Additional Electron Research Articles

Radiation‐Enhanced Annealing of Vacancy–Oxygen Defects in Cz n‐Si: Features of the Experiment, Factor of the Radiation Ionization, and a Possible Annealing Mechanism

The results of the detailed study of the accumulation and/or annealing of vacancy–oxygen (VO) complexes kinetics in the Czochralski‐grown n‐type silicon (Cz n‐Si) are presented. The samples are irradiated by electron beam pulses of different energies and intensities (J) at VO effective annealing temperatures (>300 °C). It is shown that: 1) upon high‐temperature (so‐called “hot”) irradiation Cz n‐Si at temperatures >300 °C, J can significantly stimulate VO annealing and a maximum concentration of accumulated VO defects ([VO]max, when the rates of formation and simultaneous annealing of VO complexes are equal) increases with increasing J and decreases with increasing irradiation temperature. Accelerated annealing of VO slows down sharply the growth rate of [VO]max as a function of J; 2) the VO defects introduced into Cz n‐Si at room temperature can also be annealed faster if the annealing is accompanied by additional electron irradiation of a certain intensity. It has been established that the radiation‐accelerated annealing of VO is characterized by a decrease in the activation energy from ≈1.7 to ≈0.5 eV due to radiation ionization of the Si crystal. A model of the enhanced VO annealing process is proposed.

Cu‐Driven Active Cu2Se@MXene Heterointerface Reconstruction and Co Electron Reservoir Toward Superior Sodium Storage

AbstractHeterostructure engineering and active component reconstruction are effective strategies for efficient and rapid charge storage in advanced sodium‐ion batteries (SIBs). Herein, sandwich‐type CoSe2@MXene composites are used as a model to reconstruct new active Cu2Se@MXene heterostructures by in situ electrochemical driving. The MXene core provides interconnected pathways for electron and ion conduction, while also buffering volumetric expansion to stabilize the structure. This reconstructed Cu2Se@MXene heterointerface features abundant sodium storage active sites, enhanced Na+ adsorption, and diffusion kinetics, thus increasing sodium storage capacity. Moreover, the elevated Co valence state during the discharge process allows it to act as an electron reservoir to provide additional electron supply for Cu2Se conversion and accelerate the sodium storage kinetics. When employed as an anode in SIBs, the CoSe2@MXene electrode exhibits high capacity (694 mAh g−1 at 0.1 A g−1), excellent rate performance (425 mAh g−1 at 20 A g−1), and exceptional durability (437 mAh g−1 after 10 000 cycles at 5 A g−1 with a 0.0014% capacity decay per cycle). The electrochemical reconstruction and sodium storage mechanism of Cu2Se@MXene anode is further revealed through ex situ characterization and theoretical calculations. This work provides a new approach for designing advanced conversion‐type anodes for SIBs.

Tetrahedral Al20O30 Cage: A Superchalcogen Atom.

Superatoms are stable clusters that mimic the chemical behavior of individual atoms in the periodic table. Many endeavors have been devoted to the design and characterization of various superatoms, while engineering superatoms to mimic the chemistry of chalcogens remains a challenge. In this paper, we present a new superchalcogen by evaluating a hollow tetrahedral Al20O30 cluster with theoretical calculations. By comparing the Al20O30 with its daughter dianion (Al20O30)2- in terms of stability, aromaticity, electronic properties, and chemical behavior in compounds, we find that this cluster tends to get two additional electrons to reach a more stable electronic state, which is the origin of the identity of superchalcogens. The adaptive natural density partitioning (AdNDP) analysis illustrates that this Al20O30 cluster accommodates two electrons by a 4-center-2-electron bond formed between the four face-centered Al atoms. Moreover, the Al20O30 cluster has exothermic first and second adiabatic electron affinity (EA), indicating that the dianion (Al20O30)2- is stable against spontaneous electron emission and fragmentation in the gas phase. This reflects the size advantage of superchalcogens when compared with chalcogens. Interestingly, we further study a cluster with one more electron than the superchalcogen Al20O30, namely, H@(Al20O30) and find that it is a superhalogen due to its large vertical and adiabatic EA.

