Good Electronic Conductivity Research Articles

Effect of polymerization conditions on the physicochemical and electrochemical properties of SnO2/polypyrrole composites for supercapacitor applications

A stable and unique porous SnO2/polypyrrole composite has been successfully manufactured using various SnO2 loadings (5, 8, 10, 15 and 20 wt%) by applying a direct polymerization approach and employing a cheap oxidizing agent (FeCl3). The physicochemical properties of the new composites were investigated using X-ray Diffractometer (XRD), Fourier Transform Infra-Red spectrometer (FTIR), Field Emission Scanning Electron Microscope (FESEM) and UV-Visible spectrometer. The estimated band gap energy (Eg) for SnO2/PPy composite revealed lower value ∼ 1.1 eV than pure PPy suggesting good electronic conductivity. Optimization of the polymerization parameters indicated that the prepared SnO2/PPy composite at 0°C with mass ratio 0.1 exhibited the highest specific capacitance ∼ 450 F.g−1 at 20 mV.S−1 with a significant improvement ∼ 56% with respect to the pure PPy. The optimized SnO2/PPy electrode material revealed an excellent cyclability with constant loss in the capacitance retention ∼ 5% from 500 to 1100 charge/discharge cycles till reach 94% capacitance retention after 1500 cycles. On the other hand, pure PPy displayed a continuous decrease in the capacitance retention approaching 75% after1500 cycles.

Three-dimensional ZnCo/MoS2–Co3S4/NF heterostructure supported on nickel foam as highly efficient catalyst for hydrogen evolution reaction

Exploring inexpensive and earth-abundant electrocatalysts for hydrogen evolution reactions is crucial in electrochemical sustainable chemistry field. In this work, a high-efficiency and inexpensive non-noble metal catalysts as alternatives to hydrogen evolution reaction (HER) was designed by one-step hydrothermal and two-step electrodeposition method. The as-prepared catalyst is composed of the synergistic MoS2–Co3S4 layer decorated by ZnCo layered double hydroxides (ZnCo-LDH), which forms a multi-layer heterostructure (ZnCo/MoS2–Co3S4/NF). The synthesized ZnCo/MoS2–Co3S4/NF exhibits a small overpotential of 31 mV and a low Tafel plot of 53.13 mV dec−1 at a current density of 10 mA cm−2, which is close to the HER performance of the overpotential (26 mV) of Pt/C/NF. The synthesized ZnCo/MoS2–Co3S4/NF also has good stability in alkaline solution. The excellent electrochemical performance of ZnCo/MoS2–Co3S4/NF electrode originates from its abundant active sites and good electronic conductivity brought by the multilayer heterostructure. This work provides a simple and feasible way to design alkaline HER electrocatalysts by growing heterostructures on macroscopic substrates.

Polarizable cesium cations for energy storage from electrolyte characterization to-EDLC application

In the quest for new electrolytes on electrochemical energy storage devices, we present, characterize and test a simple organic electrolyte based on cesium bis (trifluoromethanesulfonyl) imide (CsTFSI) for supercapacitor (SC) application. The physicochemical properties of CsTFSI-based electrolytes in acetonitrile (ACN) and propylene carbonate (PC), alone and mixed with LiTFSI as a co-salt, were characterized under various concentrations and temperatures and revealed a different solution organization system, depending on the solvent and nature of the salt. The solvation radii based on the Jones-Dole-Kaminsky model indicated that ACN forms a single sphere of solvation around the cation Cs+, unlike PC, which does not solvate the large and polarizable Cs cation. The CsTFSI -ACN (1 mol L−1) electrolyte presents a suitable viscosity (<1 mPa•s) and density (36 mS cm−1) for SC application, ionic mobility within an extended temperature range (−40–60 °C), and its molecular level is compatible with the porosity of activated carbon (AC) electrodes. The nanopores of the ACs display good electronic conductivity and ion transport capability, characteristic of electrochemical double-layer capacitors EDLC within an electrochemical window of 3 V and a wide temperature span, i.e., −20–40 °C. In-situ measurements of accumulated gas pressure during typical galvanostatic charge-discharge protocols exposed a minimum pressure at 40 °C (2.6 × 108 Pa for CsTFSI-ACN, 1 mol L−1) compared to standard electrolytes (Et4BF4-ACN, 1 mol L−1) and yielded specific capacitances (Csp) of 115 F g−1 at a normalized current density of 2 A g−1. Standard accelerated aging floating tests confirmed the stability of the SCs (>100 h → 12% decrease on Csp). Finally, the suitability of CsTFSI as a co-salt (with lithium bis(trifluoromethanesulfonyl)imide, LiTFSI) was demonstrated for SC devices, aiming to boost Csp (i.e.,164 F g−1 for equimolar amounts of LiTFSI and CsTFSI). The above results attest to the functionality of CsTFSI as a promising salt for energy storage applications.

