Supporting information: photocatalytic hydrogen evolution ...Supporting information: TiO2-supported Pt single atoms by surface organometallic chemistry for photocatalytic hydrogen

Supporting information:

TiO2-supported Pt single atoms by surface organometallic chemistry for photocatalytic hydrogen evolution

Gabriel Jeantelot,a Muhammad Qureshi,a Moussab Harb,*a Samy Ould-Chikh,a Dalaver H. Anjum,b Edy Abou-Hamad,b Antonio Aguilar-Tapia,c Jean-Louis Hazemann,c Kazuhiro Takanabe,a Jean-Marie Basset*a

a. Kaust Catalysis Center (KCC), Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabiab. Core Labs, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabiac. Institut Néel, UPR2940 CNRS, University of Grenoble Alpes, F-38000 Grenoble (France)

Supplementary figures:

Fig. S1 Setup used for grafting reactions

Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics.This journal is © the Owner Societies 2019

Vacuum pump

GC

argon

circulation pum

p

vacuum gauge

Cold trap

Photoreactor

Xe lamp

Stirplate

Fig. S2 Photocatalysis setup

1550 1500 1450 1400 1350 1300 1250

131213411428

1477

b) 5% PtGR:TiO2

a) 0.5% PtGR:TiO2

1342

1313

1431

c) Me2Pt(COD) (on KBr)

Abs

orba

nce

(A.U

)

Wavenumber (cm-1)

1479

1520

1452

1448

Fig. S3 Infrared spectroscopy (DRIFTS) of a) 0.5%PtGR:TiO2 ; b) 5% PtGR:TiO2 ; c) Me2Pt(COD) on KBr.

Material Band positionsPtGR:TiO2

(this work)1479 1452 1431 1342 1313

Me2Pt(COD) (this work)

1477 1448 1428 1341 1313

Cl2Pt(COD) 14791, 14762 1446,3 14512 14321, 14273, 14262

13391,3, 13402 13101, 13123

1,5-cyclooctadiene 14874,5, 14833 14485, 14474, 14433

14265, 14254, 14233

13575, 13564, 13523

13205, 13214

Table S1 Comparative table of the infrared absorption bands of the grafted materials, Pt(COD) complexes (Me2Pt(COD) ; Cl2Pt(COD)) and “free” 1,5-cyclooctadiene.

200 180 160 140 120 100 80 60 40 20 0

Cyclooctadiene adsorbed on {001}-anatase

28 ppm

46 ppm

Inte

nsity

(A.U

.)

Shift (ppm)

Fig. S4 13C MAS SSNMR spectrum of cyclooctadiene adsorbed on {001}-anatase

11550 11555 11560 11565 11570 11575 11580 115850123456789

101112

Pt powder (Pt0 ref)

(CH3)2Pt(COD) (Pt2+ ref)

0.5% PtGR:TiO2

Pt(acac)2 (Pt2+ ref)

Nor

mal

ized

abs

orba

nce

(AU

)

Energy (eV)

PtO2 (Pt4+ ref)

11550 11555 11560 11565 11570 11575-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0Pt powder data

fit components

Inte

nsity

(A.U

.)

Energy (eV)

11550 11555 11560 11565 11570 11575-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0(CH3)2Pt(COD) data

fit components

Inte

nsity

(A.U

.)

Energy (eV)11550 11555 11560 11565 11570 11575

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0Pt(acac)2

data fit components

Inte

nsity

(A.U

.)

Energy (eV)

11550 11555 11560 11565 11570 11575-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0PtO2

data fit components

Inte

nsity

(A.U

.)

Energy (eV)11550 11555 11560 11565 11570 11575

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.00.5% PtGR:TiO2

data fit components

Inte

nsity

(A.U

.)

Energy (eV)

Fig. S5 HERFD-XANES absorption spectra and fits using a pseudo-voigt function for the whiteline and arctangent function for the step. An additional lorentzian peak had to be included in the fitting model of the Pt(acac)2 sample.

