Pyrochlore electrocatalysts for efficient alkaline water electrolysis

Parrondo, Javier; George, M. T.; Capuano, Christopher; Ayers, Katherine E.; Ramani, Vijay

doi:10.1039/c5ta01771h

Cited by 106 publications

(134 citation statements)

References 58 publications

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“…As shown in Figure S4, Bi-Ir exhibits very poor OER activity, and its specific activity remains lowest as well. This finding is analogous to Javier Parrondo et al 43. results, while Kripasindhu Sardar et al 44.…”

Section: Resultssupporting

confidence: 87%

OER activity manipulated by IrO6 coordination geometry: an insight from pyrochlore iridates

Sun

Liu

Gong

et al. 2016

Sci Rep

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The anodic reaction of oxygen evolution reaction (OER), an important point for electrolysis, however, remains the obstacle due to its complicated reaction at electrochemical interfaces. Iridium oxide (IrO2) is the only currently known 5d transition metal oxide possessing admirable OER activity. Tremendous efforts have been carried out to enhance the activity of iridium oxides. Unfortunately there lies a gap in understanding what factors responsible for the activity in doped IrO2 or the novel crystal structure. Based on two metallic pyrochlores (Bi2Ir2O7 and Pb2Ir2O6.5) and IrO2. It has been found that there exists a strong correlation between the specific OER activity and IrO6 coordination geometry. The more distortion in IrO6 geometry ascends the activity of Ir sites, and generates activity order of Pb-Ir > IrO2 > Bi-Ir. Our characterizations reveal that distorted IrO6 in Pb-Ir induces a disappearance of J = 1/2 subbands in valence band, while Bi-Ir and IrO2 resist this nature probe. The performed DFT calculations indicated the distortion in IrO6 geometry can optimize binding strength between Ir-5d and O-2p due to broader d band width. Based on this insight, enhancement in OER activity is obtained by effects that change IrO6 octahedral geometry through doping or utilizing structural manipulation with nature of distorted octahedral coordination.

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Section: Resultssupporting

confidence: 87%

OER activity manipulated by IrO6 coordination geometry: an insight from pyrochlore iridates

Sun

Liu

Gong

et al. 2016

Sci Rep

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“…The Faraday efficiency of CeO 2 /FeOOH HLNTs‐NF under various overpotentials is shown in Figure S12 (Supporting Information), which shows that the Faraday efficiencies all are over 96% among the overpotentials of 250–400 mV, indicating high energy‐conversion rate. In addition, the electrocatalytic activity of FeOOH/CeO 2 HLNTs‐NF is much higher than many other nonprecious metal OER electrocatalysts in the alkaline media such as Co–Mn LDHs, α ‐Ni(OH) 2 nanosheets, CeO 2 /CoSe 2 nanobelts,[20a] Fe–Ni LDHs,[23a] NiCo LDHs,[23b] Mn 3 O 4 /CoSe 2 composites,[23c] Au@Co 3 O 4 core–shell nanocrystals, and PbRu 2 O 6 nanoparticles as shown in Table S1 (Supporting Information).…”

mentioning

confidence: 99%

Design and Synthesis of FeOOH/CeO₂ Heterolayered Nanotube Electrocatalysts for the Oxygen Evolution Reaction

et al. 2016

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FeOOH/CeO2 heterolayered nanotubes supported on Ni foam as efficient oxygen evolution electrocatalysts are reported. The hybrid structure can obviously promote the catalytic performance for the oxygen evolution reaction, such as low onset potential, high electroactivity, and excellent long-term durability. This study provides a new route to the design and fabrication of electrocatalysts with high electroactivity and durability for oxygen evolution.

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“…Neutralized Nafion is widely employed as binder in RDE experiments to evaluate catalyst activity in alkaline environments. 13,25,[40][41][42] The ink was diluted 1:10 with 24 vol% isopropanol/water and sonicated to assure a proper dispersion of the catalyst. The GC was polished with 0.05 μm alumina slurry (Pine Instruments) for at least 10 minutes to achieve a mirror-like finish.…”

Section: Deposition Of Ni(oh)mentioning

confidence: 99%

Pt/C/Ni(OH)₂Bi-Functional Electrocatalyst for Enhanced Hydrogen Evolution Reaction Activity under Alkaline Conditions

Wang

Parrondo

et al. 2017

J. Electrochem. Soc.

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The kinetics of hydrogen evolution and hydrogen oxidation reactions (HER/HOR) in alkaline electrolyte on Pt/C and a Pt/C/Ni(OH) 2 bi-functional electrocatalyst were studied. The objective was to investigate the enhancement of hydrogen evolution activity of Pt in alkaline environments in presence of transition metal hydroxides, and to determine the optimum concentration of Ni(OH) 2 to be added to maximize catalytic activity. The catalysts were prepared by mixing colloidal dispersions of nanosized Ni(OH) 2 with a commercially-sourced Pt/C catalyst dispersed in water. Rotating disk electrode (RDE) measurements were performed in 0.1 M KOH at temperatures ranging from 273.15 K to 303.15 K, and the HOR/HER kinetic currents, obtained after IR and mass transport corrections, were fitted using the Butler-Volmer equation to estimate the exchange current densities at each temperature. Arrhenius plots showed very similar activation energies for Pt/C (35 ± 6 kJ/mol) and the bi-functional catalysts (38 ± 6 kJ/mol) -Pt/C/X%Ni(OH) 2 . The maximum exchange current density (2.44 ± 0.07 mA cm −2 Pt at 303.15 K) was obtained with the catalyst containing 10 wt% Ni(OH) 2 , and was 2.4 times higher than for Pt/C (1.03 ± 0.07 mA cm −2 Pt at 303.15 K). The bi-functional catalysts were evaluated in a hydroxide-exchange membrane water electrolyzer operated with ultrapure water, and outperformed Pt/C by about 0.15 V across the entire current density range.

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Pyrochlore electrocatalysts for efficient alkaline water electrolysis

Abstract: Lead ruthenate pyrochlore showed exceptional OER activity and stability when tested in a solid-state alkaline water electrolyzer.

Cited by 106 publications

References 58 publications

OER activity manipulated by IrO6 coordination geometry: an insight from pyrochlore iridates

OER activity manipulated by IrO6 coordination geometry: an insight from pyrochlore iridates

Design and Synthesis of FeOOH/CeO₂ Heterolayered Nanotube Electrocatalysts for the Oxygen Evolution Reaction

Pt/C/Ni(OH)₂Bi-Functional Electrocatalyst for Enhanced Hydrogen Evolution Reaction Activity under Alkaline Conditions

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Pyrochlore electrocatalysts for efficient alkaline water electrolysis

Abstract: Lead ruthenate pyrochlore showed exceptional OER activity and stability when tested in a solid-state alkaline water electrolyzer.

Cited by 106 publications

References 58 publications

OER activity manipulated by IrO6 coordination geometry: an insight from pyrochlore iridates

OER activity manipulated by IrO6 coordination geometry: an insight from pyrochlore iridates

Design and Synthesis of FeOOH/CeO2 Heterolayered Nanotube Electrocatalysts for the Oxygen Evolution Reaction

Pt/C/Ni(OH)2Bi-Functional Electrocatalyst for Enhanced Hydrogen Evolution Reaction Activity under Alkaline Conditions

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Design and Synthesis of FeOOH/CeO₂ Heterolayered Nanotube Electrocatalysts for the Oxygen Evolution Reaction

Pt/C/Ni(OH)₂Bi-Functional Electrocatalyst for Enhanced Hydrogen Evolution Reaction Activity under Alkaline Conditions