A new corner-shared 1D hybrid lead halide: Broad-band photoluminescence and semiconductive properties

Hybrid metal halides with high chemistry versatility and electronic tunability is a promising material system for new-generation lighting and displaying. Lowing the dimensionality of inorganic moieties gives rise to the broad-band white emission of those materials. Here a new 1D hybrid lead bromide (dbod)Pb2Br6 (dbod2+=1,4-Diazoniabicyclo[2.2.2]octane, 1,4-dipropy2+) was synthesized using organic dbod2+ as the spacer and balance cation. The compound showed a very broad emission with a full width half-maximum of 244 nm. With good electron conductivity, this series of compounds hold potential for the application of white-light LEDs.

Honeycomb-like biomass carbon with planted CoNi3 alloys to form hierarchical composites for high-performance supercapacitors

It is a significant challenge to combine a large pseudocapacitive material with conductive honeycomb-like carbon frameworks for long-term stable supercapacitors. Herein, hierarchical composite materials are manufactured by using biomass carbon, ZIF-67, and a mild pore former (Ni(CH3COO)2) to generate alloy-type CoNi3 nanoparticles planted into conductive honeycomb-like carbon frameworks (C@ZIF-67-T). Meanwhile, the effect of carbonization temperature on the honeycomb-like pore size and the structure of composite materials is systematically investigated. As the honeycomb-like carbon skeleton structure guarantees good ionic and electronic conductivities and a large contact area, whereas the alloy nanoparticles provide a rich redox reaction for Faradaic capacitance. Therefore, the as-obtained C@ZIF-67–600 electrode presents a remarkable specific capacitance of 1044.8 F · g−1 at 1.0 A · g−1 and an ultra-long cycling stability with 30,000 cycles at 5.0 A · g−1 in a three-electrode system. In addition, the assembled C@ZIF-67–600//activated carbon asymmetrical supercapacitor exhibit a high specific capacitance of 274.4F · g−1 at 1.0 A · g−1 and a long-term stable lifespan with a capacitance retention of 87% after 20,000 cycles at 5.0 A · g−1. Besides, the asymmetrical supercapacitor also presents a maximum energy density of 85.13 Wh · kg−1 at a power density of 750 W · kg−1. Such superior electrochemical performance demonstrate that the designed electrode material provides a promising energy storage application.

