Electron Transportation Research Articles

Synergistic Bimetallic Effects of BiSb Anodes Enable Long‐Stable Sodium Storage

AbstractAlloy‐type anodes are of interest for their resource‐rich and high theoretical capacity performance in sodium‐ion batteries (SIBs). However, severe volume expansion may lead to rapid capacity decay and electrode pulverization. In this work, metallic Bi with better structure stability is rationally selected as a skeleton to form a 2D BiSb alloy to alleviate the volume expansion. Interestingly, by combining in‐situ XRD and ex‐situ TEM characterizations, a reversible multi‐step alloying sodium storage mechanism of BiSb ↔ Na(Bi, Sb) ↔ Na3(Bi, Sb) in Bi0.4Sb0.6 anode is elucidated, and the partial amorphization and expanded interlayer spacing of BiSb alloy is also revealed, which greatly alleviate volume expansion thereby enhancing electrochemical stability. Furthermore, density functional theory and kinetic calculations demonstrate that Bi0.4Sb0.6 demonstrates lower Na+ adsorption energy and Na+ diffusion energy barriers, ensuring fast electron and ion transportation during sodium storage. Benefiting from the synergistic effects of binary alloy, Bi0.4Sb0.6 exhibits a high reversible capacity and cycling stability of 446 mAh g−1 at 0.1 A g−1, and 70% high capacity after 1100 cycles at 0.5 A g−1. This work provides new insights and opportunities to develop advanced precise alloy‐type anode materials for SIBs.

Electrospun PVDF-Based Polymers for Lithium-Ion Battery Separators: A Review

Lithium-ion batteries (LIBs) have been widely applied in electronic communication, transportation, aerospace, and other fields, among which separators are vital for their electrochemical stability and safety. Electrospun polyvinylidene fluoride (PVDF)-based separators have a large specific surface area, high porosity, and remarkable thermal stability, which significantly enhances the electrochemistry and safety of LIBs. First, this paper reviewed recent research hotspots and processes of electrospun PVDF-based LIB separators; then, their pivotal parameters influencing morphology, structures, and properties of separators, especially in the process of electrospinning solution preparation, electrospinning process, and post-treatment methods were summarized. Finally, the challenges of PVDF-based LIB separators were proposed and discussed, which paved the way for the application of electrospun PVDF-based separators in LIBs and the development of LIBs with high electrochemistry and security.

High-performance wide-bandgap perovskite solar cells using poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) as the electron-transport layer

We used work-function-tuned poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the electron-transport layer for wide-bandgap (1.74 eV) perovskite solar cells (PSCs). With the coating of polyethylenimine, the work function of PEDOT:PSS was modified from −5.03 to −4.05 eV, which enabled efficient electron transportation from perovskite absorber to cathode. With this technique, the standard-structured n-i-p PSCs showed an average power-conversion-efficiency (PCE) of 18.6 %, which is higher than that (17.5 %) of inverted PSCs with PEDOT:PSS as the hole-transport layer. Moreover, the long-term stability of the PSCs was enhanced with the PCE degradation significantly suppressed from 29.7 % to 15.6 % after a 10 days’ measurement in ambient.

Carbon-based Nanocomposite Materials for Electrochemical Monitoring of Cadmium Ions

In the present era of science and technology, cadmium poisoning in humans is reported from several parts of the world and now it is a global health problem. Accumulation of cadmium in human organs and tissues, such as the liver, kidney, etc., leads to carcinogenic effects and toxicity to the organ system. Therefore, several efforts are being made to develop a monitoring system for cadmium metal ions in the environment. This review aimed to summarise the different carbon-composite materials-based electrochemical sensors reported to date for cadmium ions detection. The first section of this review provides a brief discussion on the source and harmful effects of cadmium ions, and the rest part includes different carbon (graphite, graphene, graphene oxide, carbon nanotubes, etc.)-based composite nanomaterials reported to date for the electrochemical detection of cadmium ions in different analytes. Carbon-based nanocomposite materials have been found to be very suitable for the detection of Cd(II) ions due to their boosted electron transportation and high surface, leading towards high sensitivity and high selectivity.

