S1

SUPPORTING INFORMATION

Porous NiTiO3/TiO2 nanostructures for photocatatalytic

hydrogen evolution

Congcong Xing,ab

Yongpeng Liu,c Yu Zhang,

a Junfeng Liu,

a Ting Zhang,

d Pengyi Tang,

d Jordi Arbiol,

de Lluís

Soler,b Kevin Sivula,

c Néstor Guijarro,

c Xiang Wang,

a Junshan Li,

a Ruifeng Du,

a Yong Zuo,

a Andreu

Cabot,*ae

Jordi Llorca *b

a. Catalonia Institute for Energy Research (IREC), Sant Adrià de Besòs, 08930 Barcelona, Spain

b. Institute of Energy Technologies, Department of Chemical Engineering and Barcelona Research Center in Multiscale Science and

Engineering, Universitat Politècnica de Catalunya, EEBE, 08019 Barcelona, Spain

c. Laboratory for Molecular Engineering of Optoelectronic Nanomaterials (LIMNO), École Polytechnique Fédérale de Lausanne

(EPFL), Station 6, CH-1015 Lausanne, Switzerland

d. Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona,

Catalonia, Spain

e. ICREA, Pg. Lluis Companys 23, 08010 Barcelona, Spain

* E-mails: A. Cabot: acabot@irec.cat

J. Llorca: jordi.llorca@upc.edu

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2019

S2

Content

1. Photoreactor ............................................................................................................................................. 3

2. Additional SEM characterization of the precursor materials ............................................................. 4

3. Additional TEM characterization .......................................................................................................... 5

4. Elemental composition ............................................................................................................................ 6

5. Scheme of the preparation procedure.................................................................................................... 7

6. EELS elemental maps and HRTEM of TiO2 ........................................................................................ 8

7. XRD Rietveld refinement ........................................................................................................................ 9

8. HRTEM characterization of NiTiO3/TiO2 (1%) ................................................................................. 10

9. XPS analyses .......................................................................................................................................... 11

10. TiO2:Ni annealed in argon ................................................................................................................ 12

11. Nitrogen adsorption-desorption isotherms...................................................................................... 13

12. NiTiO3 reference material ................................................................................................................. 14

13. Literature comparison ...................................................................................................................... 15

14. Photocatalytic H2 production rates .................................................................................................. 16

15. UV-vis analysis ................................................................................................................................... 17

References ...................................................................................................................................................... 18

S3

1. Photoreactor

Figure S1. a) Photograph of the system used to test the photocatalytic hydrogen generation: 1

displays the Dreschel bottle containing the ethanol-water solution (1:9 molar). 2 displays the actual

photoreactor. b) Scheme of the photoreactor.

1 2a b

Gas flow from reactant

Uvlight

Gas flow to GC

paper +material

o-ring

paper material

Uv light

o-ring

Class Tube

Class Tube

c

S4

2. Additional SEM characterization of the precursor materials

Figure S2. SEM images of TiO2:Ni (5%) produced in the following conditions: a) without HDA, b)

without H2O, c) in HDA-H2O-KCl.

200 nm 1 µm 1 µm

a b c

S5

3. Additional TEM characterization

Figure S3. TEM images of (a) TiO2, (b) TiO2:Ni (1%), (c) TiO2:Ni (2%).

200 nm 200 nm 200 nm

ca b c

S6

4. Elemental composition

Table S1. Ti and Ni atomic concentrations of TiO2, TiO2:Ni (1%, 2%, 5%) and NiTiO3/TiO2 (1%,

2%, 5%). XRD data refers to the TiO2 and NiTiO3 crystallographic phases detected and it does not

take into account any peak shift denoting the presence of Ni within the TiO2 structure.

catalysts EDX XRD XPS

Ti (atom%) Ni (atom%)Ti (atom%) Ni (atom%)Ti (atom%) Ni (atom%)

TiO2 100

TiO2:Ni (1%) 96.4 3.6 94.3 5.7

TiO2:Ni (2%) 93.6 6.4

TiO2:Ni (5%) 83.2 16.8

NiTiO3/TiO2 (1%) 96.4 3.6 4.4 95.6 94.2 5.8

NiTiO3/TiO2 (2%) 94.3 5.7 6.5 93.5

NiTiO3/TiO2 (5%) 86 14 13.3 86.7

NiTiO3 61.9 39.1

S7

5. Scheme of the preparation procedure

Figure S4. Scheme of the TiO2:Ni precursor preparation procedure: (a) TiO2:Ni, (b) NiOx/TiO2, (c)

NiTiO3/TiO2.

