Electron Microscopy Characterization Research Articles

In-situ monitoring method of femtosecond laser welding between glass and copper with acoustic emission

The use of femtosecond laser welding has created new possibilities for connecting glasses and metals, revolutionizing the fabrication and assembly of advanced electronic components. However, monitoring the connection process during femtosecond laser welding is challenging due to the small heat-affected zone and brief interaction time. This study utilizes acoustic emission to monitor femtosecond laser welding and introduces the “Sum of Relative RMS” feature to correlate connection formation with acoustic emission signals in glass-copper welding. The mechanism and signal occurrence trends during welding are explained through in-situ signal monitoring and offline scanning electron microscopy characterization. Additionally, a Convolutional Neural Network is enhanced by increasing the convolutional kernel size, integrating multi-dimensional features, and incorporating prior knowledge via a customized loss function, resulting in an increase in the accuracy of successful welding detection from 89% to 95%. This research provides new insights into the monitoring of femtosecond laser glass-metal heterogeneous welding.

In situ enhanced chlorine oxide radical generation on a novel space-confined photoanode and its application for ammonia oxidation: Structure, performance, and mechanism

Oxidizing ammonia to nitrogen is a challenge in wastewater treatment. For this challenge ammonia oxidation via chlorine oxide radicals has been proved to be a potential method. In this study, a space-confined photoanode was designed and prepared by loading RuO2 nanoparticles on TiO2/WO3 nanowires for in situ enhancing the generation of chlorine oxide radical. Scanning electron microscopy characterization confirmed that RuO2 nanoparticles were uniformly deposited on TiO2/WO3 nanowires. The generation of chlorine oxide radical was markedly boosted, and its steady-state concentration reached 2.76 × 10−12 M. This value was 3 times that of the traditional bifacial electrode (a type of electrode that has been widely used for chlorine oxide radical-related research). As a result, ammonia oxidation was greatly enhanced. In 90 min, 31.9 mg/L ammonia nitrogen could be degraded, yet only 0.94 mg/L nitrate was accumulated. In addition, the space-confined photoanode exhibited good performance for real wastewater treatment, and 41.0 mg/L ammonia nitrogen could be oxidized in 135 min. During photoelectrocatalysis, a synergistic index (47.7 %) was obtained. Besides the synergistic effect between photocatalysis and electrocatalysis, the unique morphology and structural design (TiO2/WO3 and RuO2 were mainly responsible to hydroxyl radical generation and free chlorine production, respectively) also synergistically promoted the generation of chlorine oxide radical, thereby improving ammonia oxidation. The mechanism for ammonia oxidation via chlorine oxide radicals over the space-confined photoanode was proposed based on experimental results and theoretical calculations.

Achieving High-Performance Polymer-Wrapper-Free Aligned Carbon Nanotube Field-Effect Transistors Through Degradable Polymer Wrapping and Efficient Removal Techniques.

Semiconducting carbon nanotubes (s-CNTs) have emerged as a promising alternative to traditional silicon for ultrascaled field-effect transistors (FETs), owing to their exceptional properties. Aligned s-CNTs (A-CNTs) are particularly favored for practical applications due to their ability to provide higher driving current and lower contact resistance compared with individual s-CNTs or random networks. Achieving high-semiconducting-purity A-CNTs typically involves conjugated polymer wrapping for selective separation of s-CNTs, followed by self-assembly techniques. However, the presence of the polymer wrapper on A-CNTs can adversely impact electrical contact, gating efficiency, carrier transport, and device-to-device variations, necessitating its complete removal. While various methods have been explored for polymer removal, accurately characterizing the extent of removal remains a challenge. Traditional techniques such as absorption spectroscopy and X-ray photoelectron spectroscopy (XPS) may not accurately depict the remaining polymer content on A-CNTs due to their inherent detection limits. Consequently, the performance of FETs based on pure polymer-wrapper-free A-CNTs is unclear. In this study, we present an approach for preparing high-semiconducting-purity and polymer-wrapper-free A-CNTs using poly[(9,9-dioctylfluorenyl-2,7-dinitrilomethine)-(9,9-dioctylfluorenyl-2,7-dimethine)] (PFO-N-PFO), a degradable polymer, in conjunction with a modified dimension-limited self-alignment process (m-DLSA). Comprehensive transmission electron microscopy (TEM) characterizations, complemented by absorption and XPS characterizations, provide robust evidence of the successful near-complete removal of the polymer wrapper via a cleaning procedure involving acidic degradation, hot solvent rinsing, and vacuum annealing. Furthermore, top-gated FETs based on these high-semiconducting-purity and polymer-wrapper-free A-CNTs exhibit good performance metrics, including an on-current (Ion) of 2.2 mA/μm, peak transconductance (gm) of 1.1 mS/μm, low contact resistance (Rc) of 191 Ω·μm, and negligible hysteresis, representing a significant advancement in the CNT-based FET technology.