Improving the thermoelectric properties of septuple atomic-layer SnBi2Se4 by regulating the carrier concentration through Nb doping

Layered semiconductor materials have garnered significant attention in the thermoelectric field due to their excellent electrical property and intrinsically low lattice thermal conductivity. The septuple atomic-layered ternary compound SnBi2Se4 is reported as a promising thermoelectric material in both bulk and single-layer structures based on theoretical calculations, though experimental investigation remains unexplored. In this work, the melting and hot-press sintering methods were adopted to synthesize the septuple atomic-layered SnBi2Se4. Its unique layered crystal structure contributed to significant anisotropic transport properties and reduced thermal conductivity. However, its thermoelectric performance is constrained by a low carrier concentration that limits electrical conductivity. To solve this issue, the high-valent transition metal Nb was doped at Bi site to provide additional electrons. This doping resulted in a noticeable improvement in the performance of septuple atomic-layered SnBi2Se4 due to increased electrical conductivity and decreased thermal conductivity. Finally, a peak ZT ∼ 0.17 was obtained for SnBi1.97Nb0.03Se4 at 723 K, suggesting the effectiveness of Nb doping in enhancing the performance. These results indicate that septuple atomic-layered SnBi2Se4 is a highly promising thermoelectric material, though further performance improvements are needed.

Encapsulated Fe3C boosted electrocatalytic performance for oxygen reduction reaction of N-doped carbon nanotube

The shortcomings of precious metal based catalysts have limited the development of novel energies. So, developing low-cost and high performance transition metal based catalysts is one of the most feasible way to substitute the precious metal based catalysts. In all of the developed catalysts for oxygen reduction reactions (ORR), the iron-based nitrogen doped carbon nanotube (N-CNT) show great promise. In this paper, N-CNT with Fe3C encapsulated based catalysts (Fe3C@N-CNT) were synthesized. The encapsulation structure of Fe3C@N-CNT was confirmed by HAADF-STEM, XANES, XPS, XRD, SEM and other methods. XANES tests show that the doped nitrogen of Fe3C changed the length of Fe-C bond and furtherly influenced the electron transfer between encapsulated Fe3C and outer layer N-CNT. Electrochemical tests showed that the half-wave potential and onset potential ORR of 750 °C calcinated Fe3C@N-CNT were 90 mV higher than that of 20 wt.% Pt/C. The additional electric field between Fe3C and N-CNT modulated the C-N bond of surface N-CNT and enhanced the catalytic performance for ORR. This paper reveal that constructing encapsulated additional electron providing center is an effective way to design high performance catalysts.

Ultrahigh detectivity of near-infrared organic phototransistor assisted by additional electron trap sites in a dielectric layer

This study introduced an additional electronic traps (ZnO nanoparticles) into the dielectric layer of the organic phototransistor, obtaining a high Ilight/Idark and an ultra-high detectivity while keeping the response time unchanged.

Orbital Coupling of Dual-Atom Sites Boosts Electrocatalytic NO Oxidation and Dynamic Intracellular Response.

In situ measurement of nitric oxide (NO) in living tissue and single cells is highly important for achieving a profound comprehension of cellular functionalities and facilitating the precise diagnosis of critical diseases; however, the progress is greatly hindered by the weak affinity of ultratrace concentration NO in cellular environment toward electrocatalysts. Herein, a new strategy is reported for precisely constructing orbital coupled dual-atomic sites to enhance the affinity between the metal atomic sites and NO on a class of N-doped hollow carbon matrix dual-atomic sites Co─Ni (Co1Ni1-NC) for greatly boosting electrocatalytic NO performance. The as-synthesized Co1Ni1-NC demonstrates a substantially higher current density than Ni1-NC and Co1-NC, coupled with exceptional stability with a negligible degradation rate of 0.6 µA·cm-2·h-1, which is the best among the state-of-the-art electrocatalysts for NO oxidation. Experimental and theoretical investigations collectively reveal that the pivotal role of d-d orbit coupling between Co and Ni sites enables Ni to acquire additional electrons, leading to the occupation of Ni's 3dxy/yz within the 2π orbitals of NO, thus weakening the N≡O triple bond and concurrently accelerating NO adsorption kinetics. It is demonstrated that Co1Ni1-NC-coated nanoelectrode can achieve the in situ sensing of NO in living organs and single cells.

Bismuth-Metal and Carbon Quantum Dot Co-Doped NiAl-LDH Heterojunctions for Promoting the Photothermal Catalytic Reduction of CO2.

The quest for sustainable photocatalytic CO2 reduction reactions (CRR) emphasizes the development of high-efficiency, economically viable, and durable photocatalysts. A novel approach involving the synthesis of Bi-CDs/LDH heterojunctions, incorporating plasma metals and carbon quantum dots via hydrothermal and co-precipitation methods, yields remarkable results. The optimized BCL-4 photocatalyst demonstrates exceptional performance, with C2H4 and C2H6 yields of 1.35 and 2.17µmolg-1h-1, respectively, representing substantial enhancements of 11.25 and 14.47 times compared to the LDH monomer. Moreover, the catalyst exhibits a notable selectivity of 36.6% for C2 products. Plasmonic Bi with high conductivity and carbon quantum dots synergistically enhances visible light absorption and generated additional hot electrons. The electron-trapping ability of carbon quantum dots is pivotal in creating elevated electron and CO2 concentrations at the catalyst interface, fostering conditions conducive to promoting C─C coupling reactions for the generation of C2 products.

