Good Conductivity Research Articles

Perfectly hexagonal sponge‐like NiO‐NiCo2O4 with rich electromicrostructural physiognomies for high‐efficiency electrocatalytic urea oxidation

In order to design high‐efficiency electrocatalysts for the development of urea oxidation reaction (UOR)‐based energy conversion and storage systems, herein, a very facile and kinetically controlled material growth strategy has been strategized to prepare extremely uniform and perfectly hexagonal sponge‐like NiO‐NiCo2O4 with high BET surface area (126 m2 g−1) and monomodal distribution of mesopores (~3.9 nm). The in‐depth electrochemical analyses demonstrate rich redox reversibility, high UOR current density, very‐low charge transfer and series resistance, and typical Warburg response indicative of facilitated diffusion of electrolyte ions during electrocatalytic UOR. The NiO‐NiCo2O4 requires lower overpotential for effective UOR and exhibits minimal current loss for prolonged duration. Proposedly, the multiple oxidation states of Ni and Co in NiO‐NiCo2O4, combined with its rich physicoelectrochemical physiognomies, offer lowly‐impeded electrolyte ion intercalation‐deintercalation, good electronic conductivity, higher number of accessible redox active sites, facile adsorption of urea on the electrocatalytic sites and inhibition in the blockage of active sites by side products to augment the overall UOR kinetics. The optimized approach presented in this study is poised to advance the catalyst systems for UOR, which will lead to the development of high‐efficiency urea‐based energy conversion and storage systems for prospective integration in contemporary electronic architectures.

Effect of Hot-Dipped Tin Coating Treatment on Metallurgical Bonds Between AZ91D and Cu by Composite Casting

Mg-Cu bimetallic materials have been widely studied because of their low density, good electrical conductivity, and excellent hydrogen storage properties. However, the interface bonding strength of Mg/Cu is low. In this study, we examined the effect of hot-dip tin coating (HDTC) with copper (Cu) on the interfacial metallurgical bonds between AZ91D Magnesium (Mg) alloy and Cu composite casting. A transition layer composed of Mg2Cu and MgCu2 intermetallic compounds (IMCs) formed at the interface of the AZ91D/HDTC-Cu composite casting. However, the transition layer was about 1 μm at the AZ91D/Cu interface, mainly comprising Mg(Al, Cu)2 IMC. Both the AZ91D/Cu and AZ91D/HDTC-Cu interfaces exhibited many labyrinthine Mg(Al, Cu)2 IMCs and layer-like Mg2(Al, Cu) IMCs. Moreover, the interfacial shear strength of the AZ91D/Cu was changed from 12.6 MPa to 52.4 MPa due to the solid solution of Sn atom and the precipitation of Mg2Sn IMC at the interface after HDTC treatment. Meanwhile, the shear fracture surfaces are characterized by brittle fractures.

Ultrafast Joule Heating Modification of Methane-Pyrolyzed Carbon Black for Supercapacitor Application.

Carbon black from methane pyrolysis for hydrogen is an alternative resource and can be improved for conductive material supplication. Our current work uses an ultrafast Joule heating technique to modify the methane-pyrolyzed carbon black and prepare nanoparticles of electrode material for supercapacitor application, coupled with density functional theory, structural, and electrochemical analyses. Evolution rules of the carbon and pore structures of the modified sample with an increase in temperature reveal good structure improvements. The graphitization degree of modified carbon black nanoparticles increases, and the particle morphology changes from a smooth surface, disordered structure removal, and pore formation to graphite crystallization. Band structure and state density analytical results show that the modified carbon black with a defect-free structure possesses metallic properties and exhibits good electrical conductivity. A temperature around 1576 °C to the initial graphitization was defined based on the critical point of the evolution of ordered and disordered structures, while the electrical conductivity of the carbon black nanoparticles at 2000 °C reaches 2300 S/m. The modified carbon black performed with stable charge/discharge characteristics, exhibiting a 4.31% capacitance drop at a current load of 2 A/g and a 18.31% capacitance drop at a current load of 20 A/g.

