bluuebunny/crossref_metadata_2025 huggingface dataset:
Electroreduction of CO2 on Modified Graphene Supported Sn Nanoparticles in Half-Cell and Full Cell Configuration
Authors: Bera Bapi , Aaron Douglas , Mench Matthew M
Published: December 2020

Electrochemical reduction of CO2 is a process that can reduce carbon dioxide from the atmosphere and simultaneously produce useful, value-added chemicals, specifically solar fuel [1]. Depending on the catalyst materials, CO2 can be reduced to single carbon or multi carbon products [2]. Sn nanoparticle was used to catalyze CO2 reduction to produce formate in alkaline medium. Sn nanoparticles were synthesized by the sol-gel method with different precursors at room temperature and supported with carbon black and conductive graphene nano-sheets. Graphene nano-sheets were synthesized by the conventional modified Hammer method [3]. X-ray diffraction (XRD) and transmission electron microscope (TEM) enabled insights into phase formation, shape, and size of the Sn nanoparticles. Reference materials included commercial Sn nanoparticles with carbon support (Sn:C_com), commercial Sn nanoparticles with graphene support (Sn:GN_com), Sn nanoparticle synthesised using Sn (II) 2-ethylhexanoate and Sn (II) chloride as tin precursor with carbon support as respectively (Sn:C_Tin-2-hexa) and (Sn:C_SnCl2). Three-electrode chronoamperometry showed that Sn:GN_com enabled high CO2 electrolysis current density (see Figure 1(a)). Electrochemical impedance spectroscopy (EIS) of the prepared catalysts in CO2-saturated 0.1 M KHCO3 was recorded in a three-electrode rotating disk electrode (RDE) configuration (see Figure 1(b)). The charge-transfer resistance was smallest for Sn:GN_com sample, as well. CO2 reduction was performed in a full electrochemical cell using the same architecture as a low temperature polymer electrolyte fuel cell (PEFC) in alkaline medium with anion exchange membrane. Polarization plots show a unique feature (two different slopes); this change in slope is dominated by a distinct change in the area specific resistance (ASR) value (see Figure 1(c)).

In this work, we mainly focus on the CO2 electroreduction to produce formate in a full cell with RDE (rotating disc electrode) measurements providing additional insights into catalytic properties. Our primary goal is to understand the basic underlying physical processes during CO2 reduction in the full cell set up and also find inexpensive and efficient catalytic active materials for the reduction process.

Figure 1: CO2 electrolysis (a) and impedance spectra (b) in RDE configuration with different catalyst. (c) Polarisation plots for CO2 reduction in full cell configuration with different flow rate

References:

Wang, C. Niu, and D. Wang, Journal of Colloid and Interface Science 527 (2018) 95–106.

Zhao, and J. Wang, Chemical Engineering Journal 293 (2016) 161–170.

C.-T. Hsieh, and W.-Y. Chen, Surface & Coatings Technology 205 (2011) 4554–4561.

Figure 1
(Invited) Structural and Mechanistic Details on the Oxygen Evolution Reaction on Nife Layered Double Hydroxide and Ni(OH)2
Authors: Dionigi Fabio , Ferreira de Araujo Jorge , Merzdorf Thomas , Strasser Peter
Published: December 2020

The incorporation of Fe3+ ions in Ni(OH)2 is responsible for a dramatic oxygen evolution reaction (OER) activity enhancement.1 NiFe based (oxy)hydroxides are among the most active electrocatalysts for the OER in alkaline electrolytes.2 Their crystal structure, known as layered double hydroxide (LDH), is composed of layers of edge sharing metal oxygen octahedra that are intercalated with water molecules and charge balancing anions (Figure 1).3 In contrast, Fe-free Ni(OH)2 can be synthesized in the well defined brucite-like crystal structure, which does not have intercalated species and is indicated as β-M(OH)2. Oxidative deprotonation and possibly the electrocatalytic OER reaction lead to reversible structural changes that are only observable with in operando or in situ methods.1, 4 Several reports investigated the oxidized phases, but key aspects of the catalytically OER active site remain elusive and more investigations are necessary.

In this contribution our results obtained using in operando wide angle X-ray scattering (WAXS) on crystalline NiFe LDH nanostructured catalysts and β-Ni(OH)2 catalysts will be presented.5 We identified the structure of the active catalyst state and observed that the lattice spacing under operating conditions changes reaching a similar value for both catalysts (Figure 1). Using a unique differential electrochemical mass spectrometry (DEMS) apparatus and isotope labelled experiments we further unravel mechanistic details on how the OER mechanism proceeds on these catalysts.

References

D. Friebel, M. W. Louie, M. Bajdich, K. E. Sanwald, Y. Cai, A. M. Wise, M. J. Cheng, D. Sokaras, T. C. Weng, R. Alonso-Mori, R. C. Davis, J. R. Bargar, J. K. Norskov, A. Nilsson and A. T. Bell, J Am Chem Soc, 2015, 137, 1305-1313.

M. Gong, Y. G. Li, H. L. Wang, Y. Y. Liang, J. Z. Wu, J. G. Zhou, J. Wang, T. Regier, F. Wei and H. J. Dai, J Am Chem Soc, 2013, 135, 8452-8455.

F. Dionigi and P. Strasser, Advanced Energy Materials, 2016, 6.

M. Gorlin, J. F. de Araujo, H. Schmies, D. Bernsmeier, S. Dresp, M. Gliech, Z. Jusys, P. Chernev, R. Kraehnert, H. Dau and P. Strasser, J Am Chem Soc, 2017, 139, 2070-2082.