Controlled Synthesis of 2D Ferromagnetic/Antiferromagnetic Cr7Te8/MnTe Vertical Heterostructures for High-Tunable Coercivity.

Two-dimensional ferromagnetic/antiferromagnetic (2D-FM/AFM) heterostructures are of great significance to realize the application of spintronic devices such as miniaturization, low power consumption, and high-density information storage. However, traditional mechanical stacking can easily damage the crystal quality or cause chemical contamination residues for 2D materials, which can result in weak interface coupling and difficulty in device regulation. Chemical vapor deposition (CVD) is an effective way to achieve a high-quality heterostructure interface. Herein, high-quality interface 2D-FM/AFM Cr7Te8/MnTe vertical heterostructures were successfully synthesized via a one-pot CVD method. Moreover, the atomic-scale structural scanning transmission electron microscope (STEM) characterization shows that the interface of the vertical heterostructure is clear and flat without an excess interface layer. Compared to the parent Cr7Te8, the coercivity (HC) of the high-quality interface Cr7Te8/MnTe heterostructure is significantly reduced as the thickness of MnTe increases, with a maximum decrease of 74.5% when the thickness of the MnTe nanosheet is around 30 nm. Additionally, the HC of the Cr7Te8/MnTe heterostructure can also be regulated by applying a gate voltage, and the HC increases or decreases with increasing positive or negative gate voltages. Thus, the effective regulation of HC is essential to improving the performance of advanced spintronic devices (e.g., MRAM and magnetic sensors). Our work will provide ideas for spin controlling and device application of 2D-FM/AFM heterostructures.

Self-Lubrication Mechanism of Surface-Textured Polymer-Matrix Composites under the Induction of Frictional Stress.

Polymer-matrix composites have been widely used in the manufacture of seals, bearings, electrical insulators, and self-lubricating films as engineering applications move toward lighter weight, higher strength, and corrosion resistance. However, the high-speed shear effect of the friction pairs in relative motion leads to localized heating of the polymer surface, resulting in deformation or softening of the device. Herein, acer mono maple and canna leaves were used as templates to construct polymer-matrix sulfonated polyether-etherketone/polytetrafluoro-wax (SPEEK/PFW) composites with a surface-textured structure. As the bionic texture reduces the level of direct contact between the friction pairs, the frictional thermosoftening of SPEEK occurs in the localized areas of the bumps and leads to the release of PFW stored in textures, resulting in the formation of a soft polymer sliding layer in the worn area and greatly enhancing the frictional stability. By investigation of the tribological properties of textured SPEEK/PFW composites under different loads and sliding speeds, the mechanisms from surface wear to matrix softening and spontaneous construction of a slipping layer are summarized. The results of scanning electron microscopy and three-dimensional profilometer characterization of the wear scars show the surface state of SPEEK/PFW after friction, revealing the friction-thermotropic deformation of the surface texture. The results of this study not only improve our understanding of the frictional heat-induced surface self-lubrication mechanism of textured polymer composites but also provide a reference for the development of multiphase hybrid polymer-matrix composites with excellent self-lubrication properties.