Paving “Pt···Ti” Hot Electron Transportation Bridge for Outstanding Photothermal Catalytic Reduction of CO 2

Paving “Pt···Ti” Hot Electron Transportation Bridge for Outstanding Photothermal Catalytic Reduction of CO ₂

Development of metal oxide Nanocomposite-Coated electrospun nanofibers for highly sensitive xanthine monitoring

Developing a durable, cost-effective, and readily available electroactive sensor that doesn’t depend on noble metals is crucial for the selective and sensitive monitoring of xanthine (Xn) to overcome the risks linked to metabolic disorders like gout, xanthinuria, and renal failure. Thus, to meet these requirements, herein we have designed a noble-metal-free highly sensitive and selective electrochemical sensor for Xn. We have developed an electrochemical sensor by depositing Co3O4-NiO nanoblossoms on the surface of cellulose acetate (CA) and polyaniline (PANI) based electrospun nanofibers. These electrospun nanofibers facilitate rapid diffusion of Xn molecules to the sensing interface via amine and imine groups, leading to fast response by providing a smooth pathway for transportation of electrons. Moreover, synergistic characteristics of CNNB with electrospun nanofibers contribute to the selective binding of Xn with quick response as well. Our findings reveal that fabricated material exhibits high sensitivity (5 μA μM−1), a response range (0.1–42 µM) with remarkably low limit of detection (0.03 µM). Additionally, our designed electrode demonstrates more selectivity towards Xn in the presence of other interfering species. The designed electrochemical sensor has shown greater reliability in terms of reproducibility and reusability with robust response in human serum samples.

N-doped carbon dots/SnS2 heterostructures for ultra-fast and sub-ppb-level detection of NO2 in multiple environments

Nitrogen dioxide (NO2) is one of the most common toxic gases, which not only impairs human health but also produces secondary pollutants induced by sunlight via associated photochemical reactions. Herein, we design a high-performance NO2 sensor based on the N-doped carbon dots/SnS2 (N-CDs/SnS2) heterostructure using density functional theory (DFT) calculations. The DFT results approve that the decoration of N-doped carbon dots (N-CDs) onto the SnS2 nanosheet enhances adsorption capacity and electron transportation compared with those of pure SnS2, significantly enhancing the sensing responses. In addition, these in-situ synthesized N-CDs onto SnS2 nanosheet leads to band alignment, thereby significantly improves conductivity and enhances transportation and storage properties of carriers via a synergistic interaction. Furthermore, employment of UV illumination significantly increases active adsorption sites and enhances response and recovery kinetics. As a result, the developed NO2 sensor achieves fast responses of a few seconds and a limit of detection down to sub-ppb-level with the help of UV illumination. It also shows good linearly, operated in both air and oxygen-free environments, at both room or low temperature (238 K) conditions. The developed multi-framework offers an efficient and precision detection of NO2 with ultrafast responses and ultralow concentrations in multiple environments.

A monolithic self-supporting ZnFe2O4/ZnO/ZnNi foam photocatalyst and application in the decomposition of gaseous benzene

Volatile organic compounds (VOCs) are major air pollutants which seriously affect ecological environment and pose threats to human health. In this investigation, a monolithic self-supporting ZnFe2O4/ZnO/ZNF(ZFO/ZnO/ZNF) photocatalyst was developed by in-situ growing ZnFe2O4 and ZnO on ZnNi foam (ZNF). Using benzene as a representative of the target gaseous contaminants, the optimal 5ZFO/ZnO/ZNF achieved a 99.8 % removal efficiency and 99.7 % mineralization efficiency within 20 min at an initial benzene concentration of 600 ppm under simulated sunlight irradiation. Moreover, this catalyst presents the lower ullage during gas–solid reaction, and thus enables durable recycling reuse of the photocatalyst, which still retains a 95.8 % benzene decomposition after 30th consecutive run. The mechanism studies reveal that the metal-mediated Z-type heterostructure of ZFO/ZnO/ZNF enhances rapid transportation of the photo-generated electrons and promotes redox potential, leading to the excellent photocatalytic oxidation activity and mineralization efficiency. This study highlights the potential of self-supporting monolithic metal-mediated catalysts and provides a key strategy for effective VOCs degradation.

