bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructural Engineering of Li7La3Zr2O12 Solid Electrolytes for Enhanced Stability in H2O/CO2
Authors: Lee Jong-Won , Lee Jong-Won
Published: July 2022

Solid-state batteries with nonflammable inorganic solid electrolytes provide a fundamental solution for resolving safety concerns. Moreover, mechanically robust solid electrolytes can physically block the penetration of Li dendrites, and thus, Li metal can be applied as an anode (negative electrode), boosting the energy density of the batteries. Garnet-type cubic Li7La3Zr2O12 (LLZO) has been considered as a promising candidate for solid electrolytes, due to its high Li+ conductivity and chemical/electrochemical compatibility with Li metal. When exposed to the ambient air, however, LLZO electrolytes are known to react with H2O and CO2 to form Li2CO3. Li2CO3 also grows along the grain boundaries, resulting in the significant degradation in Li+-conducting properties.

In an effort to develop LLZO electrolytes with enhanced interfacial stability, here, we investigate the composition–microstructure–stability relationship of LLZO modified with aliovalent elements (Ta and Ga) under controlled H2O and CO2 atmospheres. Dense LLZO electrolytes doped with Ta (LLZTO) and Ta/Ga (Ga-LLZTO) are synthesized via a sol-gel process, followed by high-temperature sintering (1100 °C). Microstructural analyses show that the elemental doping has a crucial role in the grain growth behavior during the sintering process, thereby modifying the density, morphology, and atomic structure of grain boundaries. The interfacial stability of doped LLZO electrolytes is examined under accelerated durability test (ADT) conditions, where the concentration of O2/H2O/CO2 is precisely controlled to promote the interfacial reaction. During the ADTs, the degradation kinetics of Li+-conducting properties is quantitatively determined using in situ AC-impedance measurements combined with ex situ surface characterizations. The Li+ conductivity of Ga-LLZTO is almost retained during the ADT, while LLZTO shows only 27% of its initial conductivity value after 24 h of ADT. The significant degradation of LLZTO is caused by the formation of Li2CO3, which is further verified by Raman mapping and X-ray photoelectron spectroscopy analysis. On the other hand, the compositional and structural characterizations suggest that the enhanced interfacial stability of Ga-LLZTO is attributed to the reduced grain boundary density with enlarged grains and the segregation of H2O/CO2-tolerant Li–Ga–O species in the grain boundaries. The findings of this study would be essential in understanding the degradation of Li+-conducting properties and in developing highly conductive and stable LLZO solid electrolytes.

References

[1] H.-S. Shin, W. Jeong, M.-H. Ryu, S. W. Lee, K.-N. Jung J.-W. Lee, Chem. Eng. J, published online.

[2] X. Huang, J. M. Su, Z. Song, T. P. Xiu, J. Jin, M. E. Badding, Z. Wen, Ceram. Int., 47(2) (2021) 2123-2130.
Ta-LLZO Garnet Processed By Spark Plasma Sintering for All Solid State Batteries
Authors: Charrad Ghassen , Taberna Pierre-Louis , Simon Patrice , Rozier Patrick
Published: July 2022

All Solid State Lithium based Batteries (ASSLB) using a stable inorganic solid state electrolyte are envisaged as the most promising answer to solve the safety issues of Li-ion batteries using inflammable organic liquid electrolyte. Garnet Li7La3Zr2O7 showing high ionic conductivity and high stability versus metallic lithium is currently the most appealing solid electrolyte to be used in oxide based ASSLB. However, its high reactivity with moisture and sensitivity to all energetic process lead to strong difficulties in obtaining stable fully dense pellets while mandatory to ensure its role as mechanical barrier to avoid the short-circuit caused by Li-dendrites [1-2]. In this work, Spark Plasma Sintering is used as both a characterization and a fast sintering techniques to determine the influence of side products and efficiency of applied processes to remove them in reaching dense pellets with high ionic conductivity.

Commercial Ta-doped LLZO powder is fully characterized using conventional techniques to identify chemical and thermal stability. SPS experiments are conducted to determine the influence of the side products on the sintering. The efficiency of powder pretreatment designed to remove side products is determined based on data collected during SPS experiments. SPS parameters (applied pressure, temperature ramping, densification dwell ...) are then optimized allowing reaching in a reproducible way pellets with high density (>97 %) and high mechanical strength. Analysis using XPS, SEM and XRD of obtained pellets shows that decomposition occurs only at the surface while the core of the pellet is made of pure cubic phase Ta-doped LLZO. Impedance spectroscopy is used to evidence the influence of side products on the electrical properties and confirms high ionic conductivity (0.5 mS/cm) and very low electronic conductivity of optimized electrolyte. The sintering temperature and dwell time are then optimized by advanced sintering techniques (high pressure, Flash SPS) allowing to prevent the chemical instability usually observed between LLZO and active materials (LiCoO2 or Li[Ni1-x-yCoxMny]O2 (NCM)) and to obtain a cathodic half-cell (LLZO/positive electrode) in one step.

References :

[1] H. Yamada, T. Ito, R. Basappa, Electrochimica Acta 222 (2016) 648–656.

