2010B1784                           BL14B2

In-situ XAFS ࢆ⏝࠸ࡓᢸᣢ㔠ࢡࣛࢫࢱ࣮ゐ፹࡟࠾ࡅࡿ㔠ᒓ㓟໬≀ࡢ㓟໬㑏ඖᣲື࡟㛵ࡍࡿ◊✲A study of redox behavior for metal oxides with deposited gold cluster using
in-situ XAFS኱ᶫ ᘯ⠊ a,c, ᓥ⏣ ᝅྐ b,c, 㔝ᮏ ಙஓ b,c, ㎞ᔱ ఙᙪ b,c, ᕝᮏ ኱♸ d, Ṋ஭ Ꮥ b,c, ᫓⏣ ṇẎ b,cHironori Ohashia,c, Satoshi Shimadab,c, Shinya Nomotob,c, Nobuhiko Karashimab,c, Daisuke Kawamotod,
Takashi Takeib,c Masatake Harutab,ca஑኱㧗᥎ࢭ, b 㤳㒔኱㝔㒔ᕷ⎔ቃ, cJST, CREST, d ஑኱㝔⌮Center for Research and Advancement in Higher Education, Kyushu University, bGraduate School of Urban Environmental Sciences, Tokyo Metropolitan University , cJST, CRESTdGraduate School of Sciences, Kyushu Universityaࣅ࣮࣒ࣛ࢖ࣥ BL14B2 ࡟࡚ࠊ㔠⢏Ꮚࢆᢸᣢࡋࡓᅄ㓟໬୕ࢥࣂࣝࢺࡢỈ⣲㞺ᅖẼୗ࡛ࡢ㑏ඖᣲືࢆ ᐃࡋࡓࠋIn-situ XAFS ࡢ⤖ᯝ࠿ࡽࠊỈ⣲㞺ᅖẼୗ࡛ 200Υࡲ࡛᪼ ࡉࡏࡓሙྜ࡟ࠊᢸᣢࡉࡏࡓ㔠⢏Ꮚࡢຠᯝ࡛ Co㻔III㻕࠿ࡽ Co㻔II㻕࡬ࡢ㑏ඖࡉࡽ࡟ Co㻔II㻕࠿ࡽ Co㻔0㻕ࡀ㒊ศⓗ࡟㉳ࡇࡿࡇ࡜ࡀࢃ࠿ࡗ