Ruthenium Nitrosyl Porphyrins Coordinated with Aryloxides Containing Internal Hydrogen Bonds

The synthesis, characterization, and redox behavior of aryloxide complexes containing an increasing number of internal hydrogen bonds (OEP)Ru(NO)(OArxH) (OEP = octaethylporphyrinato dianion; x = 0, 1, 2) are reported. These nitrosyl aryloxide compounds were characterized by X‐ray crystallography, IR and 1H NMR spectroscopy. The IR spectra displayed uNO frequencies in the 1823–1843 cm‐1 range with compounds possessing more internal hydrogen bonds demonstrating higher uNO frequencies due to diminished π‐backdonation to the Ru‐NO fragment. Comparison of the distinct uNH and δN‐H signals in the IR and 1H NMR spectra of the free and complexed OAr1H/OAr2H ligands support the notion of additional electron density being removed via intramolecular hydrogen bonding. Results of DFT calculations on the (porphine)Ru(NO)(OArxH) models (porphine = unsubstituted porphyrin) reveal that the HOMOs of these complexes have significant axial ligand contributions, whereas the HOMOs of the five‐coordinate [(porphine)RuNO)]+ cation resides mostly on the equatorial porphyrin macrocycle. The electrochemical results of these (OEP)Ru(NO)(OArxH) complexes in CH2Cl2 reveal first oxidations that occur at increasingly positive potentials when more internal hydrogen bonds are present. Based on the DFT and preliminary IR spectroelectrochemical results, we propose that the electrooxidations result in eventual dissociation of the axial aryloxide ligands.

Anaerobic Faecalicatena spp. degrade sulfoquinovose via a bifurcated 6-deoxy-6-sulfofructose transketolase/transaldolase pathway to both C2- and C3-sulfonate intermediates.

Plant-produced sulfoquinovose (SQ, 6-deoxy-6-sulfoglucose) is one of the most abundant sulfur-containing compounds in nature and its bacterial degradation plays an important role in the biogeochemical sulfur and carbon cycles and in all habitats where SQ is produced and degraded, particularly in gut microbiomes. Here, we report the enrichment and characterization of a strictly anaerobic SQ-degrading bacterial consortium that produces the C2-sulfonate isethionate (ISE) as the major product but also the C3-sulfonate 2,3-dihydroxypropanesulfonate (DHPS), with concomitant production of acetate and hydrogen (H2). In the second step, the ISE was degraded completely to hydrogen sulfide (H2S) when an additional electron donor (external H2) was supplied to the consortium. Through growth experiments, analytical chemistry, genomics, proteomics, and transcriptomics, we found evidence for a combination of the 6-deoxy-6-sulfofructose (SF) transketolase (sulfo-TK) and SF transaldolase (sulfo-TAL) pathways in a SQ-degrading Faecalicatena-phylotype (family Lachnospiraceae) of the consortium, and for the ISE-desulfonating glycyl-radical enzyme pathway, as described for Bilophila wadsworthia, in an Anaerospora-phylotype (Sporomusaceae). Furthermore, using total proteomics, a new gene cluster for a bifurcated SQ pathway was also detected in Faecalicatena sp. DSM22707, which grew with SQ in pure culture, producing mainly ISE, but also 3-sulfolacate (SL) 3-sulfolacaldehyde (SLA), acetate, butyrate, succinate, and formate, but not H2. We then reproduced the growth of the consortium with SQ in a defined co-culture model consisting of Faecalicatena sp. DSM22707 and Bilophila wadsworthia 3.1.6. Our findings provide the first description of an additional sulfoglycolytic, bifurcated SQ pathway. Furthermore, we expand on the knowledge of sulfidogenic SQ degradation by strictly anaerobic co-cultures, comprising SQ-fermenting bacteria and cross-feeding of the sulfonate intermediate to H2S-producing organisms, a process in gut microbiomes that is relevant for human health and disease.

