Electrochemistry of Phosphorous and Hypophosphorous Acid on a Pt electrode

Prokop, Martin; Bystroň, Tomáš; Bouzek, Karel

doi:10.1016/j.electacta.2015.01.097

Cited by 24 publications

(41 citation statements)

References 20 publications

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“…Its main features are typical for Pt in oxygen-free H 3 PO 4 electrolyte and have been discussed previously. 1,13,15,16 An oxidation feature is visible at 0.7 V in the positive going scan. Upon rotation, a small oxidative current appears also in the back scan around 0.7 V. The ORR polarization curve after subtraction of the basic CV is depicted in Fig.…”

Section: Resultsmentioning

confidence: 99%

Design and Application of External Reference Electrode for Kinetic Studies at Elevated Temperatures and Pressures

Fleige

Wiberg

Arenz

2017

J. Electrochem. Soc.

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We present the design and application of an external reference electrode (RE) system for kinetic studies of the oxygen reduction reaction (ORR), the cathode process in high temperature proton exchange membrane fuel cells (HT-PEMFCs), at elevated temperatures and pressures inside an autoclave. The RE system comprises a solid ion-conducting junction based on Nafion tubing. External RE was a reversible hydrogen electrode (RHE) calibrated reproducibly relative to an internal RHE with an uncertainty <±5 mV over the temperature range of 25-170 • C. Functionality of the RE system was tested by measuring ORR in concentrated H 3 PO 4 relative to a calibrated external RHE. Thus, we are confident that the development is a useful and versatile tool for kinetic studies at elevated temperatures and pressures. Fast and reliable testing of fuel cell catalysts at relevant conditions is of high importance for academia and industry alike. Recently, we introduced an elevated pressure and temperature rotating disk electrode (RDE) system that allows electrocatalytic measurements under well-defined mass transport conditions 1,2 . The setup comprised an internal silver wire RE that enabled a stable determination of the reference potential, but the obtained calibration relative to an internal RHE lacked the required accuracy (< ± 5 mV) for accurate kinetic measurements. We therefore avoided in our previous work the determination of absolute kinetic rates of the ORR at elevated temperature and pressure. An approach to more reliable reference potentials in pressurized cells is to use external RE configurations.3 Recently, external RE systems for fuel cells with solid ion-conducting junctions based on Nafion tubing or the PBI/H 3 PO 4 polymer were published. 4,5Here we present the design and test of an external RE system with solid junction specifically developed for pressurized electrochemical cells. The most meaningful RE to study ORR with respect to fuel cells is the RHE, which is a hydrogen electrode immersed in the same electrolyte and at 1 bar H 2 partial pressure. 6 Thus, we applied an external RHE and calibrated it separately relative to an internal RHE, as its determination in situ 7,8 is not practical in pressurized cells. Application of the calibrated external RE was tested for studying ORR in conc. H 3 PO 4 at elevated temperatures. Such conditions are highly relevant for high temperature proton exchange membrane fuel cells (HT-PEMFC), but usually not accessible to RDE studies due to the low oxygen solubility in the electrolyte. The results demonstrate that our development enables meaningful kinetic studies in pressurized cells and thereby overcomes the significant accuracy issues related to internal REs operated at elevated temperatures. ExperimentalThe electrolyte used in this study was 85 wt% H 3 PO 4 (Suprapur, Merck). The gases used were supplied from gas cylinders (Air Liquide, Denmark) and had a purity of at least 99.995%. The electrochemical cell was placed inside an autoclave as described previously.

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Section: Resultsmentioning

confidence: 99%

Design and Application of External Reference Electrode for Kinetic Studies at Elevated Temperatures and Pressures

Fleige

Wiberg

Arenz

2017

J. Electrochem. Soc.

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“…Moderate elevated temperatures of 45 C are sufficient to allow their formation and/or mobility. P(þIII) compounds are reducing agents [43] and might foster further degradation. This has implications for the recommendation of battery storage conditions.…”

Section: Discussionmentioning

confidence: 99%

Identification of LiPF₆Decomposition Products in Li‐Ion Batteries with Endogenous Vanadyl Sensors Using Pulse Electron Paramagnetic Resonance and Density Functional Theory

