bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leveraging Commercial Microfluidic Chips for Zeta Potential Characterization
Authors: Cottet Jonathan , Oshodi Josephine , Yebouet Jesse , Furst Ariel L , Buie Cullen R 
Published: September 2023

Bacteria zeta potential, ζ, is one of the key parameters for the deposition of bacteria on an electrode, also called electrophoretic deposition (EPD) and depends on the strain, suspension composition and pH. Measuring directly with a zetasizer is challenging due to the non-spherical shape of bacteria and the need for a lower conductivity medium which could affect the value of ζ. Electrokinetic measurements are usually performed with microchannels in PDMS [1] or in PMMA [2], both of which require expensive tools for the fabrication of either the mold or the microchannel itself. Reducing the cost and time needed to perform such measurements would enable the broader use of this technique. We anticipate solving this challenge with commercially available microfluidic chips as will be outlined in this study.
Under an electric field E in a microchannel, the electrokinetic velocity of particles in a fluid is linked to two phenomena: electrophoresis (EP) due to the zeta potential of the particle and electroosmosis (EO) due to the zeta potential of the channel wall. PMMA microchannels (Microfluidic ChipShop) with 200 µl reservoirs together with a voltage sequencer (Labsmith) controlled with LabVIEW were used to characterize the velocity of 1 µm and 2 µm polystyrene beads with different surface functionalizations (nonfunctionalized polystryrene (PS), Sulfate-modified (SU-modified), Carboxylate-modified (CO-modified) and Amine-modified (AM-modified) from Invitrogen and Magsphere suspended in 10 mM HEPES (pH 7) by applying different voltages between the inlet and outlet platinum electrodes for 90 s. Recorded time-lapse fluorescent image sequences were analyzed with ImageJ and TrackMate. Electrokinetic velocities obtained by Particle Tracking Velocimetry (PTV) at different voltages were fitted with a linear fit with a high coefficient of determination allowing the extraction of the different particle zeta potentials, which are in good agreement with the control measurements performed with a Zetasizer Ultra (Malvern Panalytical) [3]. Further, this methodology was used to characterize a prevalent strain of E. coli, yielding values in agreement with the literature.
The use of commercially available microfluidic chips in electrokinetic characterization could alleviate the need for microfabrication and allow the wider adoption of this characterization method. These measurements are ultimately critical to better understand the role of the zeta potential in EPD of microbes for an array of applications.
[1] S. Antunez-Vela, et al., Anal Chem, 2020
[2] Q. Wang et al., Science Advances, 2019
[3] J. Cottet, et al.
In preparation
Electrochemical Ethylamine Dehydrogenation to Acetonitrile on Platinum-Based Catalysts
Authors: Wu Dezhen , Li Jialu , Tang Jinyao , Peng Zhenmeng 
Published: September 2023

Hydrogen storage is a crucial link between green hydrogen generation by water electrolysis and hydrogen application in fuel cells. We very recently reported a new, electrochemical ethylamine/acetonitrile redox method for hydrogen storage [1]. This method realizes hydrogen uptake by pairing acetonitrile hydrogenation to ethylamine reaction (AHR) on cathode and hydrogen oxidation reaction (HOR) on anode, and realizes hydrogen release by pairing ethylamine dehydrogenation to acetonitrile reaction (EDR) on anode and hydrogen evolution reaction (HER) on cathode. With 8.9 wt.% theoretical storage capacity and ambient reaction conditions being demonstrated in the study, this method shows a great potential to advance hydrogen storage technology and meet the DOE target. One remaining challenge of this method was a rapid activity decay of the used commercial platinum catalyst (Pt/C) in the EDR, which caused a long-term durability issue.
In this work, we report our fundamental study of Pt catalyst deactivation mechanism in EDR and the discovery of new Pt-based catalysts. Attenuated total reflection infrared spectroscopy (ATR-IR) was employed for characterizing working catalyst surface under reactive conditions. Partially dehydrogenated intermediate species were observed to generate on Pt surface, which strongly adsorbed and caused an accumulation and blockage of the active sites. Interestingly, the catalyst showed a self-cleaning property where the intermediates can be hydrogenated back to ethylamine and released from Pt surface below 0 V vs. RHE. A group of Pt-Ni alloy catalysts were prepared and investigated the composition effect in this reaction, among which Pt3Ni exhibited 75% higher activity and significantly improved stability compared to Pt. ATR-IR experiments showed that the accumulation of intermediates on the Pt3Ni surface was much slower than that on the Pt, attributed to weakened adsorption. This work provides mechanistic insights into EDR reaction pathways and the cause of Pt catalyst deactivation and offers a Pt alloy strategy for active and stable catalyst design.
[1] Wu, D.; Li, J.; Yao, L.; Xie, R.; Peng, Z. ACS Appl. Mater. Interfaces 13, 55292 (2021).
Electrodeposition of Platinum-Transition Metal Alloys for Magnetic Thermometry
Authors: Rus Eric D , de Lima Corrêa Eduardo , Dennis Cindi L , Moffat Thomas P 
Published: September 2023