Facile synthesis of spherical-shaped CeC2–TiO2 nanocomposite electrocatalyst with boosted alkaline OER

Developing noble metal-free multifunctional electrocatalysts to catalyze water oxidation is vital for future renewable energy systems. Herein, through several defect modifications, the CeC2–TiO2 nanocomposite on the strength of enriched oxygen vacancies was successfully fabricated by facile hydrothermal method on SS (stainless steel) substrate, attributed to the conductive ability for fast electron transportation. A well-defined phase growth, vibrational bonding of metal atoms, morphological determination, and elemental composition for synthesized heterostructured electrocatalysts were revealed by XRD, FTIR, TEM, and EDX, respectively. XPS has complied to understand the moderate binding energies of CeC2–TiO2 for OER intermediates, which signifies the strong interactions between electronic states of Ce, C, Ti, and O atoms. With the plentiful catalytic active sites, the resultant CeC2–TiO2 entails low overpotentials of only 169 mV and 108.8 mV/dec Tafel slope to afford 10 mA cm−2 for OER in 1.0 M KOH are tested through cyclic and linear sweep voltammogram measurements, thereby exhibit promising activity in alkaline water electrolysis. EIS measurements revealed a decreased polarization resistance for the composite dominated by the small semicircle diameter, corresponding to the adsorption of intermediates. Finally, observed results strongly recommended that the CeC2–TiO2 catalyst exhibited superior OER performance due to excellent electrical chemical coupling between CeC2 and TiO2.

SnF2-Catalyzed Lithiophilic-Lithiophobic Gradient Interface for High-Rate PEO-Based All-Solid-State Batteries.

Polyethylene oxide (PEO)-based all-solid-state lithium metal batteries (ASSLMBs) are strongly hindered by the fast dendrite growth at the Li metal/electrolyte interface, especially under large rates. The above issue stems from the suboptimal interfacial chemistry and poor Li+ transport kinetics during cycling. Herein, a SnF2-catalyzed lithiophilic-lithiophobic gradient solid electrolyte interphase (SCG-SEI) of LixSny/LiF-Li2O is in situ formed. The superior ionic LiF-Li2O rich upper layer (17.1 nm) possesses high interfacial energy and fast Li+ diffusion channels, wherein lithiophilic LixSny alloy layer (8.4 nm) could highly reduce the nucleation overpotential with lower diffusion barrier and promote rapid electron transportation for reversible Li+ plating/stripping. Simultaneously, the insoluble SnF2-coordinated PEO promotes the rapid Li+ ion transport in the bulk phase. As a result, an over 46.7 and 3.5 times improvements for lifespan and critical current density of symmetrical cells are achieved, respectively. Furthermore, LiFePO4-based ASSLMBs deliver a recorded cycling performance at 5 C (over 1000 cycles with a capacity retention of 80.0 %). More importantly, impressive electrochemical performances and safety tests with LiNi0.8Mn0.1Co0.1O2 and pouch cell with LiFePO4, even under extreme conditions (i.e., 100 °C), are also demonstrated, reconfirmed the importance of lithiophilic-lithiophobic gradient interfacial chemistry in the design of high-rate ASSLMBs for safety applications.

SnF2‐Catalyzed Lithiophilic–Lithiophobic Gradient Interface for High‐Rate PEO‐Based All‐Solid‐State Batteries

AbstractPolyethylene oxide (PEO)‐based all‐solid‐state lithium metal batteries (ASSLMBs) are strongly hindered by the fast dendrite growth at the Li metal/electrolyte interface, especially under large rates. The above issue stems from the suboptimal interfacial chemistry and poor Li+ transport kinetics during cycling. Herein, a SnF2‐catalyzed lithiophilic‐lithiophobic gradient solid electrolyte interphase (SCG‐SEI) of LixSny/LiF‐Li2O is in situ formed. The superior ionic LiF‐Li2O rich upper layer (17.1 nm) possesses high interfacial energy and fast Li+ diffusion channels, wherein lithiophilic LixSny alloy layer (8.4 nm) could highly reduce the nucleation overpotential with lower diffusion barrier and promote rapid electron transportation for reversible Li+ plating/stripping. Simultaneously, the insoluble SnF2‐coordinated PEO promotes the rapid Li+ ion transport in the bulk phase. As a result, an over 46.7 and 3.5 times improvements for lifespan and critical current density of symmetrical cells are achieved, respectively. Furthermore, LiFePO4‐based ASSLMBs deliver a recorded cycling performance at 5 C (over 1000 cycles with a capacity retention of 80.0 %). More importantly, impressive electrochemical performances and safety tests with LiNi0.8Mn0.1Co0.1O2 and pouch cell with LiFePO4, even under extreme conditions (i.e., 100 °C), are also demonstrated, reconfirmed the importance of lithiophilic‐lithiophobic gradient interfacial chemistry in the design of high‐rate ASSLMBs for safety applications.

