Electrical Conductivity Structure Research Articles

Relationship between electrical conductivity, metallogeny, and lithospheric structure in south China

The South China Block (SCB) is located at the junction of the Pacific, Eurasian, and Indo-Australian plates. Their interaction led to large-scale multi-stage mineralization in the SCB during the Mesozoic. Several regional ore-concentration areas, such as the Middle-Lower Yangtze Metallogenic Belt (MLYMB), the Qinzhou-Hangzhou Metallogenic Belt (QHMB), the Wuyishan Metallogenic Belt (WYMB), and the Nanling Metallogenic Belt (NLMB) were formed during this process. However, the dominant mineral types of these metallogenic belts are different. To study the deep mechanisms of the different metallogenic types developed in the same tectonic background at almost the same period, the magnetotelluric sounding (MT) data from 691 sites located mainly within the eastern SCB are employed to obtain a regional lithospheric 3-D resistivity model.It could be concluded from the resistivity model that deep low-resistivity anomalies and mantle upwelling channels mainly controlled almost all the Mesozoic deposits. Large-scale low-resistivity bodies extend from the crust to the upper mantle beneath the MLYMB and the QHMB, interpreted as channels of mantle-derived magma and melts/fluids containing metallogenic elements upwelling. However, the MLYMB and the QHMB have different upper crustal ore-conducting and ore-controlling structures, thus forming porphyry copper and copper-bearing tungsten deposits. Small-scale low-resistivity anomalies are invading the high-resistivity crust in the NLMB. And remelting the upper crust, mixing, and intrusion of crust-source magma, enriching tungsten-tin elements near the NLMB. Larger-scale low-resistivity anomalies exist deep in the WYMB, remelting the lower crust and resulting in the formation of porphyry copper in it. Significantly, the upper-mantle low-resistivity anomalies beneath the eastern SCB show a spatial distribution that is gradually shallowing from south to north, probably indicating that the asthenospheric materials are upwelling from south to north, corresponding with the changing progressively of magma and metallogenic activities. We propose that the lithospheric delamination and asthenospheric upwelling caused by the far-field effects of the Paleo-Pacific Plate subduction are the sources of solid magmatic activities and related metallogeny.

Ar/NH3 Radio‐Frequency Plasma Etching and N‐doping to Stabilize Metallic Phase 1T‐MoS2 for Fast and Durable Sodium‐Ion Storage

AbstractMetallic phase 1T‐MoS2 is considered a prospective anode material for sodium‐ion batteries (SIBs) due to its remarkable electrical conductivity and unique layered structure. However, 1T‐MoS2 is thermodynamically unstable and prone to phase transition to the 2H‐MoS2 phase. Herein, self‐supporting nitrogen‐doped and carbon‐coated 1T/2H mixed‐phase MoS2 nanosheets with rich sulfur vacancies on carbon cloth (C@N‐MoS2‐p/CC) are synthesized through a hydrothermal method and Ar/NH3 radio‐frequency (RF) plasma treatment process. Density‐functional‐theory (DFT) calculations demonstrate that after Ar/NH3 RF plasma treatment, nitrogen‐doping and etching effects are realized, which combine with carbon‐coating significantly reduce the phase transition energy of 1T‐MoS2, thus triggering the phase transition and enabling the stable existence of the highly active 1T‐MoS2. As a result, the C@N‐MoS2‐p/CC exhibits outstanding sodium storage performance, with initial charge–discharge capacities of 701.0/797.0 mAh g−1 at 1 A g−1, respectively. It also demonstrates exceptional rate capabilities and ultra‐high cyclic stability, maintaining a discharge capacity of 404.2 mAh g−1 after 910 cycles at a high rate of 2 A g−1. In a full cell with Na3V2(PO4)3/CC cathode, it exhibits excellent initial charge–discharge capacities of 102.3/102.9 mAh g−1 and maintains satisfactory cycling stability after 350 cycles (86.7 mAh g−1) at 0.1 C.

