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¬ÍCN@ªÀ»³êÄ©çÌß50NÌÔ½ray Absorption Fine Structure) Éª¯çêCOÒÍÎÛ

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NH3 Ì¶ÝºCO2 ÌÝð_»ÜÆµÄ]»¦10÷C¢EÛ´qÌßTÉ¶Ý·é´qÌâíÞC£ÉÖ·éîÅÌ94÷tFm[Ið«ÅCx[Æ_f©çêñð^¦éBiÅtFm[ðìèo¹éñíÉDê½G}Å

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é±ÆÔªðªèðÓ}µÄ¢È¢ÊíÌ XAFS ªèÍCð©oµ½2) B¶¬¨ÍCñ_»YfÆf¾¯Å

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èC¼ÌLQÈ¶¬¨ªÈ¢Â«ÉàDµ¢½Å éBlM[ð 1 _²ÆÉÏ¦Ä¿Éæé X üzûÊðvCH3ReO3 ð[ICg×EàÉÅè»µÄ NH3 ÅÏ··ª·éB¬ªèðÚIÆµ½ XAFS ªè@ÆµÄC»éÆCf´qðàïµ½ Re10 NX^[iG}«íj106  úËõ March 2009 Vol.22 No.2(C) 2009 The Japanese Society for Synchrotron Radiation ResearchúËõjFig. 1

The structures of supported Re catalysts on HZSM_5 and aDFT­modeled structure of Re10 cluster.

[X ¡ æ13ñú{úËõwï§ãÜóÜ¤ñFig. 2 (a) The setup of energy­dispersive XAFS and (b) the series
of in­situ time­resolved Re LIII­edge DXAFS of the support­
ed Re10 cluster for the direct phenol synthesis from benzene
and O2 at 553 K.

ªìèo³êé±Æð in­situ XAFS \¢ðÍÉæè¾ç
©Éµ½iFig. 1jB±Ì Re10 NX^[ðx[yÑ_fÆ½³¹éÆC94÷ÌIð«Å¬â©ÉtFm[ð¶¬·éÆ¯ÉCRe10 NX^[Í_fªqÆ½µÄCs«È Re7{ Ìm}[ÖÆÏ»µ½B±Ìs«È Re7{ m}[ÍCG}½·xÅÍ NH3 ÉæÁÄÄÑ«È Re10 NX^[ÖÆÂtIÉÏ·³êéB]ÁÄCèíIÉG}TCNðñ·ÉÍCG}«í
Re10 NX^[ðìèo· NH3 ðèíIÉ·éKvªèCRe m}[ÌRe10 NX^[Ì_Ci~bNÈ\¢Ï»ðºÁÄCtFm[¬G}½ªisµÄ¢é±Æª¾ç©ÉÈÁ½iFig. 1)3)B±Ìæ¤ÈG}½ßöÉ¨¯é_Ci~bNÈG}
«\¢ÌÏ»ðA^CÅÏ@·é½ßÉCx[Æ _ f © ç Ì t F m [   ¬ ß ö É ¨ ¯ é Re LIII [DXANES ð 50 ms  É A ± ª è µ ½ i Fig. 2 jB ê A ÌDXANES ÉÍ­È­Æà 3 ÓÌzû_ªmF³êC
Re10 NX^[Ì\¢Ï»ÍCRe10 NX^[ZxÉêÅis·é±Æªí©Á½BêÊÉC±Ìæ¤ÈG}
«\¢Ì_Ci~bNÈ\¢Ï»ðº¤nÅÍCrÉÀèÈÔÌ\¢ª¶Ý·é±Æª½­C±ÌÔÌ\¢ãÅÌIð«ªá¢ÆG}½SÌÌIð«ªáºµÄµÜ¤Bµ©µÈªçCäXªJ­µ½±Ì[ICgSRe NX^[G}ÅÍC«íÅé Re10 NX^[Í

tFm[¶¬Æ¯ÉC¬â©ÉG}«ð½È¢Re m}[ÜÅÏ·³êCrÉIð«ðº°éÀèÔÌ\¢ª¶ÝµÈ¢B±Ì in­situ Ôªð DXAFSÉæéG}©gÌ\¢¬x_¤ÉæÁÄßÄCJ­µ½S Re G}ªÈº±êÙÇÜÅÉ¢tFm[IðFig. 3(a) The principle of TG_QXAFS synchronized with a poten­
tiostat. (b) Experimental set up of in­situ TG_QXAFS
measurement at SPring­8 BL01B1. (c) The series of Pt LIII­
edge TG_QEXAFS Fourier transforms of a Pt/C cathodecatalyst (Pt particle size: 2 nm) for the voltage­operatingprocess from 0.4 V to 1.0 V under N2 atmosphere.