Enhanced removal of polystyrene microplastics through coagulation using polyaluminum ferric chloride with Opuntia Milpa Alta particles

Microplastics in surface water and groundwater are posing significant risks to both ecological systems and human health. Conventional coagulants are limited in their efficacy for microplastic removal and may potentially lead to secondary pollution. The present study investigated the effectiveness of Opuntia Milpa Alta (OMA) particles, as a natural coagulant, in combination with polyaluminum ferric chloride (PAFC) to remove polystyrene (PS) microplastics. The results demonstrated the pivotal role of OMA in facilitating the coagulation. Specifically, the combination of 15 mg/L of OMA and 30 mg/L of PAFC achieved a removal rate of 94.8 %. Zeta potential analysis, scanning electron microscopy (SEM) characterization, and Fourier transform infrared spectroscope (FTIR) analysis revealed that the promotion mechanisms by OMA primarily involved charge neutralization and adsorption bridging, attributed to the presence of polygalacturonic acid from OMA's mucilage, the rough surface and the mesh structures of OMA. Influences of Cl−, SO42− and HCO3− within the concentration range found in surface and groundwater were also studied. Furthermore, a cost assessment demonstrated that the incorporation of OMA not only enhanced the coagulation performance but also reduced overall costs. These findings will provide valuable insights towards the development of cost-effective techniques for the removal of microplastics from water.

Muscle ultrastructure and histopathological findings in a Brazilian single-centre series of genetically classified telethoninopathy patients

BackgroundTelethoninopathy or TCAP-gene related Limb Girdle Muscular Dystrophy is a rare genetic disease that was first described in Brazil. There are around 100 families reported worldwide. Due to its rarity, detailed information on muscle biopsy light and electron microscopic features are lacking.Cases presentationRetrospective study of consecutive muscle biopsies performed in patients from a Neuromuscular Outpatient Clinic between 2011 and 2023. Inclusion criteria: telethoninopathy diagnosed by both immunohistochemistry and molecular studies. Seven patients (0.7% or 7/953) were found: five male and two female, admitted from 6 to 54 years old. Detailed light and electron microscopy findings are illustrated. Muscle imaging is presented. A dystrophic pattern on muscle biopsy was found in 57% (4/7) of the patients. Other 43% (3/7) presented myopathic features such as variation in fibre calibre, nuclear internalization, rimmed vacuoles, and oxidative irregularities. Morphometry disclosed type 1 lobulated fibres that were 34%, 52%, and 57% smaller than type 2 fibres, respectively, in three patients, without type 1 fibre predominance. Electron microscopy demonstrated nuclear pseudoinclusions, pyknosis, multifocal loss of the sarcolemma, and 17 nm intrasarcoplasmic filamentous inclusions. All patients presented: (1) complete absence of the immunohistochemical expression of telethonin, and (2) the homozygous c.157C > T, p.(Gln53*) pathogenic variant in exon 2 of the TCAP gene.ConclusionAnti-telethonin immunohistochemistry may be helpful in unsolved cases with nonspecific myopathic abnormalities, specially with small type 1 lobulated fibres. Appropriate diagnosis is important for adequate genetic counselling.

Facile Fabrication of Highly Crystallized, Air‐Stable, and Flexible Perovskite Micromesh Film Photodetector

