Alkaline Water Electrolysis Anode Materials

Hall, Dale

doi:10.1149/1.2113856

Cited by 118 publications

(95 citation statements)

References 30 publications

(58 reference statements)

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“…this a priori contradictory behavior is associated to the merging of Ni(OH) 2 phase, which is a well-establish anode catalyst material for alkaline water electrolysis. 18 As expected, reduced O 2 partial pressure in air strongly affects ORR reaction rate and potential difference E jump from 0.578 V up to 0.674 V @ 10 mA cm −2 .…”

Section: Xrd Sem and Tem-supporting

confidence: 68%

On Activity and Stability of Rhombohedral LaNiO3 Catalyst towards ORR and OER in Alkaline Electrolyte

Mariappan

Bhandari

Drillet

2015

ECS Electrochemistry Letters

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LaNiO 3 catalyst was synthesized by RHP method and sprayed onto a GDL. Electrochemical activity for oxygen reactions of asprepared GDE was evaluated under half-cell condition in oxygen-saturated 7 M KOH electrolyte. Best performance in terms of potential difference E between ORR and OER amounted 0.688 V @ 10 mA cm −2 for 20 wt% LaNiO 3 /C HSAG compared to 1 V for 20 wt% Pt/C Vulcan . Moreover, by increasing perovskite:carbon weight ratio up to 3:2, E in oxygen decreased down to 0.57 V that is the lowest value ever reported in the literature. However, phase segregation and loss in ORR activity was observed during cycling. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.0081506eel] All rights reserved. Because of high theoretical energy density, low toxicity and attractive price, metal-air batteries and especially zinc/air system is an interesting candidate for portable and stationary energy storage applications. However, large scale commercialization is hindered by inherent drawbacks of the zinc electrode, such as poor reversibility, low energy efficiency, shape change and dendrite formation during the charging process. Moreover, resistance towards carbonate poisoning in alkaline systems and activity/stability of bi-functional catalysts for oxygen reactions have to be improved.1 Suntivich et al. found a volcano-shape correlation between σ * -orbital occupation (e g ) of different La-based perovskites and their activity for both ORR 2 and OER 3 reactions. Among the investigated systems, LaNiO 3 appears to be one of the best candidates in terms of bifunctionality. It is meanwhile wellknown that the reaction rate of these catalysts strongly depends on particle size, intrinsic electronic conductivity, phase stability and preparation method. By co-precipitation of metal nitrate precursors with 1 M NaOH, extremely low Tafel slope value of 43 mV dec −1 (2RT/3F) for OER was measured at a pure Lanthanum Nickel Oxide phase powder without addition of binder materials. 4 This excellent value was attributed to a high carrier density (holes) and dominant presence of Ni 2+ at the surface, and to a large amount of oxygen vacancies. Not only oxidation state of the transition metal but also roughness factor of the powder material is primordial. By using a chlorine-modified precipitation route 5 to further oxidized Ni 2+ to Ni 3+ , Singh et al.,6 measured a seven times larger roughness factor in comparison to that of the product yielded by traditional precipitation method. 4 Bulk perovskite materials are generally synthesized by (i) solid-phase sintering at high temperature, typically by T > 1278 K, ...

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Section: Xrd Sem and Tem-supporting

confidence: 68%

On Activity and Stability of Rhombohedral LaNiO3 Catalyst towards ORR and OER in Alkaline Electrolyte

Mariappan

Bhandari

Drillet

2015

ECS Electrochemistry Letters

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“…20,64,67 Abundant metals can be used in large amounts at moderate costs in order to realize high surface area electrodes with thick active layers such as Raney-nickel alloys. 37,68,69 A chief improvement for the electrodes of the alkaline electrolysis cell might be realizable by microporous frameworks (such as foams 70,71 or finely woven meshes 72 ) so that the overall geometric cell area can be utilized.…”

Section: Ionic Conductivity-inmentioning

confidence: 99%

Acidic or Alkaline? Towards a New Perspective on the Efficiency of Water Electrolysis

Schalenbach

Tjarks

Carmo

et al. 2016

J. Electrochem. Soc.

260

182

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Water electrolysis is a promising technology for enabling the storage of surplus electricity produced by intermittent renewable power sources in the form of hydrogen. At the core of this technology is the electrolyte, and whether this is acidic or alkaline affects the reaction mechanisms, gas purities and is of significant importance for the stability and activity of the electrocatalysts. This article presents a simple but precise physical model to describe the voltage-current characteristic, heat balance, gas crossover and cell efficiency of water electrolyzers. State-of-the-art water electrolysis cells with acidic and alkaline electrolyte are experimentally characterized in order to parameterize the model. A rigorous comparison shows that alkaline water electrolyzers with Ni-based catalysts but thinner separators than those typically used is expected be more efficient than acidic water electrolysis with Ir and Pt based catalysts. This performance difference was attributed mainly to a similar conductivity but approximately 38-fold higher diffusivities of hydrogen and oxygen in the acidic polymer electrolyte membrane (Nafion) than those in the alkaline separator (Zirfon filled with a 30 wt% KOH solution In the endeavor to realize an environmentally-benign power supply infrastructure, water electrolysis for the production of hydrogen may prove a key technology for enabling energy conversion on a large scale.1,2 By applying a voltage to two electrodes immersed in an aqueous electrolyte, water can be electrochemically decomposed, evolving hydrogen at the negative pole, the cathode, and oxygen at the positive pole, the anode. During this process, protons or hydroxide ions must pass through the electrolyte to enable the electrochemical reactions at the electrodes. In order to achieve low extents of charge transport losses in electrolyzers, electrolytes with high conductivities are typically used. Such highly conductive electrolytes provide large quantities of ionic charge carriers (protons or hydroxide ions) and are thus either strong bases or acids. The reaction equations in acidic and alkaline aqueous regimes are displayed in Table I.Besides liquid aqueous electrolytes in combination with porous separators, polymer electrolyte membranes (PEMs) are typically used as electrolytes for water electrolysis and to separate the hydrogen and oxygen produced during operation.3 In PEMs, ionizable functional groups are embedded within a polymer matrix providing either mobile protons or hydroxide ions. 4 In an aqueous phase that is separated from the solid polymeric phase 5,6 the protons or hydroxide ions are dissolved but attracted to the oppositely charged ions of the functional group which are covalently bonded to the polymer matrix. As a result, the dissolved ions are captured inside the aqueous phase of the PEM. Hence, an advantage of solid PEMs is that pure water can supplied to the cell, which means that only the components that are in direct contact with the PEM are exposed to its corrosive alkaline or acidic aqueous ph...

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“…One major advantage of alkaline conditions is that nonprecious metal materials including nickel, cobalt and steels, can be stable. Moreover, in early work [76,77], precious metals were reported to have little or no superiority to nickel for oxygen evolution in alkaline solution. When Pt, Pd, Rh, and Ni were electrodeposited onto Ni foam and the resulting coatings tested in a water electrolysis cell at a current density of 0.2 A cm À2 in 30% KOH electrolyte at 363 K, the cell voltages .…”

Section: Anodesmentioning

confidence: 99%