to maximize the economic benefits of composites and multifunctional integration while improving the overall performance of foam concrete. The study found that the optimal IRSS content for maximizing foam concrete’s compressive strength was 15 %, which increased by 18.59 % compared to the control. Additionally, S15 specimens showed a 37.87 % increase in electrical conductivity compared to the control. In addition, the average value of the fundamental part of the dielectric constant of the S15 specimen was 7.409, the average value of the imaginary part was 3.057, and the angular tangent of the electrical loss (tanδε) value and the reflection loss were both improved, which indicated that the S15 specimen material had a better ability to absorb electromagnetic waves and had an excellent performance of electromagnetic loss.

Photoluminescent ionic liquid-poly(vinylidene fluoride) hybrid materials for UV-Vis filter applications

Smart multifunctional materials have been increasingly applied in different fields of knowledge. In particular, photoluminescent materials have been explored for displays, radiation detection, lamps or anti-counterfeiting applications, among others. This work reports the development of photoluminescent materials based on poly(vinylidene fluoride) (PVDF) polymer incorporating different contents (0, 5, 10, and 20 % w/w) of the luminescent ionic liquid (IL) 1-butyl-3-methylimidazolium tetrakis(thenoyltrifluoroacetonato)europate(III) ([Bmim][Eu(tta)4]). The inclusion of the IL induced an increase of roughness and a slightly porous structure. No changes occur in the PVDF chemical structure and thermal behaviour. A decrease in the Young Modulus was observed, from 1.75×103 ± 1.56×102 to 5.09×102 ± 2.07×102 MPa for the sample incorporating 20 % w/w of IL which acted as a plasticizer. Further, the presence of ionic charges promoted an increase in electrical conductivity. The influence of IL content on the luminance was evaluated and a proof of concept demonstrating the potential of the composites as a UV–vis filter converter is provided.

Investigating the properties of nanoparticles from heveabrasiliensis shell for coolant application in PEMFCs

Extensive consumption of petroleum-based products, which has resulted in energy depletion, prompted a need to seek alternative and renewable means of transportation. PEMFCs can achieve high power density, low operating temperatures, rapid start-up, and clean energy, making them ideal for transportation. Several studies have demonstrated that conventional cooling agents, such as water or water with ethylene glycol, do not dissipate heat efficiently in PEMFCs, resulting in deteriorating performance and a shortened operational lifespan over time. The incorporation of bio-sourced nanofluids as an alternative coolant for Proton Exchange Membrane (PEM) fuel cells is the newest venture to take over PEM fuel cell development. Utilizing bio-sourced nanofluids is being evaluated for elevating the heat conduction and decreasing the electrical conductivity of proton exchange membrane fuel cells (PEMFCs). The objective of this article is to investigate Hevea brasiliensis Shell (HBS)-based nanofluids dispersed in water and Ethylene glycol (EG) at varying concentrations of 0.1 vol%, 0.3 vol%, and 0.5 vol% by paying attention to improving heat transfer, extracting high electrical output, reducing pump loss, and increasing the longevity of cells. As an adverse effect, incorporating HBS at a 0.5 % volume concentration within an 80:20 mixture of water and ethylene glycol (W:EG) resulted in an 8 % improvement in heat transfer and a 77 % increase in electrical conductivity when compared to W:EG (80:20), which is promising as a pertinent cooling technique for PEMFC stacks.

Unravelling the impact of microclimatic changes on coastal aquifer of multiple land use through integrated techniques: A comparative study using two decadal data

Regional climatic changes reflect the microclimatic variations and these affect the water resources of a region. Urbanization and population growth significantly influence microclimates, impacting groundwater resources and Land Surface Temperature (LST). The climatic variables (rainfall and temperature) interplay with geospatial parameters such as Land Use Land Cover (LULC), LST influence the quality and quantity of groundwater. Hence, this current approach employs geospatial techniques to explore the interrelationship between these variables by studying the long-term variation for a period of 20 years (1997–2018) to assess the microclimate variation and its impact on groundwater resources of a coastal aquifers with complex lithology. Results reveal a notable increase in minimum and maximum temperatures, with an average annual rise of 0.5°C predominantly along the western part. Spatial rainfall variation for the study period was higher in the northern region influenced by urban heat islands. The change in LULC reflected a 12% increase in agricultural areas and a 1.7% expansion in habitation, accompanied by a decline in surface water bodies in 2018. Maximum increase in electrical conductivity(EC) is observed along the southern coastal region, indicating rise in ionic concentration due contamination from sea water, urban and agricultural sources, witnessed by the isotopic signatures. Comparison of the depth to groundwater between the different study periods indicate a maximum depletion of 49m in northeastern and western regions due to extraction for domestic water supply, agriculture and mining. Further, a maximum rise of 14m in the regions adjacent to the reservoirs was observed, during 2018. The current study reveals the relationship between microclimate and groundwater (quality and the quantity) is predominantly observed in the northern and western parts of the study area. Our findings suggest that managing groundwater extraction and improving land use practices are essential for sustainable development, primarily through policy and governance.