[2] M. Kotobuki, M.Koishi, Journal of Alloys and Compounds 826 (2020) 15421.
(Digital Presentation) Understanding the Influence of Fe Doping Level on Na-Ion Diffusivity for P2-Na2/3Mn1-XFexO2 (x= 0, 1/3, 1/2) sodium-Ion Battery Cathode Material Using Molecular Dynamics Simulation
Authors: Gupta Priyanka , Pushpakanth Sujatha , Gupta Madhulika , Haider Mohammad Ali , Basu Suddhasatwa
Published: July 2022

Global progression towards e-mobility to reduce the carbon footprint has led to the demand for smart grid energy storage systems. Amongst the available electrical energy storage technologies, rechargeable batteries serve as a pragmatic option to cater to the intermittent character of renewable energy supplies owing to their high energy efficiency and flexible power characteristics. In contrast to the existing lithium-ion batteries (LIBs), Na-ion batteries appear as a sustainable substitute due to their dependence on widely distributed, and abundant sodium reserves. However, the commercialization of Na-ion batteries has been hampered primarily by the inefficient performance of electrode materials particularly cathode. Among the prevailing cathode materials, the class of layered transition metal oxide with O3 and P2 structural configuration imparts decent specific capacity and has been studied extensively over the past few years. Though the presence of comparatively larger Na ions induces better initial capacity but suffer the drawback of undergoing complex phase transformation during charge-discharge cycling. Moreover, P2-phase exhibits lower diffusion energy barrier due to the direct passage of sodium ions from one prismatic site to another. Therefore, materials with the aforementioned P2 orientation have been synthesized deploying earth-abundant elements like Mn, and Fe for sodium-ion battery applications. To comprehend the diffusional behavior of Na-ions, we have carried out molecular dynamics simulation of P2-Na2/3Mn1-xFexO2 (x=0, 1/3, 1/2) material. The preliminary computational calculations reveal enhanced Na-ion self-diffusivity with increased Fe dopant onto P2-Na2/3MnO2 material, while the diffusivity showcased a decreasing trend with further increase in Fe substitution that might be ascribed to the phase stabilization aspect of Mn element and charge compensation attribute of Fe3+/Fe4+ and Mn3+/Mn4+ redox couples.
Redox Flow: How Low Can You Go? High-Throughput Battery Lifetime Characterization for Grid-Scale Energy Storage
Authors: Fell Eric M. , Aziz Michael J.
Published: July 2022

Aqueous Organic Redox Flow Batteries (AORFBs) have emerged as potentially disruptive technologies for the storage of electrical energy from intermittent renewable sources. With the goal of cost-effective, safe, and scalable stationary electricity storage systems, AORFBs could eclipse Li-ion batteries due to their inherent non-flammability, lack of materials scarcity fluctuations, and intrinsic decoupling of energy and power capacities. We have previously demonstrated that calendar life, rather than cycle life, limits molecular lifetimes in AORFBs due to various molecular instabilities that lead to side reactions, thus inhibiting performance [1]. The continued synthetic effort to produce stable redox-active organics has improved molecular design strategies to the point that the most stable chemistries now degrade at less than 1% per year [2].

With further lifetime increases, the measurement of lower capacity fade rates now necessitates higher precision coulometry methods [3] and the use of thermally accelerated decomposition protocols [4,5] to determine which stabilizing approaches are most effective without waiting for multi-month cycling tests to quantify capacity fade.

In this presentation, I highlight a high-throughput setup we have recently developed for the electrochemical screening of candidate molecules in AORFBs. We demonstrate the effect that cycling protocols can have on measured capacity fade rates and propose figures of merit for cell-to-cell variability. Finally, we explore accelerated decomposition protocols to expedite the screening process of candidate molecules for long lifetime AORFBs, which may enable massive grid penetration of intermittent renewable energy.

[1] M.-A. Goulet and M. J. Aziz, “Flow Battery Molecular Reactant Stability Determined by Symmetric Cell Cycling Methods,” Journal of The Electrochemical Society
,
165, A1466 (2018).

[2] M. Wu, Y. Jing, A. A. Wong, E. M. Fell, S. Jin, Z. Tang, R. G. Gordon, M. J. Aziz, “Extremely Stable Anthraquinone Negolytes Synthesized from Common Precursors,” Chem, 6, 1432 (2020).

[3] T. M. Bond, J. C. Burns, D. A. Stevens, H. M. Dahn, and J. R. Dahn, "Improving Precision and Accuracy in Coulombic Efficiency Measurements of Li-Ion Batteries,” Journal of The Electrochemical Society, 160, A521 (2013).

[4] D. G. Kwabi, K. Lin, Y. Ji, E. F. Kerr, M.-A. Goulet, D. De Porcellinis, D. P. Tabor, D. A. Pollack, A. Aspuru-Guzik, R. G. Gordon, and M. J. Aziz, “Alkaline Quinone Flow Battery with Long Lifetime at pH 12,” Joule, 2, 1894 (2018).

