Path Of Electrons Research Articles

Structural characteristics and microwave properties of amorphous nanogranulated composites (Co41Fe39B20)x(SiO2)1-x

We presented results of experimental studies of the structure and microwave reflective, transmitting, and absorbing properties in the frequency ranges of 8–12 GHz and 25–36 GHz of amorphous nanogranular composites (Co41Fe39B20)x(SiO2)1−x, 32.79<x < 52.00 at. %) with a thickness of 1.60–2.54 μm deposited on a lavsan base with a thickness of about 20 μm. The spectra of the reflection and transmission coefficients as a function of frequency and the dependences of the reflection, transmission and absorption coefficients on the content of the ferromagnetic filler were obtained. Using the algorithm for calculating structural and conductive characteristics of amorphous nanogranular composites from the measured values of the microwave reflection coefficient, the conductivity of granules and the mean free path of electrons were estimated using the mechanisms of closed and open circuits of the model of intragranular currents. We showed that the electron mean free path corresponded to the gaps between the granules of the studied composites with weakly expressed conducting properties.

A dual-carbon structured molybdenum selenide composites controlled via interface engineering and chemical bonding to attain high initial coulombic efficiency and rate capability of potassium-ion batteries

Molybdenum selenide (MoSe2) is considered representative anode material for Potassium-ion batteries (PIBs) by reason of its adjustable forbidden bandwidth and large interlayer spacing allowing the intercalation/deintercalation of large-sized K+. However, its inferior electronic conductivity, substantial volume variation, and aggregation make it difficult to achieve satisfactory cycling performance and rate capability. Herein, we reported a novel composite with MoSe2 nanosheets grown vertically on the surface of N-doped hollow porous carbon bowls and wrapped by ultrathin/wrinkled reduced graphene oxide layers (G-MoSe2/NHPCB) as the anode material for PIBs. The strong chemical bonds between MoSe2 and carbon materials (including C-Mo, C-O-Mo, and C-N-Mo bonds) were profitable for the charge-transfer kinetics and structural durability. The NHPCB substrate, with a large specific surface area, could significantly prohibit the aggregation of MoSe2 nanosheets and shorten the transmission path for electrons and ions. Meanwhile, the ultrathin/wrinkled graphene layers could effectively strengthen the composite structure stability and reinforce the overall conductivity. Benefitting from the distinctive structure, when evaluated as a K-ion half-cell anode, the G-MoSe2/NHPCB electrode exhibited a high discharge capacity of 601.59 mA h g−1 and initial coulombic efficiency (ICE) of 83.4% at 0.1 A/g, exceptional rate capability (261.3 mA h g−1 at 5.0 A/g) and long-term cycling stability (304.3 mA h g−1 at 1.0 A/g after 500 cycles and 214.9 mA h g−1 at 2.0 A/g after 1000 cycles). The electrochemical reaction mechanism and kinetic analysis were investigated using in-situ and ex-situ methods and first-principles calculation. This work demonstrates the advantages of G-MoSe2/NHPCB as KIBs anode materials and provides innovative thinking for the rational design of high-performance transition metal selenides with unique structures.

Facile synthesis of Co3O4 nanocrystals with superior lithium storage properties from bis (8–hydroxyquinoline) cobalt complex as anode materials for lithium–ion batteries

A simple and facile approach to synthesis Co3O4 nanocrystals by a two–step pyrolysis process of bis (8–hydroxyquinoline) cobalt complex under Ar and air atmospheres successively. The structures and physical properties of the complex, Co@C intermediate and the Co3O4 nanocrystals are characterized by the following techniques: FTIR, XRD, TGA–DTG, Raman, FESEM, HRTEM, N2 adsorption/desorption measurement and XPS. As anode materials in lithium ion batteries, the Co3O4 nanocrystals exhibit high charge/discharge specific capacity, excellent rate performance and remarkable cycle stability. The superior electrochemical properties of the Co3O4 nanocrystals could be attributed to the nanoscaled particle size, high crystallinity and high specific surface area, which is helpful to increase the number of active sites, shorten the diffusion path of lithium ions and electrons, alleviate the volume expansion effect as well as improve the dynamic characteristics during cycling.