«ð¦·Ì©C»ÌêöðªqxÅð¾·é±ÆªÅ«½3)Bx[©çÌtFm[¼Ú¬Æ¢¤50NÌÇðjÁ½±ÌS Re10 NX^[G}ÍC±êÜÅÞÌ

NX^[öÌªÈ­CS­VKÌNX^[\¢ðL·éàÌÅé B è í ½  ã Ì XAFS \ ¢ ð Í © ç CNH3Cx[C_f¤¶ºÅÌèí½ðÅÍC«úËõ March 2009 Vol.22 No.2  107

Re10 NX^[ÌÀøZxªá­Cs«È Re m}[èCG}Å

é Pt im±qªJ\[h\Ê©çdð¿wªåÉ¶ÝµÄ¢é±Æªí©Á½B±êÍCNH3 ÉæÖCIÆµÄn¯oµCdrÌò»ðø«N±·±Æªé« Re10 NX^[Ì`¬ª 2 Ô©©éÌÉÎµCí©ÁÄ¢éªC»Ì´öÆdÉG}\ÊÌ½@\ÉÂ_»½ÍñíÉ¬­C« Re10 NX^[ÌÀ¿IÈ¢ÄÍwÇð¾³êÄ¢È¢B»±ÅCR¿drÌæ¤È

é B ± Ì ú Ë õ ð  p µ ½ in­situ

wet È½nÉ¨¢Äà in­situ ªèªÂ\È XAFS @ð

Zxªá¢½ßÅ

XAFS \ ¢ðÍ ÌÊÍ CG} J­É æè Re10 NX

ìgµCR¿drì®Ìd³Ï»ÉæÁÄø«N±³ê^[ÌÀè«ðÁÅ«êÎC±ÌG}nÅòôIÉxéJ\[h Pt G}\ÊÌ½JjYðßÄ¾ç©

[]»¦iG}«jÌÁª©ßé±Æð­­¦´Éµ½4)B·éàÌÅèC±Ì¤¬ÊðîÉCàéÆÆ¤¯Åx[]»¦30÷ðÚwµ½Àp»¤ªn®µ½BR¿dr Pt G}Ì in­situ Ôªð XAFS ªèÉÍCSPring­8 Æ¤¯ÅJ­µ½ Time­GatingQuickXAFS(TG_QXAFS) @iÔªð\ 1 sjCyÑ DXAFS @i44.

ÀpR¿dr Pt im±qG}Ì­dßöÌ in­situÔªð XAFS \¢ðÍ@Ìªè´(a)ÆR¿drÌ in­situ XAFS ªè(b)ÌZ

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bgAbvð¦·Bdrd³§äÌ|eVX^bgÆms ÉP­ßöðÇÕjðp¢½BFig. 3 É TG_QXAFSÌÝðQXAFS Ìªèð¯úµCdÊìÉÎµC1 XyNroµC©ÂGlM[ø¦ÌR¿drVXeÍC©

g15bÅªè·é QXAFS ÌªèJnð 1 bÉ®ÔðnßÆ·élXÈªìÖÌÀp»ªØ]³êÄ¢¸çµÄêAÌ QXAFS ªèðsÁ½B¾çê½êAÌéBµ©µÈªçCuCNX[ªßçêéÛèàËQXAFS XyNgð k óÔÅ»ê¼ê15ªi1 ªÍÂÈ¡úCfÆ_fð´¿ÆµÄN[ÈRÆµÄ½­CG}«ÌåüãCG}à®íÌdð¿1 bÉjµCdÊìÉÎµÄ¯É·éwÖÌnoÉæéG}ò»iÏv«jÌâèðð·ªXyNgðÂÈ¬í¹é±ÆÅC15bÌªè©

éBÁÉC©®ÔÖÌÚÅÍCç 1 bÌÔªð\ðÂ TG_QXAFS ð¾½BFig. 3(c)ÔÌ¸¬ÌÛÉdrÌI/ItìðJèÔ·±ÆÉæÍ C d Ê  ì 0.4 V ¨ 1.0 V Ì Û Ì Pt LIII [ Ì TG _é±ÆªKvsÂÅ

Fig. 4(a) Changes in electric charges in a fuel cell (bold) and in Pt valence estimated by Pt LIII­edge XANES (thin).
(b) The coordination numbers of Pt_Pt (å or £) and Pt_O (ä or ¢) bonds estimated by TG_QEXAFS. (1) 0.4¨1.0 V; (2) 1.0¨0.4 V; anode: H2; cathode: N2; 333 K. Reaction mechanism for the voltage­operating processes
between 0.4 and 1.0 V on the Pt/C cathode catalyst is illustrated.