170oC

(a)

(b)

(c)

S8

6. EELS elemental maps and HRTEM of TiO2

Figure S5. Undoped TiO2 annealed at 650 °C in air: (a) STEM micrograph and EELS chemical

composition maps obtained from the yellow squared area of the STEM micrograph. Individual Ti

L2,3-edges at 456 eV (red) and O K-edge at 532 eV (green) as well as its composite. (b) HRTEM

micrograph, detail of the yellow squared region and its corresponding power spectrum.

(10-1)

(004) (103)

[010] Anatase TiO2

a b

[010] TiO2 I41MADS

S9

7. XRD Rietveld refinement

Figure S6 Refined fitting of the NiTiO3/TiO2(5%) x-ray diffraction data. Blue symbols:

experimental data; continuous red line: modified background; continuous green line: calculated

modelled structure; continuous light blue line beneath pattern: difference between observed and

calculated parameters. Blue tickmarks correspond to reflections of NiTiO3 (R-3) unit cell, lower red

ones to TiO2 (I41/amd) unit cell. GOF = 1.21. Rw = 6.99%.

[010] TiO2 I41MADS

S10

8. HRTEM characterization of NiTiO3/TiO2 (1%)

Figure S7 HRTEM micrographs of NiTiO3/TiO2 (1%), detail of the yellow squared region and its

corresponding power spectrum.

(002)

(101)

(10-1)

[010] TiO2 I41MADS

[010] TiO2 I41MADS

S11

9. XPS analyses

Figure S8. Ni 2p3/2 region (a), O 1s region (b) and Ti 2p region (c) of the XPS spectra of (1)

TiO2:Ni (1%) (2) NiOx/TiO2 (1%) and (3) NiTiO3/TiO2 (1%) samples.

Figure S9. Survey XPS spectra of TiO2:Ni (1%), NiOx/TiO2 (1%) and NiTiO3/TiO2 (1%).

ca b TiO

2 :Ni(1

%)

NiO

x /TiO

2(1

%)

472 470 468 466 464 462 460 458

20000

40000

60000

80000

100000

120000

140000

C

C

A

NiT

iO3 /T

iO2

(1%

)

868 866 864 862 860 858 856 854 852

117000

118000

119000

120000

121000

122000

123000

124000

C

C

A

868 866 864 862 860 858 856 854 852

117000

118000

119000

120000

121000

122000

123000

124000

D

D

A

868 866 864 862 860 858 856 854 852

117000

118000

119000

120000

121000

122000

123000

124000

E

E

A

868 866 864 862 860 858 856 854 852

134000

135000

136000

137000

138000

139000

140000

141000

142000

143000 C

C

A

868 866 864 862 860 858 856 854 852

134000

135000

136000

137000

138000

139000

140000

141000

142000

143000 D

D

A

868 866 864 862 860 858 856 854 852

134000

135000

136000

137000

138000

139000

140000

141000

142000

143000 E

E

A

868 866 864 862 860 858 856 854 852

51600

51800

52000

52200

52400

52600

52800

53000

53200

53400

53600 C

C

A

868 866 864 862 860 858 856 854 852

51600

51800

52000

52200

52400

52600

52800

53000

53200

53400

53600 D

D

A

868 866 864 862 860 858 856 854 852

51600

51800

52000

52200

52400

52600

52800

53000

53200

53400

53600 E

E

A

538 536 534 532 530 528 526

50000

100000

150000

200000

D

D

A

538 536 534 532 530 528 526

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

220000 C

C

A

538 536 534 532 530 528 526

40000

60000

80000

100000

120000

140000

160000

180000 D

D

A

538 536 534 532 530 528 526

40000

60000

80000

100000

120000

140000

160000

180000 C

C

A

538 536 534 532 530 528 526

50000

100000

150000

200000

E

E

A

538 536 534 532 530 528 526

40000

60000

80000

100000

120000

140000

160000

180000 E

E

A

538 536 534 532 530 528 526

20000

30000

40000

50000

60000

70000

80000

90000 D

D

A

538 536 534 532 530 528 526

20000

30000

40000

50000

60000

70000

80000

90000 C

C

A

472 470 468 466 464 462 460 458

20000

30000

40000

50000

60000

70000

80000

90000

100000

110000

120000

130000

140000

150000 D

D

A

472 470 468 466 464 462 460 458

20000

40000

60000

80000

100000

120000 C

C

A

472 470 468 466 464 462 460 458

20000

30000

40000

50000

60000

70000

80000

90000

100000

110000

120000 D

D

A

472 470 468 466 464 462 460 458

10000

20000

30000

40000

50000

60000 C

C

A

472 470 468 466 464 462 460 458

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

60000 D

D

A

868 864 860 856 852

856.0 eV

Ni 2p3/2

Sat.