Investigation of the corrosion behavior influence of carbon interlayer on aluminum collector in lithium-sulfur battery system

Due to the shuttle effect brought by polysulfides, the commercialization of lithium-sulfur batteries still faces significant difficulties. Carbon interlayer is introduced to enhance the electrochemical performance of lithium-sulfur batteries, while the drawback that the interlayer will reversely affect the performance of the current collector was ignored. The current collector has a significant influence and contribution to the cycle stability of lithium-sulfur batteries. In this study, we looked into the electrochemical stability and corrosion situation of standard aluminum foil collectors in lithium-sulfur batteries with carbon interlayer. The results show that the introduction of carbon interlayer into the lithium-sulfur batteries will make aluminum foil and carbon paper form an electronic conduction path and galvanic corrosion occurs, accelerating the corrosion of aluminum foil. Therefore, we propose a new corrosion model. During the cycle, the surface of the aluminum collector becomes a non-dense passivation film and lithium polysulfide terminal (ST−1). Then, under the action of the carbon interlayer, the passivation film peels off and the oxide film is attacked by the electrolyte, thiosulfate and polythionate, resulting in pitting holes and ultimately accelerating the corrosion of the aluminum foil collector. This research has some guiding significance for the commercial application of lithium-sulfur batteries.

Facile synthesis of FeNi nanoparticle-loaded carbon nanocomposite fibers for enhanced microwave absorption performance

The advantages of Fe, Ni metals and one-dimensional (1D) carbon materials are combined in this study using a simple method to prepare FeNi/C nanofibers for electromagnetic microwave (EM) absorption. The prepared FeNi/C nanofibers exhibit excellent EM absorption performance under dielectric/magnetic synergistic effect. At a frequency of 13.3 GHz, the minimum reflection loss (RLmin) reaches -57.15 dB, and effective absorption bandwidth (EAB) is as high as 4.0 GHz (12.5–16.5 GHz), with a thickness and filling rate of only 1.6 mm and 30 wt.%, respectively. Analysis shows that the EM absorption performance of FeNi/C nanofibers far exceeds that of single-component nanofibers and pure carbon fibers, and the excellent EM absorption performance is due to its unique microstructure and excellent electromagnetic properties. The FeNi alloy loaded on carbon nanofibers forms rich heterogeneous interfaces, and the three-dimensional (3D) conductive network composed of 1D carbon fibers increases the migration path of electrons. In addition, FeNi alloy, as an impedance regulation factor, strengthens the dielectricity of the carbon matrix while providing multidimensional magnetism, achieving impedance matching. This work is thought to contribute to the promotion of emerging absorbers by providing a novel strategy for the development of new 1D magnetic carbon-based high-performance EM absorbing materials.

Revealing the effect of Co/Cu (d7/d9) cationic doping on an electronic acceptor ZnO nanocage surface for the adsorption of citric acid, vinyl alcohol, and sulfamethoxazole ligands: DFT-D3, QTAIM, IGM-NCI, and MD analysis

The electron-spin duality and propagation of the active sites of free electrons are of interest for adsorbing the guests and fixing them with strong hydrogen bonds (HB). The coherence of the systems with the guests is one of the main parameters that favor the experimentation of new systems on primary column adsorption phenomena. The stability and the adaptable symmetries in all directions justify the use of a “nanocage” (ZnO) for studying adsorption phenomena. The formation of stable electronic charge transfer paths between sites occupied by very stable atomic orbitals ensures the success of the adsorption of the ligands. Electronic characterization (MES, FMO, DOS, and cationic doping) is used to describe the movement of the intra-Cu-Co/Zn19O20 electrons. The phenomena of charge transfer, stability, types of orbital occupations, adsorption sites, electron migration direction, conductivity, and reactivity of such systems are thoroughly explored. Based on these findings, the efficiency of a Cu–Co/Zn19O20 nanocage to adsorb three different ligands (medical ligands, prostate biomarkers, and antibiotics) is studied. From the reactivity parameter discussions, it is found that the copper or cobalt-doped nanocage-Citric Acid has a strongly electronegative index (4.40 eV and 4.91 eV) and hardness (1.99 eV and 1.82 eV) properties. The Fourier transform infrared analyses and orbital localizations (α and β) clearly demonstrate that the charge transfer occurs inter-surface, from nanocages to adsorbed ligands. Bader's theory analysis for the adsorption ligands VA (Vinyl Alcohol), CA (Citric Acid), and SMX (Sulfamethoxazole) by the doped copper and cobalt nanocages demonstrates that these systems are much more adequate for adsorbing the ligand antibiotics than the other hosts. The highly adsorbent energy of sulfamethoxazole by Cu–Zn19O20 is equal to −582.86 kJ.mol-1. The IGM-NCI/ELF analyses support these findings, revealing that the Cu/Co–Zn19O20 nanocages adsorb SMX via hydrogen bonding and van der Waals interactions, as they also did in DFT-D3 and FT-IR analyses. LOL analyses support this claim by visualizing single-pair spins in excess surrounding acceptor atoms (O) in the two systems. Molecular dynamics simulations show that SMX is quickly adsorbed by nanocages of Zn19O20 doped with copper (d9) or cobalt (d7).