Closely Compacted TiNb2O7-C Assembly for Fast-Charging Battery Anodes

The fast-charging capability of lithium-ion batteries (LIBs) is becoming more important than before to meet the increasing requirements in practical applications. Because of safe working potential (above 1 V) and moderately high specific capacity, titanium niobium oxide (TiNb2O7, TNO) shows great potential as a fast-charging anode. Herein, a TNO-C assembly consisting of active initial TNO nanoparticles with conformal carbon coating is fabricated. The small size of TNO nanoparticles provides a short diffusion distance for lithium ions, and surficial carbon layers enable good electronic conductivity within the entire assembly. Moreover, the compact structure within the TNO assembly and efficient space packing of spheroidal secondary particles are beneficial for close packing, leading to an overall short distance for electron transport and ion diffusion. As expected, the as-designed TNO-C electrode delivers a high capacity of 194 mAh g–1 under 10C, and 71% of capacity was achieved under 0.2C. Moreover, the TNO-C electrode shows stable cycling performance with capacity retention of 92.2% after 100 cycles under 2C. In addition, by pairing with a lithium nickel–cobalt manganate (LiNi0.6Co0.2Mn0.2O2, NCM) cathode, the full cell exhibits a high capacity of 140 mAh g–1 under 3C and a high capacity retention of 97.4% after 100 cycles. The rational design of a TNO-C assembly makes it an excellent anode candidate for fast-charging LIBs.

Measurement of Polarization Resistances of LSCF/YSZ/LSCF Symmetrical Cell Using Alternating Current (AC) and Direct Current (DC) Techniques

Solid oxide fuel cells (SOFCs) are electrochemical devices, which can efficiently convert the chemical energy stored in fuels such as CH4 and H2 to electrical energy. SOFCs are of great significance for the next generation of clean energy storage and conversion. Yttria stabilized zirconia (YSZ) is a common solid oxide electrolyte used in SOFCs since it has outstanding oxygen ion conductivity, especially when operated at a high temperature (>800°C). Lanthanum strontium cobalt iron oxide (LSCF) is a mixed ionic-electronic conductor (MIEC), which offers both good electronic conductivity and good oxygen ion conductivity. Electrochemical impedance spectroscopy (EIS) is typically used to study the electrochemical performance of SOFCs. However, when using the common two-electrode EIS, the electrode processes at the cathode and anode cannot be studied separately. To study the electrode processes at the cathode and anode, a three-electrode EIS (two-electrode EIS with one pseudo-reference electrode) was performed on an LSCF/YSZ/LSCF bar-shaped symmetrical cell with platinum strip electrodes as probes. The point-by-point sum of the EIS spectra across the cathode and probe and across the anode and probe was found to match the impedance across the cathode and the anode. Also, polarity was switched, and it was found that the two electrodes do not necessarily have identical polarization resistance. Direct current (DC) measurements were also used to measure the polarization resistance of two electrodes separately with good agreement with the EIS results.

Garnet-Based Composite Cathodes for All Solid-State Li Batteries

All-solid-state Li batteries are regarded as a highly promising system for future electrochemical energy storage. Oxide-ceramic based all-solid-state lithium batteries (ASB) can provide high intrinsic safety, extended operational temperature range and high energy density.As the first two are intrinsic to the materials system, one prerequisite to obtain high energy densities with such ASBs is the manufacturing of thick (approx. 150 µm), dual-conducting free-standing composite cathodes, analogous to that of conventional liquid electrolyte-based lithium batteries. However, the preparation of composite cathodes using oxide-ceramic electrolytes is challenging since high temperature sintering steps are necessary during electrode and cell manufacturing to achieve proper mechanical stability, contact between the individual phases and good ionic and electronic conductivity.[1, 2] For oxide-based ceramic electrolyte materials like Li7La3Zr2O12 (LLZ) or Li1+xAlxTi2-x(PO4)3 (LATP) a sintering temperature around 1000 °C is necessary. However, cathode active materials like spinels (e. g. Li2NiMn3O8) or layered materials (e. g. Li[Ni1-x-yCoxMny]O2 (NCM)) show thermal stability only to around 700 °C and the required sintering temperature for the electrolyte exceeds their thermal stability window.To mitigate these materials interactions, advanced sintering techniques like high-pressure Field Assisted Sintering Technique/ Spark Plasma Sintering (FAST/SPS) is required, as it allows low temperature consolidation.[3]Using high-pressure FAST/SPS we have developed a method to prepare thick mixed-conducting composite cathodes and half-cells at sintering temperatures as low as 700 °C. The analysis of these composite cathodes revealed well sintered pure phases and a homogenous distribution of cubic LLZ and cathode active material. Electrochemical tests showed promising electronic and ionic conductivity (0.4 mS cm-1) values and an increased capacity (4 mA cm-2) compared to cathodes with pure active material.FAST/SPS can, therefore, open new processing windows for ceramic-based ASSLBs to alleviate the problem of interphase formation.