[5] D. A. Stevens, R. Y. Ying, R. Fathi, J. N. Reimers, J. E. Harlow, and J. R. Dahn, "Using High Precision Coulometry Measurements to Compare the Degradation Mechanisms of NMC/LMO and NMC-Only Automotive Scale Pouch Cells,” Journal of The Electrochemical Society, 161, A1364 (2014).
Oxalate Assisted Growth of Hybrid Nickel Cobalt-Based Nanostructures for Hydrogen Generation Via Urea Oxidation
Authors: Rana Supriya , Yadav Krishna Kumar , Mehta Surinder Kumar , Jha Menaka
Published: July 2022

Hybrid mixed transition metal oxides nanostructures as spinal act as promising electrode materials for energy-related applications. In the present work, a design and synthesis of mixed metal oxide nanostructures have been done by increasing the nickel content in the crystal structure of Co3O4 spinel by using template-assisted oxalate route via conzventional coprecipitation method for syntheses. Selectively controlling the Ni: Co ratio will result in a significant change in the morphology of the nanostructures. Further, kinetically controlled thermal decomposition of nickel and cobalt oxalate precursors results in the formation of anisotropically aligned ultrafine nanoparticle self-assembly to form nanocubes and nanorods. Whereas the mixture of nickel-cobalt oxalate precursor after decomposition led to the formation of nanoparticles assembly that is interconnected and hierarchically arranged to form nanosheets that align themselves in a particular orientation to give a three-dimensional micro flower structure. This hybrid structure with increased porosity and higher exposed active sites acts as an efficient electrocatalyst to promote water and urea oxidation in alkaline media. The hybrid catalyst shows overpotential of 300 mV and -190 mV towards water oxidation in alkaline media with excellent stability for 24 h. Similarly, during urea oxidation, the significant loss in the potential to 1.31 V can be seen to achieve the current density of 10 mA/cm2 compared to the potential required in urea-free electrolysis. So, this work provides better insights for tuning snd designing the hybrid structures and regulating their morphological characteristics for enhanced catalytic performance.
Electrical Detection of Gaseous Pollutants Using Nanoporous-Based Gas Sensors
Authors: Schindelholz Mara E. , Percival Stephen J. , Small Leo J. , Henkelis Susan E. , Krumhansl Jim L. , Nenoff Tina M.
Published: July 2022

The advanced in situ detection of gaseous pollutants, such as NOx or SOx, is of great interest in many applications, such as the automotive and coal industries. We will discuss the continued advancement of our low power sensors for these pollutants, leveraging the previous successful development of impedance spectroscopy-based sensors for the detection of gaseous I2.1-3 The sensors, composed of Pt interdigitated electrodes (IDEs) with a nanoporous adsorbent layer, can be tuned to selectively adsorb gases of interest through judicious material selection, and the electrical response directly correlated to gas concentration. The current work is focused on exploring these nanoporous phases (metal-organic frameworks (MOFs), zeolites, etc.) for the real-time detection of NOx. The sensors have been successfully demonstrated for detection of trace NO2 (0.5 – 5 ppm),4 and experimental results, collected at relatively low temperature (25-50°C), will be discussed. Other recent work exploring the direct growth of crystalline MOF membranes, through the chemical functionalization of the surface of interdigitated electrodes will also be discussed.5 Direct growth of thin MOF films on surface functionalized IDEs has been shown to result in increased sensor sensitivity and a faster response time. Lastly, we will present initial results for the use of the sensors in the selective detection of NO2 in complex environments (e.g. presence of H2O, CO2, etc.).6

Acknowledgements

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & 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-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

References

Small, L.J and Nenoff, T.M., ACS Appl. Mater. Interfaces, 2017, 9 (51), 44649.

Small, L.J.; Krumhansl, J.L.; Rademacher, D.X.; Nenoff, T.M. Meso. Mater., 2019, 280, 82.

Small, L.J.; Hill, R. C.; Krumhansl, J. L.; Schindelholz, M. E.; Chen, Z.; Chapman, K.W.; Zhang, X.; Yang, S.; Schroder, M.; Nenoff, T.M., ACS Applied Materials and Interfaces, 2019, 11 (31), 27982.

Small, L.J.; Henkelis, S.E; Rademacher, D.X.; Schindelholz, M. E.; Krumhansl, J. L.; Vogel, D.J.; Nenoff, T.M, Advanced Functional Materials, 2020, 30 (50), 2006598.

Henkelis, S.E; Percival, S.J.; Small, L.J; Rademacher, D.X.; Nenoff, T.M, Membranes, 2021, 11 (3), 176.

Percival, S.J.; Henkelis, S.E; Li, M.; Schindelholz, M.E.; Krumhansl, J. L.; Small, L.J.; Lobo, R.F.; Nenoff, T.M., I Eng. Chem. Res., 2021, 60 (40), 14371.
A DFT Study of the VRFB Positive Electrode: Carbon Active Sites for the VO2
+/VO2+ Reaction
Authors: Bachman Ridge M , Hall Derek M. , Radovic Ljubisa R.
Published: July 2022

The vanadium redox flow battery (VRFB) is a promising candidate for use in grid-scale battery applications to support a deeper reliance on intermittent renewable energy. However, it suffers from a sluggish redox reaction at the positive electrode. Previous studies indicate that its performance can be improved by oxidizing a graphene-based carbon electrode and thus increasing the concentration of its oxygen-containing surface sites. While such performance enhancement does not appear to be controversial, the underlying mechanisms is far from being clear. Some authors suggest that this procedure increases the number of electrocatalytically active sites; others simply attribute it to improved wettability. In this ongoing study, we use density functional theory (DFT) to examine the role of hydroxyl and carboxyl groups, as well as free edge carbon atoms, in the oxygen transfer process at the positive electrode. Preliminary results using carefully selected model compounds (with appropriate charge C and spin multiplicity M) indicate that oxygen functional groups are unlikely to be active sites in the electrochemical redox process, which in many respects is analogous to the oxidation reduction reaction (ORR). Both the thermodynamics (less favorable adsorption energy of vanadium oxide) and the kinetics (problematic transition states) are less plausible than in analogous mechanistic steps involving carbene-type active sites. The carbene site was probed through two possible reaction mechanisms: V-down and O-down (see graph below). The former adsorption step is essentially a ‘dead-end’ process. The latter is not only thermodynamically and kinetically more feasible; it is consistent with other oxygen-mediated electron transfer processes occurring on the surface of graphene-based materials, be they catalysts or reactants. Furthermore, it has been shown in such processes that the presence of oxygen functional groups can stabilize and enhance the concentration of free carbene-type sites at graphene edges.