Detection, Analysis, and Behavior of Soft-Shorts in Solid-State Batteries

Lithium metal batteries face numerous challenges before being employed in practical energy storage systems. Chief among these is the suppression of lithium dendrites, which lead to cell shorting and thermal runaway. In the field of solid-state batteries, there is often talk of “soft-shorts”, where small lithium dendrites form, short, then disappear. However, there is no clear consensus on the definition of soft-shorts, how they behave, and what their presence means for solid electrolyte development. Here, we use composite polymer electrolytes as exemplary solid electrolytes to detect, analyze, and thoroughly describe the varied behavior of soft-shorts. We define soft-shorts and show quantitatively that both ionic and electronic current flow simultaneously in a soft-shorted cell. The amount of each current depends on dendrite size, which dictates the resistance to the electronic pathway as well as Joule heating of the thin metal filaments. This heating leads to the “burning out” of the dendrites, which is responsible for the rapid un-shorting of soft-shorted cells. We use computational modeling to quantify the dendrite properties and explain how this leads to the observed transient behavior. More persistent soft-shorts are analyzed with temperature-dependent, quantitative electrochemical impedance fitting, where it is shown that parallel ionic and electronic current paths present impedance data that can be misinterpreted without rigorous analysis. The advantages and disadvantages of several soft-short characterization techniques are discussed. In the end, we show that soft-shorts are diverse in nature and thus require diverse tools and keen eyes from researchers to avoid the over-selling of flawed materials for lithium metal batteries.

Iridium Nanosheet Catalysts Supported on Titanium Oxide for Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolysis

In order to overcome the disadvantage of intermittent production of renewable energy, Polymer electrolyte membrane water electrolysis(PEMWE), which is one of the technologies of producing hydrogen by electrolyzing water, is attracting attention. For the commercialization of PEMWE, it is important to reduce usage of iridium(Ir) for oxygen evolution reaction(OER) in the anode electrode. Many studies have been reported to reduce the amount of iridium used by developing a catalyst with higher performance than the iridium nanoparticle catalyst used as a commercial catalyst. As one of the strategies, the introduction of support materials that can increase the active area of the catalyst is drawing attention. While carbon-based supports are mainly used in other applications, in OER environments, carbon is easily corroded due to high voltage and strong acid conditions. Therefore, it is necessary to use a metal oxide support with high corrosion resistance. In particular, titanium oxide(TiO2) is one of the suitable support candidates because it is a stable material in an acidic OER environment. However, catalysts loaded on TiO2 with nanoparticles cause an electrical contact problem due to the low electrical conductivity of TiO2, which causes a degradation in activity. Many studies have reported doping methods to increase the conductivity of TiO2, but there are also reports that these methods reduce the durability of support. Thus, a new approach to synthesizing a better structure of catalysts is needed to utilize metal oxide support.Herein, we present an approach to iridium nanosheet (NS) catalysts supported on TiO2(Ir NS/TiO2). Ir NSs were synthesized by an facile method by directly annealing a mixture of Ir precursor and alkali salt. Ir NSs were supported on TiO2 to be utilized as a reaction site and also acts as an electron path to compensate for the low electrical conductivity of TiO2. Ir NS/TiO2 showed superior OER activity and stability under acidic conditions. These results showed that Ir NS/TiO2 could be utilized to reduce the amount of precious metal catalyst in PEMWE and increase the stability of OER supported catalysts.

