Impact of Ir-Valence Control and Surface Nanostructure on Oxygen Evolution Reaction over a Highly Efficient Ir-TiO2 Nanorod Catalyst

Junfang Cheng; Jun Yang; Sho Kitano; Gergely Juhasz; Manabu Higashi; Masaaki Sadakiyo; Kenichi Kato; Satoru Yoshioka; Takeharu Sugiyama; Miho Yamauchi; Naotoshi Nakashima

doi:10.1021/acscatal.9b01438

Impact of Ir-Valence Control and Surface Nanostructure on Oxygen Evolution Reaction over a Highly Efficient Ir-TiO₂ Nanorod Catalyst

Junfang Cheng, Jun Yang, Sho Kitano, Gergely Juhasz, Manabu Higashi, Masaaki Sadakiyo, Kenichi Kato, Satoru Yoshioka, Takeharu Sugiyama, Miho Yamauchi, Naotoshi Nakashima^*

^*Corresponding author for this work

Research Organization for Nano & Life Innovation

Research output: Contribution to journal › Article › peer-review

86 Citations (Scopus)

Abstract

Iridium oxide (IrO_x)-based materials are the most suitable oxygen evolution reaction (OER) catalysts for water electrolysis in acidic media. There is a strong demand from industry for improved performance and reduction of the Ir amount. Here, we report a composite catalyst, IrO_x-TiO₂-Ti (ITOT), with a high concentration of active OH species and mixed valence IrO_x on its surface. We have discovered that the obtained ITOT catalyst shows an outstanding OER activity (1.43 V vs RHE at 10 mA cm^-2) in acidic media. Moreover, no apparent potential increase was observed even after a chronopotentiometry test at 10 mA cm^-2 for 100 h and cyclic voltammetry for 700 cycles. We proposed a detailed OER mechanism on the basis of the analysis of the in situ electrochemical X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements as well as density functional theory (DFT) calculations. All together, we have concluded that controllable Ir-valence and the high OH concentration in the catalyst is crucial for the obtained high OER activity.

Original language	English
Pages (from-to)	6974-6986
Number of pages	13
Journal	ACS Catalysis
Volume	9
Issue number	8
DOIs	https://doi.org/10.1021/acscatal.9b01438
Publication status	Published - 2019 Aug 2

Keywords

Ir-oxide catalyst
in situ electrochemical XANES and EXAFS
iridium-valence-engineering
oxygen evolution reaction (OER)

ASJC Scopus subject areas

Catalysis
Chemistry(all)

Access to Document

10.1021/acscatal.9b01438

Cite this

@article{dcef56ada99b4bd7bb3a6f25047dd6d4,

title = "Impact of Ir-Valence Control and Surface Nanostructure on Oxygen Evolution Reaction over a Highly Efficient Ir-TiO2 Nanorod Catalyst",

abstract = "Iridium oxide (IrOx)-based materials are the most suitable oxygen evolution reaction (OER) catalysts for water electrolysis in acidic media. There is a strong demand from industry for improved performance and reduction of the Ir amount. Here, we report a composite catalyst, IrOx-TiO2-Ti (ITOT), with a high concentration of active OH species and mixed valence IrOx on its surface. We have discovered that the obtained ITOT catalyst shows an outstanding OER activity (1.43 V vs RHE at 10 mA cm-2) in acidic media. Moreover, no apparent potential increase was observed even after a chronopotentiometry test at 10 mA cm-2 for 100 h and cyclic voltammetry for 700 cycles. We proposed a detailed OER mechanism on the basis of the analysis of the in situ electrochemical X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements as well as density functional theory (DFT) calculations. All together, we have concluded that controllable Ir-valence and the high OH concentration in the catalyst is crucial for the obtained high OER activity.",

keywords = "Ir-oxide catalyst, in situ electrochemical XANES and EXAFS, iridium-valence-engineering, oxygen evolution reaction (OER)",

author = "Junfang Cheng and Jun Yang and Sho Kitano and Gergely Juhasz and Manabu Higashi and Masaaki Sadakiyo and Kenichi Kato and Satoru Yoshioka and Takeharu Sugiyama and Miho Yamauchi and Naotoshi Nakashima",

