In-situ polarization modulation IRRAS investigation of ammonia electrooxidation on Pt-Ir and Pt-Ru nanoparticles prepared on engineered catalyst supports

Niloofar Aligholizadeh K; Natalia Alzate-Carvajal; Ashwini R. Nallayagari; Evans A. Monyoncho; Barr Zulevi; Alexey Serov; Elena A. Baranova

doi:10.1016/j.electacta.2024.145046

In-situ polarization modulation IRRAS investigation of ammonia electrooxidation on Pt-Ir and Pt-Ru nanoparticles prepared on engineered catalyst supports

Niloofar Aligholizadeh K, Natalia Alzate-Carvajal, Ashwini R. Nallayagari, Evans A. Monyoncho, Barr Zulevi, Alexey Serov, Elena A. Baranova

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Abstract

The catalytic activity and surface reactivity of monometallic Pt and bimetallic Pt-Ir and Pt-Ru nanoparticles, supported on two distinct Engineered Catalyst Supports (ECSs), were investigated for the Ammonia Electrooxidation Reaction (AmER) in alkaline media. XRD measurements confirmed alloy formation between Pt-Ir and Pt-Ru nanoparticles, as indicated by the shift of the (111) reflection to higher 2θ values. Cyclic voltammetry, linear sweep voltammetry, and chronoamperometry experiments were conducted to assess the catalytic activity of the Pt, Pt-Ir, and Pt-Ru electrocatalysts. All bimetallic catalysts exhibited lower onset potentials compared to Pt. The differing Tafel slopes between Pt (74 mV dec⁻¹), Pt-Ir (152 mV dec⁻¹), and Pt-Ru (118–197 mV dec⁻¹) suggest that alloying Pt with Ir or Ru alters the reaction mechanisms. Furthermore, the bimetallic Pt-Ir and Pt-Ru catalysts demonstrated greater tolerance for concentrated ammonia solutions relative to Pt. In-situ Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) provided insights into the formation of N-H species, azide anions (N₃⁻), and N-O compounds. For the Pt-Ru catalyst, an additional peak around ∼3600 cm⁻¹ was observed, corresponding to OH⁻ species. The PM-IRRAS results align with the Gerischer–Mauerer mechanism, indicating that partially dehydrogenated ammonia adsorbates act as active intermediates in the oxidation of ammonia over Pt-Ir and Pt-Ru catalysts.

Original language	English
Article number	145046
Journal	Electrochimica Acta
Volume	507
DOIs	https://doi.org/10.1016/j.electacta.2024.145046
State	Published - Dec 10 2024

Funding

This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant (RGPIN05494). This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE), and by Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the U.S. Department of Energy (DOE) under Contract No DE-AC36-08GO28308. This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant ( RGPIN05494 ). This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE) , and by Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308 .

Funders	Funder number
National Renewable Energy Laboratory
Natural Sciences and Engineering Research Council of Canada	DE-AC05-00OR22725, RGPIN05494
U.S. Department of Energy	DE-AC36-08GO28308

Keywords

Ammonia electrooxidation
Bimetallic nanoparticles (Pt-Ir, Pt-Ru)
Engineered catalyst supports (ECSs)
Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS)

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10.1016/j.electacta.2024.145046

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title = "In-situ polarization modulation IRRAS investigation of ammonia electrooxidation on Pt-Ir and Pt-Ru nanoparticles prepared on engineered catalyst supports",

abstract = "The catalytic activity and surface reactivity of monometallic Pt and bimetallic Pt-Ir and Pt-Ru nanoparticles, supported on two distinct Engineered Catalyst Supports (ECSs), were investigated for the Ammonia Electrooxidation Reaction (AmER) in alkaline media. XRD measurements confirmed alloy formation between Pt-Ir and Pt-Ru nanoparticles, as indicated by the shift of the (111) reflection to higher 2θ values. Cyclic voltammetry, linear sweep voltammetry, and chronoamperometry experiments were conducted to assess the catalytic activity of the Pt, Pt-Ir, and Pt-Ru electrocatalysts. All bimetallic catalysts exhibited lower onset potentials compared to Pt. The differing Tafel slopes between Pt (74 mV dec⁻¹), Pt-Ir (152 mV dec⁻¹), and Pt-Ru (118–197 mV dec⁻¹) suggest that alloying Pt with Ir or Ru alters the reaction mechanisms. Furthermore, the bimetallic Pt-Ir and Pt-Ru catalysts demonstrated greater tolerance for concentrated ammonia solutions relative to Pt. In-situ Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) provided insights into the formation of N-H species, azide anions (N₃⁻), and N-O compounds. For the Pt-Ru catalyst, an additional peak around ∼3600 cm⁻¹ was observed, corresponding to OH⁻ species. The PM-IRRAS results align with the Gerischer–Mauerer mechanism, indicating that partially dehydrogenated ammonia adsorbates act as active intermediates in the oxidation of ammonia over Pt-Ir and Pt-Ru catalysts.",

keywords = "Ammonia electrooxidation, Bimetallic nanoparticles (Pt-Ir, Pt-Ru), Engineered catalyst supports (ECSs), Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS)",

author = "K, {Niloofar Aligholizadeh} and Natalia Alzate-Carvajal and Nallayagari, {Ashwini R.} and Monyoncho, {Evans A.} and Barr Zulevi and Alexey Serov and Baranova, {Elena A.}",

note = "Publisher Copyright: {\textcopyright} 2024",

year = "2024",

month = dec,

day = "10",

doi = "10.1016/j.electacta.2024.145046",

language = "English",

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journal = "Electrochimica Acta",