Deep insight on two luminous mechanism and optical properties of Pr doped MgGeO3 red/NIR luminescent materials

In this work, MgGeO3:Pr3+ system is prepared by high-temperature solid phase method under the condition of different temperature and Pr content. MgGeO3:Pr3+ could emit 622 nm (red), 716 nm (red), 903 nm (NIR) and 1081 nm (NIR) lights under the external excitation of 251 nm and 425–500 nm. Due to the different excitation wavelengths, MgGeO3:Pr3+ has completely different electronic transition paths, resulting in a much larger emission intensity under 251 nm excitation than that excited by 425∼500 nm. When the incident light wavelength is 251 nm, the excitation process is VB→1D2 level of Pr3+, and the emission is due to transition of 1D2→3H4, 1D2→3H5, 1D2→3H6(3F2) and 1D2→3F3,4. When the wavelength of incident light is 425∼500 nm, the excitation process is 3H4→CB, the emission is CB→1D2, and then 1D2→3H4, 1D2→3H5, 1D2→3H6(3F2) and 1D2→3F3,4. At the same time, the emission spectrum and X-ray diffraction measurements show that the most fundamental factor determining the emission intensity of the sample is the concentration of the luminescent center (Pr3+ that can emit light) in the MgGeO3 grain. Increasing the sintering temperature and Pr element content in raw materials can increase the of Pr3+ concentration in the grain (increase the concentration of the luminescent center). However, if the concentration of Pr3+ in the grain is too high, Pr3+ would lose the function of the luminescence center, resulting in a decrease in the concentration of the luminescence center, thereby reducing the luminescence intensity.

In situ irradiated XPS proved efficient charge transfer on graphdiyne (CnH2n-2) based tandem NiFe PBA/CuI/GD S-scheme heterostructure for photocatalytic hydrogen production

Due to its abundant carbon chemical bonds, large conjugated system and natural pore structure, graphdiyne (GD, CnH2n-2) shows great advantages in growth, assembly and performance regulation, and is a key material to promote innovative development in catalysis, energy and other fields. In this study, NiFe PBA cube was prepared by coprecipitate method, and then NiFe PBA/CuI/GD ternary composite photocatalyst was formed by tightly coating NiFe PBA and CuI with graphitylene material. In situ irradiated X-ray photoelectron spectroscopy characterizes the change in electron cloud density of a catalyst under illumination, so as to determine the series-type transfer path of photogenerated electrons between three single photocatalysts, thus revealing the formation of double S-scheme heterojunction. Photocurrent and fluorescence tests have confirmed that the photogenerated carriers in NiFe PBA/CuI/GD can be transferred rapidly and utilized efficiently to participate in the photocatalytic reaction under the action of strong interfacial electric field. In addition, the three-dimensional structure of NiFe PBA and CuI and the surface carbon layer synergistic effect to expand the utilization rate of visible light catalyst. This work provides a new idea for the construction of S-scheme heterojunction and the application of new carbon materials in the field of photocatalysis.

Carbon nanotubes as electron mediators for CNTs/CdS/MoS2 high efficient photodegradation of tetracycline under visible light

The ternary nanocomposites of CNTs/CdS/MoS2 was synthesized by a simple two-step hydrothermal method and characterized accordingly. In situ growth of CdS on the surface of CNTs decreased the size of CdS particles and increased its dispersibility. Moreover, CdS took advantage of the good conductivity of CNTs to accelerate the conduction of photogenerated holes and reduced the recombination efficiency of charge carriers. MoS2 grew in situ on the surface of CdS, and the interface between them formed a close contact heterostructure. The built-in electric field formed at the interface between the two forced the photogenerated electrons of CdS and the holes of MoS2 to recombine here. This property not only changed the path of photogenerated electrons and holes, but also made the surface of MoS2 becoming the active center of reduction reaction. The hybrid structure of CNTs/CdS/MoS2 in-situ composite significantly improved the photocatalytic performance. When CNTs/CdS/MoS2 was used as photocatalyst, the degradation rate of tetracycline was 96.7% under 100 min of visible irradiation, and the data was still above 95% after 5 cycles indicate. This indicated that the ternary complex has good photocatalytic performance and stability. The successful preparation of CNTs/CdS/MoS2 provides an economically feasible approach for the degradation of tetracycline.