The present work seeks to develop materials and structures with temperature-dependent magnetic properties providing optimal sensitivity for near-room temperature thermometry. Studies of the electrodeposition of Pt1-xMx (M=Ni,Co) alloys will be presented. The effects of boric acid and deposition potential on the deposition process and magnetic properties of Pt1-xNix and Pt1-xCox films will be compared. For Pt1-xNix, it was found that the presence of boric acid during deposition was accompanied by decreased Coulombic efficiency at more reducing deposition potentials, increased oxygen incorporation, and decreased magnetization relative to films deposited in the absence of boric acid.[1] Preliminary results for the Pt1-xCox system indicate its behavior is not simply analogous to the Pt1-xNix system.
[1] Rus, E. D.; L. Corrêa, E.; Groopman, E.; Williamson, T.; Hijazi, H.; Kasaei, L.; Dennis, C. L.; Moffat, T. P., Magnetic Characterization of Electrodeposited Pt1−xNix Alloy Films: Influence of Deposition Potential and the Presence of Boric Acid, J. Electrochem. Soc. 2022, 169 (9), 10.1149/1945-7111/ac8ad1.
(Invited) Interfacial Potential Distribution at Semiconductor/Liquid Interfaces: A Framework for the Quantitative Understanding of Voltammetric Data with Semiconductor (Photo)Electrodes
Authors: Maldonado Stephen 
Published: September 2023

This presentation will introduce a quantitative framework for interpreting and analyzing voltammetric data from semiconductor (photo)electrodes immersed in liquid electrolytes. The basis of the approach is to use the dielectric properties of the semiconductor, electrolyte, and interfacial layer(s) to calculate explicitly the fractional potential drops across the system that occur when a bias is applied relative to an external reference. These fractional potential drops are then used to determine the potential dependences of the forward and back charge-transfer rates between the semiconductor and redox acceptors/donors of interest. These rates, in conjunction with mass transport considerations, are used to predict voltammetric shapes from a variety of useful experimental configurations including diffusing and adsorbed redox species at either semiconductor macro- or ultramicroelectrodes. The goal of the work is to understand semiconductor voltammetric data directly rather than through the (limiting) lenses of either metal electrode responses or solid-state diodes.
The presented framework assumes charge transfer occurs predominantly through the semiconductor band edges but a description of how contributions from surface states can affect the data will be discussed. In addition, this talk will also provide examples of how this framework improves the electroanalytical utility of semiconductor voltammetry to measure semiconductor surface reactions, the flat band potential, and interfacial dielectric properties.
(Physical and Analytical Electrochemistry Division David C. Grahame Award) Vignettes of Charge Transfer Processes at Interfaces Inspired By D.C. Grahame and Previous ECS Grahame Awardees
Authors: Stevenson Keith J. 
Published: September 2023

I am very humbled to be recognized with the 2023 ECS David C. Grahame Award. My presentation will start with the acknowledgment that this award does not happen without all the efforts of students, post-doctoral fellows and colleagues over the past 30 years. Notably, the basis of all my graduate work was inspired by Grahame’s 1947 seminal work [1] on electric double layers at metal-solution interfaces. The study of “clean” pseudo-single crystalline silver electrodes enabled us to quantify and understand the electrochemical formation of stable monolayers of various anions and cations, e.g. [2,3]. In hindsight, also I recognize that these studies provided me with the fundamental underpinnings and motivations to study charge transfer processes in much more complicated semi-metal- and semiconductor-solution systems using a plethora of experimental methods during my academic career. As discussed long ago by Gerischer [4], the key distinction between metal-solution and semiconductor-solution interfaces is that the mechanisms of charge transfer processes can be divided into many groups, mainly with those with weak interactions and the reactants in the electrolyte and those with strong interactions. A more complicating factor with semiconductor-solution interfaces is that the charge-transfer process typically involves both reaction with the electrolyte and a change in the conductivity of the electrode, e.g. [5]. I will provide a series of vignettes (case studies) inspired by several previous ECS Grahame awardees of the distinctive features of different charge transfer processes and their relation to energy conversion, energy storage and chemical sensing applications.
[1] Grahame, D. C. Chem. Rev.
1947, 41, 441.
[2] Stevenson, K. J.; Gao, X.; Hatchett, D. W.; White, H. S. J. Electroanal. Chem.
1998, 447, 43.
[3] White, H. S.; Peterson, J.; Cui, Q; Stevenson, K. J. J. Phys. Chem. B
1998, 102, 2930.
[4] Gerischer, H. 1969, 18, 97.
[5] Nikitina, V. A.; Vassiliev, S. Yu; Stevenson, K. J. Adv. Ener. Mater.
2020, 1903933.
(Invited) Understanding Ion-Ion Correlations: From Liquid Electrolytes to Polymer Electrolytes
Authors: Zhang Chao 
Published: September 2023

