Catalyst Surface Research Division

(Prof.） Kiyotaka Asakura

(Assoc. Prof.) Satoru Takakusagi

(Assist Prof.) Hiroko Ariga-Miwa

Long term research missions

• Surface structure and reaction and reaction

mechanisms of catalysts

1. Ni2P surface structure

2. well-defined Inhomogeneous surface

3. Electrode surface structure for fuel cell

4. Metal structure and activity on TiO2(110)

(Takakusagi Clutster)

• Development of catalyst structure analysis methods

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Ni2P (1) Oyama, S. T.; Lee, Y. K. J. Phys. Chem. B 2005, 109

(6), 2109.

(2) d’Aquino, A. I.; Danforth, S. J.; Clinkingbeard, T. R.;

Ilic, B.; Pullan, L.; Reynolds, M. A.; Murray, B. D.;

Bussell, M. E. J. Catal. 2016, 335, 204.

(3) Liu, D.; Wang, A.; Liu, C.; Prins, R. Catal. Commun.

2016, 77, 13.

(4) Oyama, S. T.; Wang, X.; Lee, Y. K.; Chun, W. J. J. Catal.

2004, 221 (2), 263.

(5) Oyama, S. T.; Gott, T.; Zhao, H.; Lee, Y.-K. Catal. Today

2009, 143 (1–2), 94.

(6) Bando, K. K.; Wada, T.; Miyamoto, T.; Miyazaki, K.;

Takakusagi, S.; Koike, Y.; Inada, Y.; Nomura, M.;

Yamaguchi, A.; Gott, T.; Oyama, S. T.; Asakura, K. J.

Catal. 2012, 286, 165.

(7) Bando, K. K.; Wada, T.; Miyamoto, T.; Miyazaki, K.;

Takakusagi, S.; Gott, T.; Yamaguchi, A.; Nomura, M.;

Oyama, S. T.; Asakura, K. In 14th International

Conference on X-Ray Absorption Fine Structure

(xafs14), Proceedings; DiCicco, A., Filipponi, A., Eds.;

Iop Publishing Ltd: Bristol, 2009; Vol. 190, p 012158.

(8) S. T. Oyama, H. Zhao, H.-J. Freund, K. Asakura, R.

Włodarczyk, M. Sierka, "Unprecedented selectivity to

the direct desulfurization (DDS) pathway in a highly

active FeNi bimetallic phosphide catalyst", Journal of

catalysis 2012, 285, 1-5.

(9) Shamanaev, I. V.; Deliy, I. V.; Aleksandrov, P. V.;

Gerasimov, E. Y.; Pakharukova, V. P.; Kodenev, E. G.;

Ayupov, A. B.; Andreev, A. S.; Lapina, O. B.;

Bukhtiyarova, G. A. RSC Adv. 2016, 6 (36), 30372.

(10) Guan, Q.; Wan, F.; Han, F.; Liu, Z.; Li, W. Catal. Today

2016, 259, Part 2, 467.

(11) Berenguer, A.; Sankaranarayanan, T. M.; Gómez, G.;

Moreno, I.; Coronado, J. M.; Pizarro, P.; Serrano, D. P.

Green Chem. 2016, 18 (7), 1938.

3

It is good at hydrodesulfurization, hydrodenitrogenation,

hydrodeoxygenation, electrocatalytic hydrogen evolution

reaction.(1 - 11)

In order to obtain the structure and catalysis

relationship, we carried out single crystal studies on

Ni2P.

However, the surface structure is not the bulk-

terminated one.

Ni P

bulk structure P62m

Ni2P single crystal structures

P-terminated structure is more stable.

Sputtering surface (less P surface) is recovered at low temperature(<473 K)

and P-rich surface

easy diffusion path.

4

Surface stabilization (removing dangling bond ) and activity

5

The dangling bond of Ni appears at

Fermi level.

P termination removes the

dangling bond to give the low

activity.

H2

does not dissociatively adsorb

on Ni2P. Defect is necessary.

H. Ariga, M. Kawashima, S. Takakusagi, K. Asakura, Chemistry Letters 2013, 42, 1481-1483; Q. Yuan, H. Ariga, K. Asakura, Top. Catal. 2015, 58,

194-200 10.1007/s11244-015-0360-6.

Ni2P single crystal structures

P-terminated structure

is more stable.

Sputtering surface (less

P surface) is

recovered at low

temperature(<473 K)

and P-rich surface

easy diffusion path.

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Easy P diffusion

7

Activation energy

= 0.18 eV Calc

by DFT(VASP)

J. Contreras-Mora, H. Ariga-Miwa, S. Takusagi, C. Williams, K. Asakura, J.Phys.Chem.C. 2018, Accepted.

Characterization methods --

Accerlerator Base Characterizations

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PTRF-XAFS in

Poster of Prof. Takakusagi

Highly sensitive XAFS

Poster of Dr. Felix FeitneMuon studies of TiO2(110)

Poster of Dr. Felix Feitne

PTRF-XAFS in

Poster of Prof. Takakusagi

Positron diffractionUltrafast XAFS

Marx Raman XAFS

• Development of catalyst structure analysis methods

EXAFS=Extended X-ray Absorption Fine Structure

X-ray Absorbing atom

X-ray scattering atom

µ / a

rb. units

24500240002350023000Photon energy/ eV

EXAFS (40-1000 eV)XANES

µ = ln ( I0 / I )

I0 I

Element specificStructure can be revealed around X-ray absorbing atomOperando spectroscopy

Time-resolved XAFS

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QXAFS =A technique that can

measure one EXAFS spectrum in a

short time ( a few seconds in our

system) by sampling signals from

ionization chambers and

monochromator continuously with

scanning the monochromator (on

the fly). K. K. Bando, Y. Koike, T. Kawai, G. Tateno, S. T. Oyama, Y.