Long-range polaritonic heat conduction in asymmetric surrounding media

Surface Phonon Polaritons (SPhPs) as an evanescent electromagnetic surface wave supports long propagation which readily surpasses the mean free path of classical heat carriers, e.g., phonons and electrons in solids. SPhPs have emerged as a promising candidate to dominate heat transfer in thin films. Polaritonic heat transfer has two distinct advantages: superior thermal conduction and a wide range of manipulation. Here, we study the upper limit of the thermal conductivity mediated by long-range polaritons in asymmetric surrounding media, where its surface effect overwhelms the volumetric one. The thin film structure strengthens the interactions of two surface waves at the top and bottom surfaces, and the asymmetric surrounding media makes an evanescent surface wave to further penetrate the free space with a higher refractive index, but it requires a fine tuning of asymmetric permittivity of the surrounding media to reach the upper limit of energy transmission efficiency near to the modal cut-off, where the transverse wavevector becomes zero. Both analytical and numerical simulations were introduced to investigate dispersion in asymmetric surrounding media and to model the thermal conductivity of glass thin films. Anomalously high thermal conductivity of 248 W/m-K was achieved with a 50 nm thick SiO2 film in asymmetric surrounding media, yet subtly dissimilar.

The Impact of a Thick-Doping-Layer on the Charge Collection Efficiency in the P-Type Silicon Substrate of EBCMOS Devices

In order to improve the charge collection efficiency of EBCMOS, we predicted and experimentally confirmed the doping structure of the electron multiplication layer. In this study, we simulate the charge collection efficiency of EBCMOS using various doping strategies by modeling the collisional scattering of electrons with solid atoms in semiconductor materials and combining the travel paths of electrons in the electron multiplication layer. The simulation findings demonstrate that the electric field distribution in EBCMOS could be optimized by using a layered doping structure to decrease the thickness of the index strongly doped layer. The enhanced doping structure directly contributes to the enhanced charge collecting efficiency. Based on the results of the simulations, doped samples were created and evaluated. The charge collection efficiency of EBCMOS devices might be significantly increased by decreasing the thickness of the index highly doped layer to 0.1 μm, reaching 86.27%. The testing was done on a 7 μm thick P-type silicon substrate with a 1 μm thick index highly doped layer.

Revealing the plasma confinement behavior of an axial ring cusp hybrid discharge in a miniature ion thruster using PIC/MCC simulation

Micro direct current (DC) ion thrusters have broad application prospects as propulsion systems for micro spacecrafts due to their advantages of high discharge reliability and efficiency. Experiments in the literature show that the plasma discharge under the axial ring cusp hybrid (ARCH) magnetic field has higher discharge efficiency in the discharge chamber of micro DC ion thruster. In this paper, a 2d-3v axisymmetric particle-in-cell/Monte Carlo collision numerical model is developed for the ARCH discharge. This model takes the thermal electron emission including the Schottky effect, various collision processes including the Bohm-type anomalous conductivity and the uneven background gas density distribution in the cathode-anode gap into account. The spatial distributions of plasma characteristics are presented and the advantages of ARCH discharge compared with traditional 3-ring discharge in the discharge chamber of the micro DC ion thruster are analyzed. The longer electron path length and the change of ionization region improve the discharge efficiency in small-scale discharges. Two primary methods for the discharge confinement in the miniature ion thrusters, that is, the magneto-static ‘cusp confinement’ through magnetic cusps and the electrostatic ‘sheath refection confinement’ through the backplate with the lower potential are investigated. The sensitivity of macroscopic current characteristics and microscopic plasma characteristics in the ARCH discharge to the magnetic field strength and backplate biased potential are explored. It is found that there is an optimal magnetic field to maximize the utilization of propellant and minimize the discharge loss. The electrostatic ‘sheath refection confinement’ is conducive to the reduction of discharge loss, however, it is also accompanied by the decline of propellant utilization. The above results provide further support for the design optimization of the micro DC ion thruster discharge chamber.