MXenes with ordered triatomic-layer borate polyanion terminations.

Surface terminations profoundly influence the intrinsic properties of MXenes, but existing terminations are limited to monoatomic layers or simple groups, showing disordered arrangements and inferior stability. Here we present the synthesis of MXenes with triatomic-layer borate polyanion terminations (OBO terminations) through a flux-assisted eutectic molten etching approach. During the synthesis, Lewis acidic salts act as the etching agent to obtain the MXene backbone, while borax generates BO2- species, which cap the MXene surface with an O-B-O configuration. In contrast to conventional chlorine/oxygen-terminated Nb2C with localized charge transport, OBO-terminated Nb2C features band transport described by the Drude model, exhibiting a 15-fold increase in electrical conductivity and a 10-fold improvement in charge mobility at the d.c. limit. This transition is attributed to surface ordering that effectively mitigates charge carrier backscattering and trapping. Additionally, OBO terminations provide Ti3C2 MXene with substantially enriched Li+-hosting sites and thereby a large charge-storage capacity of 420 mAh g-1. Our findings illustrate the potential of intricate termination configurations in MXenes and their applications for (opto)electronics and energy storage.

Microporous Zr-metal-organic frameworks based-nanocomposites for thermoelectric applications

In the area of energy storage and conversion, Metal-Organic Frameworks (MOFs) are receiving more and more attention. They combine organic nature with long-range order and low thermal conductivity, giving them qualities to be potentially attractive for thermoelectric applications. To make the framework electrically conductive so far, thermoelectricity in this class of materials requires infiltration by outside conductive guest molecules. In this study, an in-situ polymerization of conductive polyaniline inside the porous structure of MOF-801 was conducted to synthesize PANi@MOF-801 nanocomposites for thermoelectrical applications. The growth of polyaniline chains of different loadings inside the host MOF matrix generally enhanced bulk electrical conductivity by about 6 orders of magnitude, leading to Seebeck coefficient value of -141 µVK−1 and improved thermal stability. The unusual increase in electrical conductivity was attributed to the formation of highly oriented conductive PANi chains inside the MOF pores, besides host–guest physical interaction, while the Seebeck coefficient enhancement was because of the energy filtering effect of the developed structure. Modulating the composition of PANi@MOF-801 composites by varying the aniline: MOF-801 ratio in the synthesis bath from 2:1 and 1:1 to 1:2 leads to a change in the semiconductor properties from p-type semiconductor to n-type. Among the examined composites with n-type semiconducting properties exhibited the highest ZT value, 0.015, and lowest thermal conductivity, 0.24 Wm−1 K−1. The synthesized composites have better performance than those recently reported for a similar category of thermoelectric materials related to MOF-based composites.

Structural and electrical conductivity studies of Polyaniline - WO3 hybrid nanocomposites for gas sensing applications