Thermal effects of ternary Casson nanofluid flow over a stretching sheet: An investigation of Thomson and Troian velocity slip

The present research analyzes the properties of a Casson ternary nanofluid over a stretching sheet with Thomson and Troian slip conditions, taking into consideration the influences of electromagnetohydrodynamic (EMHD). The ternary nanofluid comprises three different nanoparticles, which include titanium dioxide (TiO2), copper (Cu), and silver (Ag), all being suspended in oil, which is the base fluid. They are involved because of their good thermal conductivity and chemical stability, and AgCuTiO2 /Oil nanofluid is a composite of copper, titanium oxide, and oil. Hence, carrying out the said procedure, the ternary nanofluid becomes AgCuTiO2/Oil. The sheet is, however, thought to be stretching vertically while the flow is determined by the effect of the gravity force through the free convention. Moreover, the phenomena of EMHD, porous medium, thermal slip, thermal radiation, Joule heating, and heat source/sink are included to make the energy equation more real-life. This leads to a set of partial differential equations (PDEs) based mathematical models transformed into ordinary differential equations (ODEs)-appropriate similarity transformation. The Runge–Kutta–Fehlberg (RKF-45) method solves the given ordinary differential system. According to the research’s findings, the temperature of the ternary Casson nanofluid rises when the suspension of silver, copper, and titanium dioxide nanoparticles increases, and the velocity of flow for merely silver and copper decreases when the density decreases. This causes the flow rate to be constricted through the velocity slip condition, at the same time as the nanofluid’s temperature increases.

Preparation of Microfiltration Membrane with Good Conductivity and Its Antifouling Performance

Membrane fouling restricts the widespread adoption and application of membrane separation technology. Electrically assisted membrane filtration has proven effective in mitigating this issue. The development of conductive membranes is crucial in this process. In this study, graphene oxide (GO), titanium dioxide (TiO2), and multi-walled carbon nanotubes (MWCNT) were incorporated into polypyrrole/polyvinylidene fluoride (PPy/PVDF) to create the composite conductive membranes GO/PPy/PVDF, TiO2/PPy/PVDF and MWCNT/PPy/PVDF. These membranes demonstrated strong acid resistance, but lacked resistance to strong alkali corrosion. The hydrophilicity of the composite membranes improved compared to that of PPy/PVDF, with the TiO2/PPy/PVDF membrane exhibiting the highest hydrophilicity, evidenced by a contact angle of only 57.52°. The membrane conductivity of MWCNT/PPy/PVDF significantly increased, being 3.27 times that of the PPy/PVDF membrane, due to the inherent excellent conductivity of MWCNT and the increased electron transfer channels. Among the membranes tested, the TiO2/PPy/PVDF membrane, with outstanding hydrophilicity, achieved a water flux of up to 1085L·h−1m−2. It also showed superior antifouling characteristics, with a high flux recovery rate (97.10%) and a low irreversible fouling rate (2.90%) when tested against bovine serum albumin and sodium alginate as foulants.

Ag@MXene-cellulose nanofiber composite for electromagnetic interference shielding, sensing, and actuating

With the development of flexible electronic devices, the development of flexible and multi-functional materials becomes increasingly important. In this study, we prepared Ag@MXene-cellulose nanofiber (AMC) multi-functional composites with a three-dimensional (3D) conductive network structure, which can be used for electromagnetic interference (EMI) shielding, pressure sensing, and actuating. AMC has good electrical conductivity (18.04 S cm-1) and EMI shielding effectiveness (37.7dB). The microstructure of the AMC surface gives it the potential to be applied in the pressure sensor. AMC is humidity-sensitive and has excellent electrical/photo-thermal conversion properties. Thus, AMC can be used to fabricate humidity-driven actuators and electrical/light-driven actuators. Finally, three multi-functional devices/systems have been carefully designed to achieve the fabrication of multi-functional devices/systems that rely on only one raw material, which significantly simplifies the preparation of multi-functional devices. We hope this research will open up new ways for artificial muscles, soft robots, and EMI shielding devices.