Mass transport in electrolytes is one of the most important design focuses of electrochemical devices such as batteries, fuel cells, and supercapacitors. Compared to the infinitely dilute solution, ion-ion correlations play a central role in determining the structure-property relationships in the concentrated solution. Therefore, disentangling ion-ion correlations and establishing their impact on transport coefficients is a fundamental and pressing issue in the field of electrolyte materials.
In this talk, I will present the recent works of my group and collaborators on using molecular dynamics simulations to understand ion-ion correlations. In particular, we looked into this issue by exploring the synergy between liquid electrolytes and polymer electrolytes following the physical chemistry route started by Onsager. This has led to a number of interesting results on the relationship between the ion-pairing and the deviation from the Nernst-Einstein relation [1-3], and shed light on resolving the controversy of the negative transference number found in polymer electrolytes [4].
References:
[1] Y. Shao, M. Hellström, A. Yllö, J. Mindemark, K. Hermansson, J. Behler, and C. Zhang, “Temperature effects on the ionic conductivity in concentrated alkaline electrolyte solutions”, Phys. Chem. Chem. Phys. 2020, 22: 10426.
[2] Y. Shao, K. Shigenobu, M. Watanabe, and C. Zhang, “Role of viscosity in deviations from the Nernst–Einstein relation”, J. Phys. Chem. B, 2020, 124: 4774.
[3] H. Gudla, Y. Shao, S. Phunnarungsi, D. Brandell, and C. Zhang, “Importance of the ion-pair lifetime in polymer electrolytes”, J. Phys. Chem. Lett.,
2021, 12: 8460.
[4] Y. Shao, H. Gudla, D. Brandell, and C. Zhang, “Transference number in polymer electrolytes: mind the reference-frame gap”, J. Am. Chem. Soc.,
2022, 144: 7583.
(Invited) Toward Rigorous Modeling of Metal-Metal, Metal-Oxide and Oxide-Oxide Interfaces for the Electrochemical Oxygen Cycle
Authors: Zeng Zhenhua 
Published: September 2023

To achieve Net-Zero Emissions by 2050, hydrogen and hydrogen fuel cells will play a significant role in powering vehicles. In this presentation, I will show, through first-principles-based modeling, how to achieve rigorous modeling of solid-solid interface for the hydrogen and oxygen evolution reactions in electrolysis and the oxygen reduction reaction in fuel cells; and how the fundamental understanding paves the way toward developing both model electrocatalysts and industrial electrocatalysts with significantly improved performance. Specifically, I will introduce the following three topics.
[1] metal-metal interfaces: strain evolution and strain tuning of epitaxial, stepped and free-standing platinum group metals for the oxygen reduction reaction in fuel cells.(1)
[2] metal-oxide interfaces: stability and activity of monolayer oxide/Pt interface toward improving the hydrogen evolution reaction in alkaline conditions.(2)
[3] oxide-oxide interfaces: self-consistent modeling of active phases, reaction centers, and catalytic mechanisms of Ni- and Co-based layered double hydroxides for the oxygen evolution reaction.(3, 4)

L. Wang, Z. Zeng, W. Gao, T. Maxson, D. Raciti, M. Giroux, X. Pan, C. Wang, J. Greeley, Tunable intrinsic strain in two-dimensional transition metal electrocatalysts. Science
363, 870-874 (2019).