Szczuka

Jakes

Eichel

et al. 2021

Adv Energy and Sustain Res

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“…In order to further demonstrate the selectivity of α‐MnO 2 towards ORR in hypophosphite solution, a commercial Pt/C catalyst with 20 % metal loading was taken for comparison due to its strong oxygen reduction capability and slight hypophosphite electrochemical oxidation activity . The experiments were performed under the same conditions as mentioned above.…”

Section: Figurementioning

confidence: 99%

“…[11,18] The experiments were performedu nder the same conditions as mentioned above.A ss hown in Figure 2b,t he Pt/C catalyste xhibits high activity for O 2 electrochemical reduction ( Figure 2b,b lue dash line) in O 2 -saturated KOH solution. [11,18] The experiments were performedu nder the same conditions as mentioned above.A ss hown in Figure 2b,t he Pt/C catalyste xhibits high activity for O 2 electrochemical reduction ( Figure 2b,b lue dash line) in O 2 -saturated KOH solution.…”

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confidence: 99%

“…In order to furtherd emonstrate the selectivity of a-MnO 2 towards ORR in hypophosphite solution,acommercial Pt/C catalyst with 20 %m etal loading wast aken for comparison due to its strong oxygen reduction capability and slight hypophosphite electrochemical oxidationa ctivity. [11,18] The experiments were performedu nder the same conditions as mentioned above.A ss hown in Figure 2b,t he Pt/C catalyste xhibits high activity for O 2 electrochemical reduction ( Figure 2b,b lue dash line) in O 2 -saturated KOH solution. However,w ith the presence of both hypophosphite and O 2 ,t he Pt/C catalyst displays an evident decreasei nt he cathodic current (Figure 2b,r ed solid line) during the negative scan as well as an increase in anodic currentd uring the positive scan.…”

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confidence: 99%

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Hypophosphites as Eco‐Compatible Fuels for Membrane‐Free Direct Liquid Fuel Cells

Ren-he

Mou-cheng

Haller

et al. 2018

Chemistry A European J

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Crossover of liquid fuel remains a severe problem for conventional direct liquid fuel cells even when polymer electrolyte membranes are applied. Herein, we report for the first time a membrane-free direct liquid fuel cell powered by alkaline hypophosphite solution. The proof-of-concept fuel cell yields a peak power density of 32 mW cm under air flow at room temperature. The removal of the polymer electrolyte membrane is attributed to the high reactivity and selectivity of Pd and α-MnO towards the hypophosphite oxidation on the anode and oxygen reduction on the cathode, respectively. The discharge products are analyzed by P NMR spectroscopy and the faradaic efficiencies have been calculated after discharging at 10 mA cm for 20 hours. The non-toxicity of hypophosphite and membrane-free fuel cell structure provide huge potential for future applications.

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Electrochemistry of Phosphorous and Hypophosphorous Acid on a Pt electrode

Cited by 24 publications

References 20 publications

Design and Application of External Reference Electrode for Kinetic Studies at Elevated Temperatures and Pressures

Design and Application of External Reference Electrode for Kinetic Studies at Elevated Temperatures and Pressures

Identification of LiPF₆Decomposition Products in Li‐Ion Batteries with Endogenous Vanadyl Sensors Using Pulse Electron Paramagnetic Resonance and Density Functional Theory

Hypophosphites as Eco‐Compatible Fuels for Membrane‐Free Direct Liquid Fuel Cells

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Electrochemistry of Phosphorous and Hypophosphorous Acid on a Pt electrode

Cited by 24 publications

References 20 publications

Design and Application of External Reference Electrode for Kinetic Studies at Elevated Temperatures and Pressures

Design and Application of External Reference Electrode for Kinetic Studies at Elevated Temperatures and Pressures

Identification of LiPF6Decomposition Products in Li‐Ion Batteries with Endogenous Vanadyl Sensors Using Pulse Electron Paramagnetic Resonance and Density Functional Theory

Hypophosphites as Eco‐Compatible Fuels for Membrane‐Free Direct Liquid Fuel Cells

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Identification of LiPF₆Decomposition Products in Li‐Ion Batteries with Endogenous Vanadyl Sensors Using Pulse Electron Paramagnetic Resonance and Density Functional Theory