More Like this

1. Measurement of Polarization Resistance of LSM + YSZ Electrodes on YSZ using AC and DC Methods

   Alex Szendrei, Taylor D. (January 2019, Fuel cells)

   Most of the measurements of electrode polarization resistance are conducted using electrochemical impedance spectroscopy (EIS). The electrochemical devices, however, are typically used in a DC mode. The objective of the present work was to measure electrode polarization resistance using both EIS and DC techniques. A solid cylinder of 8YSZ of diameter ~1.17 cm and length ~5.00 cm was made by powder pressing followed by sintering. LSM + YSZ electrodes were applied on the two end surfaces of the cylinder upon which gold mesh was placed. Four Pt electrodes/probes were painted along the circumference. During DC measurements, DC voltage was applied across the end electrodes and potentials were measured at all four probes. The current was also measured. From these measurements electrode polarizations were estimated separately for the two electrodes as a function of current. EIS was conducted across the two end electrodes as well as across electrode-1 and probe-2, and across probe-2 and electrode-2. This allowed the determination of the polarization resistances of the two electrodes separately. Point by point additions of the electrode-1/probe-2 and probe-2/electrode-2 spectra matched the electrode-1/electrode-2 spectra. There was good agreement between the DC and the EIS measurements. 

   more » « less
2. Voltammetry Peak Tracking for Longer-Lasting and Reference-Electrode-Free Electrochemical Biosensors

   https://doi.org/10.3390/bios12100782  

   McHenry, Adam; Friedel, Mark; Heikenfeld, Jason (October 2022, Biosensors)

   Electrochemical aptamer-based sensors offer reagent-free and continuous analyte measurement but often suffer from poor longevity and potential drift even with a robust 3-electrode system. Presented here is a simple, software-enabled approach that tracks the redox-reporter peak in an electrochemical aptamer-based sensor and uses the measurement of redox peak potential to reduce the scanning window to a partial measure of redox-peak-height vs. baseline (~10X reduction in voltage range). This same measurement further creates a virtual reference standard in buffered biofluids such as blood and interstitial fluid, thereby eliminating the effects of potential drift and the need for a reference electrode. The software intelligently tracks voltammogram peak potential via the inflection points of the rising and falling slopes of the measured redox peak. Peak-tracking-derived partial scanning was validated over several days and minimized electrochemically induced signal loss to <5%. Furthermore, the peak-tracking approach was shown to be robust against confounding effects such as fouling. From an applied perspective in creating wearable biosensors, the peak-tracking approach further enables use of a single implanted working electrode, while the counter/reference-electrode may utilize a simple gel-pad electrode on the surface of the skin, compared to implanting working, counter, and reference electrodes conventionally used for stability and reliability but is also costly and invasive. Cumulatively, peak-tracking provides multiple leaps forward required for practical molecular monitoring by extending sensor longevity, eliminating potential drift, simplifying biosensor device construction, and in vivo placement for any redox-mediated sensor that forms parabolic-like data. 

   more » « less
3. Development of Electrochemical 6-Well Plates and Its Stability as an Immunosensor

   https://doi.org/10.1149/1945-7111/ac519e  

   Cui, Feiyun; Zhou, Zhiru; Qu, Bin; Zhou, Qin; Zhou, H. Susan (February 2022, Journal of The Electrochemical Society)

   Developing low-cost and multiplexing electrochemical (EC) devices for bioassay is imperative. Herein, a polymer-based EC device, named EC 6-well plate, was proposed and fabricated using a non-photolithography method. Polyethylene terephthalate glycol (PETG) was used as a substrate and laser-cut polyester (PET) film was used as a mask for patterning the electrodes. The diameter of the working electrode (WE) was 900 μ m, and each WE-modifying step only requires 1 μ l of reagent. Acrylic mold with wells (60 μ l) was bonded to the PETG substrate. Miniaturization of reference electrodes (RE) was discussed. The solid-state Ag/AgCl RE-based three-electrode system, the Au three-electrode system (3E), and Au two-electrode system (2E) were prepared and employed to develop an immunosensor for toxin B detection. Differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were applied to test the stability of the EC immunosensor. The solid-state Ag/AgCl RE-based system showed a standard deviation of open circuit potential (OCP) of 4.6 mV. The 3E system and 2E system showed the standard deviations of OCP of 0.0026 mV and 0.32 mV, respectively. It revealed that the EC 6-well plate with the 3E system is excellent for developing an EC immunosensor. 

   more » « less
4. Print‐and‐Plate Architected Electrodes for Electrochemical Transformations Under Flow

   https://doi.org/10.1002/adfm.202419748  

   Barber, Dylan M; Edgar, Sofía; Emanuel, Michael S; Nelwood, Michael D; Ahn, Bok Yeop; Román‐Manso, Benito; Cochard, Thomas; Platero, Justin; Amini, Kiana; Rycroft, Chris H; et al (March 2025, Advanced Functional Materials)

   Abstract Flow cell electrodes are typically composed of porous carbon materials, such as papers, felts, and cloths. However, their random architecture hinders the fundamental characterization of electrode structure‐performance relationships during in situ operation of porous electrochemical flow systems. This work describes a “print‐and‐plate” method that combines direct ink writing of micro‐periodic lattices with a two‐step metal plating process that converts them into highly conductive (sheet resistance 40 mΩ sq⁻¹) electrodes. Theiroperandoperformance is assessed in an anthraquinone disulfonic acid half‐cell using widefield electrochemical fluorescence microscopy, where output current and fluorescence intensity are in excellent agreement. The pressure drop associated with flow through three electrode designs is determined via simulations from which the most efficient design is identified and manufactured via print‐and‐plate. Confocal fluorescence microscopy is then used to create a 3D map of the state of charge (SOC) inside this print‐and‐plate electrode. The experimental state of the charge map is in good agreement with computational predictions. The rapid design, simulation, and fabrication of print‐and‐plate electrodes enable fundamental investigations of how architected porosity affects electrochemical performance under flow. 

   more » « less
5. Promotion of oxygen reduction reaction on a double perovskite electrode by a water-induced surface modification

   https://doi.org/10.1039/d0ee03283b  

   Kim, Jun Hyuk; Yoo, Seonyoung; Murphy, Ryan; Chen, Yu; Ding, Yong; Pei, Kai; Zhao, Bote; Kim, Guntae; Choi, YongMan; Liu, Meilin (March 2021, Energy & Environmental Science)

   null (Ed.)

   Highly efficient air electrodes are a key component of reversible fuel cells for energy storage and conversion; however, the development of efficient electrodes that are stable against water vapor remains a grand challenge. Here we report an air–electrode, composed of double perovskite material PrBa 0.8 Ca 0.2 Co 2 O 5+δ (PBCC) backbone coated with nanoparticles (NPs) of BaCoO 3−δ (BCO), that exhibits remarkable electrocatalytic activity for oxygen reduction reaction (ORR) while maintaining excellent tolerance to water vapor. When tested in a symmetrical cell exposed to wet air with 3 vol% H 2 O at 750 °C, the electrode shows an area specific resistance of ∼0.03 Ω cm 2 in an extended period of time. The performance enhancement is attributed mainly to the electrocatalytic activity of the BCO NPs dispersed on the surface of the porous PBCC electrode. Moreover, in situ Raman spectroscopy is used to probe reaction intermediates ( e.g. , oxygen species) on electrode surfaces, as the electrochemical properties of the electrodes are characterized under the same conditions. The direct correlation between surface chemistry and electrochemical behavior of an electrode is vital to gaining insight into the mechanisms of the electrocatalytic processes in fuel cells and electrolysers. 

   more » « less