NASICON type KTi2(PO4)3 decorated by NTCDA-derived carbon layer for enhanced lithium/sodium storage

NASICON type KTi2(PO4)3 decorated by NTCDA-derived carbon layer (KTP/NC) was prepared as anode material to obtain sustainable lithium/sodium ion storage (LIBs/SIBs). Due to its prominent capacitance, good electronic conductivity and ability to constrain volume, the KTP/NC composite realizes highly electrochemical kinetics both in LIBs and SIBs. For LIBs, the KTP/NC composite delivers a superior reversible capacity of 598.1 mAh g−1 after 200 cycles at 0.5C, impressive cyclability with 225.5 mAh g−1 after 3000 cycles at an ultrahigh current density of 26.1 C and conspicuous rate performance of 160.6 mAh g−1 even at 52.2 C. In addition, the composite has a wide operation-temperature window with favorable capacities of 147.1–372.9 mAh g−1 from −10 °C to 50 °C. As for SIBs, the KTP/NC composite maintains a stable discharge capacity of 112.5 mAh g−1 after 700 cycles at a current density of 2.6 C and conspicuous rate performance of 86.7 mAh g−1 at 5.2 C. The KTP/NC anode exhibits discharge capacities of 29.9–112.6 mAh g−1 from −10 °C to 40 °C. The results demonstrate that the KTP/NC composite would be a promising electrode material for LIBs and SIBs.

Design and application of MOFs and derived composite materials inlithium-sulfur batteries

Against the background of increasingly prominent energy crisis and environmental problems, electrochemical energy storage technology has been developed rapidly. Among the competitors in the field of “beyond lithium” energy storage, lithium-sulfur batteries (Li-S) have become the most promising new energy storage technology owing to the advantages of high theoretical specific capacity, high mass energy density, environmental friendliness and low cost. However, there are still some bottleneck problems to be solved in the development of lithium-sulfur batteries, such as poor conductivity of cathode materials, polysulfide shuttle effect and electrode volume changes during charge and discharge. As the key components of lithium-sulfur batteries, the design and preparation of electrode and separator materials play the important roles in solving these problems and improving the overall performance of the batteries. Metal-organic frameworks (MOFs) and their derived composite materials exhibit the advantages of light weight, good electron and ion conductivity, abundant channels and uniform distribution of active sites to be used as electrode or separator modification materials for lithium-sulfur battery. In addition, this kind of composite material also possesses the characteristics of controllable morphology and composition, abundant source and adjustable pore size, which are convenient for mechanism research. Herein, we comprehensively introduce the composition, working mechanism and application of lithium-sulfur batteries. Importantly, we also review the research progress of MOFs and derivatives as cathode materials and separator materials in lithium-sulfur batteries in recent years. The prospects of the materials in improving the performance of lithium-sulfur batteries are also prospected.

Mixed MXenes: Mo1.33CTz and Ti3C2Tz freestanding composite films for energy storage