Briefing: Selective laser sintering technology to print walnut shell/phenolic resin new biomass-based porous electrode

In this paper, porous carbon electrodes were prepared by using walnut shell and phenolic resin as matrix materials, combined with selective laser sintering (SLS) technology and carbonization process. The effects of different ratios and temperatures on the macroscopic morphology, graphitization degree, electrical conductivity and pore structure of the carbonized parts were investigated. The results show that the lower proportion of walnut shell and the higher carbonization temperature increase the degree of graphitization. High temperature has a significant effect on the conductivity. The conductivity at 1000 °C is 7.5197 S·cm−1, which is 752 % higher than that at 600 °C, while the conductivity at 30 % walnut shell content is only 75.4 % higher than that at 50 %. This study provides a new reference for the preparation of carbon electrodes with complex shape and structure by biomass consumables.

Explicating Electrical Conductivity and Melt Structure of the SiO2–MnO–TiO2 Welding Fluxes with Various MnO/TiO2 Mass Ratios

Explicating Electrical Conductivity and Melt Structure of the SiO2–MnO–TiO2 Welding Fluxes with Various MnO/TiO2 Mass Ratios

Reversible Switching Between Microwave Absorption and EMI Shielding of VO2 Composite Foam.

Developing lightweight composite with reversible switching between microwave (MW) absorption and electromagnetic interference (EMI) shielding is promising yet remains highly challenging due to the completely inconsistent attenuation mechanism for electromagnetic (EM) radiation. Here, a lightweight vanadium dioxide/expanded polymer microsphere composites foam (VO2/EPM) is designed and fabricated with porous structures and 3D VO2 interconnection, which possesses reversible switching function between MW absorption and EMI shielding under thermal stimulation. The VO2/EPM exhibits MW absorption with a broad effective absorption bandwidth of 3.25GHz at room temperature (25 °C), while provides EMI shielding of 23.1dB at moderately high temperature (100 °C). This reversible switching performance relies on the porous structure and tunability of electrical conductivity, complex permittivity, and impedance matching, which are substantially induced by the convertible crystal structure and electronic structure of VO2. Finite element simulation is employed to qualitatively investigate the change in interaction between EM waves and VO2/EPM before and after the phase transition. Moreover, the application of VO2/EPM is demonstrated with a reversible switching function in controlling wireless transmission on/off, showcasing its excellent cycling stability. This kind of smart material with a reversible switching function shows great potential in next-generation electronic devices.

Human mesenchymal stromal cells-laden crosslinked hyaluronic acid-alginate bioink for 3D bioprinting applications in tissue engineering.

Three-dimensional (3D) bioprinting is considered one of the most advanced tools to build up materials for tissue engineering. The aim of this work was the design, development and characterization of a bioink composed of human mesenchymal stromal cells (hMSC) for extrusion through nozzles to create these 3D structures that might potentially be apply to replace the function of damaged natural tissue. In this study, we focused on the advantages and the wide potential of biocompatible biomaterials, such as hyaluronic acid and alginate for the inclusion of hMSC. The bioink was characterized for its physical (pH, osmolality, degradation, swelling, porosity, surface electrical properties, conductivity, and surface structure), mechanical (rheology and printability) and biological (viability and proliferation) properties. The developed bioink showed high porosity and high swelling capacity, while the degradation rate was dependent on the temperature. The bioink also showed negative electrical surface and appropriate rheological properties required for bioprinting. Moreover, stress-stability studies did not show any sign of physical instability. The developed bioink provided an excellent environment for the promotion of the viability and growth of hMSC cells. Our work reports the first-time study of the effect of storage temperature on the cell viability of bioinks, besides showing that our bioink promoted a high cell viability after being extruded by the bioprinter. These results support the suggestion that the developed hMSC-composed bioink fulfills all the requirements for tissue engineering and can be proposed as a biological tool with potential applications in regenerative medicine and tissue engineering.

Achieving Long Cycle Life of Zn-Ion Batteries through Three-Dimensional Copper Foam.