Abstract Conducting polymer – metal oxide based hybrid nanocomposites are a fascinating class of materials for miniaturized and flexible gas sensor devices. They exhibit enhanced physiochemical properties such as sensitivity, selectivity towards various volatile and hazardous chemical and bioanalytes. Our study focuses on conducting polyaniline (PANI) and WO3 nanocomposites, where different weight percentages (wt.%) of WO3 nanoparticles are embedded within the conducting PANI matrix using an in-situ oxidation polymerization synthesis technique. The surface morphology analysis indicated that the WO3 nanoparticles with an average grain size of ~200 nm are homogeneously distributed within the PANI nanofibers. The Fourier Transform Infra-Red (FTIR) spectrum analysis showed that the absorption peaks at 1111,1291, 1385, 1474, and 1560 cm−1 are typical of the conducting PANI emeraldine phase. We attribute the additional broad peak ranging between 840 to 720 cm−1 in the spectrum to WO3 phase, wherein, the intensity of the peak increases with WO3 content in case of hybrid composites. Current-voltage (I-V) characteristics for all our samples showed linear behaviour up to 1.2 volts. Temperature-dependent DC electrical conductivity (σ) studies measured from room temperature to 120°C for pure PANI, and PANI-WO3 composites showed an enhanced electrical conductivity of values up to 0.12 S/cm for PANI as compared to WO3 with σ ~ 1.4 x 10−3 S/cm. Pure PANI exhibits semiconducting behavior with an increase in electrical conductivity with temperature due to the charge carrier delocalization within the dispersed PANI backbone. The addition of higher concentrations of WO3 in composites leads to a metallic-like behavior, characterized by a decrease in electrical conductivity with temperature. These observations are attributed to the field-assisted band bending effects at the interfaces of PANI and WO3. Our composites show desired electrical characteristics suitable for gas sensing applications.

Zinc and [Zinc, Nickel]: Co‑doped SnO2 nanoparticles as prospective electron transport layer materials for efficient lead free-MASnI3 perovskite solar cells

In this study, we explore the potential of both pristine and doped tin oxide (SnO2) as promising materials as the electron transport layer (ETL) for efficient lead free-methylammonium tin iodide (MASnI3) perovskite solar cells (PSCs). The pristine, Zinc (Zn) doped, and Nickel (Ni)-Zn co-doped SnO2 nanoparticles with a constant concentration of Zn while changing the concentration of Ni were synthesized by using the hydrothermal method. The effect of doping and co-doping on optical, structural, and electrical properties of SnO2 nanoparticles was investigated using different microscopic and spectroscopic tools. The X-ray diffractograms showed that pristine, doped, and co-doped SnO2 nanoparticles have better crystallinity and tetragonal rutile crystal structure. The fingerprint functional groups and elemental composition were confirmed by FTIR absorption peaks, EDX, and XPS, respectively. The UV–Vis DRS spectroscopy results revealed that the optical band gap reduced from 2.90 eV for pristine SnO2 to 2.26 eV for co-doped 1 wt (wt) % Ni-Zn-SnO2 nanoparticles and can be tuned with a variation of wt % of Ni. Further, the photoluminescence emissions of all SnO2 nanoparticles in the range of 307 to 494 nm are related to oxygen vacancies or defects. Moreover, BET results confirms larger surface area for 1 wt % Ni-Zn-SnO2, which can help in better electron-hole pair separation. The electrical conductivity studies confirm that the synthesized nanoparticles exhibit excellent ohmic contact behavior and show a notable increase in electrical conductivity for 1 wt% Ni-Zn-SnO2 nanoparticles. Further, the suitability of both pristine and doped SnO2 as ETL material for the MASnI3-based PSCs was simulated using SCAPS-1D software. The best power conversion efficiency of 29.60 % was achieved for FTO/1 wt % Ni-Zn-SnO2/MASnI3/Spiro-OMeTAD/Au. This investigation highlights the potential of co-doped materials as promising candidates for the development of efficient PSCs.

Harnessing the potential of cube-like Holmium doped bismuth niobate (Ho–Bi5Nb3O15) amalgamated with rGO sheets for rapid photocatalytic elimination of crystal violet and acetylsalicylic acid