Inada, M. Nomura, K. Asakura, Journal of Physical Chemistry

C 2011, 115, 7466-7471 10.1021/jp11657z.

DXAFS =Energy dispersion is

made by polychromator. The

beams are focused on the

sample and dispersed again to

be detected by position sensitive

detector to give the whole

spectrum at once. (µs )A. Yamaguchi, T. Shido, Y. Inada, T. Kogure, K. Asakura, M.

Nomura, Y. Iwasawa, Bull.Chem.Soc.Jpn. 2001, 74, 801-808.

Pump Probe XAFS setup for Photocatalyst

Sample: 0.6 mM WO3 suspensionpump laser: 400 nm 270 mJ/cm2@945 HzX-ray pulse width: 100 ps(FWHM)

J. Synchrotron Radiat. 2007, 14, 313.J. Synchrotron Radiat. 2009, 16, 110.

2p→5d

R. Abe, et. al. J. Am. Chem. Soc. 2008, 130, 7780-7781

Photoexcited State of WO3

: LIII

XANES at PF-AR

Single bunch operation

k = 0.5(1) ns -1

The excited state decayed in 10 ns.→It was successfully fitted with a single exponential function.

1.Uemura, Y.; Uehara, H.; Niwa, Y.; Nozawa, S.; Sato, T.; Adachi, S.; Ohtani, B.; Takakusagi, S.; Asakura, K., In

Situ Picosecond Xafs Study of an Excited State of Tungsten Oxide. Chem. Lett. 2014, 43 977-979.

Pump probe XAFS at SACLA

Experiments at SACLA SPring-8

SACLA~30 fs

~50 fsSample: 4 mM WO3 suspensionpump laser: 520 mJ/cm2@15 HzX-ray pulse width: 30 fs(FWHM)Time resolution: 500 fs

Ultra fast XAFS on WO3 in the photoabsorption process

peak A : Edge shift due to formation of W5+ < 1 pspeak C : decrease of absorption from eg orbitals ~ 200 ps

Three distinct peaks were found in the differential spectra.

peak B which was not found in the previous experiments was observed.

Y. Uemura, D. Kido, Y. Wakisaka, H. Uehara, T. Ohba, Y. Niwa, S.

Nozawa, T. Sato, K. Ichiyanagi, R. Fukaya, S. Adachi, T. Katayama,

T. Togashi, S. Owada, K. Ogawa, M. Yabashi, K. Hatada, S.

Takakusa, Y. Yokoyama, B. Ohtani, K. Asakura, Angew.

Chem.Int.Ed 2016, 55, 1364-1367 10.1002/anie.201509252.: Y.

Uemura, H. Uehara, Y. Niwa, S. Nozawa, T. Sato, S. Adachi, B.

Ohtani, S. Takakusagi, K. Asakura, Chemistry Letters 2014, 43

977-979.

Problems of XAFS

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XAFS is element specific but not bond specific.

Low Z element requires low X-ray energy so that operando

measurement is difficult due to the absorption of low energy x-ray by

gas phase.

Using the X-ray and resonance of neighboring atom, bond-specific

XAFS may possible.

Possibility of MARXPossibility of MARXPossibility of MARXPossibility of MARX----RAMANRAMANRAMANRAMAN

1. XAFS is element-specific. But it is not

bond-specific.

Pt-C can not be distinguished from C in electrode.

MARPE may be possible.

2. It is difficult to carry out in situ for Low-Z

element.

N, C has to be measured in soft X-ray regions.

X-ray Raman can do it but low intensity.

Combination will make it possible to

realize both.

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. (A. Kay, C.S. Fadley, RMultiatom resonant

photoemission: a method for determining near-

neighbor atomic identities and bonding.

Science. 281,679(1998). )

(K. Tohji, Y. Udagawa, Physical Review B 1987,

36, 9410-9412. )

MARX-RAMAN(Multi atom resonance X-ray Raman)

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MARX Raman

Resonant

X-ray Raman

Vaccum level

X-rayEmission

Vaccum levelPhotoelectron

X-ray

Atom A Atom B

. (A. Kay, C.S. Fadley, RMultiatom resonant

photoemission: a method for determining near-

neighbor atomic identities and bonding.

Science. 281,679(1998). )

MARX-RAMAN of TaN.

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Improvement of 4 D resolutions(Space Energy Angle and Time)

Time Resolution

Special resolution

Energy resolution

Angle resolution

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Tada, M.; Ishiguro, N.; Uruga, T.; Tanida,

H.; Terada, Y.; Nagamatsu, S.-i.; Iwasawa,

Y.; Ohkoshi, S.-i., [Small Mu ]-Xafs of a

Single Particle of a Practical

Niox/Ce2zr2oy Catalyst. Phys Chem

Chem Phys 2011, 13, 14910-14913.

Singh, J.; Lamberti, C.; van Bokhoven, J. A., Advanced X-Ray Absorption and Emission Spectroscopy: In Situ Catalytic Studies. Chemical Society reviews 2010, 39, 4754-4766.

Koike, Y.; Ijima, K.; Chun, W. J.; Ashima, H.; Yamamoto, T.; Fujikawa, K.; Suzuki, S.; Iwasawa, Y.; Nomura, M.; Asakura, K., Structure of Low Coverage Ni Atoms on the Tio2(110) Surface - Polarization Dependent Total-Reflection Fluorescence Exafs Study. Chem. Phys. Lett. 2006, 421, 27-30.

Summary and future

Catalytic properties of Ni2P(0001) or (101b0)

Electrochemistry and hydrogen evolution reaction.

Investigations of intermetallic surfaces.

Development of new techniques for characterizations

with 4 D resolutions.

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