Exclusive formation of alloy phases via anchoring technique—From bimetallic catalysts to electrocatalysis

I. Borbáth, D. Gubán, I. Bakos, Z. Pászti, G. Gajdos, I. Sajó, Vass, A. Tompos

Research output: Contribution to journalArticle

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Abstract

Alloy-type Sn-Pt/C electrocatalysts with desired Pt/Sn = 3.0 ratio have been prepared using commercial 20 wt.% Pt/C (20Pt/C (Q: Quintech)) and home-made 20Pt/C (H) catalysts by means of Controlled Surface Reactions. According to in situ XPS and in situ XRD studies the exclusive incorporation of Sn onto the Pt sites was achieved resulting in exclusive formation of Pt-Sn alloy phase. No evidence of the presence of SnO2 phase was found by means of the XRD and EDS analysis. According to in situ XPS studies pre-treatment of the air exposed catalyst in H2 even at 170 °C resulted in complete reduction of the ionic tin to Sn0, suggesting alloy formation. After contact of Sn-Pt/C catalysts with air Sn tends to segregate to the surface, where it oxidizes to a certain extent. Reversible interconversion of PtSn ↔ Sn4+ + Pt in the presence of O2 and H2 was convincingly demonstrated by in situ XPS and in situ XRD studies. The electrocatalytic performance of the alloy catalysts was tested in CO oxidation and oxygen reduction reaction (ORR). Only minor changes of the surface composition of the Sn-20Pt/C electrocatalysts were observed after 20 polarization cycles. Better performance in the CO electrooxidation for our Sn-Pt/C catalysts compared to the state-of-art CO tolerant PtRu/C benchmark was demonstrated. Optimal surface composition of the Sn-20Pt/C (H) catalysts results in increased activity in the ORR compared to the Sn-20Pt/C (Q) and both parent 20Pt/C catalysts.

Original languageEnglish
Pages (from-to)58-70
Number of pages13
JournalCatalysis Today
Volume306
DOIs
Publication statusPublished - May 15 2018

Fingerprint

Electrocatalysis
Catalysts
Carbon Monoxide
X ray photoelectron spectroscopy
Electrocatalysts
Surface structure
Oxygen
Tin
Electrooxidation
Surface reactions
Air
Contacts (fluid mechanics)
Energy dispersive spectroscopy
Polarization
Oxidation

Keywords

  • Anode catalyst
  • CO electrooxidation
  • Controlled surface reactions
  • Oxygen reduction reaction
  • PtSn
  • PtSn/C electrocatalysts

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

Cite this

Exclusive formation of alloy phases via anchoring technique—From bimetallic catalysts to electrocatalysis. / Borbáth, I.; Gubán, D.; Bakos, I.; Pászti, Z.; Gajdos, G.; Sajó, I.; Vass, ; Tompos, A.

In: Catalysis Today, Vol. 306, 15.05.2018, p. 58-70.

Research output: Contribution to journalArticle

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AU - Borbáth, I.

AU - Gubán, D.

AU - Bakos, I.

AU - Pászti, Z.

AU - Gajdos, G.

AU - Sajó, I.

AU - Vass,

AU - Tompos, A.

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AB - Alloy-type Sn-Pt/C electrocatalysts with desired Pt/Sn = 3.0 ratio have been prepared using commercial 20 wt.% Pt/C (20Pt/C (Q: Quintech)) and home-made 20Pt/C (H) catalysts by means of Controlled Surface Reactions. According to in situ XPS and in situ XRD studies the exclusive incorporation of Sn onto the Pt sites was achieved resulting in exclusive formation of Pt-Sn alloy phase. No evidence of the presence of SnO2 phase was found by means of the XRD and EDS analysis. According to in situ XPS studies pre-treatment of the air exposed catalyst in H2 even at 170 °C resulted in complete reduction of the ionic tin to Sn0, suggesting alloy formation. After contact of Sn-Pt/C catalysts with air Sn tends to segregate to the surface, where it oxidizes to a certain extent. Reversible interconversion of PtSn ↔ Sn4+ + Pt in the presence of O2 and H2 was convincingly demonstrated by in situ XPS and in situ XRD studies. The electrocatalytic performance of the alloy catalysts was tested in CO oxidation and oxygen reduction reaction (ORR). Only minor changes of the surface composition of the Sn-20Pt/C electrocatalysts were observed after 20 polarization cycles. Better performance in the CO electrooxidation for our Sn-Pt/C catalysts compared to the state-of-art CO tolerant PtRu/C benchmark was demonstrated. Optimal surface composition of the Sn-20Pt/C (H) catalysts results in increased activity in the ORR compared to the Sn-20Pt/C (Q) and both parent 20Pt/C catalysts.

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