Synthesis of unique morphologies in photocatalytic materials, coupled with utilization of wide-spectrum solar energy through rare earth doping, holds significant promise to maximize the potential of photocatalysts. Herein in, cube-like Holmium (Ho) doped Bi5Nb3O15 was synthesized by the hydrothermal method and integrated with reduced graphene oxide (rGO) sheets. As synthesized Ho–Bi5Nb3O15@rGO composite along its analogs i.e., Bi5Nb3O15 and Ho–Bi5Nb3O15 was characterized by XRD, SEM, FT-IR, TGA, I–V, EIS, Mott-Schottky and photo-current measurements. Phase studies showed that crystallite size for Bi5Nb3O15, Ho–Bi5Nb3O15, and Ho–Bi5Nb3O15@rGO was 27.4, 25.5, and 13.5 nm, respectively. Optical analysis exhibited a reduction in the band gap in consequent to Ho doping from 2.54 to 2.19 eV for Ho–Bi5Nb3O15. Conductivity and photo-current measurements showed a remarkable increase in both electrical conductivity and photo-response of Ho–Bi5Nb3O15 upon its incorporation into rGO matrix, reaching maximum values of 1.72 × 10−2 S/m and 0.66 μA, respectively. The enhanced photocatalytic activity of Ho–Bi5Nb3O15@rGO was ensured through the outstanding photo-degradation efficiency (96.5 %) against crystal violet (CV), greater than Bi5Nb3O15 (49 %) and Ho–Bi5Nb3O15 (63.4 %). Additionally, Ho–Bi5Nb3O15@rGO showed sufficient potential towards the degradation of acetylsalicylic acid (ASA) with 79.1 % photo-degradation. This elevated photocatalytic activity of Ho–Bi5Nb3O15@rGO is believed to be contributed by the collaborative outcomes aroused from the Ho-doping and heterojunction fabrication among cubical Ho–Bi5Nb3O15 and rGO sheets. Hence, our work proposes an efficient strategy for the development of innovative photolytic materials for sustainable wastewater remediation.

Crystal structure, stability, and transport properties of Li2BeAl and Li2BeGa Heusler alloys: a DFT study

In this study, the structural, elastic, electronic, and thermoelectric properties of full Li2BeAl and Li2BeGa Heusler alloys were explored using density functional and the Boltzmann transport theories. The GGA and HSE approximations have been used for the exchange–correlation potential. Results indicated that these two compounds are more energetically stable in the inverse Heusler structure. Additionally, both Li2BeAl and Li2BeGa Heusler alloys were found to be mechanically stable due to the positive values of the elastic constants. Also, the high values of the Young's modulus indicate that these compounds are stiff and exhibit a semi-metallic nature. The band gaps were determined to be 0.13 eV and − 0.22 eV for Li2BeAl and Li2BeGa alloys, respectively, using the GGA approximation. By employing the HSE hybrid functional, however, the band gap for Li2BeAl increased to 0.26 eV, and for Li2BeGa, it decreased to − 0.16 eV. Regarding thermoelectric properties, Seebeck coefficient, electrical conductivity, electronic and lattice thermal conductivities, power factor, and the figure of merit have been calculated for both Li2BeAl and Li2BeGa Heusler alloys at different temperatures. Seebeck coefficient in both alloys decreases with increasing the temperature and has the highest value at 300 K. Thermal conductivity and electrical conductivity increase with increasing the temperature, which confirms the intermetallic behavior of the Heusler alloys. The results obtained for both alloys show that n-type doping has better thermoelectric properties than p-type doping. The maximum value of the figure of merit (ZT) was obtained for n-type doping, which was 1.43 at 660 K for Li2BeAl and 0.39 at 1000 K for Li2BeGa alloy. The high values of ZT especially for electron-dopped Li2BeAl suggest the great potential of this material for use in thermoelectric devices. This study suggests that the proposed materials have potential applications in spintronic devices and thermoelectric materials due to their intermetallic character and effective thermoelectric coefficients.

A Sensitive Enzymatic Electrochemical Biosensor for Cholesterol Based on Cobalt Ferrite@Molybdenum Disulfide/Gold Nanoparticles.

Cholesterol is essential in biological systems, and the level of cholesterol in the body of a person acts as a diagnostic marker for a variety of diseases. So, in this work, we fabricated an enzymatic electrochemical biosensor for cholesterol using cobalt ferrite@molybdenum disulfide/gold nanoparticles (CoFe2O4@MoS2/Au). The synthesized composite was used for the determination of cholesterol by voltametric methods. The electroactive material CoFe2O4@MoS2/Au was successfully verified from the physiochemical studies such as XRD, Raman, FT-IR, and XPS spectroscopy along with morphological FESEM and HRTEM characterization. CoFe2O4@MoS2/Au showed outstanding dispersion in the aqueous phase, a large effective area, good biological compatibility, and superior electronic conductivity. The microflower-like CoFe2O4@MoS2/Au was confirmed by scanning electron microscopy. The image of transmission electron microscopy showed decoration of gold nanoparticles on CoFe2O4@MoS2 surfaces. Furthermore, a one-step dip-coating technique was used to build the biosensor used for cholesterol detection. In addition to acting as an enabling matrix to immobilize cholesterol oxidase (ChOx), CoFe2O4@MoS2/Au contributes to an increase in electrical conductivity. The differential pulse voltammetry method was used for the quantitative measurement of cholesterol. The calibration curve for cholesterol was linear in the concentration range of 5 to 100 μM, with a low limit of detection of 0.09 μM and sensitivity of 0.194 μA μM-1 cm-2. Furthermore, the biosensor demonstrates good practicability, as it was also employed for identifying cholesterol in real samples with acceptable selectivity and stability.