Metallic zinc anodes in aqueous zinc-ion batteries (ZIBs) suffer from dendritic growth, low Coulombic efficiency, and high polarization during cycling. To mitigate these challenges, current collectors based on three-dimensional (3D) commercial copper foam (CCuF) are generally preferred. However, their utilization is constrained by their thickness, low electroactive surface area, and increased manufacturing expenses. In this study, the synthesis of cost-effective current collectors with exceptionally large surface areas designed for ZIBs that can be cycled hundreds of times is reported. A zinc-coated CuF anode (Zn/CuF) was prepared with a 3D porous CuF current collector produced by the dynamic hydrogen bubble template (DHBT) method. Electrochemically generated copper foam could be obtained within seconds while offering a thickness as low as 30-40 μm (CuF5 achieved a thickness of ∼38 μm in 5 s) via the DHBT method. The excellent electrical conductivity and open pore structure of the 3D porous copper scaffold ensured the uniform deposition/stripping of Zn during cycling. During the 500 h Zn deposition/stripping process, the as-synthesized CuF5 current collector offered fast electrochemical kinetics and low polarization as well as a relatively high average Coulombic efficiency of 99% (at a current density of 5 mA cm-2 and a capacity of 1 mAh cm-2). Furthermore, the symmetric cell exhibited low voltage polarization and a stable voltage profile for 1000 h at a current density of 0.1 mA cm-2. In addition, full cells containing the Zn/CuF anode coupled with an as-synthesized α-MnO2 nanoneedle cathode in aqueous electrolyte were also prepared. Capacities of 266 mAh g-1 at 0.1 A g-1 and 94 mAh g-1 at 2 A g-1 were achieved after 200 charge/discharge cycles with a stable Coulombic efficiency value close to 99.9%.

High-performance electrosorption of lanthanum ion by Mn3O4-loaded phosphorus-doped porous carbon electrodes via capacitive deionization

Transition-metal-oxide@heteroatom doped porous carbon composites have attracted considerable research interest because of their large theoretical adsorption capacity, excellent electrical conductivity and well-developed pore structure. Herein, Mn3O4-loaded phosphorus-doped porous carbon composites (Mn3O4@PC-900) were designed and fabricated for the electrosorption of La3+ in aqueous solutions. Due to the synergistic effect between Mn3O4 and PC-900, and the active sites provided by Mn–O–Mn, C/PO, C–P–O and Mn–OH, Mn3O4@PC-900 exhibits high electrosorption performance. The electrosorption value of Mn3O4@PC-900 was 45.34% higher than that of PC-900, reaching 93.02 mg g−1. Moreover, the adsorption selectivity reached 87.93% and 89.27% in La3+/Ca2+ and La3+/Na+ coexistence system, respectively. After 15 adsorption-desorption cycles, its adsorption capacity and retention rate were 50.34 mg g−1 and 54.12%, respectively. The electrosorption process is that La3+ first accesses the pores of Mn3O4@PC-900 to generate an electric double layer (EDL), and then undergoes further Faradaic reaction with Mn3O4 and phosphorus-containing functional groups through intercalation, surface adsorption and complexation. This work is hoped to offer a new idea for exploring transition-metal-oxide @ heteroatom doped porous carbon composites for separation and recovery of rare earth elements (REEs) by capacitive deionization.

Enhancing extraction of betalains from beetroot (Beta vulgaris L.) using deep eutectic solvents: optimization, bioaccessibility and stability