Flexible and free-standing MXene decorated biomass-derived carbon cloth membrane anodes for superior lithium-ion capacitors

Two-dimensional transition metal materials, MXenes, have attracted tremendous attention in energy storage applications due to their layered structure, good electrical conductivity, and abundant functional groups. In this work, Ti3C2Tx MXene nanosheets and carbon nanotubes (CNTs) were uniformly sprayed and successfully loaded on the cotton nonwoven fabric-derived carbon cloth (CC) substrate by electrostatic self-assembly. The as-prepared flexible MXene-CNTs-CC membrane electrodes with enlarged interlayer spacing and high conductivity fabric support exhibited excellent electrochemical performance. In terms of lithium-ion batteries, the optimized MXene-CNTs-CC anode delivered an ultrahigh initial discharge capacity of 2277.5 mAh g−1 at 0.1 A g−1 along with notable cyclability (1149.8 mAh g−1 after 100 cycles) and rate capability (544.1 mAh g−1 after 200 cycles at 2 A g−1) in half cells. The full cells assembled with LiCoO2 cathode also displayed good cycling stability with a high reversible discharge capacity of 833.5 mAh g−1 after 100 cycles at 0.1 A g−1. Remarkably, the further constructed lithium-ion capacitors with the designed porous carbon nanofiber cathode could maintain energy densities of 121.5 to 20.8 Wh kg−1 with the corresponding power densities of 125 to 12,500 W kg−1, and achieved capacitance retention of 76.3 % after 10,000 cycles at 1 A g−1, demonstrating excellent long-term cycle durability.

High-performance electromagnetic absorbing Ni/C composites derived from Ni-MOF materials: Effects of organic ligands and pyrolysis temperatures

Magnetic carbon-based materials derived from nickel organic framework (Ni-MOF) are considered to be a kind of electromagnetic wave (EMW) absorbing materials with great potential and application value. However, the precise design of Ni-MOF-derived magnetic carbon-based materials remains a huge challenge. In the present work, through the modulation of organic ligand and pyrolysis temperature, Ni/C composites with excellent electromagnetic absorption properties are obtained due to their improved multiple loss and optimized impedance matching. Specifically, the organic ligand and pyrolysis temperature affect the degree of graphitization of the carbon frame and the specific surface area of the Ni/C composites, thus changing the conductivity, magnetic properties and electromagnetic parameters. In particular, the sample Ni/C-2-500 using H2BPDC as the organic ligand and calcined at 500 °C gives an RLmin of –50.37 dB and an EAB of 6.0 GHz at a packing rate of 30 wt% and a thickness of 2.5 mm, which covers the entire Ku band. In addition, Ni/C-2-500 exhibits good thermal conductivity. Therefore, this study provides an idea for exploring MOF materials and their derivatives with tunable EMW absorbing properties and heat conduction advantages prepared by different organic ligands.

Titanate nanorod/reduced graphene oxide-filled poly (vinylidene fluoride) fibers as piezoelectric nanogenerators

To investigate the influence of nanorod ceramic powders MTiO3 (M: Mg, Co, Ni) as fillers on the electrical performance, piezoelectric nanogenerators (PENG) device, were constructed using the electrospinning method with polyvinylidene fluoride (PVDF), reduced graphene oxide (RGO), and ceramic powders. The composite nanofibers were characterized using SEM, EDX, ATR-FTIR, EDS-mapping analysis, and XRD. Sensing capacity of the PVDF-RGO-MTiO3 nanofiber-based PENG were compared. Utilizing CoTiO3 (CT) in the PENG resulted in a voltage output of 17.03, which exhibited the best piezoelectric response. Observations revealed that mechanical stimulation could charge different capacitors, suggesting a viable platform for removing the requirement of an external power source for operating portable devices. With varying resistances in the circuit, the resistance of 104 Ω produced the maximum power density of 1.40 mW/cm2. When comparing the P-RGO-CT composite to pure PVDF, the differential scanning calorimetric analysis revealed that the thermal stability and crystallinity percentage increased. Tensile testing was used to evaluate the mechanical characteristics of P-RGO-CT PENG. The maximum stress and breaking strain that the nanofiber film can tolerate are 50 kPa and 33.9%, respectively. EIS investigations obtained that the real intrinsic internal resistance of the P-RGO-CT PENG electrode is lower than PVDF, demonstrating the good conductivity of the synthesized PENG electrode. The impedance spectrum of the PENG electrode is almost parallel to the Zim axis, demonstrating good capacitance performance.