F. Dionigi, Z. Zeng, I. Sinev, T. Merzdorf, S. Deshpande, M. B. Lopez, S. Kunze, I. Zegkinoglou, H. Sarodnik, D. X. Fan, A. Bergmann, J. Drnec, J. F. De Araujo, M. Gliech, D. Teschner, J. Greeley, B. Roldan Cuenya and P. Strasser, submitted 2019.

Figure 1. Shift of the (003) diffraction peak associated to the interlayer distance for NiFe LDH catalysts between the resting state (black) and OER active state (red).5 3D structural model of the as prepared NiFe LDH.

Figure 1
(Invited) Electrochemical Extraction and Conversion of CO2 from Seawater
Authors: Digdaya Ibadillah A. , Sullivan Ian , Lin Meng , Han Lihao , Cheng WenHui , Atwater Harry A. , Xiang Chengxiang("CX")
Published: December 2020

Capture and conversion of CO2 from anthropogenic emission is becoming an increasingly important social responsibility as the concentration of atmospheric CO2 continues to rise above record high levels. To achieve carbon negative conditions in the long term, capture and extraction of CO2 directly from air and seawater will likely play a much bigger role. The concentration of the present CO2 in the atmosphere is ~400 ppm, or 0.00079 kg m−3. As a result, a large volume of air needs to be processed in direct air capture processes. In contrast, world ocean constitutes the largest carbon sink, absorbing about 40% of anthropogenic CO2 since the beginning of industrial era with an effective CO2 concentration of 2.1 mmol kg−1, or 0.095 kg m−3 in seawater, which is a factor of 120 times larger than in the atmosphere. Thus, extraction of CO2 from seawater provides an alternative and unique approach in the global carbon removal technological landscape.

Herein, a new bipolar membrane electrodialysis (BPMED) cell design, in which the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at the electrodes were replaced with reversible redox couple reactions with minimal thermodynamic and kinetic voltage losses, was designed, constructed and evaluated. At an operating current density of 3.3 mA cm−2, and a seawater flow rate of 37 ml min−1, a record low electrochemical energy consumption of 155.4 kJ mol−1 or 0.98 kWh kg−1 of CO2 was achieved. The demonstrated BPMED cell also exhibited a high CO2 extraction efficiency of 71% of total dissolved inorganic carbon (DIC). We also demonstrated, for the first time, the direct coupling between the CO2 extraction from seawater via BPMED and electrochemical CO2 reduction (CO2R) into fuels and chemicals. The outlet CO2 stream from the BPMED was fed into tandem custom-built vapor-fed GDE cells to first perform the oxygen reduction reaction (ORR) using a nanoparticle Ag-based catalyst followed by CO2R using Cu or Ag as the electrocatalyst. This configuration allowed us to convert CO2 from seawater to fuels and valuable chemicals such as carbon monoxide, ethylene, ethanol, and propanol with total Faradaic efficiency (FE) of up to 73% at current densities of 58 mA cm−2 using CO2R Cu electrocatalyst and to carbon monoxide with selectivity of up to 95% at current densities of 11.15 mA cm−2 using CO2R Ag electrocatalyst.

Figure 1
Ion-Enhanced Conversion of CO2 to Formate on Porous Dendrite Bismuth Electrodes with High Efficiency and Durability
Authors: Piao Guangxia , Park Hyunwoong
Published: December 2020

Facile synthesis of efficient electrocatalysts that can selectively convert CO2 into value-added chemicals remains a challenge. This study presents the electrochemical synthesis of porous Bi dendrite electrodes and details on their activity toward CO2 conversion to formate in aqueous bicarbonate solutions. The as-synthesized multi-layered porous dendrite Bi electrodes exhibit the faradaic efficiency (FE) of ~100% of formate production. The added halides and cations significantly influence the steady-state partial current density for formate production (J
FM) (Cl- > Br- ~ I-; Cs+ > K+ > Li+). Density functional theory calculations have revealed that the reaction pathway involving the species *OCOH occurs predominantly, while co-existence of Cs+ and Cl- changes the overall reactions more spontaneously. A photovoltaic cell-assisted electrocatalysis produces formate with FEs of ~95% (J
FM ~10 mA cm-2) at an overall solar conversion efficiency of ~8.5%. The Bi electrodes maintain their activity over 360 h without a change in the surface states.

Figure 1
Pd Shape-Controlled Nanoparticles Decorated with Metals for Electrochemical Nitrate and Nitrite Reduction
Authors: Lim Jeonghoon , Park Jinho , Lee Seung Woo , Hatzell Marta C.
Published: December 2020

Nitrate (NO3
-) pollution of groundwater occurs due to anthropogenic activities such as the overuse of nitrogen-rich agriculture fertilizers. Furthermore, nitrite (NO2
-) causes adverse effects on human health such as methemoglobinemia (“blue baby syndrome”) and cancer. Currently, physicochemical technologies such as reverse osmosis or ion exchange are used for nitrate removal, but these approaches are not sustainable as waste disposal of the brines remains a critical challenge (requiring the use of expensive post-treatment processes). Electrochemical NO3
- remediation; however, offers several advantages when compared to physiochemical approaches for nitrate removal as NO3
- is directly converted to harmless dinitrogen (N2) gas resulting in no waste production. The main challenge with electrochemical NO3
- reduction is the low activity and selectivity of the NO3
- to N2. The activity is limited by the rate-determining step (NO3(ads)
- to NO2(ads)
-), and selectivity is determined by the reduction of NO2(ads)
-to N2 and/or ammonium (NH4
+).