ࡓࠋ࣮࣮࢟࣡ࢻ㸸 㔠ゐ፹ࠊin-situ XAFSࠊỈ⣲㑏ඖ⫼ᬒ࡜◊✲┠ⓗ㸸 ໬Ꮫⓗ࡟Ᏻᐃ࡛࠶ࡿ㔠ࡣࠊࢼࣀ⢏Ꮚ࡜ࡋ࡚㓟໬≀࡞࡝࡟ᢸᣢࡍࡿࡇ࡜࡛ప ࡟࠾ࡅࡿ CO 㓟໬࡟௦⾲ࡉࢀࡿ≉␗࡞ゐ፹άᛶࢆⓎ⌧ࡍࡿ [1][2]ࠋ㏆ᖺࠊ㔠ࡀࢡࣛࢫࢱ࣮ࢧ࢖ࢬ࡟࡞ࡿ࡜ࡇࢀࡲ࡛ሗ࿌ࡉࢀ࡞࠿ࡗࡓゐ፹≉ᛶࡀⓎ⌧ࡍࡿࡇ࡜ࡀࢃ࠿ࡗ࡚ࡁࡓࠋࡑࡢ୰࡛ࡶ㓟໬ࢥࣂࣝࢺᢸᣢ㔠ゐ፹
㻔Au/Co3O4㻕࡟ࡘ࠸࡚ࡣࠊ≉࡟ゐ፹ⓗ㑏ඖ཯ᛂ୰࡟࠾࠸࡚ࠊ㔠ࡀᢸయࡢ㑏ඖࢆಁ㐍ࡍࡿᶵ⬟ࢆᣢࡘࡓࡵ࡟ゐ፹άᛶࡀୖ᪼ࡍࡿࡢ࡛ࡣ࡞࠸࠿ࠊ࡜⪃࠼ࡽࢀࡿ⯆࿡῝࠸ᐇ㦂⤖ᯝࡀᚓࡽࢀࡓࠋࡲࡓࡇࡢᐇ㦂⤖ᯝ࡟㛵㐃ࡋ࡚ࠊ㔠ࢼࣀ⢏Ꮚࢆᢸᣢࡉࡏࡓ㓟໬ࢥࣂࣝࢺࡣࠊ㓟໬ࢥࣂࣝࢺࡢࡳࡢሙྜ࡜ẚ㍑
ࡋ࡚ࠊỈ⣲Ẽὶ୰࡛ࡢ㑏ඖ ᗘࡢⴭࡋ࠸పୗࡀほ ࡉࢀࡓࠋࡍ࡞ࢃࡕࠊ㓟໬ࢥࣂࣝࢺࡣ㔠࡟ࡼࡗ࡚㑏ඖࡉࢀࡸࡍࡃ࡞ࡗࡓ࡜⪃࠼ࡿࡇ࡜ࡀ࡛ࡁࡿࠋࡋ࠿ࡋ࡞ࡀࡽࡑࡢ⌧㇟ࢆࡑࡢሙほ ࡛ ᐃࡋࡓ౛ࡣᑡ࡞ࡃࠊỴᐃⓗ࡞ドᣐࡣ࡞࠸ࠋࡇࡢࡼ࠺࡟ࠊ㔠ࡀᢸయࡢ㔠ᒓ㓟໬≀࡟ఱࡽ࠿ࡢᙳ㡪ࢆཬࡰࡋ࡚࠸ࡿࡇ࡜ࡀࢃ࠿ࡗࡓࡀࠊࡑࡢຠᯝࡀ࡝ࡢࡼ࠺࡞᮲௳࡛Ⓨ⌧ࡍࡿࡢ࠿࡟ࡘ࠸࡚ヲ⣽ࡀࢃ࠿ࡗ࡚࠾ࡽࡎࠊ᫂☜࡞ゐ፹タィᣦ㔪ࡀ❧ࡓ࡞࠸ࡓࡵᡭ᥈ࡾࡢ≧ែࡀ⥆࠸࡚࠸ࡿࠋ௒ᅇࡢᐇ㦂࡛ࡣࠊỈ⣲ὶ㏻ୗ࡛ࡢ XAFS ᐃ࠿ࡽ㔠ᒓ㓟໬≀ࡢ㓟໬㑏ඖᣲືࢆホ౯ࡍࡿࠋࡇࢀࡽࡢ⤖ᯝ࠿ࡽࠊ㔠ࢡࣛࢫࢱ࣮ࡀ㔠ᒓ㓟໬≀ࡢ㓟໬㑏ඖ࡟࡝ࡢࡼ࠺࡟ᐤ୚ࡋ࡚࠸ࡿࡢ࠿ࢆ᫂ࡽ࠿࡟ࡍࡿࡇ࡜ࢆ◊✲ࡢ┠ⓗ࡜ࡋࡓࠋᐇ㦂㸸 ᅄ㓟໬୕ࢥࣂࣝࢺᢸᣢ㔠ゐ፹ࡣࠊ◪㓟ࢥࣂࣝࢺ㻔II㻕Ỉ⁐ᾮ࡜ࢸࢺࣛࢡࣟࣟ㔠㻔III㻕㓟Ỉ⁐ᾮࢆ⏝࠸ࡓࠋᚑ᮶ࡢඹỿἲ㸦CP ἲ㸧ࢆ⏝࠸࡚ㄪ〇ࡋࠊ✵Ẽୗ࡛ 300Υ4 ᫬㛫↝ᡂࡉࡏ㔠㻔0㻕ࢆᢸᣢࡉࡏࡓ≧ែ࡜ࡋࡓࠋSPring-8 ࡢ BL14B2 ࣅ࣮࣒ࣛ࢖ࣥ࡟࡚㏱㐣ἲ࡟ࡼࡿ Co-K ➃ XAFS ᐃࢆ⾜ࡗࡓࠋࢧࣥࣉࣝࢆ⢊ᮎ≧ែ࡛ ᐃྍ⬟࡞ᑓ⏝ࡢ in-situ ᐃ࢞ࣛࢫࢭࣝ㸦⮬స㸧࡟ᑟධࡋࠊỈ⣲ୗ࡛᪼ ࡋࠊ200 oC ࡟ಖࡕ࡞ࡀࡽ in-situ XAFS ࢫ࣌ࢡࢺࣝࢆ ᐃࡋࡓࠋࢫ࣌ࢡࢺࣝࡢゎᯒ࡟ࡣ Ifeffit ࡢ Athenaࢆ⏝࠸ࡓࠋ⤖ᯝ࠾ࡼࡧ⪃ᐹ㸸 ᅗ 1 ࡟ඹỿἲ࡛ㄪ〇ࡋࡓᅄ㓟໬୕ࢥࣂࣝࢺᢸᣢ㔠ゐ፹ࢆ᪼ ࡉࡏࠊ200Υ࡛Ỉ⣲㞺ᅖẼୗ࡛ᐃࢆ㔜ࡡࡓ࡜ࡁࡢ Co-K ➃ࡢ XANES ࢫ࣌ࢡࢺࣝࡢ᫬㛫ኚ໬ࢆ♧ࡍࠋࢫ࣌ࢡࢺࣝࡣ㠀ᖖ࡟」㞧࡞ኚ໬ࢆࡍࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋ྾཰➃ࡢࢫ࣌ࢡࢺࣝࡢᙧ≧࠿ࡽ Co㻔III㻕࡜ Co㻔II㻕ࡢΰྜ≧ែ࡛࠶ࡿࡇ

Normalized Absorption

Normalized Absorption࡜ࡀண᝿ࡉࢀࡓࡀࠊࢫ࣌ࢡࢺࣝࡢ XANES㡿ᇦࢆࡇࡢ 2 ࡘ࡛ Fitting ࡋࡓ࡜ࡇࢁࠊ࡝
1.6
ࡢẚ⋡࡟࠾࠸࡚ࡶⰋ࠸ྜ⮴ࡀᚓࡽࢀ࡞࠿
1.4
noiseࡗࡓࠋࡑࡇ࡛ࠊ྾཰➃┤๓ࡢ㒊ศ㸦ࣉࣞ
1.2࢚ࢵࢪࣆ࣮ࢡ㸧࡟╔┠ࡋࡓࠋ྾཰➃┤๓
1.0㒊ศࢆᣑ኱ࡋࡓࢫ࣌ࢡࢺࣝࢆᅗ 2 ࡟♧
0.8ࡍࠋࡇࡢࢫ࣌ࢡࢺ࡛ࣝࡣ 7.71 keV ௜㏆࡟ࠊ
0.6
Co㻔II㻕, Co㻔III㻕࡛ࡣぢࡽࢀ࡞࠸ࣆ࣮ࢡࡀฟ
0.4⌧ࡋ࡚࠸ࡿࠋࡇࢀࡣࠊᶆ‽≀㉁ࡢ ᐃ࠿
ࡽ Co㻔0㻕ࡢࣆ࣮ࢡ࡛࠶ࡿ࡜ᖐᒓࡉࢀࡿࠋ
0.2
Co㻔0㻕ࡣ྾཰➃௜㏆࡛ࡢ᫂░࡞ࣆ࣮ࢡᙧ0.0≧ࡀ࡞࠸㸦྾཰➃௜㏆ࡢᙧ≧ࡀࡼࡾ
7.68
7.71
7.74
7.77
7.80
7.83
arctan 㛵ᩘ࡟㏆࠸㸧ࡇ࡜࠿ࡽࠊXANES ࢫ
Photon Energy / keV࣌ࢡࢺ࡛ࣝࡣ Co㻔II㻕ࡸ Co㻔III㻕ࡢࣆ࣮ࢡ࡟
ᅗ 1㸬Ỉ⣲㞺ᅖẼ࡛ 200Υ࡟ಖᣢࡋࡓሙྜࡢඹỿἲ࡛ㄪ〇ࡋ㞃ࢀ࡚ Co㻔0㻕ࡢࣆ࣮ࢡࡀᏑᅾࡋ࡚࠸ࡓ࡜
ࡓ Au / Co3O4 ࡢ Co-K ➃ XANES ࢫ࣌ࢡࢺࣝࡢ᫬㛫ኚ⪃࠼ࡿࡇ࡜ࡀ࡛ࡁࡿࠋ௨ୖࡢࡇ࡜࠿ࡽࠊ໬㸦▮༳ࡢ᪉ྥࡣࣆ࣮ࢡࡢ᫬㛫ኚ໬ࡢ᪉ྥࢆ♧ࡍ㸧.