Anion photoelectron imaging and theoretical study of Cu(CO)3−

Photoelectron velocity map images of Cu(CO)3− have been experimentally recorded in the 700–1100 nm range. The infrared-inactive Cu-C symmetric stretching modes for Cu(CO)3 (v2 ≈ 367 cm−1) and Cu(CO)3− (v2 ≈ 408 cm−1), as well as the electron affinity (1.03±0.11 eV) of Cu(CO)3, are accurately determined from high resolution photoelectron spectra. In combination with quantum chemical calculations and bonding analyses, the coordination bonds in both Cu(CO)3− are Cu(CO)3 are found to be due to back-donation π bonding type, formed via electron promotion from Cu’s 4s orbital to the 4p orbital, which is consequently donated to the unoccupied anti-bonding π* orbitals of the carbonyl groups. The attachment of an additional electron to Cu(CO)3 strengthens the Cu-CO coordination, making Cu(CO)3− more stable. The intramolecular interactions between the Cu/Cu− and carbonyl groups are found to be primarily governed by electrostatic forces and orbital interactions.

Earth-abundant FeSO4-based conversion-type cathode for rechargeable sodium-ion batteries

Sodium-ion batteries (SIBs) have gained prominence as the ideal choice for next-generation large-scale energy storage systems owing to advantages such as sodium abundance and cost-effectiveness. However, their synthesis requires harsh conditions such as high pressure and temperature, and the cathode materials exhibit poor electrical conductivity and sluggish kinetics, hindering SIBs from meeting the requirements for practical applications. In this study, a conversion-type Gr/FeSO4 nanocomposite based on earth-abundant and environmentally friendly elements was developed using a high-energy mechanical ball-milling method. The conversion reaction in FeSO4 was triggered via a simple direct-contact pre-sodiation method, wherein the FeSO4 particles were reversibly converted to Fe0 and Na2SO4 and recovered in the next charging process. Meanwhile, graphene in Gr/FeSO4 acted as a conductive matrix that provided additional electron transfer paths, resulting in increased ionic and electronic conductivities and enhanced diffusion kinetics. Owing to these matrices, the as-prepared Gr/FeSO4 nanocomposite exhibited remarkable long-term cyclability. This study highlights the advantages of combining pre-sodiation and conversion reactions for cathodes and demonstrates the feasibility of employing naturally abundant FeSO4 for high-performance SIBs.

Optimization of Metal Capping Layer Design for Enhanced Mobility in Indium Gallium Zinc Oxide (IGZO) Thin Film Transistors

Given the increasing demand for high frame rates and fast response times in high-end displays, various strategies have been explored to enhance the mobility of IGZO TFTs. In general, plasma treatment and elemental doping are widely utilized methods for this purpose [1], [2]. However, these approaches often encounter a trade-off between electrical properties and reliability, prompting ongoing research to overcome such challenges. Another approach to improve mobility involves increasing the electron concentration of the back channel by incorporating a metal capping layer (MCL) between the source and drain [3]. However, excessive electron concentration in the back channel can induce increased off-current and hump phenomenon, resulting in degraded electrical properties [4]. Most research on MLC has primarily focused on improving mobility by using different metals, while there has been little research on the trade-off between electrical properties and carrier concentration based on MCL design [5]. In this paper, we investigated the influence of MCL design on electrical properties and present the optimized metal capping layer design which does not degrade electrical properties. Experiment A heavily doped P++ silicon with thermally oxidized SiO2 (200 nm) was used as a substrate, onto which a 20 nm thick IGZO was deposited by RF sputtering. Subsequently, the IGZO channel was patterned using a standard photolithography process, and a Ti/Al/Ti layer was deposited via e-gun evaporation to form the source and drain (S/D) electrodes. Finally, an Al-metal capping layer was deposited in the middle of the back channel between the source and drain to form the MCL, which covers a range of 6.6% to 70.8% of the IGZO back channel. Result and Discussion Based on experimental results, IGZO TFTs with an MCL coverage of 70.8% exhibited a more than twofold increase in mobility compared to pristine samples. This enhancement is attributed to the increased electron concentration that results from the redox reaction between the MCL and IGZO. However, a specific threshold of MCL coverage can trigger the hump phenomenon. In addition, this threshold varied depending on the MCL design. This suggests that the formation of additional sub-channels and electron distributions contributing to the hump phenomenon differs with each design. Therefore, we explored various MCL designs to identify the optimal structure that enhances mobility without compromising electrical properties. These findings suggest a design strategy for high-mobility devices in high-end displays, potentially applicable to backplane technology. Reference [1] Zan, H. W., Tsai, W. W., Chen, C. H., & Tsai, C. C, Advanced Materials, 23(37), 4237-4242, 2011.[2] Kawai, H., Kataoka, J., Saito, N., Ueda, T., Ishihara, T., & Ikeda, K, MRS Bulletin, 46(11), 1044-1052, 2021.[3] Yoon, C. S., Kim, H. T., Kim, M. S., Yoo, H., Park, J. W., Choi, D. H., ... & Kim, H. J, ACS Applied Materials & Interfaces, 13(3), 4110-4116, 2021.[4] Lee, B. H., Sohn, A., Kim, S., & Lee, S. Y, Scientific reports, 9(1), 886, 2019.[5] Kim, J., Park, J. B., Zheng, D., Kim, J. S., Cheng, Y., Park, S. K., ... & Facchetti, A, Advanced Materials, 34(45), 2205871, 2022.Fig.1 The transfer characteristics of IGZO TFTs with various MCL coverage, indicating two MCL types: (a) increasing MCL width with fixed length and (b) increasing MCL length with fixed width. Figure 1

PEM Electrocatalysis in a Stirred-Tank Bioreactor Enables Growth of Clostridium Ragsdalei with CO2 and Electrons

Developing sustainable synthesis processes is a primary objective for the chemical industry since harsh process conditions and usage of fossil resources increase greenhouse gas emissions and the carbon footprint. Making use of CO2 as a feedstock to produce value-added organic chemicals is an attractive opportunity to realize a circular carbon economy. Moreover, electric energy generated by solar panels or wind power stations could be saved in stable chemical products. We combined both aspects in a novel bio-electrochemical system (BES) in which a PEM electrolysis cell is coupled to a standard stirred tank bioreactor. Precious group metal-free (PGM-free) catalysts consisting of atomically dispersed active metal sites in nitrogen-doped porous carbon matrix (M-N-C where M= Co, Ni, Zn etc.) enabled electrocatalytical CO2 reduction to CO (CO2RR) in an aqueous environment. The acetogenic bacterium Clostridium ragsdalei directly converts the CO into organic acids and alcohols. Besides, the competing hydrogen evolution reaction (HER) delivers H2 as an additional electron carrier that can be consumed together with CO2. Bacteria are more flexible towards the stoichiometry of their substrates (CO, H2 and CO2), demonstrating an advantage over chemical synthesis processes that often require exact stoichiometries. Further, mild process conditions in bioprocesses allow for more sustainable production. The BES consists of a stirred-tank bioreactor adapted to function together with an electrolysis cell. The cathode and anode are stacked in a membrane-electrode-assembly (MEA) mounted at the bottom with the cathode facing the bioreactor (Figure 1). The fully controlled BES is continuously gassed with CO2 and driven in a potentiostatic mode. A Zn/Co-N-C catalyst coated on carbon support was selective for the CO2 reduction to CO (Schwarz et al., 2024). CO and H2 were continuously produced at the cathode in an applied cell voltage range of -2.2 to -3.2 V. At lower applied voltages (≤ -2.5 V), the catalyst was more selective towards CO formation, whereas a higher cell voltage of -3.2 V caused the HER to take over the CO2RR. During electrofermentations, the cell voltage was increased stepwise to supply sufficient carbon and electron sources to C. ragsdalei. The MEA construction was modified continuously to improve autotrophic batch electrofermentations with C. ragsdalei. Optimizing the compression between the cathode and anode improved the stability of current flows and prolonged the total process time from 3 to 6 days. Increasing the initially low area-to-volume ratio of the cathode with the electrocatalyst (0.0012 cm-1) allowed a higher CO formation rate. CO generation has been limiting the whole electrocatalytical CO2 fermentation process. Furthermore, developing more selective and stable electrocatalysts towards the CO2RR improved the faradaic efficiency. Switching from a two-electrode to a three-electrode setup enabled a more precisely controlled galvanostatic operation with defined CO formation rates sufficient for C. ragsdalei to grow and produce acetate and ethanol in considerable amounts. Reference Schwarz I, Rieck A, Mehmood A, Bublitz R, Bongers L, Weuster-Botz D, Fellinger T-P (2024): PEM electrolysis in a stirred-tank bioreactor enables autotrophic growth of Clostridium ragsdalei with CO2 and electrons. ChemElectroChem 11: e202300344. Acknowledgements Funding by the German Research Foundation (DFG) within the framework of the priority program SPP 2240 (research projects WE 2715/17-1 and FE 1590/1-1) is gratefully acknowledged. Figure 1

Development of a Direct Electron Transfer-Type Enzymatic Sensor for the Spermine in Saliva, a Marker of Pancreatic Cancer