To achieve an efficient activity and selectivity for the electrochemical denitrification, we develop Pd shape-controlled nanoparticles and introduce secondary metals on the surface of Pd electrocatalysts by chemical reduction methods. The decorated metals promote the reduction of NO3
- to NO2
- (rate determining step) and the Pd facets enhances the selectivity of NO2
- to N2. Rotating ring disk electrode (RRDE) tests enabled the measurement of improved activity and selectivity of NO3
- to N2 using shape-controlled Pd that contain surface modifications (metal atoms). This study demonstrates that electrochemical nitrate reduction is an important approach to reduce environmental impacts associated with removing NO3
- from water.
Electrodeposited Ni-Fe-Co Alloys for Magnetoelastic Resonators
Authors: Pillars Jamin R. , Langlois Eric D. , Monson Todd C. , Gucik Mary Louise , Pearce Charles Joseph , Delaney Robert , Maadi Ayham
Published: December 2020

Magnetoelastic materials such as CoFe and NiFeCo alloys display Joule magnetostriction. This property of ferromagnetic materials is usually minimized as a loss mechanism in applications such as inductor or transformer cores. Though, for use as a resonating material in a sensor application, this material provides a battery-less system where an external device can apply a magnetic field and receive a magnetic “signal” in return based upon the resonant frequency, geometry, and mass. As-deposited CoFe and NiFeCo films have no measurable resonant frequency when analyzed with a vector network analyzer and biasing Helmholtz coils. To control magnetic properties of the electrodeposited alloys, the stoichiometry was controlled and additional elements such as boron, niobium, silicon, germanium, and holmium were added to the chemistry. The electrical resistivity was increased and the magnetic properties such as permeability, coercivity, and magnetic saturation were controlled and comparable to commercial, extruded ribbon materials such as Metglas. Annealing studies in a magnetic field, applied both parallel and perpendicular to the easy axis of the NiFeCoBNbSi and other alloy films, were used to adjust the anisotropy and the permeability of the material.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525, SAND2020-5481 A . The views expressed in the article do not necessarily represent the views of the U.S. Department of Energy or the United States Government.
Polymers Doped with Carbon Nanoparticles As Hot Electron Emission Materials for HECL Bioaffinity Assays
Authors: Kulmala Sakari , Salminen Kalle , Kulmala Aija
Published: December 2020

This contribution presents simple methods to fabricate hot electron-emitting composite electrodes. Hot electron-induced electrochemiluminescence (HECL) typically utilizes luminophores as labels in sensitive bioaffinity assays, where the electrodes can inject hot electrons into aqueous electrolyte solutions, possessing more energy than that of conduction band edge of water and hence generate hydrated electrons as a mediating species and HECL for detection of labels utilized. In this study, the hot electron emitting composite electrodes fabricated by doping polymer materials with few different types carbon particles and coating metal substrates with the above-mentioned composite layers with different carbon-polymer mass fractions. An aromatic Tb(III) chelate was used as a probe, that is known not to be excited on the basis of traditional electrochemistry but to be efficiently electrically excited in the presence of hydrated electrons, and during injection of hot electrons into aqueous solution. Thus, the presence of hot, prehydrated or hydrated electrons at the close vicinity of the composite electrode surface were monitored by electrogenerated chemiluminescence. These inexpensive and easily fabricated composite electrode materials can be used in HECL bioaffinity assays and other applications of hot electron electrochemistry. Finally, it is shown that the present types composite electrodes can be fabricated by printing and used in real-world immunoanalysis of human C-reactive protein.
Rare Earth Doped Nanoparticles for Theranostics
Authors: Vetrone Fiorenzo
Published: December 2020

In the biomedical field, research has recently focused on nanoparticle-based “theranostic” agents for the treatment of diverse diseases, including cancer. This new paradigm in personalized medicine intends to exploit nanoplatforms that carry both therapeutic and diagnostic (theranostic) modalities. Compared with delivering drugs or imaging agents separately, theranostic agents can simultaneously deliver them to specific sites, enabling detection and treatment of disease in a single procedure. Many theranostic nanoplatforms are triggered by light, however, the vast majority of these are limited in that the ultraviolet or visible excitation light used has minimal applicability in biological applications. Rare earth doped nanoparticles, on the other can be excited with biologically friendly near-infrared light (in the biological windows) and can emit in the ultraviolet, visible or near-infrared regions through a multiphoton upconversion process while simultaneously emitting in the near-infrared region (also in the 3 biological windows) through a Stokes or downshifted process. Hence, the upconversion luminescence can be used to trigger the therapeutic application (drug delivery, photodynamic therapy, etc.) while the near-infrared luminescence can be used for the diagnostic modality (bioimaging, nanothermometry/temperature sensing, etc).

In this presentation, we will introduce rare earth doped nanoparticles and demonstrate their usefulness in theranostics. In particular, we will show that complex nanoparticle architectures can endow further functionality to these nanoparticles and discuss how they can be used for temperature sensing (nanothermometry) in biological systems.
Electrochemical Sensing of Ethyl Acetate Volatile Organic Biomarker Using Cobalt Functionalized TiO2 Nanotubes
Authors: Misra Mano , Vadlamani Bhaskar , Dhabarde Nikhil , Tembo Prichard , Subramanian Vaidyanathan
Published: December 2020