Deep eutectic solvents (DESs) are the next generation of green solvents that are considered for their stability and biocompatibility. This study used 10 different DESs synthesized from choline chloride, alcohols, organic acids and sugars. Red beet betalains were extracted using three conventional solvents and DESs. Characterization experiments of DESs suggested that the electrical conductivity, pH, viscosity, water activity, density and chemical structure were greatly affected by the composition of the hydrogen bond acceptors (HBA) and hydrogen bond donors (HBD). Betacyanin, betaxanthin and total betalain contents ranges were 23.68–702.17, 21.49–467.77, and 45.17–1169.94 mg kg−1, respectively, with choline chloride (ChCl): glucose (Glu) (1:2) giving the highest values. ChCl:Glu was chosen for the optimization process considering the molar ratio (ChC = 1:Glu = 0.75–1.75), water content (15–35%) and temperature (30–60 °C) factors for the central composite design. The optimum conditions were recorded as 1:0.75 molar, 30.83% water content, and 30 °C, respectively. Under optimum conditions, the yields of betalain, betacyanin and betaxanthin were found to be 1192.17 ± 23.63, 738.83 ± 17.87, and 453.34 ± 5.93 mg kg−1, respectively. Bioaccessibility analysis and stability tests were performed on the extracts obtained under optimum conditions. Stability tests revealed that the betalains of red beetroot are less stable in the light than in the dark. Bioaccessibility values for betacyanin, betaxanthin, and betalain were found to be 44.67 ± 1.40, 75.02 ± 1.20, and 56.21 ± 1.33%, respectively. Green extraction of betalains from red beetroot using DES, such as ChCl:Glu, is promising for a strong stabilization and high bioaccessibility of betalains.Graphical

Modulating functional groups of GO to improve the electrochemical performance of Si/rGO anode

Silicon (Si)-based materials show attractive potentials as the anode for lithium-ion batteries (LIBs) due to their high theoretical specific capacity. For the conventional silicon/reduced graphene oxide (Si/rGO) composites, the electrical conductivity, C/O ratio, and defect structure of reduced graphene oxide (rGO) significantly impact their electrochemical properties. Herein, we use three methods to prepare graphite oxide (GO) to adjust the percentage of functional groups, which further enhance the physicochemical properties of rGO and thus improve the electrochemical properties of Si/rGO. The GOs were synthesized through Hummers method (labeled as GO-1), Hummers method with H2O modulation (labeled as GO-2), and Hummers method with H2O and H3BO3 modulation (labeled as GO-3). Due the H2O promotes the production of hydroxyl and epoxy groups, and H3BO3 forms complexes with hydroxyl groups,the ratio of hydroxyl and epoxy groups in GO-1 to GO-3 is increased. After reduction process, the reduced rGO-3 exhibits a high C/O ratio, large structural defects, and excellent electrical conductivity. Because of the excellent properties of rGO-3, as an electrode material, Si/rGO-3 exhibits excellent electrochemical performance, with the highest reversible capacity of about 780.8 mAh/g after 150 cycles at 1 A/g and a good rate performance of 657.0 mAh/g at 5 A/g. This work proves that modulation of rGO from the GO with different oxygen-containing functional groups lead to enhanced ionic conductivity, cyclic stability, and rate capability of the Si/rGO electrodes.

Fully Additively Manufactured Counter Electrodes for Dye-Sensitized Solar Cells.

In dye-sensitized solar cells (DSSCs), the counter electrode (CE) plays a crucial role as an electron transfer agent and regenerator of the redox couple. Unlike conventional CEs that are generally made of glass-based substrates (e.g., FTO/glass), polymer substrates appear to be emerging candidates, owing to their intrinsic properties of lightweight, high durability, and low cost. Despite great promise, current manufacturing methods of CEs on polymeric substrates suffer from serious limitations, including low conductivity, scalability, process complexity, and the need for dedicated vacuum equipment. In the present study, we employ and evaluate a fully additive manufacturing route that can enable the fabrication of CEs for DSSCs in a high-throughput and eco-friendly manner with improved performance. The proposed approach sequentially comprises: (1) material extrusion 3-D printing of polymer substrate; (2) conductive surface metallization through cold spray particle deposition; and (3) over-coating of a thin-layer catalyzer with a graphite pencil. The fabricated electrodes are characterized in terms of microstructure, electrical conductivity, and photo-conversion efficiency. Owing to its promising electrical conductivity (8.5 × 104 S·m-1) and micro-rough surface structure (Ra ≈ 6.32 µm), the DSSCs with the additively manufactured CEs led to ≈2.5-times-higher photo-conversion efficiency than that of traditional CEs made of FTO/glass. The results of the study suggest that the proposed additive manufacturing approach can advance the field of DSSCs by addressing the limitations of conventional CE manufacturing platforms.