Figure 1
(Keynote) Opportunities and Challenges of Organic Redox Flow Batteries
Authors: Liu Tianbiao
Published: July 2022

Aqueous organic redox flow batteries (AORFBs) represent a promising energy storage technology for the integration of renewable energy and balancing electricity grids because of their technical merits of decoupled energy and power, sustainable and tunable redox active materials, and non-flammable and low cost aqueous supporting electrolytes. This presentation will review recent efforts in developing new flow battery chemistries, including viologen (anolyte), quinone (anolyte), TEMPO (catholyte), ferrocene (catholyte), and ferrocyanide (catholyte). The merits and drawbacks of representative acidic, pH neutral, and alkaline AORFBs will be discussed and compared. A number of research strategies will be discussed to develop high-performance redox active electrolytes to enable energy dense, durable, low-cost flow battery technologies. Particularly, this presentation emphasizes that in-depth mechanistic understandings of redox active electrolytes play crucial roles in developing advanced organic redox flow batteries towards sustainable, long-duration energy storage.

References:

(1) Luo, J.; Hu, B.; Hu, M.; Liu, T. L. "Status and Prospects of Organic Redox Flow Batteries towards Renewable Energy Storage", ACS Energy Lett. 2019, 4, 2220-2240.

(2) Wu, W.; Luo, J.; Wang, F.; Yuan, B.; Liu, T. L. "A Self-Trapping, Bipolar Viologen Bromide Electrolyte for Aqueous Redox Flow Batteries", ACS Energy Lett. 2021, 6, 2891-2897.

(3) Luo, J.; Hu, B.; DeBruler C. Zhao, Y.; Yuan B;. Hu, M.; Wu, W.; Liu, T. L. "Unprecedented Capacity and Stability of Ammonium Ferrocyanide Catholyte in pH Neutral Aqueous Redox Flow Batteries", Joule 2019, 4, 149-163.

(4) Hu, B.; Luo, J.; Hu, M.; Yuan B.; Liu, T. L.* "A Neutral, Metal Free Aqueous Organic Redox Flow Battery Employing an Ammonium Anthraquinone Anolyte", Angew. Chem. 2019, 58, 16629-16636.

(5) DeBruler C.; Hu, B.; Moss, J.; Liu, X. Luo, J.; Sun, Y; Liu, T. L. "Designer Two Electron Storage Viologen Anolyte Materials for Aqueous Organic Redox Flow Batteries", Chem 2017, 3, 961-978.

(6) Hu, B.; DeBruler C., Rhodes, Z.; Liu, T. L. "Long Cycling Aqueous Organic Redox Flow Battery for Sustainable and Safe Energy Storage", J. Amer. Chem. Soc. 2017, 139, 1207-1214.

(7) Liu, T.; Hu, B.; DeBruler, C.; and Luo, J. "Materials for Use in Aqueous Organic Redox Flow Batteries", US patent No., 10,934,258, 2021.

(8) Liu, T.; Wei, X.; Sprenkle, V.; Wang, W. "Aqueous electrolytes for redox flow battery systems", US patent No. 14,690,224, 2016.
Critical Role of Electrochemical Proton Insertion for the Hydrogen Evolution Reaction on Tungsten Oxides
Authors: Spencer Michael A. , Fortunato Jenelle , Augustyn Veronica
Published: July 2022

The local electrochemical environment can affect electrochemical reactivity by determining the interactions between the electrode, reactant, reaction intermediates, and products. One method for tuning the local electrochemical environment is through confinement in porous materials. However, experimental evidence of the role of confinement on electrochemical reactivity in porous materials remains elusive due to the challenges of decoupling confinement effects from other variables, such as high surface area. In this work, we compared the structure, morphology and electrochemical reactivity of WO3
∙H2O and a hybrid organic-inorganic layered material, octylamine-expanded WO3 (OA-WO3). We investigated the electrochemical response in three electrolytes to understand how interlayer modification affects cation adsorption at the outer surface and cation and proton insertion into the bulk of the metal oxide. While the WO3
∙H2O could reversibly insert protons and lithium ions, OA-WO3 significantly suppressed cation insertion. Interestingly, as OA-WO3 was cycled within a narrow potential window in a sulfuric acid electrolyte, the material transformed to WO3
∙2H2O, which was evidenced by features in the cyclic voltammograms as well as ex situ Raman spectroscopy and X-ray diffraction. Additionally, we determined that the conversion from OA-WO3 to WO3
∙2H2O was possible via a chemical reaction by stirring in sulfuric acid – thus resulting in two materials with similar surface areas and particle morphologies. These similar material properties enable the study of how the cation insertion behavior and chemical nature of confined molecules between layers of a transition metal oxide framework influence the electrocatalytic activity toward the hydrogen evolution reaction (HER). Our results showed that the presence of octylamine in the interlayer of WO3 required a ~210 mV higher overpotential compared to WO3
∙H2O for the HER, and the onset of the HER did not appear until after a reduction reaction associated with proton insertion occurred at a more negative potential compared to proton insertion in WO3
∙H2O. We discuss three hypotheses for how proton insertion leads to HER activity in WO3
∙
xH2O: 1) proton insertion changes the electronic band structure of WO3
∙
xH2O, 2) the presence of bulk protons can influence ∆GH,ads at the surface sites, and 3) inserted protons may participate in the HER mechanism on WO3
∙
xH2O. Overall, this work demonstrated how tuning the interlayer structure and chemistry of bulk layered materials enables the study of electrochemical reactivity under confinement. Using this materials design approach, our results revealed a correlation between proton insertion capacity and the activity of a transition metal oxide toward the HER, where high proton insertion capacity led to lower HER overpotential.
Revealing the Role of Mo Doping in Promoting Oxygen Reduction Reaction Performance of Pt3Co Nanowires
Authors: Deng Zhiping , Wang Xiaolei
Published: July 2022