108  úËõ March 2009 Vol.22 No.2

úËõjQXAFS Fourier Ï·ÅéB[X ¡ æ13ñú{úËõwï§ãÜóÜ¤ñÓ«±Ì in­situ ªè©çCdÊìÉR¿drZà¤SÊÉnÁÄ²w±¸¢½åwåw@wn¤

ÅN±édC»w½Æ Pt G}Ì\¢Ï»Ì¼ûÉÂ¢È»wêUÌâVNT³öÉ[­´Ó\µã°Ü·B{¤ÄC8 ÂÌ½ßöSÄÌ½¬xèðZo·é±ÆÉÍCGlM[Á¬í¤@\úËõÈw¤{ÝÌ¬÷µ½B|eVX^bgÅvªµ½dCÊÌÏ»©

BL12C C NW2A C  P x õ È w ¤  Z  ^ [ SPring­8ç Í d q Ú ® ½  Ì ¬ x è  ª  Ü è C Pt LIII [ ÌBL01B1 Ìr[CðpµÄsíêÜµ½BGl

QXANES Ìs[NgbvÊÏ©çÍ Pt ÷±qÌ¿idM[Á¬í¤@\Ììº¹¡³öCîcNGy³öCdq§xjª¾çêCTG_QEXAFS ÌJ[utBbeBJASRI/SPring­8 Ìc¹÷³öCF¯êüÆmCJc

OðÍÍ Pt_Pt yÑ Pt_O ÌzÊyÑ£Ì£mCÁ¡ajmÉ±ÌêðØèÄ[­äç\µã°Ô Ï» ð ^¦ éB Fig. 4 ÉC 0.4¨ 1.0 Vi dr I tß

 G}»w¤Cg^©®ÔéæÅ·BOä»wòöjCyÑ1.0¨0.4 VidrIßöjÌ¼ûÌßöÉ¨®ïÐR¿drJ­Z^[ÉàC´Ó\µã°Ü·B¯éep[^ÌÔÏ»CyÑevfÌðÍ©ç¾çQl¶£ê½¬xèðîÉµ½J\[h\Ê½@\ð¦·B8
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é± Æªí©Á ½Bá¦Î CdrÌOFF ßöÉ¨¢ÄÍCÜ¸dC»wIÈ½ª ke10.39s|1, ke20.049 s|1 ÅisµÄZàðd¬ª¬êÄ©
çCäÁ­èÆ Pt_O Ì`¬i0.013 s|1 jÆ Pt ÷±qÌÑdikd0.011 s|1jªis·é±Æªí©Á½BZÌd³ðJñHd³æè­µ½1.4 V ÜÅÁ³¹éÆC1.0 V ÈºÅÍêèÅ

Á½ Pt_Pt ÌzÊª¸­µCPt_O ÌzÊÍ0.7ÜÅÁµ½B2 nm Ì Pt
÷±qÌ\Êðèßé Pt ÌÍñ 5 Å

é±Æ©

1)

a) T. Matsushita and R. P. Phizackerley: Jpn. J. Appl. Phys.
21, 2223_2228 (1981); b) U. Kaminaga, T. Matsushita andK. Kohra: Jpn. J. Appl. Phys. 20, L355_L358 (1981).
2) R. Bal, M. Tada, T. Sasaki and Y. Iwasawa: Angew. Chem.
Int. Ed. 45, 448 (2006).
3) M. Tada, R. Bal, T. Sasaki, Y. Uemura, Y. Inada, S. Tanaka,
M. Nomura and Y. Iwasawa: J. Phys. Chem. C 111, 10095(2007).
4) M. Tada, S. Murata, T. Asaoka, K. Hiroshima, K. Okumura,
H. Tanida, T. Uruga, H. Nakanishi, S. Matsumoto, Y. Inada,
M. Nomura and Y. Iwasawa: Angew. Chem. Int. Ed. 46, 4310
(2007).

çC±Ì Pt_O ÌzÊÌlÍC_f´qª Pt ÷±qÌ\ÊÅ½·é¾¯ÅÈ­Cæ 2 wÚÜÅöèñÅ¢
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éóCÅÌZd³Áª Pt Ìnoðis³¹CG}ò»ðø«N±·±Æª¦´³ê½4)B5.

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úËõ March 2009 Vol.22 No.2  109