Food spoilage detection is crucial in preventing foodborne illnesses caused by consumption of spoiled food. The current study explores the potential use of in-situ cobalt functionalized TiO2 nanotubes (iCo-TNT) in the electrochemical detection of ethyl acetate, a Volatile Organic Biomarker (VOB) released from spoiled tomato. iCo-TNTs were synthesized by electrochemical anodization using titanium sheet as the working electrode and platinum sheet as the counter electrode in an electrolyte of 0.5 wt.% CoF2, 0.5 wt.% HF, and 2.5 wt.% H2O composition. The anodized tubes were annealed in oxygen flow to ensure the formation of anatase phase. The morphology of iCo-TNT was characterized using SEM and tubes were found to have an inner diameter, wall thickness and length of ~40 nm, ~8 nm and ~1.1 µm respectively. The electrochemical sensing of ethyl acetate was carried out using amperometry in a standard three electrode configuration. Amperometry studies were conducted using iCo-TNT as the working electrode, at a bias voltage of -0.3 V vs an Ag/AgCl reference electrode, with 1mM incremental addition of ethyl acetate VOB in DI water blank solution. The sensor response current was found to be linear and increasing with ethyl acetate addition in the concentration range 0 mM to 4 mM. Furthermore, a mechanism for interaction of ethyl acetate with iCo-TNT was proposed.
Fast Screening Tests for Early Detection of Gastric Cancer
Authors: Van Staden Raluca , Ilie-Mihai Ruxandra Maria , Gheorghe Damaris Cristina
Published: December 2020

There is a real need of new screening methods for early diagnosis of gastric cancer. Biomarkers such as CEA, CA19-9 and p53, if found earlier in the biological samples can indicate the presence of gastric cancer. Different sensors based on modified graphene materials were designed and characterized for the screening tests of the mentioned biomarkers in biological samples. The proposed sensors showed low limits of quantification and high sensitivity and selectivity levels. The recoveries of the biomarkers in biological samples were higher than 95.00% with RSD lower than 1.00%.
High Detectivity Ammonia Gas Sensor of Pentacene Based Organic Material with OXIDE MESH
Authors: Lee Sang Yeol , Lee Byeong Hyeon , Lee Ji Ye , Park So Yeon
Published: December 2020

Ammonia gas sensing properties of pentacene based organic gas sensor fabricated by thermal evaporation method on amorphous oxide semiconductor (a-SiInZnO) mesh. The amorphous oxide semiconductor mesh layer was fabricated by RF sputtering and conventional photolithography. Insertion of a dense mesh layer has been found to significantly improve gas sensing properties. In the case of a conventional pentacene thin film, the SEM image analysis resulted in a uniform surface. This means that ammonia gas cannot be adsorbed well on the surface. The insertion of the mesh layer improves the surface volume ratio of the organic thin film and induces more ammonia gas to be adsorbed on the pentacene surface. As a result, it was confirmed that even when the ammonia gas concentration was 5 ppm or less, the detection rate was higher than that of a conventional pentacene thin film. It is expected to be applied to various high-sensitivity organic-based gas sensors.
(Sensor Division Outstanding Achievement Award Address) Towards Biosensor Enabled Smart Dressings for Management of Chronic Wounds: Advances and Perspectives
Authors: Bhushan Pulak , Lahade Shashikant Vitthalrao , Kamat Vivek A. , Lev-Tov Hadar A. , Kirsner Robert S. , Bhansali Shekhar
Published: December 2020

This presentation covers an approach towards integrating enzymatic biosensors to monitor wound healing. The importance of wound care in recovery not only facilitates timely healing, but also assists in preventing further infection and minimize scarring. To prevent complications, preserve tissue function, and facilitate healing, accurate evaluation and management of wounds is vital. Present wound diagnostics include visually recording the wound area and depth to assess healing progress. However, there are no methods available for monitoring the biochemical events in the wound. This biosensor was fabricated by immobilizing uricase (UOx) natural catalyst for UA as the enzyme and, multi-walled carbon nanotubes (MWNT) and gold nanoparticles (Au) as electron exchange matrix. These results show that this biosensor can be used to monitor UA in physiological concentrations.
Electrochemical Biosensors Integrating Metallic and Non-Metallic Nanomaterials for Biomedical Applications
Authors: Lee Hye Jin Jin
Published: December 2020

In this talk, I will present our latest efforts made on creating highly sensitive and selective electrochemical biosensors integrating either carbon nanotubes or gold nanoparticles in addition to biological molecules or polyelectrolytes for medical diagnostic applications. Single or multi-walled carbon nanotubes and graphenes wrapped with polyelectrolytes were implemented onto screen printed carbon electrode (SPCE) surfaces for enhancing the sensors sensitivity. Whereas target analyte selective enzymes were utilized to improve the selectivity. The oppositely charged polyelectrolyte coated carbon nanomaterials and enzymes were immobilized on the electrode surface via a simple layer by layer assembly process. Our interest of analytes were hypoxanthine, xanthine, uric acid, dopamine and serotonin, which can be used for diagnosis of various diseases including cardiovascular disorders and game addiction syndrome. The developed biosensors were successfully applied to both normal and patient serum analyses. In addition, a brief introduction of utilizing target selective DNA aptamer coated gold nanoparticles deposited on SPCE for the selective voltammetric detection of protein tyrosine kinase-7, which is known to be a potential lung cancer biomarker. Finally, I will discuss future aspects and challenging issues of our nanomaterial integrated biosensing methodologies.
Electrochemical Amplification Methods in Observation of Single Nanoparticle Collisions
Authors: Kwon Seong Jung
Published: December 2020

We describe the electrochemical detection of single nanoparticle (NP) collision at a less catalytic electrode. We could observe the various single NP collision through the enhanced current by electrocatalytic redox recycling. The current responses were caused by random individual events as a function of time rather than the usual continuous current caused by an ensemble of a large number of events. The overall current transient such as spike-like or staircase, changed depending on the reaction mechanism of collided NP. The height and frequency of the peak current are proportional to the applied potential and the particle concentration.

Single iridium oxide (IrOx) NP collision at a less catalytic electrode surface such as the NaBH4-treated Pt or the bare Au ultramicroelectrode (UME) was investigated. The overall current transient consists of repeated current spikes, superimposed on a current decay to reach a steady-state value.

