Catalyst Surface Research Division(Prof.） Kiyotaka Asakura(Assoc. Prof.) Satoru Takakusagi(Assist Prof.) Hiroko Ariga-Miwa

Long term research missions

2• 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

3Ni2P(1)

It is good at hydrodesulfurization, hydrodenitrogenation,hydrodeoxygenation, electrocatalytic hydrogen evolution
reaction.(1 - 11)

(2)

(3)
(4)

In order to obtain the structure and catalysis
relationship, we carried out single crystal studies on
Ni2P.
However, the surface structure is not the bulkterminated one.
bulk structure

P62m

(5)
(6)

(7)

(8)

(9)

(10)
(11)

Ni

P

Oyama, S. T.; Lee, Y. K. J. Phys. Chem. B 2005, 109(6), 2109.
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.
Liu, D.; Wang, A.; Liu, C.; Prins, R. Catal. Commun.
2016, 77, 13.
Oyama, S. T.; Wang, X.; Lee, Y. K.; Chun, W. J. J. Catal.
2004, 221 (2), 263.
Oyama, S. T.; Gott, T.; Zhao, H.; Lee, Y.-K. Catal. Today
2009, 143 (1–2), 94.
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.
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.
S. T. Oyama, H. Zhao, H.-J. Freund, K. Asakura, R.
Włodarczyk, M. Sierka, "Unprecedented selectivity tothe direct desulfurization (DDS) pathway in a highly
active FeNi bimetallic phosphide catalyst", Journal ofcatalysis 2012, 285, 1-5.
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.
Guan, Q.; Wan, F.; Han, F.; Liu, Z.; Li, W. Catal. Today
2016, 259, Part 2, 467.
Berenguer, A.; Sankaranarayanan, T. M.; Gómez, G.;
Moreno, I.; Coronado, J. M.; Pizarro, P.; Serrano, D. P.
Green Chem. 2016, 18 (7), 1938.

4
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.

5Surface stabilization (removing dangling bond ) and activity
The dangling bond of Ni appears atFermi level.
P termination removes thedangling bond to give the lowactivity.
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.

6Ni2P single crystal structures

P-terminated structure
is more stable.
Sputtering surface (lessP surface) is
recovered at lowtemperature(<473 K)
and P-rich surface
easy diffusion path.

7
Easy P diffusion

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.

•Development of catalyst structure analysis methods

PTRF-XAFSPTRF-XAFS inin
PosterPoster ofof Prof.
Prof. Takakusagi
Takakusagi

Highly sensitive XAFS
Poster of Dr. Felix Feitne

8Muon studies of TiO2(110)Poster of Dr. Felix Feitne

Characterization methods -Accerlerator Base Characterizations
Marx Raman XAFS
Positron diffraction

Ultrafast XAFSEXAFS=Extended X-ray Absorption Fine Structureµ/ arb. units

XANES

EXAFS (40-1000 eV)

I0Iµ = ln ( I0 / I )X-ray scattering atom
X-ray Absorbing atom
23000

23500
24000
24500
Photon energy/ eVElement specific
Structure can be revealed around X-ray absorbing atom
Operando spectroscopy

10Time-resolved XAFSQXAFS =A technique that canmeasure one EXAFS spectrum in ashort time ( a few seconds in oursystem) by sampling signals fromionization chambers andmonochromator continuously withscanning the monochromator (onthe 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 ismade by polychromator. Thebeams are focused on thesample and dispersed again tobe 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 suspension
pump laser: 400 nm 270 mJ/cm2@945 Hz
X-ray pulse width: 100 ps(FWHM)

2p→5d

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

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

Photoexcited State of WO3 : LIII XANES at PF-AR
Single bunch operation
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.

k = 0.5(1) ns -1

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

Pump probe XAFS at SACLA
SPring-8Experiments at SACLA~30 fs~50 fs

SACLA

Sample: 4 mM WO3 suspension
pump laser: 520 mJ/cm2@15 Hz
X-ray pulse width: 30 fs(FWHM)
Time resolution: 500 fs

Ultra fast XAFS on WO3 in the photoabsorption process
Three distinct peaks were
found in the differential spectra.
peak A : Edge shift due toformation of W5+ < 1 pspeak C : decrease of absorption
from eg orbitals ~ 200 ps

peak B which was not found in
the previous experiments wasobserved.
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, 43977-979.

15Problems of XAFSXAFS 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 bygas phase.
Using the X-ray and resonance of neighboring atom, bond-specific
XAFS may possible.

Possibility of MARXMARX-RAMAN

16

1. XAFS is element-specific. But it is notbond-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.

. (A. Kay, C.S. Fadley, RMultiatom resonant
photoemission: a method for determining nearneighbor atomic identities and bonding.
Science. 281,679(1998). )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 torealize both.
(K. Tohji, Y. Udagawa, Physical Review B 1987,36, 9410-9412. )17MARX-RAMAN(Multi atom resonance X-ray Raman)
Vaccum level
X-rayEmission

Resonant
X-ray Raman

Vaccum level

X-ray

Photoelectron

MARX Raman

Atom A

Atom B. (A. Kay, C.S. Fadley, RMultiatom resonant
photoemission: a method for determining nearneighbor atomic identities and bonding.
Science. 281,679(1998). )18
MARX-RAMAN of TaN.

19Improvement of 4 D resolutions(Space Energy Angle and Time)Time Resolution
Special resolution

Tada, M.; Ishiguro, N.; Uruga, T.; Tanida,H.; Terada, Y.; Nagamatsu, S.-i.; Iwasawa,Y.; Ohkoshi, S.-i., [Small Mu ]-Xafs of aSingle Particle of a Practical
Niox/Ce2zr2oy Catalyst. Phys Chem
Chem Phys 2011, 13, 14910-14913.

Energy resolution
Angle resolution

Singh, J.; Lamberti, C.; vanBokhoven, J. A., Advanced XRay Absorption and Emission
Spectroscopy: In Situ CatalyticStudies. 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 theTio2(110) Surface - Polarization Dependent
Total-Reflection Fluorescence Exafs Study.
Chem. Phys. Lett. 2006, 421, 27-30.

20
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.