Highly active and durable electrocatalysts towards oxygen reduction reaction (ORR) are imperative for the commercialization application of proton exchange membrane fuel cells. By manipulating ligand effect, structural control, and strain effect, we report here the precise preparation of Mo-doped Pt3Co alloy nanowires (Pt3Co-Mo NWs) as the efficient catalyst towards ORR. The as-prepared Pt3Co-Mo NWs deliver high specific activity (0.596 mA cm-2) and mass activity (MA, 0.84 A mg
-1Pt), much higher than those of undoped counterparts. Besides activity, Pt3Co-Mo NWs also demonstrate excellent structural stability and cyclic durability even after 50,000 cycles (76% MA retain), again surpassing control samples without Mo dopants. The superior catalytic performance can be attributed to several structural advantages. First, both ultrafine nanowire morphology and controlled growth ensure the exposure of abundant highly active high-index facets, resulting in increased electrochemical active surface area (ECSA, 141 m2 g−1
Pt). Second, one dimensional (1D) Pt nanostructure, particularly ultrafine Pt nanowires, are less subject to dissolution, aggregation, and even Ostwald ripening than nanoparticles, leading to much-improved durability. Third and most importantly, the Mo doping directly changes the local electronic structure of both element Pt and Co, not only effectively endowing the Pt3Co electrocatalysts with an enhanced activity but also efficiently preventing element Co from leaching leading to improved durability.

The geometric phase analysis (GPA) strain maps and the density function theory (DFT)calculations were conducted to further analyze the role of Mo dopants. GPA strain maps reveal that Mo dopants are inclined to be the tensile strain cores, generating local lattice expansion to adjust the excessively compressive strain effect introduced by Co alloying. Benefiting from the optimized d-band center, the oxygen binding energy (Eo) on Pt3Co-Mo slabs is closest to the optimal value compared with those of undoped counterparts. Moreover, the energy required to remove Co atoms from Pt3Co slab with Mo doping is increased by 0.195 eV compared to the slab without Mo doping, indicating the electronic effect of Mo dopants to stabilize Co. This work provides not only a facile methodology but also an in-depth investigation of the relationship between structure and properties to provide general guidance for future design and optimization.
Controlling DNA Spacing in a Monolayer, Using DNA Nano-Cubes
Authors: Grzedowski Adrian , Ma Tianxiao
Published: July 2022

DNA SAMs have received a lot of research interest recently as a suitable platform for modern biosensors. However, there are some shortcomings that remain to be addressed, such as uneven coverage of monolayer, or the spacing between the DNA strands that is hard to control. Here, we present DNA nanostructured cubes as an improved platform for DNA SAM based sensors. The DNA nano-cubes allow for a precise control of ssDNA spacing on the surface and have a great functionalization possibility. We have modified the nanostructures to include thiolated surface anchor and a fluorescence reporter. Cubes were deposited gold electrode via Au-S bonds and analyzed, using AFM and in-situ fluorescence microscopy.
Stepping Beyond Cyclic Voltammetry: Obtaining the Electronic Properties of Electrified Solid-Liquid Interfaces
Authors: Wong Raymond , Yokota Yasuyuki , Wakisaka Mitsuru , Inukai Junji , Kim Yousoo
Published: July 2022

Organically tailorable monolayers of ferrocene-terminated alkanethiol self-assembled monolayers (Fc SAM, Fig. 1a) on Au surfaces are attractive model systems to elucidate the molecular-level physicochemical properties of solid-liquid electrochemical (EC) interfaces [1]. In particular, Fc SAM has been shown to be an attractive spectroscopic molecular probe for photoelectron spectroscopy because the Fe heteroatom is at a fixed position above the electrode surface. Thus, this allows photoelectron spectroscopy to ascertain the electronic and structural properties at a fixed position above the electrode surface [2-3]. The ability to obtain molecular-level structure-function-property relationships with Fc SAM has relevance to bio(chemical) sensors, micro-actuators, and molecular electronics.

Here, we use X-ray and ultraviolet photoelectron spectroscopy combined with an electrochemical cell (EC-XPS/UPS) to electrochemically control the Fc SAM and spectroscopically probe the corresponding electronic and structural changes [2-3]. To perform our experiments, electrochemical (EC) measurements are performed in a separate and dedicated EC chamber in a solution environment under Ar atmosphere, followed by evacuation and finally transfer to the XPS/UPS analysis chamber [2-3]. The EC chamber contains a retractable PTFE (polytetrafluorethylene) cell and utilizes a hanging meniscus setup. I will discuss the merits and challenges of EC-XPS/UPS methodology in the context of other approaches.