Collisions of Ag NPs with a more electrocatalytic Au or Pt surface have been observed. Depending on the applied potential to the UME, the current response of Ag NPs collision onto the UME resulted in various shape changes. A staircase decrease, a blip decrease, and a blip increase of the hydrazine oxidation current were obtained at an applied potential of 0.33 V, 0.80 V, and 1.3 V, respectively.

The current response of ascorbic acid stabilized Cu single NP collision on Au UME surface was observed. Here, the glucose oxidation electrocatalyzed by oxidized Cu NP was used as the indicating reaction. In this system, the NP collision signals were obtained simultaneously by both direct particle electrolysis and electrocatalytic amplification.
Atomically-Dispersed Functional Materials: From Single-Atom Electrocatalysts to Single-Atom Nanozymes
Authors: Du Dan (Annie) , Lin Yuehe
Published: December 2020

Nanomaterials with enzyme‐like activities, or nanozymes, have attracted lots of attention recently due to their advantages such as low cost, superior activity, and high stability. The complex structure and composition of nanozymes has led to extensive investigation of their catalytic sites at an atomic scale, and to an in‐depth understanding of the biocatalysis mechanisms.

Single-atom catalysts (SACs) offer the unique feature of maximum atomic utilization, providing a potential pathway to improve the catalytic activity of nanozymes. Recently, we have demonstrated a Fe-N-C single-atom nanozyme (SAN) that exhibits high peroxidase-like activity. The SAN consists of atomically dispersed Fe─Nx moieties hosted by metal–organic frameworks (MOF) derived porous carbon. Due to high single-atom active Fe dispersion and the large surface area of the porous support, the SAN provided a high specific activity which was almost at the same level as natural horseradish peroxidase (HRP). Besides, the Fe-N-C based SAN presented much better storage stability and robustness against harsh environments compared with natural enzymes. The biosensing applications of the SAN and their major challenges will be discussed.

References:

L. Jiao, H. Yan, Y. Wu, W. Gu, C. Zhu, D. Du, Y. Lin. When Nanozymes Meet Single-Atom Catalysis. Angew. Chem. Int. Ed. 2019, doi.org/10.1002/ange.201905645

C. Zhu, S. Fu, Q. Shi, D. Du, Y. Lin. Single-Atom Electrocatalysts. Angew. Chem. Int. Ed. 2017, 56, 13944-13960.

N. Cheng, J. Li, D. Liu, Y. Lin, D. Du. Single-Atom Nanozyme Based on Nanoengineered Fe-N-C Catalyst with Superior Peroxidase-Like Activity for Ultrasensitive Bioassays. Small, 2019, 1901485.

X. Niu, Q. Shi, W. Zhu, D. Liu, H. Tian, S. Fu, N. Cheng, S. Li, J. N Smith, D. Du, Y. Lin. Unprecedented peroxidase-mimicking activity of single-atom nanozyme with atomically dispersed Fe-Nx moieties hosted by MOF derived porous carbon. Biosensors & Bioelectronics, 2019, 142, 111495.

Y Wu, L Jiao, X Luo, W Xu, X Wei, H Wang, H Yan, W Gu, BZ Xu, D Du, Y. Lin, C. Zhu. Oxidase‐Like Fe‐N‐C Single‐Atom Nanozymes for the Detection of Acetylcholinesterase Activity. Small, 2019, 15, 1903108

L Jiao, W Xu, H Yan, Y Wu, C Liu, D Du, Y Lin, C Zhu. Fe-NC Single-Atom Nanozyme for the Intracellular Hydrogen Peroxide Detection. Anal. Chem., 2019, 91, 11994-11999
Low-Temperature and Highly Enhanced NO2 Sensing Performance of Au-Functionalized WO3 Microspheres with a Hierarchical Nanostructure
Authors: Shen Yanbai , Zhao Sikai , Jia Lijun
Published: December 2020

Hierarchically nanostructured WO3 microspheres that had two types of Au functionalization modes (Au-loaded mode and Au-doped mode) were characterized in terms of their microstructure and NO2 sensing performance. Pure, Au-loaded, and Au-doped WO3 microspheres were synthesized using a hydrothermal method, followed by a dipping method for Au-loaded WO3 microspheres. Microstructure characterization indicated that uniform microspheres with 3–6 μm in diameter were assembled from numerous well-defined individual WO3 nanorods with a single crystal hexagonal structure. The morphology and size of the WO3 microspheres were not affected by the functionalization of the Au nanoparticles, and the W, O, and Au elements were well-distributed in the WO3 microspheres. The NO2 sensing properties indicated that the Au nanoparticles not only improved the sensor response and reproducibility but also decreased the operating temperature at which the sensor response reached a maximum. Gas sensors based on pure, Au-loaded, and Au-doped WO3 microspheres exhibited a linear relationship between the sensor response and NO2 concentration. The sensing performance was significantly enhanced in the following order: pure, Au-loaded, and Au-doped WO3 microspheres. This result is due to the modulation of the depletion layer via oxygen adsorption as well as chemical and electronic sensitization of Au nanoparticles.
Electrochemical Analysis of Soft Particles Via Collision Event
Authors: Kim Byung-Kwon
Published: December 2020

Single particle analysis using particle collision on electrodes has recently been actively studied. This single particle collision method is a good way to analyze particle composition, size, concentration, diffusion coefficient, and behavior in solution. This method can be roughly classified into two methods. The first is a method of analyzing a staircase current decrease that occurs when a particle collides with an electrode. The second method is to observe a current increase by measuring the electrochemical reaction that occurs when particles collide the electrode. Recently, we have analyzed the emulsions (water/oil and oil/water), bacteria, red blood cells and polymers by the current change which occurs when the particles collide with the electrode. Through this method, particle size, distribution, concentration, and particle behavior in solution were analyzed.
(Invited) Near Infrared Optical Probes for Imaging Neuromodulators with High Spatiotemporal Resolution
Authors: Beyene Abraham
Published: December 2020

Dopamine neurotransmission plays critical roles in brain function in both health and disease and aberrations in dopamine neurotransmission are implicated in several psychiatric and neurological disorders, including schizophrenia, depression, anxiety, and Parkinson’s disease. Until recently, measuring the dynamics of dopamine and other neurotransmitters of this class could not be achieved at spatiotemporal resolutions necessary to understand how dopamine regulates the plasticity and function of neurons and neural circuits, and how dysfunctions in this regulation lead to disease. Probes that satisfy critical attributes in spatial and temporal resolution, and chemical selectivity are needed to facilitate investigations of brain neurochemistry.