Asymmetric sandwiched nanofibrillated cellulose composites prepared by one-pot vacuum filtration for ultrahigh electromagnetic interference shielding

High-efficiency electromagnetic interference (EMI) shielding composite films (EMI shielding effectiveness (SE) value > 100 dB) with a small thickness are imminently desired for eliminating the serious electromagnetic wave pollution. Herein, asymmetric sandwiched silver-coated four-needle zinc oxide whisker/nanofibrillated cellulose/Ti3C2Tx (F-ZnO&Ag/NFC/Ti3C2Tx) composite films consisting of the loose F-ZnO&Ag sedimentary layer and compact upper Ti3C2Tx layer were successful fabricated by a facile one-pot vacuum filtration method in combination with gravity-induced delamination. Arising from the favorable electrical conductivity and unique asymmetric sandwich structure, electromagnetic waves can be trapped and dissipated in the F-ZnO&Ag skeletons and strongly multiply reflected between top Ti3C2Tx layer and bottom F-ZnO&Ag layers. Thereby, F-ZnO&Ag/NFC/Ti3C2Tx-30.4 exhibits the ultrahigh averaged EMI SET of 103.9 dB (the maximal value of 123.8 dB) at a low thickness of merely 209 μm, which is far superior to that of almost all the reported NFC composites at the similar thickness to date. In the real EMI shielding application test, composite films are confirmed to block signal transmission and switch off the toy car system. Such simple and high-efficiency asymmetric sandwich structure design makes a great progress towards preparing and adjusting thin EMI shielding composite films for the promising application prospects in advanced electronics and communication technology.

Rapid mechanochemical synthesis of high-performance Na4Fe2.94Al0.04(PO4)2(P2O7)/C cathode material for sodium-ion storage

Na4Fe3(PO4)2(P2O7) is regarded as a promising cathode material for sodium-ion batteries due to its affordability, non-toxic nature, and excellent structural stability. However, its electrochemical performance is hampered by its poor electronic conductivity. Meanwhile, most of the previous studies utilized spray-drying and sol–gel methods to synthesize Na4Fe3(PO4)2(P2O7), and the large-scale synthesis of the cathode material is still challenging. This study presents a composite cathode material, Na4Fe2.94Al0.04(PO4)2(P2O7)/C, prepared via a straightforward ball-milling technique. By substituting Al3+ minimally into the Fe2+ site of NFPP, Fe defects are introduced into the structure, hindering the formation of NaFePO4 and thereby enhancing Na-ion diffusion kinetics and conductivity. Additionally, the average length of AlO bonds (2.18 Å) is slightly smaller than that of FeO bonds (2.19 Å), contributing to the superior structural stability. The smaller ionic radii of Al3+ induce lattice contraction, further enhancing the structural stability. Moreover, the surface of material particles is coated with a thin layer of carbon, ensuring excellent electrical conductivity and outstanding structure stability. As a result, the Na4Fe2.94Al0.04(PO4)2(P2O7)/C cathode exhibits excellent electrochemical performance, leading to high discharge capacity (128.1 mAh g−1 at 0.2 C), outstanding rate performance (98.1 mAh g−1 at 10 C), and long cycle stability (83.7 % capacity retention after 3000 cycles at 10 C). This study demonstrates a low-cost, ultra-stable, and high-rate cathode material prepared by simple mechanical activation for sodium-ion batteries which has application prospects for large-scale production.

Research on the brain phantom for transcranial electromagnetic neuromodulation

Transcranial magnetic stimulation (TMS), a widely used neuroregulatory technique, has been proven to be effective in treating neurological and psychiatric disorders. The therapeutic effect is closely related to the intracranial electric field caused by TMS, thus accurate measurement of the intracranial electric field generated by TMS is of great significance. However, direct intracranial measurement in human brain faces various technical, safety, ethical and other limitations. Therefore, we have constructed a brain phantom that can simulate the electrical conductivity and anatomical structure of the real brain, in order to replace the clinical trial to achieve intracranial electric field measurement. We selected and prepared suitable conductive materials based on the electrical conductivity of various layers of the real brain tissue, and performed image segmentation, three-dimensional reconstruction and three-dimensional printing processes on each layer of tissue based on magnetic resonance images. The production of each layer of tissue in the brain phantom was completed, and each layer of tissue was combined to form a complete brain phantom. The induced electric field generated by the TMS coil applied to the brain phantom was measured to further verify the conductivity of the brain phantom. Our study provides an effective experimental tool for studying the distribution of intracranial electric fields caused by TMS.