ࢥࣂࣝࢺࡢ≧ែࡣᅄ㓟໬୕ࢥࣂࣝࢺ࠿ࡽ㓟໬ࢥࣂࣝࢺ㻔II㻕࡬ࠊࡉࡽ࡟㔠ᒓࢥࣂࣝࢺ
0.4
࡬࡜ኚ໬ࡋ࡚࠸ࡃࡇ࡜ࡀࢃ࠿ࡗࡓࠋ ࡇࢀࡲ࡛ࡣࠊH2-TPR㸦᪼ ⬺㞳ἲ㸧࡟
0.3
ࡼࡗ࡚ࠊ㔠⢏Ꮚࢆᢸᣢࡉࡏࡓሙྜ࡜ࡉࡏ
࡞࠸ሙྜ࡛ࡣࠊࢥࣂࣝࢺࡢ㑏ඖ ᗘ࡟኱ࡁ࡞㐪࠸ࡀฟࡿࡇ࡜ࡀ♧၀ࡉࢀ࡚࠸ࡓࡀࠊ
0.2
௒ᅇࡢ in-situ XAFS ࡟ࡼࡗ࡚ࡇࡢኚ໬ࡀࠊCo㻔II㻕ࠊCo㻔0㻕࡬ࡢ㑏ඖ࡟ࡼࡿࡶࡢࡔ࡜࠸
0.1
࠺ࡇ࡜ࡀࢃ࠿ࡗࡓࠋࡇࢀࡣࠊH2-TPR ࡟Ḟࡅ࡚࠸ࡿࠕࡑࡢሙ࡛ࡢ Co ࡢ≧ែศᯒࠖ
0.0ࡀ࡛ࡁࡿ in-situ XAFS ࡢ≉ᚩࢆ཯ᫎࡋࡓ
7.700
7.705
7.710
7.715
⤖ᯝ࡜࡞ࡗ࡚࠸ࡿࠋ ୍᪉࡛ࠊH2-TPR ࠿ࡽ♧၀ࡉࢀ࡚࠸ࡓ
Photon Energy / keVࠕCo㻔0㻕࡬ࡢ㑏ඖࠖࡀ XANES ࢫ࣌ࢡࢺࣝᅗ 2㸬Ỉ⣲㞺ᅖẼ࡛ 200Υ࡟ಖᣢࡋࡓሙྜࡢඹỿἲ࡛ㄪ〇ࡢゎᯒ࠿ࡽ 200Υ࡛ࡣ᏶඲࡟⾜ࢃࢀ࡞࠸ࡋࡓ Au / Co3O4 ࡢ Co-K ➃ XANES ࢫ࣌ࢡࢺࣝࡢ᫬ࡇ࡜ࡀ᥎ᐃࡉࢀࠊCo㻔III㻕ࡢ 200Υ࡟࠾ࡅ㛫ኚ໬㸦ࣉ࢚ࣞࢵࢪࣆ࣮ࢡ௜㏆, ᅗ 1 ࡢᣑ኱ᅗ, ▮ࡿỈ⣲࡟ࡼࡿ㑏ඖࡣẁ㝵ⓗ࡟᏶඲࡟ࡣ㐍༳ࡢ᪉ྥࡣࣆ࣮ࢡࡢ᫬㛫ኚ໬ࡢ᪉ྥࢆ♧ࡍ㸧.