Bismuth oxide nanoflakes grown on defective microporous carbon endows high-efficient CO2 reduction at ampere level

Carbon dioxide electroreduction is a green technology for artificial carbon sequestration, which is being delayed from industrialization due to the lack of efficient catalysts at high current conditions. Herein, the Bi2O3 nanoflakes were uniformly grown on a defective porous carbon (PC). This self-assembling Bi2O3/PC catalyst was applied to drive CO2 electroreduction at 1.0 A, 1.5 A and 2.0 A while the Faradaic efficiency of formate reaches 91.50 %, 86.30 % and 84.22 %, respectively. Density functional theory calculations revealed the intrinsic defect of carbon is able to give electron to Bi through O bridge, which increased the electron aggregation of Bi and lowered the generation energy barrier of *OCHO intermediate. Additionally, the unique 3D network of staggered Bi2O3 enhances the CO2 adsorption and favors the electron transportation. By integrating all above advantages into a solid electrolyte-type cell, we are able to produce pure formic acid in a rate of 15.48 mmol h−1 at ampere current.

Electronic regulation by constructing RGO/MoCQD/CF double interface to enhance performance in solar cells

The intrinsic defects such as the low electrical conductivity and sluggish kinetics for counter electrode seriously hinder its ability to meet the requirements of daily applications for dye-sensitized solar cells (DSSCs). Herein, to propel the development of DSSCs toward ultra-high stability and fast dynamics, the counter electrode (CE) of RGO/MoCQD/CF nanoreactors are created by sandwiching stable MoC quantum dots (QDs) in two distinct carbon matrices {Reduced Graphene Oxide (RGO) and Carbon Flower (CF)}. The multi-structured nanoreactors both effectively enhance stability of catalysis by forming sandwich structure and offers homogeneous dispersion of MoCQD to avoid its agglomeration. Numerous electrons assemble at the RGO contact, which can disrupt the balanced charge state and and modify the electronic structures of Mo sites to expedite reaction kinetics and I3- catalytic activity, according to studies using density functional theory and X-ray photoelectron spectroscopy. Additionally, the framework also contains the advantage of the vast uniformly dispersed active sites, a fast ion–electron transportation channel, and reactive structures that facilitate electrolyte infiltration. By virtue of integration of multiple advantages, DSSC with RGO/MoCQD/CF CE brings excellent performance, i.e., high PCE (9.08 %) and ultra-long cycling performance (96 h), offering great potential for make use of basically viable DSSC.

Ti[sbnd]F bridged IL-CuCQDs-F/TiO2 inverse opal composite for boosting CO2 visible-photo reduction via slow photon effect

Photocatalytic reduction of CO2 exhibits unsatisfactory photocatalytic performance owing to the inefficient separation of photogenerated electron-hole pairs, low CO2 capture efficiency and limited visible light absorption on most photo-catalysts. Herein, TiF bridged IL-CuCQDs-F/TiO2 inverse opal composite (IO-CFTi) was constructed for boosting CO2 visible-photo reduction via slow photo effect. In this work, ethylenediaminetetraacetic acid (EDTA(Cu)) and imidazole ionic liquid 1-(2-Hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HOEtMIM][BF4]) were employed to confine grow of IL-CuCQDs-F within TiO2 inverse opal supporter via TiF bonds connection. Unique IL-CuCQDs-F efficiently expended light absorption towards visible region, and the confined growth of IL-CuCQDs-F within the TiO2 inverse opal cavity achieved the photoelectric conversion and efficient CO2 capture. Moreover, their TiF bonding interface of IO-CFTi assisted photogenerated electron transportation from TiO2 to CO2 for its reduction in this system. Consequently, IO-CFTi achieved a substantially increased CO production rate of 78.1 μmol·h−1·g−1 with 98 % selectivity. This improved performance in CO2 photoreduction positions the nanocomposite as a promising material for preservation of the environment and conversion of energy.