Validating a UK Geomagnetically Induced Current Model Using Differential Magnetometer Measurements

AbstractExtreme space weather can damage ground‐based infrastructure such as power lines, railways and gas pipelines through geomagnetically induced currents (GICs). Modeling GICs requires knowledge about the source magnetic field and the electrical conductivity structure of the Earth to calculate ground electric fields during enhanced geomagnetic activity. The electric field, in combination with detailed information about the power grid topology, enable the modeling of GICs in high‐voltage (HV) power lines. Directly monitoring GICs in substations is possible with a Hall probe, but scarcely realized in the UK. Therefore we deployed the differential magnetometer method (DMM) to measure GICs at 12 sites in the UK power grid. The DMM includes the installation of two fluxgate magnetometers, one directly under a power line affected by GICs, and one as a remote site. The difference in recordings of the magnetic field at each instrument yields an estimate of the GICs in the respective power line segment via the Biot‐Savart law. We collected data across the UK in 2018–2022, monitoring HV line segments where previous research indicated high GIC risk. We recorded magnetometer data during several smaller storms that allow detailed analysis of our GIC model. For the ground electric field computations we used recent magnetotelluric (MT) measurements recorded close to the DMM sites. Our results show that there is strong agreement in both amplitude and signal shape between measured and modeled line and substation GICs when using our HV model and the realistic electric field estimates derived from MT data.

Carbon nanowall-based gas sensors for carbon dioxide gas detection

Carbon nanowalls (CNWs) have attracted significant attention for gas sensing applications due to their exceptional material properties such as large specific surface area, electric conductivity, nano- and/or micro-porous structure, and high charge carrier mobility. In this work, CNW films were synthesized and used to fabricate gas sensors for carbon dioxide (CO2) gas sensing. The CNW films were synthesized using an inductively-coupled plasma (ICP) plasma-enhanced chemical vapor deposition (PECVD) method and their structural and morphological properties were characterized using Raman spectroscopy and electron microscopy. The obtained CNW films were used to fabricate gas sensors employing interdigitated gold (Au) microelectrodes. The gas sensors were fabricated using both direct synthesis of CNW films on interdigitated Au microelectrodes on quartz and also transferring presynthesized CNW films onto interdigitated Au microelectrodes on glass. The CO2 gas-sensing properties of fabricated devices were investigated for different concentrations of CO2 gas and temperature-ranges. The sensitivities of fabricated devices were found to have a linear dependence on the concentration of CO2 gas and increase with temperature. It was revealed that devices, in which CNW films have a maze-like structure, perform better compared to the ones that have a petal-like structure. A sensitivity value of 1.18% was obtained at 500 ppm CO2 concentration and 100 °C device temperature. The CNW-based gas sensors have the potential for the development of easy-to-manufacture and efficient gas sensors for toxic gas monitoring.

Catkin-derived carbon microtubes for hybrid anode materials of high-performance lithium ion batteries

As a common biological waste, catkin shows negligible economic value and is hazardous to the environment and human respiratory health. To turn waste into treasure, in this work, a hybrid anode is successfully prepared by using the catkin-derived 1D hollow carbon microtube as dispersing agents to well disperse the MnO particles via a simple one-step pyrolysis method. Benefiting from the high electrical conductivity and hollow microtubule structure of the catkin-derived carbon, as well as the evenly dispersion of the MnO particles and the interfacial energy storage of Mn0/Li2O interfaces, the lithium ion battery based on the resultant MnO/C hybrid anode exhibits outstanding rate performance (high reversible specific capacity of 1365 mAh g−1 at a current density of 0.1 A g−1 and maintains 451 mAh g−1 even at a high current density of 6.4 A g−1) and superior cycling stability (retains ∼100 % after 1000 cycles at a current density of 0.8 A g−1). This work conforms to the development concept of green environmental protection and realizes the unity of economic and social benefits.