note = "Funding Information: This work was supported by Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST). The synchrotron radiation experiments were performed using the BL44B2 beamline in SPring-8 (Japan) with the approval of RIKEN Funding Information: This work was supported by Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST). The synchrotron radiation experiments were performed using the BL44B2 beamline in SPring-8 (Japan) with the approval of RIKEN. Publisher Copyright: {\textcopyright} 2019 American Chemical Society.",

year = "2019",

month = aug,

day = "2",

doi = "10.1021/acscatal.9b01438",

language = "English",

volume = "9",

pages = "6974--6986",

journal = "ACS Catalysis",

issn = "2155-5435",

publisher = "American Chemical Society",

number = "8",

}

TY - JOUR

T1 - Impact of Ir-Valence Control and Surface Nanostructure on Oxygen Evolution Reaction over a Highly Efficient Ir-TiO2 Nanorod Catalyst

AU - Cheng, Junfang

AU - Yang, Jun

AU - Kitano, Sho

AU - Juhasz, Gergely

AU - Higashi, Manabu

AU - Sadakiyo, Masaaki

AU - Kato, Kenichi

AU - Yoshioka, Satoru

AU - Sugiyama, Takeharu

AU - Yamauchi, Miho

AU - Nakashima, Naotoshi

N1 - Funding Information: This work was supported by Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST). The synchrotron radiation experiments were performed using the BL44B2 beamline in SPring-8 (Japan) with the approval of RIKEN Funding Information: This work was supported by Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST). The synchrotron radiation experiments were performed using the BL44B2 beamline in SPring-8 (Japan) with the approval of RIKEN. Publisher Copyright: © 2019 American Chemical Society.

PY - 2019/8/2

Y1 - 2019/8/2

N2 - Iridium oxide (IrOx)-based materials are the most suitable oxygen evolution reaction (OER) catalysts for water electrolysis in acidic media. There is a strong demand from industry for improved performance and reduction of the Ir amount. Here, we report a composite catalyst, IrOx-TiO2-Ti (ITOT), with a high concentration of active OH species and mixed valence IrOx on its surface. We have discovered that the obtained ITOT catalyst shows an outstanding OER activity (1.43 V vs RHE at 10 mA cm-2) in acidic media. Moreover, no apparent potential increase was observed even after a chronopotentiometry test at 10 mA cm-2 for 100 h and cyclic voltammetry for 700 cycles. We proposed a detailed OER mechanism on the basis of the analysis of the in situ electrochemical X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements as well as density functional theory (DFT) calculations. All together, we have concluded that controllable Ir-valence and the high OH concentration in the catalyst is crucial for the obtained high OER activity.

AB - Iridium oxide (IrOx)-based materials are the most suitable oxygen evolution reaction (OER) catalysts for water electrolysis in acidic media. There is a strong demand from industry for improved performance and reduction of the Ir amount. Here, we report a composite catalyst, IrOx-TiO2-Ti (ITOT), with a high concentration of active OH species and mixed valence IrOx on its surface. We have discovered that the obtained ITOT catalyst shows an outstanding OER activity (1.43 V vs RHE at 10 mA cm-2) in acidic media. Moreover, no apparent potential increase was observed even after a chronopotentiometry test at 10 mA cm-2 for 100 h and cyclic voltammetry for 700 cycles. We proposed a detailed OER mechanism on the basis of the analysis of the in situ electrochemical X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements as well as density functional theory (DFT) calculations. All together, we have concluded that controllable Ir-valence and the high OH concentration in the catalyst is crucial for the obtained high OER activity.

KW - Ir-oxide catalyst

KW - in situ electrochemical XANES and EXAFS

KW - iridium-valence-engineering

KW - oxygen evolution reaction (OER)

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U2 - 10.1021/acscatal.9b01438

DO - 10.1021/acscatal.9b01438

M3 - Article

AN - SCOPUS:85071019338

SN - 2155-5435

VL - 9

SP - 6974

EP - 6986

JO - ACS Catalysis

JF - ACS Catalysis

IS - 8

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