The Solar Aspect System of the Hard X-ray Imager Onboard ASO-S

The ASO-S/HXI is a bi-grids modulating instrument for solar hard X-ray imaging, whose collimator contains 91 pairs of tungsten grids. Since the solar disk is invisible in hard X-rays, a Solar Aspect System (SAS) is required to provide the pointing of hard X-ray imager (HXI) for locating X-ray sources on the solar disk. In addition, the knowledge of the alignment and relative twist of the corresponding front–rear grid pairs is important for image reconstruction as well as locating flares. Therefore, the SAS system was designed to monitor the alignment status of HXI grids and to provide the pointing direction of the HXI collimator with two subsystems DM and SA during the whole life cycle of HXI. DM measures the centroids of the front frosted glasses and the solar disk. SA images the Sun and provides precise relative locations of the solar disk center. Both work in the visible light of 565–585 nm. With all the data together, we can solve with an inversion algorithm the alignment status of the front and rear grids, the relative twist, and the pointing direction. We tested and validated the SAS design with both the simulation model and ground coordinate measuring machine. Here we present the detailed system design, the testing results, the inversion algorithm, and the in-orbit status of the SAS. Currently, the SAS has realized the rotational measurement accuracy of about 4 arcsec, and a translational measurement accuracy of about 15 μm, and the SAS pointing data has been used in both imaging calibration for flare locations and imaging corrections for the platform drifting effect. The high-cadence precise measurement (better than 0.3 arcsec) of the pointing will allow the study of source locations at different energies and therefore help us to understand electron acceleration and transportation in flares.

Magnesiothermic reduction SiO coated with vertical carbon layer as high-performance anode for lithium-ion batteries

Silicon monoxide (SiO), as one of the most competitive anode materials for lithium-ion batteries (LIBs), has received considerable attention. Nevertheless, poor initial Coulombic efficiency (ICE) and larger volume change are the main obstacles to the application of SiO. Here, we suggest a controllable route for the modification of micro-sized SiO via magnesiothermic reduction. To prevent the excessive growth of Si grains caused by the overheating reaction, the solid-state thermal reaction between Mg and SiO is achieved by mixing a certain proportion of NaCl at a suitable temperature, resulting in a loose surface and porous structure of SiO particles, which is conducive to the transportation of lithium ions and electrons. Combined with chemical vapor deposition (CVD), the carbon-coated SiOx composites (M-SiOx@C-R, where R is the molar ratio for Mg and SiO) exhibit unique morphology structure and remarkable electrochemical characteristics. As expected, the vertical carbon network improves the conductivity and alleviates the volume expansion of SiOx. Notably, the M-SiOx@C-0.75 electrode offers a large initial specific capacity of 2283.17 mAh g−1 with a higher ICE of 86.03 % at 100 mA g−1. Furthermore, the full cells using M-SiOx@C-0.75 composite as the negative electrode and LiNi0.8Co0.1Mn0.1O2 (NCM811) as the positive electrode were assembled. After 150 cycles, the full cell still delivers a high specific capacity of 72.22 mAh g−1 (with a retention rate of 47 %). This work provides a feasible route for the fabrication of applicable SiO-based anode materials.

Enhance electrochemical sensing of ascorbic acid and dopamine using V-CuO/GO nanocomposite

The electrochemical detection of Ascorbic acid and dopamine is crucial due to their vital roles in biological processes. Both biomolecules coexist in the human body and have the same oxidation potential, leading to electrode fouling and overlapping of oxidation potential. Accurate detection enables monitoring their levels in biological samples, aiding in disease diagnosis and treatment. This study presents the fast and green synthesis of a highly sensitive and selective electrochemical biosensor for the simultaneous detection of dopamine and ascorbic acid. The change in spherical cluster morphology into nanorods enhances the electrode's electroactive surface area, enhancing sensor sensitivity and selectivity. Electrochemical characterization techniques, including cyclic voltammetry and electrochemical impedance spectroscopy, demonstrated excellent electron transportation and low charge transfer resistance. The sensor exhibited simultaneous detection with a low limit of detection of 8 µM for dopamine and 6.9 µM for ascorbic acid, with a wide linear working range. Additionally, the sensor showed excellent selectivity and repeatability with a vast potential gap at simultaneous detection, making it suitable for clinical and food industry applications.