Introduction Pancreatic cancer (PC) has one of the worst prognoses among cancers because of the scarcity of early symptoms and the delay of early diagnosis. Current most available and advanced diagnosis methods of PC are based on imaging technologies such as computed tomography, positron emission tomography, magnetic resonance imaging, and endoscopic ultrasonography. However, such imaging methods cannot diagnose PC at an early stage. Patients diagnosed with PC often have metastasized, and only less than 30% of PC patients can undergo surgical resection. Therefore, there is an urgent need for more accurate, simple, and innovative methods for PC early diagnosis. Recently, salivary spermine has attracted attention as a new biomarker for PC <Asai et.al., Cancers, 2018>, and studies aimed at detecting spermine are attempted. Thus, we focused on the electrochemical measurements of spermine using enzyme.Electrochemical enzymatic biosensors are categorized into three generation principles based on the electron acceptors used for the oxidative half reaction. The 1st generation principle uses oxygen as the electron acceptor. However, the signal is affected by the oxygen concentration and a high applied potential is required to detect hydrogen peroxide. The 2nd generation principle requires the use of synthetic electron acceptors or mediators. The 3rd generation principle utilizes enzymes which are capable of direct electron transfer (DET) to the electrode, does not require any additional electron acceptors. Notably, the 3rd generation principle-based sensor can monitor target by applying relatively lower potentials, therefore will not be influenced by redox-active interferents. Considering the salivary sample contains variety of ingredient potentially interferants for enzymatic spermine monitoring, the DET-type enzymatic sensors are ideal. However, those have never been reported. In this work, we present the development of the 3rd generation principle based enzymatic sensor for spermine by employing a unique Methods SpdH was recombinantly produced using E. coli and purified by Ni2+ affinity chromatography. An electrochemical enzymatic sensor was constructed by immobilizing SpdH on gold electrodes. The DET properties of the enzyme-immobilized electrode were evaluated by cyclic voltammetry with an Ag/AgCl reference electrode and a Pt wire counter electrode, respectively. Chronoamperometry measurement was performed with SpdH immobilized gold electrodes using artificial saliva or phosphate buffer, where spermine was spiked with different concentrations. Results and Discussions For spermine measurement, we selected SpdH which was expected to be capable of DET with electrode, which was predicted from its unique protein structure. The crystal structure of SpdH shows the presence of heme b and FAD as the co-factors of the enzyme with a distinctive character. The heme b locates on the surface of the enzyme and is expected to accept electron from FAD and can transfer electrons to the electrode. The cyclic voltammetry observation showed the spermine-concentration dependent peak current increase in the absence of any additional electron acceptor, revealing that the enzyme harbors DET ability with electrode. The spermine concentration dependent currents increase was also observed by chronoamperometry measurement. The limit of detection of the enzymatic electrode was sub-micromolar level, which covers the physiologically relevant ranges of spermine. Furthermore, the electrode did not respond to electrochemically active interferants due to its characteristic of low redox potentials of heme being measurable at low potentials.This is the first report to construct a spermine sensor with a DET-type enzyme. DET-type enzymes allow simple electrode configurations operating at lower potentials. These features are less susceptible to redox-active interferents. The current achievements promise the future realization of a simple diagnosis method for PC using a non-invasive specimen, saliva. Figure 1