Using EC-XPS/UPS, we are able to discriminate anion dependencies (Fig. 1b-d) with respect to the Fe oxidation state, monolayer thickness, and changes to the valence structure regarding the highest occupied molecular orbital (HOMO. Lastly, we are able to spectroscopically probe the changes relating to the interfacial potential distribution across the electrode-monolayer-electrolyte interface or so-called “potential drop” in the form of systematic potential-induced binding energy shifts in the XPS/UPS spectra. Further details will be provided at the presentation.

Fig. 1

(a) Ferrocene-terminated alkanethiol SAM on Au. Schematic of electrode-monolayer-electrolyte interface and interfacial potential distribution. (b) Cyclic voltammograms at 50 mV s-1 in 0.1 M NaTFSI or NaPF6 (c-d) Fe 2p3/2 spectra of Fc SAM, pristine and after anodic/cathodic polarization at 0.625 and 0 V, respectively.

References

[1] K. Uosaki, Electrochemistry
12, 1105-1113 (1999).

[2] R. A. Wong, Y. Yokota, M. Wakisaka, J. Inukai, Y. Kim, J. Am. Chem. Soc.
140, 13672-13679 (2018).

[3] R. A. Wong, Y. Yokota, M. Wakisaka, J. Inukai, Y. Kim, Nat. Commun.
11, 1-9 (2020).

Figure 1
(Digital Presentation) OER Catalysts Supported on Layered Zirconium Phosphate Nanomaterials
Authors: Colon Jorge L
Published: July 2022

Learning from nature, instead of using expensive catalysts such as platinum for splitting water, cheaper alternatives (such as cobalt, iron, or nickel) could be used for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Hydrogen solar fuel produced in artificial photosynthesis schemes for water splitting could be used in fuel cells. However, obtaining efficient catalysts based on earth-abundant materials is still difficult, particularly for the OER. Recent theory has shown that nanoscopic confinement of catalysts increases the stability and efficiency of catalysts for OER. We have designed and develop earth-abundant electrocatalysts for oxygen reduction and water splitting using nanostructured layered inorganic materials of zirconium phosphate (ZrP). We have demonstrated improved electrocatalytic activity of ZrP nanomaterials loaded with metal ions suitable for the OER of water splitting. Adsorbing Co or Ni catalysts on the ZrP nanoparticles surface proved to improved OER activity compared to intercalated catalysts. A comparison between adsorbed Co or Ni catalysts and those catalysts on exfoliated ZrP hexagonal nanoplatelets proved that those on exfoliated nanoplatelets were more active, with diminished overpotentials and reduced Tafel plot slopes as well as higher mass activities. More recently, comparison between Co and Ni catalyst on ZrP particles with different morphologies (hexagonal platelets, rods, cubes, and spheres) revealed that the more active Co catalysts are those on hexagonal ZrP platelets, whereas the best Ni catalysts are those on ZrP spheres. Finally, encouraging recent results with a cobalt porphyrin catalyst and bimetal catalysts will be presented, as well as recent XAS operando results. These results demonstrate that ZrP nanoparticles are suitable supports for electrocatalysis of the OER and water splitting.

Sponsored by the NSF-PREM Center for Interfacial Electrochemistry for Energy Materials (CIE2M) grant DMR-1827622.
Gas-Selective Semiconducting Oxide Nanowires from Novel Processing Methods
Authors: Annerino Anthony , Gouma Perena
Published: July 2022

Presented here are sensor nanomaterials that can be used for the skin-based gas “smelling” of disease. Skin testing may provide rapid and reliable results, using specific “fingerprints” or unique patterns for a variety of diseases and conditions. These can include metabolic diseases, such as diabetes and cholesterol-induced heart disease; neurological diseases, such as Alzheimer’s and Parkinson’s; quality of life conditions, such as obesity and sleep apnea; pulmonary diseases, such as cystic fibrosis, asthma, and chronic obstructive pulmonary disease; gastrointestinal tract diseases, such as irritable bowel syndrome and colitis; cancers, such as breast, lung, pancreatic, and colon cancers; infectious diseases, such as the flu and COVID-19; as well as diseases commonly found in ICU patients, such as urinary tract infections, pneumonia, and infections of the blood stream. Focusing on the most common gaseous biomarkers emitted from human skin, which are nitric oxide and carbon monoxide, and certain abundant volatile organic compounds (acetone, isoprene, ammonia, alcohols, sulfides), it is argued here that effective discrimination between the diseases mentioned above is possible by capturing the relative sensor output signals from the detection of each of these biomarkers and identifying the distinct gaseous “fingerprint” of each disease with the presented nanomaterials synthesized by novel processing methods.
(Invited) Biosensors for Healthy Communities
Authors: Mitra Sushanta
Published: July 2022