AbstractPerovskite materials such as organic‐inorganic MAPbX3 (X = Cl, I, Br) have attracted broad interests in photoelectric applications, such as image sensors and photovoltaics. Here, a facile and general approach, called soft‐print solvent‐assisted evaporation crystallization (SSEC) is reported, for fabrication of highly crystallized, air‐stable, and flexible perovskite micromesh films, including organic–inorganic (MAPbX3) and inorganic (CsPbX3) perovskite. Scanning and transmission electron microscopy (SEM/TEM) characterization reveals their high crystallinity without obvious grain boundaries. The photodetectors constructed based on MAPbI3 micromesh films exhibit a typical responsivity of ≈352 A W−1 and detectivity of ≈5.7 × 1013 Jones (at 650 nm in wavelength). The MAPbI3 micromesh film also shows good mechanical stability when bended at different bending radius, and after 800 bending cycles, they still exhibit highly reproducible photocurrent and on/off switching ratios. Furthermore, they are also air‐stable that they can survive for >20 days in high humid environments (65–75%) with <10% reduction in photocurrent. This work provides a facile and scalable approach for fabrication of highly crystallized, stable, and flexible perovskite micromesh films for a variety of optoelectronic applications with improved performance and durability.

Distinguishing the Rhombohedral Phase from Orthorhombic Phases in Epitaxial Doped HfO2 Ferroelectric Films.

Epitaxial strain plays an important role in the stabilization of ferroelectricity in doped hafnia thin films, which are emerging candidates for Si-compatible nanoscale devices. Here, we report on epitaxial ferroelectric thin films of doped HfO2 deposited on La0.7Sr0.3MnO3-buffered SrTiO3 substrates, La0.7Sr0.3MnO3 SrTiO3-buffered Si (100) wafers, and trigonal Al2O3 substrates. The investigated films appear to consist of four domains in a rhombohedral phase for films deposited on La0.7Sr0.3MnO3-buffered SrTiO3 substrates and two domains for those deposited on sapphire. These findings are supported by extensive transmission electron microscopy characterization of the investigated films. The doped hafnia films show ferroelectric behavior with a remanent polarization up to 25 μC/cm2 and they do not require wake-up cycling to reach the polarization, unlike the reported polycrystalline orthorhombic ferroelectric hafnia films.

Judicious Fluorination of Perovskite Quantum Wells Enables Over 25% Efficiency in Inverted Solar Cells

AbstractThe photovoltaic performance of inverted perovskite solar cells (PSCs) is often hindered by trap‐induced non‐radiative recombination and photochemical degradation occurring at the upper interfaces and the grain boundaries of perovskite films. Herein, ortho‐, meta‐, and para‐isomers of fluorophenylethylammonium iodine (F‐PEAI) organic spacer molecules are evaluated for the construction of perovskite quantum wells (2D or quasi‐2D, PQWs) to encapsulate 3D perovskites. Among the three variants, p‐F‐PEAI leads to the most symmetric charge distribution and the weakest steric hindrance which resulting in reinforced interactions with PbI2 and perovskite, the enhanced out‐of‐plane orientation is confirmed by Grazing incidence wide‐angle X‐ray scattering (GIWAXS) results. Density functional theory and crystal orbital Hamilton population (COHP) calculations further confirm that p‐F‐PEAI engages most strongly with the perovskite structure. Moreover, transmission electron microscopy (TEM) characterization is used to illustrate that p‐F‐PEAI‐assisted 2D PQWs effectively passivate both the grain boundaries and surfaces of perovskites. This configuration facilitates effective surface passivation, improves charge carrier transport, and significantly suppresses non‐radiative recombination. The resultant inverted PSCs achieve an excellent power conversion efficiency (PCE) of 25.03% with a fill factor (FF) of 85.11%. The unencapsulated devices exhibit enhanced long‐term stability under ambient environments and continuous light illumination.

Acetonitrile-Based Local High-Concentration Electrolytes for Advanced Lithium Metal Batteries.