Fast-Charging Li4Ti5O12 Anode Driven By Light

The development of fast-charging lithium-ion batteries (LIBs) is crucial for achieving significant market adoption of electric vehicles (EVs). The successful achievement of fast-charging LIBs depends on efficient charge transfer and the diffusivity of lithium ions. The photo-assisted battery system exhibits promising fast-charging properties. Previous research has shown that direct exposure to white light can induce a more oxidized center in a spinel LiMn2O4 (LMO) cathode, accelerating its charging rate.[ 1] Recently, our group found that illumination with red light on an operating LMO cathode induces an Mn d-d electron excitation, simultaneously shrinks the Mn-Mn lattice, and facilitates faster delithiation of the LMO cathode.[ 2] Consequently, the charging time of the battery decreases. This encourages us to consider whether the photon energy from a specific wavelength of light can also enhance the lithiation process on the anode side. Spinel Li4Ti5O12 (LTO) is a promising material for faster-charging anodes due to its small volume charge and high-rate capability in lithium intercalation. However, the system displays slow lithium diffusivity due to poor bulk ionic conductivity. To examine the photon effect of light on these anodes, we demonstrate the photo-accelerated fast-charging (lithiation process) mechanism with an LTO spinel anode.The thin film LTO's energy band gap (Eg), approximately 3.4 eV, was determined through intense UV-visible (UV-Vis) absorption spectrum analysis, assessed in a transmission mode employing Tauc’s Law. This indicates that an LED light with photon energy around 3.4 eV might trigger rapid charging by exciting electron transfer to the T-t2g band. To explore the impact of light on the fast-charging behavior of the LTO electrode, current was measured while applying a constant voltage of 1.2 V. During the 20-minute chronoamperometry experiment, utilizing the 3.4 eV UV LED to illuminate the cell resulted in a progressive increase in current. This current increase peaked at approximately 200s, leading to a maximum average capacity increase of 13 mA h g-1. This suggests that UV illumination accelerates the lithiation process compared to the dark state, particularly favoring the early lithiation stage. Subsequently, a red LED emitting 2 eV photon energy was used to illuminate the same cell, resulting in no discernible change in current levels compared to the dark state. Electrochemical impedance spectroscopy (EIS) further revealed a significant reduction in charge transfer resistance of the window cell when illuminated with UV light compared to both the dark state and red illumination. This alteration in electrode reaction kinetics at the interface suggests a distinct influence of different light wavelengths on the charging process.In addition to assessing charge transfer at the electrode interface, galvanostatic intermittent titration technique (GITT) analysis was conducted at a 2 C rate to further elucidate diffusion within the LTO electrode. The GITT curves reveal that the diffusion of Li+ ions was approximately 1.3 times faster when the cell was illuminated by UV light compared to dark conditions. Consequently, we deduce that photo-accelerated fast charging can also occur during the lithiation process (reduction reaction) of anode materials, driven by optical forces.To delve into the underlying mechanisms, we conducted first-principles density functional theory (DFT) calculations. The outcomes revealed that the generation of additional electrons in LTO results in a reduction in the bandgap and shifts the Fermi level above the conduction band minimum, effectively transforming LTO into an active conductor of electricity. These calculations indicate that UV light illumination has the capability to surmount the bandgap of LTO, generating electron-hole pairs and thereby facilitating charge transfer and lithium-ion diffusion.In conclusion, our study showcased that UV light illumination on the LTO anode can lead to a faster charging speed of approximately 17% compared to dark conditions. We posit that the observed phenomenon of photo-accelerated fast charging in LTO is linked to the formation of electron-hole pairs in intrinsically wide-bandgap insulators or semiconducting materials. This discovery holds considerable implications for the advancement of fast charging technologies for lithium-ion batteries, potentially mitigating range anxiety concerns and facilitating the widespread adoption of electric vehicles.Acknowledgments: This work was supported by funding from Royal Dutch Shell plc. Argonne National Laboratory operates under contract no. DE-AC02-06CH11357 with the U.S. Department of Energy Office of Science. We gratefully acknowledge use of the Bebop or Swing or Blues cluster in the Laboratory Computing Resource Center at Argonne National Laboratory and supported by the U.S. Department of Energy Office of Science.Reference[1] A. Lee et al., Nat. Commun., 10, 4946 (2019).[2] J. Lipton et al., Cell Reports Physical Science, 3, 101051 (2022).

Role of cavity strong coupling on single electron transfer reaction rate at electrode-electrolyte interface.

The physicochemical properties of molecules can be modulated through polariton formation under strong electromagnetic confinement. Here, we discuss the possibility of exploiting this phenomenon to increase the electron transfer rate at an electrode-electrolyte interface. Electron transfer theory under strong electromagnetic confinement can be extended to the electrode-electrolyte interface, and single-electron transfer reactions can be simulated using Gerischer's theory. Although single electron transfer in free space is well described using Marcus theory, the vacuum electric field can facilitate an additional electron transfer pathway via virtual photon excitation under cavity strong coupling conditions. Therefore, this binary reaction pathway for single electron transfer can yield a quasi-two-particle electron transfer process. This quantum behavior can dominate when the mode volume is small and when there are a large number of molecules in the vacuum electric field. Exploitation of polaritons in single electron transfer reactions can lead to enhanced electrochemical energy conversion systems.