Rational Construction of Honeycomb-like Carbon Network-Encapsulated MoSe2 Nanocrystals as Bifunctional Catalysts for Highly Efficient Water Splitting.

The scalable fabrication of cost-efficient bifunctional catalysts with enhanced hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance plays a significant role in overall water splitting in hydrogen production fields. MoSe2 is considered to be one of the most promising candidates because of its low cost and high catalytic activity. Herein, hierarchical nitrogen-doped carbon networks were constructed to enhance the catalytic activity of the MoSe2-based materials by scalable free-drying combined with an in situ selenization strategy. The rationally designed carbonaceous network-encapsulated MoSe2 composite (MoSe2/NC) endows a continuous honeycomb-like structure. When utilized as a bifunctional electrocatalyst for both HER and OER, the MoSe2/NC electrode exhibits excellent electrochemical performance. Significantly, the MoSe2/NC‖MoSe2/NC cells require a mere 1.5 V to reach a current density of 10 mA cm-2 for overall water splitting in 1 M KOH. Ex situ characterizations and electrochemical kinetic analysis reveal that the superior catalytic performance of the MoSe2/NC composite is mainly attributed to fast electron and ion transportation and good structural stability, which is derived from the abundant active sites and excellent structural flexibility of the honeycomb-like carbon network. This work offers a promising pathway to the scalable fabrication of advanced non-noble bifunctional electrodes for highly efficient hydrogen evolution.

Epsilon‐negative materials with lower percolation threshold derived from segregated structures

AbstractEpsilon‐negative materials (ENM) at radio frequency, usually designed based on percolation theory, recently drew much attention because of their potential applications in capacitors, transistors, and antennas. However, randomly distributed conductive functional materials cannot achieve directional long‐range electron transportation within the material, resulting in decreased utilization efficiency. The morphology design of the substrate material can change the distribution state and electron transfer pathway of conductive fillers. By controlling the size of the polystyrene (PS) and the content of multi‐walled carbon nanotubes (MWCNTs), PS/MWCNTs composites with random structures and segregated structures were designed, both of which exhibited negative permittivity with increasing MWCNTs content. Further investigation revealed that negative permittivity behavior is due to the establishment of the conductive network and the plasma oscillation of free electrons. Moreover, components with segregated structures have lower percolation thresholds, as directional electron transport is achieved and conductive fillers are efficiently utilized. This work provides a new method for guiding the electron transport pathway and effectively changing the distribution state of conductive fillers in ENM.Highlights Negative permittivity is achieved by plasma oscillation at radio frequency. The segregated structure leads to a decrease in the percolation threshold. Epsilon‐negative materials have good prospects in inductive components.

Nickel cerium oxide-modified disposable and portable sensor for the rapid monitoring environmentally hazardous organophosphate pesticide in water and vegetable samples

The main novelty of this developed method is the detection of the hazard organophosphate pesticide fenitrothion (FNT) in real samples using a nickel cerium oxide (NiCeO) bimetallic oxide for electrocatalytic sensing in pond water, lake water, and various food samples such as brinjal, and bitter gourd. Extensive analytical and electrocatalytic assessments revealed that the NiCeO combination significantly improves electron transportation and augments the creation of electroactive sites. The resulting sensor exhibited remarkable performance characteristics, including a low detection limit, a wide linear range, and high sensitivity to FNT under pH-optimized electrocatalytic conditions, with values of ca. 1.8 nM, ca. 1–5747.3 μM, and ca. 104.383 (±0.002) μA μM−1 cm−2, respectively. Moreover, the NiCeO sensor demonstrated excellent recovery rates in real-world samples. The overall outstanding performance of the fabricated sensor indicates its excellent ability for real-time monitoring of FNT in ecological system.