Acetonitrile (AN) is a compelling electrolyte solvent for high-voltage and fast-charging batteries, but its reductive instability makes it incompatible with lithium metal anodes (LMAs). Herein, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) is used as the diluent to build an AN-based local high-concentration electrolyte (LHCE) to realize dense, dendrite-free, and stable LMAs. Such LHCE exhibits an exceptional electrochemical stability window close to 6V (vs Li+/Li), excellent wettability, and promising flame retardancy. Compared to a baseline carbonate-based electrolyte, its electrochemical performance is prominent: the overpotential of lithium nucleation is minimal (only 24mV), the average half-cell coulombic efficiency (CE) reaches 99.5% at 0.5mAcm-2, and its practicality in full cells with LiFePO4 (LFP) and LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes is also demonstrated. Compounding factors are identified to decipher the superiority of the AN-based LHCE. From the respect of solvation structures, both the elimination of free AN molecule and the diluent separation would contribute to prevention of anodic AN decomposition. Based on cryogenic electron microscopy (Cryo-EM) characterization and theoretical simulations results, the produced solid-electrolyte interphase (SEI) layer is uniform and compact. Thus, this work demonstrates a successful application of AN-based electrolytes in LMAs-traditionally deemed impractical-via the combined regulation of solvation and SEI structures.

Flexible LaNiO3 film with both high electrical conductivity and mechanical robustness

Lanthanum nickel oxide (LaNiO3, LNO) films exhibit excellent electrical conductivity but poor mechanical properties, considerably limiting their further development in the field of flexible electronics. In this study, flexible LNO thin films of different thicknesses were fabricated on a unique two-dimensional (2D) mica platform using a simple metal organic deposition technique. The obtained LNO films exhibited a pseudocubic phase without impurities. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) characterisations proved that the films were well-crystallised, dense, and flat, with controllable thickness. In addition, the flexible LNO/mica element possesses low resistivity (5 × 10−4 Ω cm), translucency, and good bending resistance. The electrical resistivity can remain stable under various bending radii (r = 10∼2 mm), thousands of bending cycles, and a wide temperature range (28–200 °C), demonstrating good durability, mechanical stability and temperature resistance. Furthermore, a ferroelectric BiFeO3 film was constructed based on the obtained conductive LNO electrode, which exhibited typical ferroelectric characteristics. This excellent performance suggests that the flexible LNO electrode is promising for flexible electronic applications.

Porosity and Organic Content in the Tuscaloosa Marine Shale: Insights from Focused Ion Beam-Scanning Electron Microscopy Characterization

Porosity and Organic Content in the Tuscaloosa Marine Shale: Insights from Focused Ion Beam-Scanning Electron Microscopy Characterization

Transmission Electron Microscopy Characterization of Deformation Features in Refractory High Entropy Alloys

Transmission Electron Microscopy Characterization of Deformation Features in Refractory High Entropy Alloys

Preparation and Selective Adsorption Performance of the Carboxymethyl Salix psammophila Wood Powder-Imprinted Membrane for Tetracycline.

Carboxymethyl Salix psammophila wood powder-imprinted membranes (CMSM-MIPs) were prepared by using wet spinning technology and molecular-imprinting technology for the selective removal of tetracycline from wastewater. Scanning electron microscopy, X-ray diffraction, thermogravimetry, and X-ray photoelectron spectroscopy characterizations demonstrate that CMSM-MIPs retain the membranous structure of Carboxymethyl Salix psammophila wood powder membranes, successfully encapsulate thin layers of imprinted polymers on the membrane surface, and exhibit excellent thermal stability. The adsorption results showed that CMSM-MIPs had the highest selective adsorption capacity for tetracycline, which was 253.8 mg/g. In addition, the adsorption capacities for oxytetracycline and chlortetracycline were 208.8 and 188 mg/g, respectively. It can be observed that CMSM-MIPs not only exhibit a high adsorption capacity for tetracycline but also demonstrate good adsorption capacities for oxytetracycline and chlortetracycline. The experimental results showed that CMSM-MIPs were best fitted with pseudo-second-order kinetics and most consistent with Freundlich fitting. The regeneration experiment showed that CMSM-MIPs still had good regeneration performance after 5 regeneration cycles. In conclusion, the CMSM-MIPs can not only have the natural adsorption performance of Salix psammophila wood powder but also give it higher selectivity through molecular imprinting, so as to achieve efficient removal of target organic pollutants in water.