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T1 - In-situ polarization modulation IRRAS investigation of ammonia electrooxidation on Pt-Ir and Pt-Ru nanoparticles prepared on engineered catalyst supports

AU - K, Niloofar Aligholizadeh

AU - Alzate-Carvajal, Natalia

AU - Nallayagari, Ashwini R.

AU - Monyoncho, Evans A.

AU - Zulevi, Barr

AU - Serov, Alexey

AU - Baranova, Elena A.

PY - 2024/12/10

Y1 - 2024/12/10

N2 - The catalytic activity and surface reactivity of monometallic Pt and bimetallic Pt-Ir and Pt-Ru nanoparticles, supported on two distinct Engineered Catalyst Supports (ECSs), were investigated for the Ammonia Electrooxidation Reaction (AmER) in alkaline media. XRD measurements confirmed alloy formation between Pt-Ir and Pt-Ru nanoparticles, as indicated by the shift of the (111) reflection to higher 2θ values. Cyclic voltammetry, linear sweep voltammetry, and chronoamperometry experiments were conducted to assess the catalytic activity of the Pt, Pt-Ir, and Pt-Ru electrocatalysts. All bimetallic catalysts exhibited lower onset potentials compared to Pt. The differing Tafel slopes between Pt (74 mV dec⁻¹), Pt-Ir (152 mV dec⁻¹), and Pt-Ru (118–197 mV dec⁻¹) suggest that alloying Pt with Ir or Ru alters the reaction mechanisms. Furthermore, the bimetallic Pt-Ir and Pt-Ru catalysts demonstrated greater tolerance for concentrated ammonia solutions relative to Pt. In-situ Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) provided insights into the formation of N-H species, azide anions (N₃⁻), and N-O compounds. For the Pt-Ru catalyst, an additional peak around ∼3600 cm⁻¹ was observed, corresponding to OH⁻ species. The PM-IRRAS results align with the Gerischer–Mauerer mechanism, indicating that partially dehydrogenated ammonia adsorbates act as active intermediates in the oxidation of ammonia over Pt-Ir and Pt-Ru catalysts.

AB - The catalytic activity and surface reactivity of monometallic Pt and bimetallic Pt-Ir and Pt-Ru nanoparticles, supported on two distinct Engineered Catalyst Supports (ECSs), were investigated for the Ammonia Electrooxidation Reaction (AmER) in alkaline media. XRD measurements confirmed alloy formation between Pt-Ir and Pt-Ru nanoparticles, as indicated by the shift of the (111) reflection to higher 2θ values. Cyclic voltammetry, linear sweep voltammetry, and chronoamperometry experiments were conducted to assess the catalytic activity of the Pt, Pt-Ir, and Pt-Ru electrocatalysts. All bimetallic catalysts exhibited lower onset potentials compared to Pt. The differing Tafel slopes between Pt (74 mV dec⁻¹), Pt-Ir (152 mV dec⁻¹), and Pt-Ru (118–197 mV dec⁻¹) suggest that alloying Pt with Ir or Ru alters the reaction mechanisms. Furthermore, the bimetallic Pt-Ir and Pt-Ru catalysts demonstrated greater tolerance for concentrated ammonia solutions relative to Pt. In-situ Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) provided insights into the formation of N-H species, azide anions (N₃⁻), and N-O compounds. For the Pt-Ru catalyst, an additional peak around ∼3600 cm⁻¹ was observed, corresponding to OH⁻ species. The PM-IRRAS results align with the Gerischer–Mauerer mechanism, indicating that partially dehydrogenated ammonia adsorbates act as active intermediates in the oxidation of ammonia over Pt-Ir and Pt-Ru catalysts.

KW - Ammonia electrooxidation

KW - Bimetallic nanoparticles (Pt-Ir, Pt-Ru)

KW - Engineered catalyst supports (ECSs)

KW - Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS)

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U2 - 10.1016/j.electacta.2024.145046

DO - 10.1016/j.electacta.2024.145046

M3 - Article

AN - SCOPUS:85204451090

SN - 0013-4686

VL - 507

JO - Electrochimica Acta

JF - Electrochimica Acta

M1 - 145046

ER -

In-situ polarization modulation IRRAS investigation of ammonia electrooxidation on Pt-Ir and Pt-Ru nanoparticles prepared on engineered catalyst supports

Abstract

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Keywords

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