Polymerization-Achieved Cyclodextrin Slide-Ring Supramolecular Hydrogel Self-Generating Flexible Electronic Device.

Supramolecular flexible electronic devices are one of the research hotspots due to their application in the fields of chemistry, biology, and materials. Herein, we reported a slide-ring supramolecular flexible electronic device, which is constructed by acrylamide (AAm), acrylic acid (AA), carboxymethyl-α-cyclodextrin (CM-α-CD), PEG20000 diacrylate (PEG20000DA), and calcium chloride via the photoinitiated polymerization, displaying not only the mechanical force-responded self-generation but also the human-computer information transfer. As compared with the polymer hydrogel, the addition of α-CD polypseudorotaxane to the hydrogel has notably enhanced both the tensile length and the tensile toughness, making it more suitable for flexible electronic device applications. The hydrogel can be stretched to ca. 15 times its original length and quickly recovers after the external force is removed. In addition, it also exhibits a conductivity of 0.21 S/m, demonstrating good electrical conductivity. Significantly, based on the slide-ring supramolecular array for energy harvesting, it can generate an open-circuit voltage of 420 V using the contact separation method for testing, which can be used as a flexible electronic device for human-computer information transfer.

Ultraviolet Radiation Driven Multifunctional Polyvinyl Alcohol Based Hybrid Polymer Nanocomposites

ABSTRACTHerein we report the tailoring of the band gap of polyvinyl alcohol (PVA)/graphene oxide (GO), PVA‐Ag (silver), PVA/GO‐Ag, and PVA/GO/Ag/GA (glutaraldehyde) employing ultraviolet (UV) irradiation. Nanocomposites were fabricated by the in situ solution casting method. Among fabricated, PVA/GO/Ag/GA was identified as the nanocomposite having enhanced properties. The structural and chemical studies confirm enhanced interfacial interaction and crosslinking between PVA and GO in the presence of GA. GA crosslinked PVA/GO‐Ag nanocomposite shows a reduction in band gap and enhanced dc conductivity compared to other composites. Post‐UV irradiation studies show PVA/GO/Ag/GA exhibits mechanical stability and good conductivity. The band gap of PVA/GO/Ag/GA decreased from 5.27 eV (unirradiated) to 2.66 eV for 24 h of UV exposure. As the exposure time increased to 48 h, the band gap increased to 5.16 eV and finally band gap decreased to 4.47 eV for 72 h of UV exposure. This reveals that though there is no linear variation in the energy gap with UV exposure time but accurate reproducibility was observed. This brings about the possibility of tailoring the band gap of PVA/GO/Ag/GA with better electrical conductivity (3.4 × 10−9 Sm−1) and good mechanical stability which is very crucial for optoelectronic applications. Additionally, for 72 h of UV radiation exposure, the PVA/GO/Ag/GA composite demonstrates UV transmittance of 3.3%, underscoring its UV shielding capability.