⾜ࡏࡎࠊCo㻔III㻕ࠊCo㻔II㻕ࠊCo㻔0㻕ࡢΰᅾࡋࡓ≧ែ࡛࠶ࡿ࡜⪃࠼ࡽࢀࡿࠋࡇࢀࡣࠊCo㻔0㻕ࡣ㔠⢏Ꮚࡢ௜㏆࡟࠶ࡿ⾲㠃㏆ഐࡢ Co㻔II㻕ࡢࡳࡀ Co㻔0㻕࡬࡜㑏ඖࡋ࡚࠸ࡿࡇ࡜㸦㓟໬ࢥࣂࣝࢺ඲య࡟ᑐࡍࡿ Co㻔0㻕࡬ࡢ㑏ඖ㔞ࡀ H2-TPR ࠿ࡽண᝿ࡉࢀࡿࡼࡾࡶⴭࡋࡃᑡ࡞࠸㸧ࢆ♧ࡋࠊ㓟໬≀⢏ᏊࡢỈ⣲Ẽὶ୰࡛ࡢ㑏ඖᣲື࡜ࡋ࡚⯆࿡῝࠸⤖ᯝ࡛࠶ࡿࠋ
௒ᚋࡢㄢ㢟㸸
௒ᚋࡣࠊ⢏Ꮚᚄไᚚࡉࢀࡓᵝࠎ࡞኱ࡁࡉࡢ㔠⢏Ꮚࢆᢸᣢࡉࡏࡓゐ፹ࡸࠊࢩࣜ࢝ࡢࡼ࠺࡞Ỉ⣲ὶ
㏻ୗ࡛ኚ໬ࡋ࡞࠸㔠ᒓ㓟໬≀࡟㓟໬ࢥࣂࣝࢺ࡜㔠⢏Ꮚࢆ୧᪉ᢸᣢࡉࡏࡓࡼ࠺࡞ゐ፹࡛ྠᵝࡢᐇ㦂ࢆ⾜࠸ࢥࣂࣝࢺࡢ㑏ඖᣲືࡢ㐪࠸ࢆㄪ࡭ࡿࡇ࡜࡛ࠊࡼࡾయ⣔ⓗ࡞㆟ㄽࢆࡍࡿᚲせࡀ࠶ࡿࠋᢸᣢ㔞ࢆኚ໬ࡍࡿࡇ࡜࡛ࢥࣂࣝࢺࡢ㑏ඖ㏿ᗘࡣᙜ↛ኚ໬ࡍࡿࡇ࡜ࡀண᝿ࡉࢀࡿࠋ㔠ࡢ⢏Ꮚᚄࡣᢸᣢ㔞ࡶኚ໬ࡍࡿ࡟ࡘࢀ࡚ኚ໬ࡍࡿ࡛࠶ࢁ࠺ࠋࡇࡢྠ᫬ ᐃࡣࠊin-situ XAFS ࡢࡳ࡛ほ ࡛ࡁࡿ㈗㔜࡞ࢸ࣮࣐࡛࠶ࡾࠊ௒ᚋ✚ᴟⓗ࡟ྲྀࡾ⤌ࡳࡓ࠸࡜⪃࠼࡚࠸ࡿࠋཧ⪃ᩥ⊩㸸
[1] M. Haruta, T. Kobayashi, H. Sano, N. Yamada: Chem. Lett., 16, 405 㻔1987㻕.
[2] M. Haruta, S. Tsubota, T. Kobayashi, H. Kageyama, M. J. Genet, B. Delmon: J. Catal., 144, 175 㻔1989㻕.