Z. Zeng, K.-C. Chang, J. Kubal, N. M. Markovic, J. Greeley, Stabilization of ultrathin (hydroxy)oxide films on transition metal substrates for electrochemical energy conversion. Nature Energy
2, 17070 (2017).

F. Dionigi, Z. Zeng, I. Sinev, T. Merzdorf, S. Deshpande, M. B. Lopez, S. Kunze, I. Zegkinoglou, H. Sarodnik, D. Fan, A. Bergmann, J. Drnec, J. F. d. Araujo, M. Gliech, D. Teschner, J. Zhu, W.-X. Li, J. Greeley, B. R. Cuenya, P. Strasser, In-situ structure and catalytic mechanism of NiFe and CoFe layered double hydroxides during oxygen evolution. Nature Communications
11, 2522 (2020).

F. Dionigi, J. Zhu, Z. Zeng, T. Merzdorf, H. Sarodnik, M. Gliech, L. Pan, W.-X. Li, J. Greeley, P. Strasser, Intrinsic Electrocatalytic Activity for Oxygen Evolution of Crystalline 3d-Transition Metal Layered Double Hydroxides. Angew. Chem., Int. Ed.
60, 14446-14457 (2021).

Figure 1
Li Transport in Defected LiNiO2 from First Principles: Diffusion, Nucleation, and Charge Transfer
Authors: Xiao Penghao 
Published: September 2023

Electrochemical intercalation of Li in battery electrodes involves a few types of kinetic processes, including diffusion in inhomogeneous media, phase nucleation/transition, and surface charge transfer. They span several length and time scales and are often coupled with each other, which makes it challenging to identify the rate-limiting step and extract kinetic parameters by fitting an empirical model. Using layered cathode LiNiO2 as an example, I will present how all these processes can be incorporated in one atomistic model without empirical inputs, which reals the kinetic competition between different processes. In this scheme, the energetics of various local environments were calculated by the density functional theory (DFT). And the obtained data were used to train a surrogate Hamiltonian with the cluster expansion method. Then the kinetic Monte Carlo (KMC) simulations were conducted with ion hopping barriers updated on-the-fly based on the Brønsted−Evans−Polanyi (BEP) relation. The charge transfer barriers at the electrode-electrolyte interface were calculated separately using the constant-voltage eNEB method1.
The simulation results shown below largely reproduce the experimental voltage profile of LiNiO2
2. Both the hysteresis and the irreversible capacity loss (IRC) at the first discharge are captured. The rate limiting step switches as the Li concentration changes during cycling. Moreover, the layered LiNiO2 is never perfect and there are always some excess Ni in the Li layer, which significantly affects the electrochemical performances. My simulations peek into the atomistic origins of these effects. The excess Ni formed in the bulk during synthesis increase IRC by impeding Li diffusion3; the excess Ni near the surface formed during cycling due to oxygen loss traps Li in the fatigued particles by suppressing Li-poor phase nucleation below certain Li concentration4.
References:

Duan, Z. & Xiao, P. Simulation of Potential-Dependent Activation Energies in Electrocatalysis: Mechanism of O-O Bond Formation on RuO2. Journal of Physical Chemistry C
125, 15243–15250 (2021).

Kurzhals, P. et al. The LiNiO2 Cathode Active Material: A Comprehensive Study of Calcination Conditions and their Correlation with Physicochemical Properties. Part I. Structural Chemistry. J Electrochem Soc
168, 110518 (2021).

Phattharasupakun, N. et al. Correlating Cation Mixing with Li Kinetics: Electrochemical and Li Diffusion Measurements on Li-Deficient LiNiO2 and Li-Excess LiNi0.5Mn0.5O2. J Electrochem Soc
168, 090535 (2021).

Xu, C. et al. Bulk fatigue induced by surface reconstruction in layered Ni-rich cathodes for Li-ion batteries. Nat Mater
20, 84–92 (2021).