MXenes are a class of 2D materials with outstanding properties, including high electronic conductivity, hydrophilicity, and high specific capacitance. In particular, Mo 1.33 CT z MXene has a high specific capacitance, whereas films of Ti 3 C 2 T z MXene possess high flexibility and high electronic conductivity. The fabrication of composite materials based on these two MXenes is therefore motivated, taking advantage of combining their good properties. In this article, we introduce a one-step approach to prepare composite MXene films using pristine Mo 1.33 CT z and Ti 3 C 2 T z MXenes. The composite films display superior flexibility and electronic conductivity, as well as high capacitance, up to 1380 F cm −3 (460 F g −1 ), in 1 M H 2 SO 4 . A capacitance retention of 96% is obtained after 17,000 cycles. In addition, the capacitance retentions are about 56% and 25% at scan rates of 200 mV s −1 and 1000 mV s −1 , respectively. A significant rise in the capacitance at high rates, 875 F cm −3 (282 F g −1 ) at a current density of 20 A g −1 , is achieved by using a 3 M H 2 SO 4 solution. The use of composite MXene as negative electrodes for asymmetric supercapacitor devices, as well as lithium-ion batteries, is also discussed. This work suggests new pathways for the use of MXene composites with double transition metals (Mo and Ti) in energy storage devices. • Simple, fast, and robust synthesis approach to fabricate mixed MXene films using Mo 1.33 CT z and Ti 3 C 2 T z pristine MXenes. • The mixed MXene films display good flexibility and high electronic conductivity (up to 140 S cm −1 ). • The mixed MXene films deliver a high capacitance (1380 F cm −3 ) and feature 96% retention after 17,000 cycles in 1 M H 2 SO 4 . • A significant rise in the rate performance is observed in 3 M H 2 SO 4 solution (875 F cm −3 at current density 20 A g −1 ). • Mixed MXene electrodes are employed as negative electrodes for asymmetric supercapacitor devices.

Synthesis of SnO2@MnO2@graphite nanosheet with high reversibility and stable structure as a high-performance anode material for lithium-ion batteries

In this study, SnO2@MnO2@graphite (SMG) anode material is prepared via a facile ball-milling approach combined with hydrothermal treatment. SnO2 and MnO2 nanoparticles are evenly dispersed on numerous sheet-like graphite. MnO2 can not only play a catalytic role for facilitating the conversion reaction of Sn/Li2O to SnO2, but also as a barrier to impede the coarsening of Sn in the composite. Meanwhile, graphite nanosheets could serve as an ideal volume expansion buffer and good electron conductor. Consequently, the SMG anode delivers superior reversible capacity of 1048.5 mAhg−1, ideal rate capability of 522.2 mAhg−1 at 5.0 A g-1 and stable long-life cyclic performance of 814.8 mAhg−1 at 1.0 A g-1 after 1000 cycles. This result indicates that the incorporation of MnO2, graphite nanosheet and SnO2 have a great potential in enhancing the performance of SnO2-based anode for battery applications.

Enhanced electrochemical performance of Li-S battery via structural transformation of N,O dual-doped carbon host material

Poor electronic conductivity and “shuttle effect” as well as large volume change during cycling hinder the further practical applications of lithium-sulfur batteries (LSBs). Here, N,O dual-doped carbons were developed as sulfur host with adjustable porosity, graphited degree and surficial chemistry by simply changing molten inorganic salts (none, NaCl, NaCl/FeCl3) during sintering with aniline-pyrrole copolymer. NaCl promotes the graphitization and porosity with multi-scaled porous carbon host (CH2). NaCl/FeCl3 boosts doping content and facilitates transformation of both chemical state of doping elements and morphology to micro-meso pores dominated nanosheet (CH3) from little porous bulk (CH1). The flexible CH3 nanosheet with micro-mesopores could physically block dissolved Li2Sn (4 ≤ n ≤ 8) and provide large interfacial area to guarantee good electronic conductivity and ionic transport of the sulfur cathode for improving the electrochemical reactions kinetics. Furthermore, the high content doped pyrrolic N and epoxidized O in CH3 enhance chemical adsorption of soluble Li2Sn and accelerate the conversion process between Li2Sn and Li2S2/Li2S. Hence, CH3/S system exhibits ∼30% and ∼167% higher capacity than CH2/S and CH1/S after 200 cycles at 0.2 C. Our results clarify the working mechanism of carbon morphology and nitrogen, oxygen co-doping state tuning and promote the development of high-electrochemical performance LSBs.