High temperature electrical breakdown and energy storage performance improved by hindering molecular motion in polyetherimide nanocomposites

Polyetherimide (PEI) is widely used as a material for high temperature and high power energy storage capacitors in new energy vehicles and other fields. However, as the temperature increases, the electrical conductivity increases and the breakdown strength decreases, which greatly reduces the energy storage density of the capacitor and limits the application range. In order to clarify the influence mechanism of high temperature on the breakdown and energy storage performance of dielectrics, this paper established a charge capture and molecular displacement (CTMD) breakdown model based on the expansion motion of molecular segments to study the charge transport and molecular chain motion process of PEI nanocomposites (PNCs) at high temperature. The results show that at 100 °C, compared with pure PEI, the internal maximum molecular displacement of PEI PNCs with appropriate doping content (3 wt%) is reduced by 28.79 %, and the breakdown strength is increased by 11.20 %. Appropriate nano-doping can effectively increase the movement difficulty of molecular chains and reduce the activation volume that provides energy for charge transport. Thus, charge transport is inhibited, current density is reduced, and Joule heat accumulation is avoided. Finally, the high temperature breakdown and energy storage performance are improved.

Largely Enhanced Thermoelectric Performance of Flexible Ag2Se Film by Cationic Doping and Dual-Phase Engineering.

Recent studies have shown that silver selenide is a promising thermoelectric material at room temperature. Herein, flexible films with a nominal composition of (Ag1-xCux)2Se are prepared by a simple and efficient one-pot method combined with vacuum-assisted filtration and hot pressing. The thermoelectric properties of the films are regulated by both cationic doping and a dual-phase strategy via a wet chemical method. As the x increases, not only Cu is doped into the Ag2Se, but different new phases (CuAgSe and/or CuSe2) also appear. The (Ag1-xCux)2Se film with x = 0.02 composed of Cu-doped Ag2Se and CuAgSe shows a high PF of ∼2540 μW m-1 K-2 (ZT ∼ 0.90) and outstanding flexibility at room temperature. The high thermoelectric properties of the film are due to the effect of Cu doping and the CuAgSe phase, including the increase in electrical conductivity caused by doping, the enhanced phonon scattering at the Ag2Se/CuAgSe interface, and the interaction between the energy filtering effect and the doping effect. In addition to the high output performance (PDmax = 28.08 W m-2, ΔT = 32.2 K), the flexible device assembled with the (Ag0.98Cu0.02)2Se film also has potential applications as a temperature sensor.

A unified hybrid micromechanical model for predicting the thermal and electrical conductivity of graphene reinforced porous and saturated cement composites

Graphene fillers have gained widespread attention as functional reinforcements for cement composites due to their excellent physical properties. The prediction of the thermal and electrical properties of graphene reinforced cement composites (GRCCs) is of great importance for developing intelligent and multifunctional civil engineering materials and structures. In this current work, a unified hybrid micromechanical model combining effective medium theory (EMT) and Mori-Tanaka-Benveniste (MTB) is developed to simultaneously predict the thermal and electrical conductivity of the GRCCs with considering pores and saturation, in which mechanisms including phonon transport, electron tunnelling and Maxwell-Wagner-Sillars (MWS) polarization are incorporated. Graphene nanoplatelets (GNPs) reinforced cement composites (GNPRCCs) samples are prepared and tested to validate the developed unified model. The results show that the electrical conductivity of the GNPRCCs is more sensitive to saturation than the thermal conductivity. When the porosity n = 0.2 and the GNP concentration is 1 wt%, the relative thermal and electrical conductivity increases by 5 % and 193 %, respectively, when the saturation index increases from 0.6 to 1. Elongated pores are more favorable for the formation of ionic networks for electrical conductivity in the saturated GNPRCCs, while spherical pores are more beneficial for heat transport. Elongated graphene fillers are preferred for enhancing both the thermal and electrical conductivity of dry and saturated GNPRCCs. The work is envisaged to provide guidelines for developing multifunctional cement composites.