Utilizing Industrial By-Products in Autoclaved Aerated Concrete: A Sustainable Approach

<p><span style="font-family:"Times New Roman","serif";font-size:11.0pt;" lang="EN-US">The feasibility of utilizing natural zeolite (NZ), phosphogypsum (PG), and aluminium (Al) powder (AP) as replacements for fly ash in autoclaved aerated concrete (AAC) is assessed in this research. This study examines the influence of NZ, PG and AP on AAC's fresh state properties, mechanical behavior, and thermal characteristics. Gas foaming properties were analyzed using X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR).  Results show that natural zeolite and aluminum powder have acceptable foaming properties that contribute to AAC’s porosity and lightness when combined with phosphogypsum. The optimal dosage of PG, along with 10% and 20% zeolite and aluminum powder, enhances AAC performance through a synergistic effect. PG substitution for fly ash reduced density and increased the pH of the AAC slurry, affecting foam generation. Incorporation of PG potentially reduced workability due to its smaller particle size and larger surface area. Despite this, NZ, PG, and AP combinations resulted in AAC with satisfactory strength and flexural properties. AAC with phosphogypsum showed good strength, density, and thermal conductivity, though thermal conductivity was highest in control AAC. This study demonstrates these materials' potential to meet AAC’s construction requirements economically and efficiently dispose of phosphogypsum. Future research should explore other material combinations and their impacts on AAC, supporting sustainable construction and resource management. </span></p>

Cobalt-nickel sulfide hierarchical hollow microspheres to boost electrochemical activity for supercapacitors

Cobalt-nickel bimetallic sulfides are promising candidates for supercapacitors due to their high theoretical specific capacity, good electrical conductivity and fast redox kinetics. Nevertheless, they confront challenges such as poor cycling stability, volume expansion, and complicated synthesis methods. To address these issues, in this work, a MOF-assisted synthesis strategy is developed to achieve the one-pot formation cobalt-nickel sulfide hollow microspheres. The 2D nanosheet-constructed hierarchical hollow configuration promotes rapid electron/ion transfer, provides more active sites and effectively mitigates volume expansion during cycling. The optimized Co1Ni4S exhibits high electrochemical performance, such as a specific capacity of 277.2 mA h/g (2217 F g−1) at 1 A g−1, remarkable cycling stability with ∼100 % retention after 5000 cycles, and favorable rate capability with 84.8 % retention at 20 A g−1. Furthermore, an aqueous asymmetric supercapacitor (ASC) assembled with the Co1Ni4S and active carbon (AC) derived from lotus pollen achieves an energy density of 86.9 Wh kg−1 at 800.1 W kg−1, along with significant cycling stability (97.1 % retentions over 30,000 cycles). These superior results showcase a simple one-step method for developing superior-performing electrode materials applicable to advanced supercapacitors.

Synthesis and Characterisation of iron doped manganese oxides for thermal energy storage

Iron-doped manganese oxides were synthesized using a co-precipitation method and thermodynamically characterized to demonstrate their potential as a thermochemical energy storage medium. Thermochemical energy storage, via chemical bonds that employ reversible redox reactions, is a promising approach to tackle solar thermal energy storage. Hysteresis loops observed confirm that the pore network consisted of mesopores that were not filled with pore condensate, and the narrow loop indicates a narrow size distribution. Barrett-Joyner-Halenda (BJH) studies of all the synthesized materials showed that they have a high mesoporous and specific area, essential for supplying reduced diffusion channels over the Mn oxides, Good conductivity through electron transfer, with the presence of active sites allow the study thermochemical approaches. The BJH studies showed the material MnOFe2 (2.5:1) to have a higher pore area, which is effective in the adsorption process of the material.