Flexible MXene/rGO/CuO hybrid aerogels for high performance acetone sensing at room temperature

The design and construction of high-performance room temperature gas-sensing materials have attracted great attention in the field of current gas sensor technology. Herein, we report an efficient approach for the production of ultrafine CuO nanoparticles-decorated three-dimensional (3D) hybrid aerogel by employing MXene (Ti3C2Tx) and reduced graphene oxide (rGO) nanosheets as cobuilding blocks. Benefiting from the synergistic effects of highly interconnected porous networks, large specific surface areas, homogeneous CuO nanoparticles dispersion, and good electron conductivity, the resulting 3D MXene/rGO/CuO aerogel expresses high acetone-sensing performance at room temperature (RT). The sensor response toward 100 ppm acetone is 52.09 % at RT with the fast response time (∼6.5 s) and recovery time (∼7.5 s), excellent reproducibility and selectivity. The strategy of compositing 3D graphene/MXene architectures with metal oxide semiconductor provides a novel pathway for the future development of RT gas sensors.

3D Network of Sepia Melanin and N‐ and, S‐Doped Graphitic Carbon Quantum Dots for Sustainable Electrochemical Capacitors

AbstractOrganic electrode materials operating in aqueous electrolytes offer the opportunity to avoid toxic, critical, and expensive materials for electrochemical energy storage. When deposited on carbon current collectors, redox active organic materials add faradaic to electrostatic capacitance contribution to the electrodes. Here, a 3D network electrode material is reported upon, based on sepia melanin, a quinone macromolecule, and nitrogen‐ and sulfur‐doped graphitic carbon quantum dots (N,S GCQDs) designed to achieve good electronic conductivity and electrolyte wettability. The effect of various undoped and doped carbon quantum dots is also investigated, synthesized from acetic acid and sucrose instead of graphite, on the electrochemical performance of sepia melanin. Sepia/N,S GCQD shows optimum areal capacitance (≈180 mF cm−2) that is about twice as high as sepia (≈77 mF cm−2) with lower charge transfer resistance (1 ohm for sepia/N,S GCQDs compared to 10 ohms for sepia). The sepia/N,S GCQD symmetric supercapacitor in 0.5 m Na2SO4(aq) exhibits promising capacitance retention ≈92% after 10 000 cycles at 5 A g−1, 100% coulombic efficiency, 11 µW h cm−2 and 102 mW cm−2 maximum energy and power densities. The work paves the way for stable and potentially biodegradable supercapacitor electrode materials for environmentally benign electrochemical energy storage.

A COF-Like N-Rich Conjugated Microporous Polytriphenylamine Cathode with Pseudocapacitive Anion Storage Behavior for High-Energy Aqueous Zinc Dual-Ion Batteries.

Conducting polymers with good electron conductivity and rich redox functional groups are promising cathode candidates for constructing high-energy aqueous zinc batteries. However, the glaring flaw of active-site underutilization impairs their electrochemical performance. Herein, wereport a poriferous polytriphenylamine conjugated microporous polymer (CMP) cathode capable of accommodating Cl- anions in a pseudocapative-dominated manner for energy storage. Its specific 3D, covalent-organic-framework-like conjugated network ensures high accessibility efficacy of N active sites (up to 83.2% at 0.5 A g-1 ) and distinct physicochemical stability (87.6% capacity retention after 1000 cycles) during repeated charging/discharging courses. Such a robust CMP electrode also leads to a zinc dual-ion battery device with a high energy density of 236 W h kg-1 and a maximum power density of 6.8kW kg-1 , substantially surpassing most recently reported organic-based zinc batteries. This study paves the way for the rational design of advanced CMP-based organic cathodes for high-energy devices.