Influence of Alkyd Composite Coatings with Polyaniline Doped with Different Organic Acids on the Corrosion of Mild Steel

Composite coatings prepared by mixing 5 wt.% polyaniline with commercial alkyd-based paints were applied on carbon steel. The polyaniline emeraldine chloride salt was prepared by procedure recommended by IUPAC, including deprotonation by ammonia hydroxide, and reprotonation with sulfamic, succinic, citric, and acetic acids with different doping degrees or oxidation states. The steel samples with base and composite coatings were immersed in 3% NaCl and the corrosion current density was determined after 96 h in situ using the ASTM 1,10-phenanthroline method. The samples were also inspected by optical microscopy. It was shown that the composite coatings reduced the possibility of blister formations and delamination. The corrosion current density and the appearance of the corrosion products, whose area was determined by ImageJ software, closely followed the initial oxidation state of the polyaniline. It was also shown that damaged composite coatings with higher degrees of oxidized (doped) polyaniline were more prone to formation of corrosion products. The role of the initial state of the polyaniline is discussed. It is suggested that such behavior could be connected to the oxygen reduction reaction mechanism that proceeds mainly via two electron paths on the polyaniline particles, releasing a much smaller amount of hydroxyl ions, which is responsible for the delamination and blister formation of the commercial coatings.

Synergistic Metal‐Nonmetal Active Sites in a Metal‐Organic Cage for Efficient Photocatalytic Synthesis of Hydrogen Peroxide in Pure Water

AbstractPhotocatalytic synthesis of hydrogen peroxide (H2O2) is a potential clean method, but the long distance between the oxidation and reduction sites in photocatalysts hinders the rapid transfer of photogenerated charges, limiting the improvement of its performance. Here, a metal‐organic cage photocatalyst, Co14(L−CH3)24, is constructed by directly coordinating metal sites (Co sites) used for the O2 reduction reaction (ORR) with non‐metallic sites (imidazole sites of ligands) used for the H2O oxidation reaction (WOR), which shortens the transport path of photogenerated electrons and holes, and improves the transport efficiency of charges and activity of the photocatalyst. Therefore, it can be used as an efficient photocatalyst with a rate of as high as 146.6 μmol g−1 h−1 for H2O2 production under O2‐saturated pure water without sacrificial agents. Significantly, the combination of photocatalytic experiments and theoretical calculations proves that the functionalized modification of ligands is more conducive to adsorbing key intermediates (*OH for WOR and *HOOH for ORR), resulting in better performance. This work proposed a new catalytic strategy for the first time; i.e., to build a synergistic metal‐nonmetal active site in the crystalline catalyst and use the host–guest chemistry inherent in the metal‐organic cage (MOC)to increase the contact between the substrate and the catalytically active site, and finally achieve efficient photocatalytic H2O2 synthesis.

Synergistic Metal-Nonmetal Active Sites in a Metal-Organic Cage for Efficient Photocatalytic Synthesis of Hydrogen Peroxide in Pure Water.

Photocatalytic synthesis of hydrogen peroxide (H2O2) is a potential clean method, but the long distance between the oxidation and reduction sites in photocatalysts hinders the rapid transfer of photogenerated charges. Here, a metal-organic cage photocatalyst, Co14(L-CH3)24, is constructed by directly coordinating metal sites (Co sites) used for O2 reduction reaction (ORR) with non-metallic sites (imidazole sites of ligands) used for H2O oxidation reaction (WOR), which shortens the transport path of photogenerated electrons and holes, and improves the transport efficiency of charges and activity of photocatalyst. Therefore, it can be used as an efficient photocatalyst with a rate of as high as 146.6 μmol g-1 h-1 for H2O2 production under O2-saturated pure water without sacrificial agents. Significantly, the combination of photocatalytic experiments and theoretical calculations proves that the functionalized modification of ligands is more conducive to adsorbing key intermediates (*OH for WOR and *HOOH for ORR), resulting in better performance. This work proposed a new catalytic strategy for the first time, that is, to build a synergistic metal-nonmetal active site in the crystalline catalyst and use the host-guest chemistry inherent in MOC to increase the contact between the substrate and the catalytic active site, and finally achieve efficient photocatalytic H2O2 synthesis.

Field parameters investigation of CO2 splitting in atmospheric DBD plasma by multi-physics coupling simulation and emission spectroscopy measurements