THE EFFECT OF REPETITIVE METAL CASTING ON THE TENSILE STRENGTH OF DENTURES

Background: Dentures or prostheses function to replace chewing and dental arch structures. Denture plates used in dentistry are made with acrylic resin, metal, or a combination of acrylic and metal. Metals are shiny, opaque chemical substances and good conductors of heat and can be polished. Recycling or reusing used metal is an option in making prostheses because the price of new metal is increasing, and metal recycling is quite effective. Purpose: To determine the effect of repeated metal casting on the strength of the metal frame denture base. Method: The current research is a laboratory study with a tensile test in the form of dumbbells with iso 22674 with a length of 15 ± 1 mm and a diameter of 3 ± 1 mm. This research used 18 CoCr metal samples divided into three groups, namely 100% new metal group (control), 50% new + 50% repeated composition group, and 100% repeated group. Result: The mean strain of the new 100% CoCr metals group was 0.133%, strain mean of the new 50% CoCr + 50% repeated metals group was 0.1%, and the strain of the 100% repeated CoCr metals group was 0.066%. The average modulus of elasticity (MPa) for the new 100% CoCr metals group is 7866, or 711 MPa, the new 50% CoCr + 50% repeat metals group is 7538, or 833 MPa, the 100% CoCr metals group is 6659, or 336 MPa. Conclusion: The new 100% CoCr metal group has a higher average tensile strength value than the 50% new CoCr metal + 50% repeated group, and the lowest is the 100% repeated CoCr metal group.

Unraveling MOF growth in colloids with controllable dual-doping through ultrafast sintering for wide temperature range LIBs

Metal-organic frameworks (MOFs) offer versatile building blocks for high-performance materials across practical applications. Crystallization studies reveal MOF complex pathways crucial for biological and synthetic systems, yet understanding remains incomplete. Here, we employ in-situ liquid phase transmission electron microscopy (LPTEM) to scrutinize the growth dynamics of ZIF-8 in colloidal environments, aiming to deepen our comprehension of MOF crystallization. This study employs in-situ LPTEM to investigate ZIF-8 nanoparticle growth, revealing the combination of classical and non-classical nucleation processes in the same batch leading a challenge to control nanoparticle morphology and size, while heterogeneous nucleation is dominant giving monodispersed nanoparticle at the presence of ZIF-8 seeds in mother solution. Additionally, integrating MOF-derived carbon materials in lithium-ion batteries (LIBs) faces challenges in achieving high-performance, controllable N-doping and long-term stability. Ultrafast high-temperature sintering (UHS) is utilized to carbonize ZIF-8, regulating N-doping hard carbon with Zn single atoms doping. Results show optimal morphology at 800 °C for 20 s, yielding higher concentration of Zn-doping, higher N-doping levels, and good conductivity compared to conventional sintering in tube furnace. LIB tests demonstrate exceptional cycling performance and stability across wide temperatures. This UHS strategy for ZIF-8 contributes to establishing a balance between Zn-N-doping and the degree of graphitization, thus providing an interdisciplinary approach that offers efficient MOF derivative synthesis for promising wide temperature range applications of LIBs.

Electrochemically Assisted Cobalt/MXene Membrane for Effective Water Treatment: Synchronously Improving Catalytic Performance and Anti-Interference Ability.

Catalytic membrane technology for water treatment is often constrained by a trade-off between permeability and catalytic efficiency as well as interference from coexisting anions and organic matter in natural water matrices. Herein, a novel cobalt-loaded MXene (Co/MXene) 2D membrane with good hydrophilicity, electrical conductivity, and PMS activation function is constructed. The negative voltage is exerted on the membrane to significantly enhance its PMS activation efficiency and anti-interference capacity toward effective water treatment. Under -2 V, the optimal Co/MXene catalytic membrane displays 100% rhodamine b (RhB) removal within a residence time of only 1.1 s, whose RhB degradation kinetic constant (k of 6.85 s-1) is 17.6 times higher than that of the Co/MXene catalytic membrane alone and is also greatly superior to other advanced catalysts and catalytic membranes. Meanwhile, the catalytic membrane displays obvious anti-interference ability in the presence of various coexisting substances of the water matrix and performs well in treating the secondary effluent of coking wastewater. The radical-dominated (SO4•- and •OH) mechanism accompanied by the nonradical species (1O2 and Co(VI)═O) is revealed in the system, and the reactive species production is obviously enhanced under negative voltage. Experimental results and theoretical calculations jointly confirm the key role of electrochemical assistance in enhancing membrane performance, which not only facilitates cycling of Co3+/Co2+ for enhanced PMS activation via improving PMS adsorption and promoting charge transfer from Co to PMS but also hinders interference from coexisting substances in water via electrostatic repulsion.