To address this need, we developed an ultrasensitive near-infrared “turn-on” nanosensor (nIRCat) for the catecholamines dopamine and norepinephrine and implemented nIRCat to study endogenous dopamine dynamics in brain tissue. nIRCats are synthesized from photostable and near infrared emissive functionalized single wall carbon nanotubes (SWCNT) and exhibit maximal relative change in fluorescence intensity (ΔF/F0) of up to 35-fold, with a dynamic range that spans physiological concentrations of their target brain analytes. We demonstrate that nIRCat can detect electrically and optogenetically evoked release of dopamine in brain tissue, revealing putative hotspots of activity that exhibited a log-normal distribution in size, ranging from 2 – 10 µm for mice brain tissue in the dorsomedial striatum. Furthermore, the synthetic nature of the molecular recognition platform afforded compatibility with dopamine-receptor targeting antipsychotics and psychoactive drugs and permitted studies of how such receptor-targeting drugs modulate evoked dopamine release. This assay revealed presynaptic correlates of drug activity at the level of putative dopamine release sites, which had heretofore been inaccessible to probe with existing tools. Our results suggest that nIRCat technology may uniquely support similar explorations of processes that regulate dopamine neuromodulation at the level of individual synapses, and exploration of the effects of receptor agonists and antagonists that are commonly used as psychiatric drugs as well as drugs that lead to substance use disorder. We conclude that SWCNTs can serve as versatile synthetic optical scaffolds for monitoring interneuronal chemical signaling in the brain extracellular space at spatial and temporal scales pertinent with the encoded neurochemical information.
Solid-State Diffusion Coefficient of Li Ions in Li[Ni1/2Mn3/2]O4 Determined By the Diluted Electrode Method
Authors: Sugawa Jun , Masuda Shumpei , Ariyoshi Kingo
Published: December 2020

The input- and output-power of lithium-ion batteries strongly depend on the rate capability of the lithium insertion electrode used as positive and negative electrodes. In our previous studies, the rate capability of the electrodes have revealed that the diffusion of Li ions in the electrolyte inside the electrode is a rate-determining step [1]. Recently, the use of a dilute electrode in which a part of the active material is replaced with a spectator material makes the Li ion transport process in the solid phase rate-determining. In other words, the diluted electrode method allows to measure the rate capability of the material and to determine the solid-state Li-ion diffusion coefficient in an active material.

In this study, we investigate the dependence of the rate capability of materials on the particle size. The material used was Li[Ni1/2Mn3/2]O4 (LiNiMO), which is a 5V class positive electrode material whose rate capability have been variously changed depending on the crystal structure, particle size, and reaction mechanism. LiNiMO with different particle size was synthesized by changing the synthesis temperature from 800 ℃ to 1100 ℃. The particle size of LiNiMO increased with rising the synthesis temperature. Dilute electrodes containing 10 wt% of LiNiMO active material was prepared and the rate capability tests were carried out. The lower the synthesis temperature, the better the rate capability. The sample with the smallest particle size (> 1㎛) synthesized at 800 ℃ showed 4 times higher rate capability compared to the sample with the largest particle size (7 ㎛) synthesized at 1100 ℃. This result suggests that the smaller the particle size of the material, the shorter the diffusion distance of lithium ions in the solid phase, and thus the superior rate capability was exhibited.

In the presentation, based on the results of these rate tests, the solid-state diffusion coefficient of Li ions in the LiNiMO was determined, and the relationship between physicochemical properties such as particle size, crystal structure, and reaction mechanism of LiNiMO and the diffusion coefficient was investigated.

[1] K. Ariyoshi et al., J. Electrochem. Soc., 165, A3965-A3970 (2018).

Figure 1
Synthesis of β-Mn2V2O7 Anode Materials Using Facile Green Strategy for High Performance Rechargeable Lithium Ion Batteries
Authors: Lee Seunggyeong , Song Moonsoo , Sambandam Balaji , Alfaruqi Muhammad Hilmy , Kim Jaekook
Published: December 2020

Vanadium-based mixed metal oxides are of interest because of their high energy density, variable oxidation states, and high specific capacities.

Within the family of manganese vanadium oxides, earth abundant β-Mn2V2O7 (MnVO) has attracted considerable attention because of its fascinating crystal structures with key building blocks of several extended M-O and V-O polyhedral units.

Herein we report the β-Mn2V2O7 (MnVO) were synthesized by a simple and cost-effective zeolitic imidazolate frame- work precipitation technique using water as the sole solvent and reported for excellent electrochemical Li storage properties. The anode delivers specific capacities of 868 and 751 mAh g-1 at rates of 500 and 2000 mAh g-1 after 180 and 400 cycles, respectively.
In-Situ EIS to Investigate Effect of C-Rate on Impedance Spectra of Positive Electrodes with Different Ratio of Conductive Additives in Lithium Ion Batteries
Authors: Kojima Fumiya , Hoshi Yoshinao , Watanabe Hikari , Shitanda Isao , Itagaki Masayuki
Published: December 2020

Active materials, conductive additives and binders are widely used for the fabrication of positive electrodes of lithium ion batteries (LIBs). The electrochemical performance of positive electrodes is affected by the addition rate of conductive additives on the electrode 1). It is important to investigate the effect of the addition rate of conductive additives on the electrode performance of the positive electrode during charge-discharge cycle in order to develop LIBs that can charge and discharge at high C-rate. In the present study, the in-situ EIS 2) was employed to investigate the effect of C-rate on impedance spectra of positive electrode with different additive rates of conductive additives.