Sample: Oxidation number: White line pseudo- R-factor: χ²/ν:

Voigt area (arbitrary units):

Pt powder (ref.) 0 7.1 0.002 0.004(CH3)2Pt(COD) (ref.) +2 11.3 0.002 0.005Pt(acac)2 (ref.) +2 12.2 0.001 0.02PtO2 (ref.) +4 20.9 0.009 0.030.5% PtGR:TiO2 12.5 0.003 0.01

Table S2 fitting results of Pt-L3 edge HERFD–XANES of 0.5% Pt:{001}-anatase, along with four Pt references

0.5% PtGR:TiO2 Pt metallic powder

Pt(COD)(Me)2 PtO2

Fig. S6 Contour plots of the wavelet transform magnitude showing the (k,R) localization of each FT-EXAFS contribution measured at the Pt L3-edge for 0.5%PtGR:TiO2, Pt metallic powder, Pt(COD)(Me)2, and PtO2

4 6 8 10 12-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0 Data fit

k2 (k

) (Å

-2)

Wavenumber (Å-1)0 1 2 3 4 5 6

0

2

4

6

8

10

12

14

16

18

20 data fit

(R

) (Å

-3)

Radial distance (Å)

Scatter Coordination number

S02 R (Å) σ2 (Å2) ΔE0 (eV)

Pt-Pt 12 (defined) 0.77 ±0.04 2.763 ±0.002 0.0042 ±0.0003 7.6 ± 0.4

Fig. S7 Platinum foil EXAFS fitting using only the first Pt-Pt scattering path to determine the amplitude reduction factor (S02). k-

range = 2.8 – 12 ; dk=1 ; R-range = 1.373 – 3.415 ; χ2/ν = 234.12 ; R-factor = 0.42 %

Figure S8 O-Pt-O DFT-optimized structure

Fig. S9 Complete DFT-optimized structures for the Pt reduction by CO reaction with the Ti-O-Pt(COD)-F-Ti structure.

Fig. S10 Proposed mechanism for Pt reduction by CO for the Ti-O-Pt(COD)-O-Ti structure

400 600 800 10000

20

40

60

80P

hoto

n flu

x (µ

Mol

.s-1.m

-2.n

m-1)

Wavelength (nm)

225-387 nm

Xe lamp photon distributionCell area: 38.5 cm2

Figure S11 Xenon lamp photon distribution.

0 10 20 30 400

10

20

30

40

50

60

70

{001}-anatase (support) data fit

Oxygen evolution reaction4-point average

0.5%PtGR:TiO2

data fit

OE

R ra

te (µ

mol

/h)

Time (h)

Fig. S12 OER activity and exponential decay fits of {001}-anatase and 0.5%PtGR:TiO2. First 30 minutes excluded due to gas mixing kinetics in the reactor

Fig. S13 TEM micrographs of 0.5%PtGR:TiO2 after photocatalysis with sacrificial methanol. Only nanoparticles are visible

0 2 4 6 8 100

10

20

30

40

50

0

10

20

Rat

e (µ

mol

/h)

Time (h)

0

5

10

15

20

25

30

35

40

TOF

(h-1)

p(H

2) (m

bar)a)

0 2 4 6 8 10

0

10

20

30

40

50

0

10

20

Rat

e (µ

mol

/h)

Time (h)

b)

p(H

2) (m

bar)

Fig. S14 Backwards reaction rates measured on: a) impregnated 0.5%PtNP:TiO2 and b) support blank ({001}-anatase) showing no noticeable activity.

Bibliography:

1 J. Mink and G. Keresztury, Appl. Spectrosc., 1993, 47, 1446–1451.

2 J. A. Baldwin, I. S. Butler and D. F. R. Gilson, Inorganica Chim. Acta, 2006, 359, 3079–3083.

3 D. B. Powell and T. J. Leedham, Spectrochim. Acta Part A Mol. Spectrosc., 1972, 28, 337–341.

4 G. G. Barna and I. S. Butler, J. Raman Spectrosc., 1978, 7, 168–172.

5 Spectr. Database Org. Compd., SDBS No.: 2054.