Micro and nanotechnology have enabled groundbreaking innovation to detect and predict different disease conditions and at the same time detect key analytes and microorganisms that have a profound impact on our health. This invited talk will start with the detection of Listeria monocytogenes, a food-borne pathogen that causes listeriosis, based on Mach Zehnder interferometry. This will be followed by demonstrating a miniaturization technique for ELISA on a micro-chip to detect vector-borne diseases such as Dengue NS1. Towards the fight for COVID-19, a sustainable technology based on a paper strip with conjugated nanoparticles and aptamers will be discussed. Equally important is access to clean water for healthy communities. In this direction, some of the innovative technologies developed in recent years for the rapid detection of E. coli in water will be discussed. Finally, a new technology, a dip-and-fold paper device for the detection of pesticides in water, will be demonstrated.
(Invited) Self-Powered Sensors and Systems for Healthcare Applications
Authors: Lin Zong-Hong , HO Teresa
Published: July 2022

The self-powered sensors developed by us can function without external power supply. By directly converting mechanical energy or thermal energy into electric outputs, the output values of the developed sensors will be varied upon the sensing of target biomolecules or metal ions. With the simplicity, low-cost fabrication and label-free sensing mechanism, the developed self-powered sensors demonstrate great potential to serve as new prototypes of portable devices for the onsite sensing of samples. And as far as the development of wearable electronics is concerned, power supply has always been the bottleneck to overcome. We also utilized commercial textiles and proteins/hydrogels to fabricate biocompatible, portable, and lightweight generators to harvest biomechanical energy from human motions or thermal energy from body heat in the environment to directly power wearable electrochemical systems for humidity/temperature/sweat detections (ions, glucose, and lactate) and antibacterial applications. The developed wearable systems also show their adaptability to be integrated with next-generation smart textiles.
Wearable Acetone Monitoring
Authors: Annerino Anthony , Srinivasan Manoj , Gouma Perena
Published: July 2022

Most research aimed at measuring biomarkers on the skin is only concerned with sensing chemicals in sweat, but these methods are not truly noninvasive because they require substantial and often inconvenient amounts of sweat to get a reading. This project aims to create a truly non-invasive wearable sensor that continuously detects the gaseous acetone (a biomarker related to metabolic disorders) that ambiently comes out of the skin. Composite films of the intrinsically conducting polymer polyaniline and cellulose acetate, previously shown to exhibit a mechano-chemical actuation response to gaseous acetone, were tested for electrical response to low concentrations of gaseous acetone and possible interferents in dry, breathing quality air at room temperature.
(Digital Presentation) Development of an Electrochemical Microfluidic Device with on-Platform Sample Collection
Authors: Shafique Houda , Siavash Moakhar Roozbeh , del Real Mata Carolina , Abdel Fatah Tamer , Isaac Hosseini Imman , Yedire Sripadh Guptha , de Vries Justin , Strauss Julia , Mahshid Sara
Published: July 2022

As the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to develop, the need for portable rapid testing platforms remains prevalent to provide patients with accurate and quantitative diagnostic and serosurveillance information at the point-of-care. The current gold standard detection techniques like RT-PCR and ELISA require trained personnel to perform lengthy protocols, resulting in a long turnover from sample collection to result acquisition. Herein, we propose an electrochemical microfluidic device for on-platform detection of viral proteins and antibodies at the point-of-care in a multiplexed manner. Miniaturization technology through the use of microfluidic devices offers numerous advantages including low reagent consumption, high fluidic control, reduced reaction times, inexpensive applications, and the possibility of throughput analysis. Electrochemical detection can provide advantages in cost effective fabrication, high sensitivity and simple instrumentation using a standard 3-electrode (working, reference, and counter) setup. Our platform proposes the design of an electrochemical cell with an enhanced working electrode to act as the detection assay with microfluidic channels to facilitate sample collection and pre-treatment; an integrated saliva collection kit and lancing device enabled the use of both untreated saliva from direct self-collection and whole blood from a finger prick. Automated fluid manipulation reduced the potential of user contamination through the implementation of suction-based flow. The electrochemical microfluidic device was encased in a 3D-printed cartridge for the fabrication of a fully integrative technology on a single platform with the potential to be used at the point-of-care in both clinical and commercial applications using direct biofluids.
(Digital Presentation) Review on Electronic Interfaces for Electrochemical Sensor – Enabling Research from the Lab to Market
Authors: Sundeep Dola , K Varadharaj Eswaramoorthy
Published: July 2022

The recent development in the material sciences and facility to synthesis different types of materials made way for advances in electrochemical sensors. A lot of research articles being published on electrochemical sensors on different applications such as human health (metabolites, nutrients, biomarkers of diseases, or development pathologies), potential hazards (environmental pollutants, food contaminants, genotoxic chemicals, etc.), structural monitoring, animal health diagnosing, corrosion detection, Lab-on-chip solutions, etc. Most of the sensors are characterized in any of the detection principle measurement of current (amperometric), charge accumulation or a measurable potential (potentiometric) or change in the conductive properties of medium (conductometric), change in the impedance due to the change in the properties of the material due to species/analyte to be detected (impedimetric) and field-effect which exploits transistor principle to change in current a result of a potentiometric effect at a gate electrode. Most of the reported results are conducted by sophisticated expensive instruments. Researchers are unable to accentuate their research from their lab to market due to a lack of awareness of the instrumentation being used in the instrument. The prominent results of the lab need to be converted into any of the devices like point-of-care (POC), point-of-care testing (POCT), point-of-test (POT), point-of-interest/point-of-incidence (POI), or portable field device. The present review focuses on low-level measurements like quantifying microampere in resolution with nano ampere, mV changes as well as a few ohms to a few kilo-ohms. The current paper also explains to choose suitable components to design analog frontend to acquire signals from different types of electrochemical sensors. Current work also aims to create awareness on available Application-specific integrated circuits (IC) to design suitable instrumentation for the electrochemical sensor. Different power sources and Packaging techniques are also discussed to make the device portable, wearable, implantable, etc. Recent advancements in ultra-low power with more computational power capability microcontroller with various communication technologies appropriate to make device also elucidated in the paper. Thus, the paper imparts the required knowledge to do translation research on electrochemical biosensors.
(Keynote, Digital Presentation) Why Au Nanoparticles Could Behave As a Glucose Oxidase Mimic
Authors: DONG Shaojun
Published: July 2022