The positive electrode with different additive rates of acetylene black (AB) was fabricated by screen printing. The mixture of the slurry containing LiCoO2 powder, AB, polyvinylidene fluoride and N-methylpyrrolidone were screen-printed on the aluminum foil. In the present study, the positive electrode with different additive rates of AB was used for the impedance measurement. The spherical natural graphite fabricated on cupper foil was used as the negative electrode and a lithium wire was used as the reference electrode (RE). All measurements were carried out by the three-electrode cell (Toyo system co. ltd.) at room temperature in an argon atmosphere.

The 3D impedance of positive electrode, negative electrode and full cell was measured by in-situ EIS during charge and discharge. In the 3D impedance of positive electrode, three loops were observed on the Nyquist plane during charge and discharge. As the diameter of loop in the low frequency range was decreased with the increase of the state of charge (SOC), this loop may be related to the time constant composed of the charge transfer resistance R
ct and the electric double layer capacitance 2). In order to examine the effect of C-rate on impedance of positive electrode, the changes of R
ct values during charge and discharge were estimated from the instantaneous impedance at arbitrary SOC on 3D impedance of positive electrode. The relationship between C-rate and additive rates of AB on the impedance of positive electrode was discussed.

References:

1) F. Y. Su, C. H. You, Y. B. He, W. Lv, W. Cui, F. Jin, B. Li, Q. H. Yang and F. Kang, J. Mater. Chem., 20, 9644-9650 (2010).

2) M. Itagaki, K. Honda, Y. Hoshi, I. Shitanda, J. Electroanal.
Chem., 737, 78–84 (2015).
Improved Cyclability of LiNi0.8Co0.1Mn0.1O2 Coated with Al2O3 through Atomic Layer Deposition
Authors: DongWook Kim , Balasubramaniam Ramkumar , Ganesan Bala Krishnan , Moorthy Megala , Seol Jaechang , Lee Seon Yeong , Lee Yun-Sung
Published: December 2020

Atomic layer deposition(ALD) for surface coating was applied to improve the stability of NCM811 at higher voltages. The Al2O3 coating is done in a uniform and conformal way on prefabricated electrodes using atomic layer deposition that significantly prevented surface degradation over prolonged cycling. First cycle capacity of 190, 199, 188 and 166 mAh g-1 is obtained for pristine, 2, 5 and 10 cycles of ALD coated samples at 0.2C and maintains 145, 158, 151 and 130 mAh g-1 for high current rate of 2C in room temperature. The optimized Al2O3 modified cathode retained 75% of its capacity after 500 cycles at 5C with 0.05% capacity decay per cycle, compared with 46.5% retention for a pristine electrode, at an elevated temperature. Despite the insulating nature of Al2O3 coating, a nanometer (nm) coating layer is sufficient to improve the elevated temperature performance. The protective nature of Al2O3 coating in preventing the detrimental surface reactions at high temperature is understood from the morphology changes between the pristine and cycled electrodes.
Improvements to Multi-Scale, Mechano-Electrochemical Modeling Methods
Authors: Pereira Drew Joseph , Garrick Taylor R. , Weidner John W.
Published: December 2020

Automotive battery manufacturers are working to improve individual cell and overall pack design by increasing their performance, durability, and range, while reducing cost; and active material volume change is one of the more complex aspects that needs to be considered during this process. Designers try to control or mitigate the effects of volume change using a variety of methods: inserting foam layers into battery packs, programming specific charging algorithms, using multiple active materials, etc. However, designers must resort to extensive testing to fully develop these methods for each new battery design because of the complexity in measuring and understanding the links between active material volume change’s mechano-electrochemical effects on the electrode and cell level. A multi-scale modeling approach shows promise to comprehensively account for active material volume change. In the work shown here, a mechano-electrochemical model was employed [1-4] to explore mechano-electrochemical relationships: (1) understanding the effects of realistic mechanical behavior of each cell component including foam packaging, (2) understanding the effects of thermodynamically non-ideal volume change behavior, and (3) relative lithiation (thus, volume change) behavior for electrodes with multiple active materials (such as a silicon-graphite composite anode). The unique ties between active material voltage, active material volume, and N:P capacity ratio will be discussed as well.

References

T. R. Garrick, K. Higa, S.-L. Wu, Y. Dai, X. Huang, V. Srinivasan and J. W. Weidner, Journal of The Electrochemical Society, 164, E3592 (2017).