Magnetron Sputter Deposition of Amorphous Silicon–SiO2 Quantized Nanolaminates

Quantization effects in nanolaminate structures of oxide materials are proposed and experimentally demonstrated only recently. Herein, the material combination of amorphous silicon and SiO2 deposited by magnetron sputtering is investigated and it is shown that the quantization effect can be observed indeed. Transmission electron microscopy characterization gives evidence of continuous layers of amorphous silicon and SiO2 with well‐defined interfaces. The deposition process is described and the tunability of the refractive index and the bandgap energy is demonstrated. By doing so, the advantages of this novel material over classical optical materials are shown and feasibility is proved. As an example, a longpass optical interference filter with edge at 720 nm is deposited using quantized nanolaminates as the high and SiO2 as the low refractive index material. This filter can be deposited successfully with close match to the design. It shows a blocking range throughout the visible spectrum whereas a comparable filter based on SiO2–TiO2 only blocks 500–700 nm.

A single dose of VEGF-A circular RNA sustains in situ long-term expression of protein to accelerate diabetic wound healing

Diabetic foot ulcer (DFU), which is characterised by damage to minute blood vessels or capillaries around wounds, is one of the most serious and dreaded complications of diabetes. It is challenging to repair chronic non-healing DFU wounds. Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis and promotes wound healing in DFU. However, it is difficult to sustainably deliver VEGF to the wound site owing to its poor stability and easy degradation. To overcome this challenge, lipid nanoparticles (LNP) encapsulating circular RNA (circRNA) encoding VEGF-A have been developed to continuously generate and release VEGF-A and accelerate diabetic wound healing. First, VEGF-A circRNA was synthesized using group I intron autocatalysis strategy and confirmed by enzyme digestion, polymerase chain reaction, and sequencing assay. VEGF-A circRNA was encapsulated in ionizable lipid U-105-derived LNP (U-LNP) using microfluidic technology to fabricate U-LNP/VEGF-A circRNA. For comparison, a commercially ionizable lipid ALC-0315-derived LNP (A-LNP) encapsulating circRNA (A-LNP/circRNA) was used. Dynamic light scattering and transmission electron microscopy characterization indicated that U-LNP/circRNA had spherical structure with an average diameter of 108.5 nm, a polydispersity index of 0.22, and a zeta potential of -3.31 mV. The messenger RNA (mRNA) encapsulation efficiency (EE%) of U-LNP was 87.12%. In vitro transfection data confirmed better stability and long-term VEGF-A expression of circRNA compared with linear mRNA. Assessment of cytotoxicity and innate immunity further revealed that U-LNP/circRNA was biocompatible and induced a weak congenital immune response. Cell scratch and angiogenesis tests demonstrated the bioactivity of U-LNP/VEGF-A circRNA owing to its VEGF-A expression. In situ bioluminescence imaging of firefly luciferase (F-Luc) probe and ELISA demonstrated that circRNA had long-term and strong expression of VEGF-A in the first week, and a gradual decrease in the next week at the wound site and surrounding areas. Finally, a diabetic mouse model was used to validate the healing effect of U-LNP/VEGF-A circRNA formulation. The results showed that a single dose of U-LNP/VEGF-A circRNA administered by dripping resulted in almost complete wound recovery on day 12, which was significantly superior to that of U-LNP/VEGF-A linear mRNA, and it also outperformed recombinant human vascular endothelial growth factor (rhVEGF) injection and A-LNP/circRNA dripping. Histological analysis confirmed the healing efficiency and low toxicity of U-LNP/VEGF-A circRNA formulation. Together, VEGF-A circRNA delivered by U-105-derived LNP showed good performance in wound healing, which was ascribed to the long-term expression and continuous release of VEGF-A, and has potential applications for the treatment of diabetic foot ulcer wounds.