Rational design of conductive metal-organic frameworks and aligned carbon nanofibers for enhancing the performance of flexible supercapacitors.

Carbonaceous materials are attractive active materials for the manufacture of flexible electrochemical double-layer capacitors (EDLCs) because of their high electrical conductivity, large surface area, and inherent resilience against deformation. However, compared to pseudocapacitors, which store electrochemical energy via faradaic redox reactions, EDLCs generally exhibit inferior energy density. One potential approach to addressing this issue is to incorporate highly porous and electrically conductive materials into carbonaceous material-based EDLCs. In this paper, we present a hybrid electrode consisting of a conductive metal-organic framework (c-MOF) with high electrical conductivity and unique porous structure combined with a mat of aligned carbon nanofibers (ACNFs). Its highly ordered structure facilitates electronic/ionic transport, increasing the areal capacitance by up to 3.9 times compared to randomly-oriented carbon nanofibers (RCNFs). An additional increase in areal capacitance (+64%) is achieved by introducing c-MOF (RCNFs: 25.4 mF cm-2; ACNFs: 98.7 mF cm-2; c-MOF/ACNF: 161.8 mF cm-2). Additionally, an ACNF mat exhibits excellent mechanical flexibility and electrochemical reliability, making it highly suitable for the assembly of freestanding flexible supercapacitors. By optimizing the electrochemical performance of c-MOF/ACNF and its suitability for utilization in flexible energy storage systems, this study presents a promising avenue for the practical implementation of c-MOF-based supercapacitors.

Analysis of the Geoelectric Field in Sweden Over Solar Cycles 23 and 24: Spatial and Temporal Variability During Strong GIC Events

AbstractGeomagnetic storms can produce large perturbations on the Earth magnetic field. Through complex magnetosphere‐ionosphere coupling, the geoelectric field (E) and geomagnetic field (B) are highly perturbed. The E is the physical driver of geomagnetically induced currents. However, a statistical study of the E in Sweden has never been done before. We combined geomagnetic data from the International Monitor for Auroral Geomagnetic Effects network in Northern Europe with a 3‐D structure of Earth's electrical conductivity in Sweden as the input of a 1‐D model to compute the E between 2000 and 2018. Northwestern Sweden presents statistically larger E magnitudes due to larger |dB/dt| variations in the north than in the south of Sweden and relative lower conductivity in the west compared to central and eastern Sweden. In contrast, the 15 strongest daily maximum |E| events present more frequently a maximum magnitude in central Sweden (62.25°N) and their relative strengths are not the same for all latitudes. These results highlight the different regional response to geomagnetic storms, which can be related to ground conductivity variability and the complex magnetosphere‐ionosphere coupling mechanisms.

Advancing electrocatalytic urea synthesis: Insights from 2D benzenehexathiolate coordination nanosheets

Urea, widely used in agriculture and industry, is conventionally produced at substantial energy consumption and CO2 emissions. The use of green and renewable electricity for electrochemical urea synthesis has emerged as an appealing alternative. A variety of catalysts have been explored for urea synthesis. A two-dimensional metal benzenehexathiolato (BHT) coordination nanosheet has high electrical conductivity and diverse coordination structures, making this type of nanostructure an ideal platform for urea synthesis electrocatalysis. Herein, density functional theory (DFT) simulations were employed to probe their electrochemical stability and reaction mechanisms. For Cu-BHT and Ni-BHT, low limiting potentials and C-N coupling barriers were observed, which indicate promising catalytic performance. S-ligands within TM-BHT improved stability and catalytic performance. As a result of this study, advanced catalysts and novel urea synthesis mechanisms can be designed and explored in the future.