T. R. Garrick, X. Huang, V. Srinivasan and J. W. Weidner, Journal of The Electrochemical Society, 164, E3552 (2017).

T. R. Garrick, K. Kanneganti, X. Huang and J. W. Weidner, Journal of The Electrochemical Society, 161, E3297 (2014).

D. J. Pereira, J. W. Weidner and T. R. Garrick, Journal of The Electrochemical Society, 166, A1251 (2019).

D. J. Pereira, M. A. Fernandez, K. C. Streng, X. X. Hou, X. Gao, J. W. Weidner, and T. R. Garrick, Journal of The Electrochemical Society, 167, 080515 (2020).
Fluoride-Ion Conductivity of La-Sr-F-S Multiple-Anion Compounds
Authors: Tachibana Shintaro , Ide Kazuto , Tojigamori Takeshi , Yamasaki Hisatsugu , Kotani Yukinari , Orikasa Yuki
Published: December 2020

Fluoride-ion batteries using solid-state electrolytes exhibit the high theoretical energy density and one of the candidates for next-generation rechargeable batteries [1]. For fluoride-ion batteries, the ion carrier is monovalent fluoride ion, which can realize the multi-electron reactions of counter cations in active materials of fluoride compounds. However, it is far from practical use because there is no solid electrolyte which has high ionic conductivity and a wide electrochemical potential window like lithium-ion conductors. The previously reported fluoride-ion conductors such as PbSnF4 [2] and La0.9Ba0.1F2.9 [3] contain single carrier ion, fluoride ions. To our best knowledge, there is few report on the solid electrolyte materials containing multiple-anion compounds [4].

In the field of material sciences, mixed-anion compounds have recently attracted attention, and unique structures with multiple anions have been reported [5]. Compared with existing materials such as oxides and fluorides, mixed-anion compounds have the possibilities to exhibit innovative functions due to their specific crystal and coordination structure. Therefore, using multiple-anion compounds could realize much higher physical properties than ever before.

In this study, we synthesized La-Sr-F-S compounds containing fluoride and sulfides ions as anions by solid-state reaction under vacuum. The crystal structure of the synthesized compound was characterized by X-ray diffraction. In order to measure the conductivity and the fluoride-ion transport number of the synthesized compounds, electrochemical impedance spectroscopy and the DC conductivity measurement were performed, respectively. Moreover, cyclic voltammetry was performed to evaluate electrochemical potential window. In the synthesis, F－- deficient and F－-excess type of La-Sr-F-S compounds were successfully synthesized by controlling the weight ratio of starting materials. We discuss the mechanism to realize fast fluoride ion conduction comparing them.

Reference:

[1] M.A. Reddy and M. Fichitner, J. Mater. Chem, 21, 17059–17062 (2011).

[2] N. I. Sorokin, P. P. Fedorov, O. K. Nikol’skaya, O. A. Nikeeva, E. G. Rakov, and E. I. Ardashinikova, Inorg. Chem., 37, 1178-1182 (2017)

[3] C. Rongeat, M. A. Reddy, R. Witter, and M. Fichtner, ACS Appl. Mater. Interfaces, 6(3), 2103-2110 (2014).

[4] S. Mater, J. Reau, L. Rabardel, G. Demazeau, and P. Hagenmuller, Solid State Ionics, 11, 77-81(1983).

[5] H. Kageyama, K. Hayashi, K. Maeda, J.P. Attfield, Z. Hiroi, J.M. Rondinelli, and K.R. Poeppelmeier, Nature Comm., 9 772(2018)
Lithium Storage Properties of Rocksalt-Type Li-Excess Titanium Sulfides
Authors: Shinoda Miyuki , Yabuuchi Naoaki
Published: December 2020

In recent years, the demands for lithium-ion batteries has increased rapidly all over the world. To further increase the energy density, Li-excess electrode materials which deliver higher reversible capacities have been actively studied as advanced positive electrode materials. A Li-excess sulfide, Li2TiS3, delivers a large reversible capacity on the basis of reversible anion redox.1) Li2TiS3 has the advantage of high electronic conductivity even though it is composed of Ti4+ ions without valence electrons. This is a characteristic feature of sulfides that is different from an oxide counterpart, Li2TiO3. In this study, we study factors affecting on electrode performance of Li2TiS3 and discuss reaction mechanisms as the potential high-capacity positive electrode material for lithium-ion batteries.

Li2TiS3 was prepared by mechanical milling. Li2S and TiS2 were used as precursors, and the mixture of the precursors were mixed by using a zirconia pot and zirconia balls. Crystal structures of the samples were examined by using an X-ray diffractometer. Composite electrodes consisted of 80 wt% active materials, 10 wt% acetylene black and 10 wt% polyvinylidene fluoride, pasted on aluminum foil as a current collector. Metallic lithium was used a negative electrode. The electrolyte solutions used were 1.0 M LiPF6 dissolved in ethylene carbonate:dimethyl carbonate (3:7 by volume) and 5.3 M LiFSA dissolved in trimethylphosphine as a concentrated electrolyte solution.2) Two-electrode cells were used and cycled at a rate of 20 mA g-1 at room temperature.

Figure 1 shows the X-ray diffraction patterns of the precursors and the sample after mechanical milling. From Fig. 1, diffraction lines of the starting materials with high crystallinity disappear after mechanical milling and broad diffraction lines after milling are assigned into a cation-disordered rocksalt-type structure with low crystallinity. Although Li2TiO3 is electrochemically inactive, Li2TiS3 delivers a large reversible capacity of over 300 mA h g-1 in Li cells. However, the reversible capacity of Li2TiS3 is reduced to approximately 150 mA h g-1 after the 30 cycles test with the aprotic electrolyte solution with 1 M LiPF6 as shown in Fig. 2. On the other hand, Li2TiS3 delivers a reversible capacity of 230 mA h g-1 even after 50 cycles with the concentrated electrolyte solution (5.3 M LiFSA) because dissolution of the sulfide could be suppressed for the concentrated electrolyte solution with less free solvents.3) From these results, we discuss the factors affecting electrode performance of Li2TiS3 for advanced positive electrode materials with sulfide ions.

References

(1) Atsushi Sakuda et al., Scientific Reports.
8, 15086 (2018).

(2) Jianhui Wang et al., Nature Energy.
3, 22–29 (2018).

(3) Takayuki Doi et al., ChemistrySelect.
2, 8824-8827 (2017).

Figure 1