Spent coffee grounds enhanced compressive strength of cement mortar: an optimization study

This paper presents an optimization study of spent coffee grounds (SCG) as cement mortar additives to enhance mortar strength. In recent years, sustainable materials have begun finding their way into cement mortar, with SCG being one. There is limited optimization study on the SCG addition in mortars, hence this study was performed to optimize the curing time and SCG addition in cement mortar to achieve the highest compressive strength through response surface methodology. Scanning Electron Microscopy (SEM) characterization was carried out on the SCG particles to identify their physical properties. An Energy Dispersive X-ray (EDX) analysis was carried out to identify its chemical properties. Simultaneously, a workability test, the flow table test, is conducted to study the effect of SCG on the flowability of the cement mortar mixes. The synergistic effect between SCG content in cement mortar mixes and the curing period was statistically studied and analyzed. Both parameters were then optimized to obtain the best performance mix of SCG in cement mortar. It was found that 1.1% SCG and a curing day of 68 days produced the highest compressive strength (33.4MPa) of cement mortar. The Response Surface Methodology (RSM)-optimized cement mortar mix presented at least a 12.62% improvement in compressive strength from control cement mortar without SCG additives (28.77MPa). Experimental validation of the optimum condition showed a good agreement with a deviation of 3.12% in three replicates, thus indicating that the optimum model in this work can be used to model the compressive strength of the SCG-cement mortar mixture.

Unraveling Mechanism for Microstructure Engineering toward High-Capacity Nickel-Rich Cathode Materials.

Microstructural engineering on nickel-rich layered oxide (NRLO) cathode materials is considered a promising approach to increase both the capacity and lifespan of lithium-ion batteries by introducing high valence-state elements. However, rational regulation on NRLO microstructures based on a deep understanding of its capacity enhancement mechanism remains challenging. Herein for the first time, it is demonstrated that an increase of 14mAhg-1 in reversible capacity at the first cycle can be achieved via tailoring the micro and nano structure of NRLO through introducing tungsten. Aberration-corrected scanning transmission electron microscopy (STEM) characterization reveals that the formation of a modified microstructure featured as coherent spinel twin boundaries. Theoretical modeling and electrochemical investigations further demonstrate that the capacity increase mechanism is related to such coherent spinel twin boundaries, which can lower the Li+ diffusion barrier and thus allow more Li+ to participate in deeper phase transitions. Meanwhile, the surface and grain boundaries of NRLOs are found to be modified by generating a dense and uniform LiWxOy phase, which further extends its cycle life by reducing side reactions with electrolytes. This work enables a comprehensive understanding of the capacity-increased mechanism and endows the remarkable potential of microstructural engineering for capacity- and lifespan-increased NRLOs.

One-step electrochemical preparation of platinum nanoparticle decorated self-healing reduced graphene oxide three-dimensional nanoarray for portable detection of bisphenol A

Highly selective and sensitive analysis of bisphenol A (BPA) in many plastic products remains its significance. We explored a simple, highly sensitive, and inexpensive electrochemical sensor based on a self-healing three-dimensional nanoarray (3DN) via a single-step electrochemical preparation of both platinum nanoparticles (PtNPs) and reduced graphene oxide (rGO) on a glassy carbon electrode for the portable detection of bisphenol (BPA) in plastic bottled waters. The structure of PtNPs/3DNrGO was confirmed by electron microscope and spectroscopic characterization. Electrochemical characteristics indicated that PtNPs/3DNrGO could decrease the oxidation overpotential due to the self-healing effect of the physical interaction between PtNPs and hydroxyl groups of rGO with an increase in the active surface area. The PtNPs/3DNrGO exhibited remarkably efficient electrocatalytic performance for the oxidation of BPA. The PtNPs/3DNrGO sensor for BPA demonstrated a wide linear range from 0.7 to 20 µM with a low limit of detection of 6 nM (S/N = 3) and effective performance including high sensitivity, high repeatability, and excellent selectivity. The developed sensor had been effectively implemented to assess BPA in plastic samples with desirable impacts. The interaction mechanism of both PtNPs and rGO was inferred by density functional theory. The proposed electrochemical sensor enabled the development of a portable, low-cost, and user-friendly monitoring of water quality, which will offer theoretical support for environmental monitoring.