Figure 1
Toward Understanding Interfacial Phenomena of Anion Exchange Membrane Water Electrolyzers: Investigating the Role of Electrolyte pH Gradient with Operando Raman Spectroscopy
Authors: Maxwell Derrick , Kendrick Ian , Mukerjee Sanjeev 
Published: September 2023

There is growing industrial appeal of anion exchange membrane water electrolyzers (AEMWEs) to produce hydrogen. A significant challenge remains that AEMWE durability testing is not standardized, and more minute interfacial degradation mechanisms between ionomer, catalyst, membrane, and electrolyte are not well characterized. Of particular interest is the impact of electrolyte selection on the polarization performance. There is a general desire to achieve reliable operation with environmentally obtained saltwater as the electrolyte, although this presents numerous challenges manifesting in typically poor long-term durability. Saltwater presents complexities in determining electrolyzer component interfacial phenomena.
Performance of AEMWEs is typically benchmarked with hydroxide or carbonate solutions, therefore providing more direct opportunities to study fundamental mechanisms with regards to interactions between surfaces. Of particular interest is the presence of electrolyte anion concentration gradients that depend on the polarization state of the oxygen evolution reaction electrode (OER). We demonstrated in our early work with operando Raman probing of a custom designed spectroelectrochemical cell that there is initial evidence of spatially resolved anion gradients from the OER electrode surface into bulk electrolyte in a half cell configuration. We hypothesize that local pH changes near an electrode surface may impact the polarization via transport limited ion exchange and the relative overpotential of the overall cell, ultimately leading to an iterative and long-term contribution to decaying cell durability.
We continue our work with a series of in-situ Raman experiments with a full cell configuration: OER electrode with PGM free catalyst, hydrogen evolution reaction (HER) electrode with PGM free catalyst, and anion conductive polymer membrane. Both electrodes also contain an ionically conductive polymer, or ionomer, that serves as a binder. By increasing the complexity of the system to match that of an industrially relevant configuration, we aim to probe the spatially resolved pH gradient with both potassium hydroxide and potassium carbonate solutions of varying concentrations. We utilized a custom, 3D printed, flow cell design comprising a sapphire observation window and isolated electrolyte flow chambers.
Operando Raman spectroscopy measurements were conducted primarily with potassium carbonate solutions by tracking the spatially resolved changes in relative peak intensity of carbonate and bicarbonate signatures. With regards to the carbonate-bicarbonate equilibrium, we calculate changes in pH as the probe approaches the surface of an electrode. We finally connect our findings to a proposed mechanism for the interfacial phenomena relative to cell durability as a function of concentration changes and operating voltages.
(Invited) Correlative Spectroscopy to Elucidate the Factors Controlling the Kinetics of Oxygen Evolution
Authors: Stephens Ifan Erfyl Lester 
Published: September 2023

It is particularly challenging to catalyse oxygen evolution under the acidic conditions of polymer electrolyte membrane (PEM) electrolysers. All compounds, apart from IrOx and RuO
x
, are catalytically inactive or unstable. In alkaline electrolysers, a wider range of materials are available, including non precious metal oxides based on Co and Ni.
Herein, I will discuss our recent mechanistic studies on model oxygen evolution catalysts, including RuOx, IrOx, doped CoOxHy and NiOxHy.1-6 I will correlate operando spectroscopy to X-ray absorption spectroscopy, to reveal the factors controlling the factors controlling the kinetics for water oxidation. Density functional theory measurements provide a molecular scale explanation for the observed phenomena.
1 Rao, R. R., Corby, S., Bucci, A., Garcia-Tecedor, M., Mesa, C. A., Rossmeisl, J., Gimenez, S., Lloret-Fillol, J., Stephens, I. E. L. & Durrant, J. R.
J. Am. Chem. Soc.
144, 7622, (2022).
2 Bozal-Ginesta, C., Rao, R. R., Mesa, C. A., Wang, Y. X., Zhao, Y. Y., Hu, G. F., Anton-Garcia, D., Stephens, I. E. L., Reisner, E., Brudvig, G. W., Wang, D. W. & Durrant, J. R.
J. Am. Chem. Soc.
144, 8454, (2022).
3 Rao, R. R., Stephens, I. E. L. & Durrant, J. R.
Joule
5, 16, (2021).
4 Bozal-Ginesta, C., Rao, R. R., Mesa, C. A., Xinyi, L., Hillman, S. A. J., Stephens, I. E. L. & Durrant, J. R.
ACS Catalysis
, (2021).
5 Rao, R. R., Kolb, M. J., Giordano, L., Pedersen, A. F., Katayama, Y., Hwang, J., Mehta, A., You, H., Lunger, J. R., Zhou, H., Halck, N. B., Vegge, T., Chorkendorff, I., Stephens, I. E. L. & Shao-Horn, Y.
Nature Catalysis
3, 516, (2020).
6 Roy, C., Rao, R. R., Stoerzinger, K. A., Hwang, J., Rossmeisl, J., Chorkendorff, I., Shao-Horn, Y. & Stephens, I. E. L.
Acs Energy Letters
3, 2045, (2018).