Influence of an ultrathin Mn ‘spy layer’ on the static and dynamic magnetic coupling within FePt/NiFe bilayers

Abstract We explore whether insertion of an ultrathin Mn ‘spy layer’ within a magnetic hard/soft bilayer can enable depth-sensitive element-specific measurements of the static and dynamic magnetization, while avoiding significant disruption of the original magnetic state. MgO(110)/FePt(100 Å)/NiFe(200 Å)/Mn(t Mn Å)/NiFe(200 Å) samples with Mn thicknesses of t Mn = 0, 5, and 10 Å were fabricated by magnetron sputtering and studied by element-selective x-ray magnetic circular dichroism (XMCD), vector network analyzer ferromagnetic resonance (VNA-FMR), and x-ray detected ferromagnetic resonance (XFMR). For t Mn = 5 Å, the magnetic reversal properties remain broadly similar to t Mn = 0 Å. For t Mn = 10 Å, the two NiFe layers decouple with XMCD hysteresis loops at the Mn edge showing two switching events that suggest the presence of two distinct Mn-containing regions. While the Mn moments within each region have ferromagnetic order, their relative alignment is antiparallel at high field. Analysis of the magnetic data and additional scanning transmission electron microscopy measurements point to the presence of a Mn layer at the lower NiFe/Mn interface, and the formation of a NiFeMn alloy at the upper Mn/NiFe interface. The Mn moments of the former region lie antiparallel to those of the underlying NiFe layer. The VNA-FMR data suggests that for t Mn = 5 and 10 Å, the interfacial exchange coupling at the FePt/NiFe is suppressed and the in-plane uniaxial magnetic anisotropy of the NiFe is increased, perhaps due to migration of Mn towards the buried interface. The above findings show that Mn is a problematic magnetic spy, and that a Mn thickness of less than 5 Å would be required.

Construction of nitrogen-doped graphene/BiOCl Schottky heterojunction for efficient photocatalytic degradation and CO2 reduction

The advancement of an efficient photocatalyst via a straightforward process is critical for environmental remediation and energy conversion. In this study, a series of multifunctional nitrogen-doped graphene/BiOCl (NGBOC) Schottky heterojunction photocatalysts were successfully prepared by hydrothermal method. The systematic characterization and analysis results showed that the addition of NG guided the formation and growth of BiOCl to thinner and smaller nanosheets, during which, under the strong interaction between both, more abundant oxygen vacancies were introduced into BiOCl and a small amount of N element was doped in lattices, ultimately BiOCl and NG with excellent electron transport form Schottky heterojunction. This series of favorable effects not only improve the adsorption capacity of BiOCl to pollutants, but also accelerate the separation and migration rate of photogenerated carriers. Under visible light, the 3NGBOC with optimal content of NG exhibits the highest photocatalytic activity for the degradation of Rhodamine B (RhB) and tetracycline (TC), which is more than four times higher than that of the reference BiOCl. Meanwhile, The NGBOC photocatalysts is highly reusable and has the potential to be recycled five times. Besides, under simulated sunlight, the conversion rate of CO2 to CO over 3NGBOC was about twice that of a single BiOCl. In addition, capture experiments and room temperature electron paramagnetic resonance (EPR) strongly support the dominant role of hydroxyl radicals and superoxide radicals in photocatalytic reactions. This study reveals the design and preparation of multifunctional BiOCl-based Schottky heterojunction photocatalyst, provides a green economic strategy and promising scheme for promoting environmental remediation and energy conversion.

Open Sn Framework Structure Hosting Bi Guest atoms-Synthesis, Crystal and Electronic Structure of Na13Sn26Bi.

The large variety of structures of Zintl phases are generally well understood since their anionic substructures follow bonding rules according to the valence concept. But there are also exceptions, which make the semiconductors especially interesting in terms of structure-property relationships. Although several Na-Sn-Pnictides with a variety of structural motives are known, up to this point no ternary compound in the Na-Sn-Bi system has been described. In this paper we present the Zintl-phase Na13Sn25.73Bi1.27 comprising a complex, open-framework structure of Sn atoms, with one mixed Sn/Bi site, hosting Na atoms. An additional Bi atom is loosely connected with only weak contacts to the framework filling a larger cavity within the network. According to band structure calculations of the two ordered variants with either full occupation of the mixed site with Sn or Bi, resulting in Na13Sn26Bi and Na13Sn24Bi3, respectively, both compounds are semiconductors with band gaps of 0.5 eV. A comparison of the band structures with the structurally related binary compounds Na5Sn13 and Na7Sn12 shows that only the perfectly charge balanced Na7Sn12 is a semiconductor whereas Na5Sn13 is metallic. The rather specific electronic situation in the ternary compound is traced back to the loosely bound Bi atom, which acts as a guest atom according to Bix@Na13Sn26-yBiy, with x=1 and y=0.27, capable to change its oxidation state and thus to uptake additional electrons allowing the system to be a semiconductor. Therefore, Na13Sn25.73Bi1.27 can be understood as a rare example of an open framework structure of Sn atoms comprising Bi atoms in the cavities.