SPHERICAL GRAPHENE FILM GROWN ON CARBIDE FOR SENSOR MATRIX

Graphene has amazing applications for sensors due to its excellent performances like high strength and good conductivity, but the transfer issue is in the way of its application perspective. Direct growth of spherical graphene films (SGFs) on cemented carbide may offer a good avenue for various applications in sensor technology, especially for electrochemical sensors. Four common methods for graphene preparation are chemical stripping, chemical vapor deposition (CVD), metal catalysis, and laser fabrication; and subject to transfer issues during usage. In order to overcome this limitation, the fabrication of in-situ growth of SGFs on carbide is proposed as a solution for constructing sensor matrices. This review explores various in-situ SGFs and their potential applications in sensors. The findings presented here shed light on transfer-free graphene with controllable structures that can serve as excellent candidates for sensor matrices.

Experimental Investigation of the Enhancement of Heat Transfer Rate in Automobile Radiator Using Low Concentration Hybrid Nanofluids

Engine coolant, also called antifreeze, is essential to a vehicle's performance since it controls engine temperature, keeps the cooling system from freezing in cold weather and prevents corrosion. To increase engine cooling efficiency, this study looks into using low-concentration hybrid nanofluids to accelerate heat transfer rates in automobile radiators. To maximise heat dissipation within the radiator system, the project focuses on the synthesis, characterisation and practical applications of these nanofluids. Through an extensive literature review, various nanoparticles, including metallic and oxide-based particles, were evaluated for their compatibility and effectiveness in enhancing heat transfer. The chosen nanoparticles underwent thorough characterisation for size, shape and surface properties to determine their suitability for dispersion in a base coolant. Reduced Graphene is known for its good thermal conductivity, making it an ideal candidate for enhancing cooling rates in various applications hence keeping this in mind, this experiment compares and investigates the heat transfer rate in the radiator of an automobile with a hybrid combination of Reduced Graphene Oxide (RGO) + Copper Oxide (CuO) with ethylene glycol and distilled water, at volume fractions of 0.001%, 0.005% and 0.01%. The results show a notable increase in the efficiency of the radiator both in terms of pressure drop and effectiveness. A maximum of 9.2 and 1.5 times increase in temperature drop is recorded at 0.001%, a maximum of 12.3 and 2.08 times increase in temperature drop is noted at 0.005% and the highest of 17.9 and 3.03 times increase in temperature drop is tabulated at 0.01% volume fraction of copper oxide and 0.01% the volume fraction of RGO hybrid nanofluid. It can safely be concluded that compared to the sixty experiments conducted, the recommended nanofluid among them would be Ethylene Glycol and Distilled Water + 0.01% concentration of RGO and CuO hybrid as they have exhibited higher pressure drop, effectiveness and reduction in temperature.

PVA/chitosan-based multifunctional hydrogels constructed through multi-bonding synergies and their application in flexible sensors

Hydrogels have garnered significant interest as promising materials for flexible wearable devices. However, it remains a major challenge to develop multifunctional hydrogels. In this study, we prepared a multifunctional hydrogel based on the polyvinyl alcohol (PVA) and chitosan (CS), which is characterized by high strength, good electrical conductivity, and resistance to freezing and water retention. The hydrogel formulation utilizes p-carboxyphenylboronic acid (PBA) and MXene in combination with freeze-thaw cycling and glycerin (GL) immersion technology. Additionally, we explored the applications of this hydrogel in motion detection and sensing. Research results indicate that the hydrogel has excellent mechanical properties, achieving a strength of up to 3.42 MPa, with modulus and toughness improved by 7 times and 5 times, respectively, compared to pure PVA hydrogels. Moreover, when the MXene dispersion is at 8 vol%, the conductivity is 163.15 mS/m, and we explore their applications in strain sensing (GF = 7.03) and motion detection. The hydrogels exhibit a good strain range (600 %) and a fast response time (42 ms), as well as regular and stable electrical signals demonstrated at joints and breathing, providing strategic support for the application of this hydrogel in the field of smart wearable flexibility.