CO2 dissociation in DBD plasma was thoroughly studied by combining dissociation experiments, multi-physics coupling simulation and in-situ emission spectroscopy measurements. Evolution of spatial–temporal distributions of key field parameters such as discharge mode, electron density (Ne), electron temperature (Te), intermediate concentration and reaction rates were analyzed in depth, to uncover the underlying reaction mechanism. The specific energy input (SEI) had a large impact on CO2 conversion and energy efficiency, and there was a trade-off between plasma power and gas flow rate. The highest CO2 conversion was achieved a maximum of 15.5% at SEI = 177 J·cm−3 in this work. Meanwhile, the spectrum shows that there was a large amount of CO2+, CO, O, and O2 in the plasma. In addition, we proposed and validated a reduced CO2 splitting plasma chemistry set to explore the field parameter and key reactin rates distributions. According to the multiphysics modelling, the discharge gap greatly affected the discharge form of DBD, which will subsequently influence CO2 splitting. In discharge gap > 1.75 mm formation of discharge channels remarkably decreased, and an over small discharge gap (δg < 1.25 mm) would restrain the electric field range, causing shorter motion path of charged particles and less free electrons, both of which hindered the conversion of CO2. A thinner dielectric layer can promote CO2 conversion, due to the reduction in breakdown field strength and increase of high-energy electrons. Electron impact reactions (e + CO2 → CO + O−, e− + CO2 → CO + O + e−), reactions of the excited CO2* (CO2 + CO2* → CO2 + CO + O, CO2*+O → CO + O2) mainly contributed to the CO2 dissociation.

A novel strategy for large-scale preparation of flexible high-conductivity carbon fiber paper for supercapacitors

In order to solve the problems of high cost and high brittleness of commercial carbon fiber paper, a low-cost mass production method of carbon fiber paper for flexible super capacitor was proposed. The dispersant CMC-Na is utilized to achieve uniform dispersion of chopped carbon fiber in a water system through ultrasonic dispersion. Sheath-core composite (PE/PET) fiber not only enhances the tensile strength of CFP but also consolidates the electrode network structure formed based on carbon fiber structure. The CFP-3 electrode, impregnated with 3 % AC phenolic resin, exhibits excellent mechanical and electrochemical properties. SEM images reveal that AC is deposited on each carbon fiber and that the CFP-3 electrode retains its three-dimensional structure (with a porosity of 71.2 %), providing an effective permeation path for electrons (with an electrical conductivity of 0.871 S m−1). The CFP-3 electrode can restore its original shape after folding and bending without damage. Electrochemical tests demonstrate that the CFP-3 electrode has a high areal capacitance of 507.2 mF cm−2 at a current density of 0.5 mA cm−2. At a current density of 10 mA cm−2, the capacitance retention rate of the CFP-3 electrode is 96.1 % after 5000 charge-discharge cycles, owing to the well-interconnected structure of the carbon fiber paper. Furthermore, when used as a direct electrode, CFP exhibits excellent stability. Most notably, the cost of producing the CFP-3 electrode (0.0314 m2) is only $0.195, significantly lower than that of commercial products, excluding equipment, utilities, and labor costs. This research provides valuable insights for the low-cost, large-scale production of paper-based flexible supercapacitors.

Construction of high performance aqueous asymmetric supercapacitor based on multi walled carbon nanotube/MgMn2O4 composite

MgMn2O4 nanoplates like structure are synthesized by fast and easiest co-precipitation method. The end product is figured out by numerous characteristic techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), field emission electron microscope (FESEM), selected area electron diffraction (SAED) and Brunauer-Emmett-Teller (BET) surface area analysis. Further, the nanostructure material is subjected as electrode material for energy storage performance. The specific capacitance of 821 F g−1 is observed at 1 A g−1 from MgMn2O4 nanoplates. The specific capacitance of prepared MgMn2O4 nanomaterial is further boosted by small amount of multi walled carbon nanotubes (MWCNTs) and, high specific capacitance of 1208 F g−1 is observed at 1 A g−1 from MWCNT/MgMn2O4 composite. Furthermore, the aqueous asymmetric supercapacitor (ASC) is constructed where MWCNT/MgMn2O4 is used as positive electrode and activated carbon (AC) is used as negative electrode. The ASC device reveals the high energy density of 54.39 W h kg−1 with power density of 775.46 W kg−1 at 1 A g−1. Furthermore, two parallel connected red color light-emitting diodes (LEDs) are lit by series connected two ASCs. In addition, a kitchen timer and toy motor fan are also powered by series connected two ASCs. The enhanced supercapacitive performance of composite material is ascribed to the surface roughness of nanoplates, where small voids on the surface of the nanoplates provide more accommodation for electrolytic ions, and connectivity of nanoplates through MWCNTs provide suitable electronic path for electrons/ions during charging/discharging process. This attractive performance reveals that MWCNT/MgMn2O4 may be considered as prospective electrode material for high energy storage performance of supercapacitors.