Bottom-up construction of three-dimensional porous MXene/nitrogen-doped graphene architectures as efficient hydrogen evolution electrocatalysts

The exploration of highly-active non-platinum electrocatalysts with low-cost has been regarded as a crucial way to alleviate the major bottleneck in electrocatalytic hydrogen evolution reaction (HER) technology. Herein, we demonstrate the bottom-up construction of three-dimensional (3D) hybrid architectures built from Ti3C2Tx MXene and nitrogen-doped graphene nanosheets (MX/NG) through a facile and cost-effective co-assembly approach. The as-derived MX/NG architectures are endowed with a number of distinctive structural advantages, such as large specific surface areas, 3D cross-linked porous frameworks, ultrathin walls, optimized electronic structures, and good electron conductivity. As a result, exceptional HER performances with a relatively low onset potential, a small Tafel slope, and reliable long-term stability are achieved on the optimized MX/NG electrode, markedly outperforming those of bare Ti3C2Tx and NG electrodes.

Hydrazine hydrate-assisted adjustment of sulfur-rich MoS2 as hydrogen evolution electrocatalyst

The activity of MoS2 toward hydrogen evolution reaction (HER) originated from different sulfur configurations and phases. Metallic 1T phase of MoS2 with good electronic conductivity and abundant electrocatalytic active sites is favorable for electrocatalysis. In addition, bridging S22- has been verified as the major active sites for HER. However, there is a lack of in-depth understanding for the coexistence of 1T phase and bridging S22- of MoS2. Herein, a facile hydrazine hydrate-assisted method is reported to synthesize sulfur-rich MoS2. Specifically, when higher ratio of 1T to 2H phase was obtained, a higher proportion of bridging S22- to terminal S22- was produced simultaneously. With an optimum amount of hydrazine hydrate, MoS2 exhibits a low overpotential of 173 mV at a current density of 10 mA cm−2, a small Tafel slope of 56.6 mV dec−1, and long-term stability in 0.5 M H2SO4 solution. This work provides a new insight for improving the electrocatalytic activity of MoS2 via a simple method.

Electrochemical Deposition of Cu Metal-Organic Framework Films for the Dual Analysis of Pathogens.

Metal-organic framework (MOF) thin films with flexible nature and prominent qualities have opened doors to new technological applications in different fields. Herein, we propose an electrochemical biosensor for the dual detection of Staphylococcus aureus based on the electrodeposition of Cu metal-organic framework (Cu-MOF) thin films. The promising sensing layer with features of good electronic conductivity and enhanced electron-transfer property can not only identify S. aureus through specific micrococcal nucleases in the supernatant but also detect the pathogen directly via aptamer recognition. The dual analysis design ensures the accuracy of this method for S. aureus detection in the range of 7-7 × 106 cfu/mL with the limits of detection of 1.9 and 5.2 cfu/mL. Moreover, the analytical method validation confirmed that the biosensor could efficiently work in complex biological samples, showing good selectivity and specificity and great potential for clinical diagnosis. More importantly, the current proposed strategy is simple and easy to implement without the need for extra signaling elements, which is convenient for timely clinical detection.

Two-Dimensional Planar BGe Monolayer as an Anode Material for Sodium-Ion Batteries.

Using first-principles swarm intelligence structure prediction computations, we explore a fully planar BGe monolayer with unique mechanical and electrical properties. Theoretical calculations reveal that a free-standing BGe monolayer has excellent stability, which is confirmed by the cohesive energy (compared to experimentally synthetic borophene and germanene monolayers), phonon modes (no imaginary frequencies appeared in the phonon spectrum), ab initio molecular dynamics (AIMD) simulations (no broken bonds and geometric reconstructions), and mechanical stability criteria. The metallic feature of the BGe monolayer can be maintained after absorbing different numbers of Na atoms, ensuring good electronic conductivity during the charge/discharge process. The calculated migration energy barrier, open-circuit voltage, and theoretical specific capacity of the BGe monolayer are much better than those of some other two-dimensional (2D) materials. These findings render the BGe monolayer a potential candidate for reversible Na-ion battery anode materials with desirable performance.