The Au nanoparticle has been found to be the excellent glucose oxidase mimic, while the catalytic process has rarely been studied. Here, we revealed that the process of glucose oxidation catalyzed by Au nanoparticles is the same as that of natural glucose oxidase, namely, a two-step reaction including the dehydrogenation of glucose and the subsequent reduction of O2 to H2O2 by two electrons. Pt, Pd, Ru, Rh, and Ir nanoparticles can also catalyze the dehydrogenation of glucose, except that O2 is preferably reduced to H2O. Using the electron transfer property of noble metal nanoparticles, we overcame the limitation that H2O2 must be produced in the traditional two-step glucose assay and realized the rapid colorimetric detection of glucose. Noble metal nanoparticles have also been found to mimic various enzymatic electron transfer reactions including cytochrome c, coenzymes as well as nitrobenzene reductions.
(Digital Presentation) In Vivo Electrochemical Measurement of Dopamine in Adult Drosophila Mushroom Body
Authors: Shin Mimi , Venton B. Jill
Published: July 2022

Dopamine is a neuromodulator that is secreted to the synapse to relay chemical signals to target neurons. Abnormal levels of dopamine release leads to various neurodegenerative diseases. Therefore, measuring dopamine is essential to understand how dopamine is regulated under normal and pathological conditions. Drosophila melanogaster, the fruit fly, is an ideal model system for studying fundamental neurological processes and diseases because of the availability of sophisticated genetic tools and well conserved neurological processes between mammals and flies. Majority of neuroscience studies involved in modifying a gene and measure the effect of genetic mutation on output behaviors. However, dopamine release is highly dynamic because of the complex activity of dopamine transporters and autoreceptors. Therefore, to understand how dopamine signaling controls the behavior, a direct measurement of changes in dopamine release is necessary. Fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode is an electrochemical technique that trace concentration changes in dopamine release on the sub-second time scale. Our lab pioneered directly measuring various endogenous neuromodulators in the fly central nervous system with FSCV. Initially, these studies were performed in ex vivo preparations, where brains were isolated from larvae and adult fly, and thus could not monitor neuromodulators during behavior. In this study, we developed in vivo FSCV method to measure phasic dopamine in the mushroom body (MB) during behavior for the first time. The MB in fly has been extensively studied as an associative center for regulating olfactory learning and memory. First, acetylcholine stimulation was applied to the MB heel and medial tip to characterize dopamine signaling and to demonstrate the feasibility of in vivo FSCV in intact fly brain. Application of 0.2 pmol acetylcholine released 0.36 ± 0.06 µM dopamine in the medial tip, which is slightly higher than 0.22 ± 0.06 µM dopamine in the heel. Compartmental differences in evoked release suggest heterogeneity of dopamine regulation in the MB. Nisoxetine, a dopamine transporter inhibitor, and flupentixol, a D2 antagonist, increased stimulated dopamine release. We then applied the in vivo method to monitor changes in behaviorally evoked dopamine release during sugar feeding. Sugar feeding evoked 0.31 ± 0.09 µM dopamine in the medial tip of MB. Flupentixol significantly increased sugar evoked release implying D2 receptor acts as autoreceptor and regulates dopamine signaling during sugar feeding. Therefore, this developed in vivo FSCV method is a great addition to the existing tools to measure endogenous neuromodulators in the fly and valuable for studying real-time dopamine signaling during behavior. This in vivo method also can be further extended to better understand how dopamine and other neuromodulators regulate complex behaviors, such as reward associated learning and memory formation.
Noninvasive Colorimetric Detection of Insulin Using a Chromogenic Substrate
Authors: Syed Zia , Wang Zhuo , Krishnan Sadagopan
Published: July 2022

At the peak of technologies such as continuous glucose monitoring and insulin delivery are available today, they still pose a challenge on the individuals to continuously monitor their glucose levels to keep their hypoglycemia in check. Apart from being expensive, the constant needles pricking, delay in reading venous blood glucose are common drawbacks of such technologies. The other methods for detecting insulin are enzyme-linked immunosorbent assay (ELISA), chemiluminescence immunoassay (CLIA), radioimmunoassay (RIA), chromatography. Especially in the pandemic era access to such device-based test methods is becoming increasingly difficult for resource-limited countries due to the economic collapse from the year 2020. To address the changing needs, in our lab, we have focused on developing a colorimetric noninvasive, highly selective, and rapid detection method for insulin detection as the model bioanalyte. Our sensor is based on taking advantage of the magnetic property of functionalized nanoparticles with sandwich immunoassay. The method is selective and accurate. Insulin-bound HRP conjugate upon addition of the chromogenic substrate, 3′, 5, 5′-tetramethylbenzidine develops a blue color. The intensity of the color directly correlates with the insulin concentration. Our method can detect picomolar insulin within five mins in buffer solutions. Testing real biofluids is our ongoing effort.