868 864 860 856 852

Binding Energy (eV)

Ni 2p3/2

Sat.856.07 eV

Inte

nsity (

a.u

.)

Ni 2p3/2

Sat.856.3 eV

537 534 531 528

Binding Energy (eV)

O 1s

533.2 eV

O 1s

531.09 eV

O 1s

534.7 eV

O 1s

531.0 eV

O 1s

533.1 eV

537 534 531 528

O 1s

534.9 eV

O 1s

531.0 eV

O 1s

533.0 eV

Ti 2p1/2

464.5 eV

Ti 2p3/2

459.0 eV

471 468 465 462 459

Ti 2p1/2

464.5 eV

Ti 2p3/2

458.9 eV

Binding Energy (eV)

471 468 465 462 459

Ti 2p1/2

464.4 eV

Ti 2p3/2

458.7 eV

1000 800 600 400 200 0

Inte

nsity (

a.u

.)

NiTiO3/TiO2

NiOx/TiO2

TiO2:Ni

O 1

sT

i 1s

C 1

s

Binding Energy (eV)

Ni 2p

S12

10. TiO2:Ni annealed in argon

Figure S10. TEM image of NiOx/TiO2 (5%) annealed in argon.

Figure S11. XRD pattern of TiO2 and NiOx/TiO2 (1%, 2%, 5%) annealed in argon.

200 nm

20 30 40 50 60 70 80

*

*

*

TiO2 JCPDS:01-073-1764

NiOx/TiO2 (5%)

NiOx/TiO2 (2%)

NiOx/TiO2 (1%)

TiO2Inte

nsity (

a.u

)

2 (Degree)

NiOx

S13

11. Nitrogen adsorption-desorption isotherms

Figure S12. Nitrogen adsorption (open symbols) and desorption (filled symbols) isotherms

measured of (a) NiOx-TiO2(1%) and (b) NiTiO3-TiO2(1%) at 77.3 K.

0.0 0.2 0.4 0.6 0.8 1.0

Adsorption

Desorption

Relative pressure (P/P0)

Qu

an

tity

ad

so

rbe

d (

a.u

.)

BET Specific surface 28.0 m2/g

NiOx-TiO2(1%)

0.0 0.2 0.4 0.6 0.8 1.0

Adsorption

Desorption

Relative pressure (P/P0)

Qu

an

tity

ad

so

rbe

d (

a.u

.)

BET specific surface 40.8 m2/g

NiTiO3-TiO2(1%)

a b

S14

12. NiTiO3 reference material

Figure S13. SEM images of NiTiO3

Figure S14. XRD pattern of NiTiO3

400 nm

20 40 60 80

NiTiO3 JCPDS:01-076-0335Inte

nsity (

a.u

.)

2(Degree)

NiTiO3

S15

13. Literature comparison

Table S2. Comparison of the hydrogen evolution rate and the apparent quantum yield with reported

Ni-Ti-O systems.

Photocatalyst H2 Evolution Rate

μmol h-1 g-1 Reaction conditions AQY %

Ref.

Ni/NiO/N-TiO2-x 185 110W λ˃420nm 7.5 S1

0.23%Ni(OH)2 on TiO2 900 3W 365nm 12.4 S2

0.25wt% NiO-TiO2 261 3W 365nm 1.7 S3

TiO2-Ni(HCO3)2-2.5% 377 300W 380nm (±5nm) 6.24 S4

0.32% Ni(NO3)2-TiO2 163 3W 365nm 8.1 S5

Mesoporous NiO/TiO2 240 3W 365nm 1.7 S6

Pt NiO/TiO21:1 molar ratio

1,250 400W UV 7.8

S7

Hollow NiTiO3/TiO2(1%) 11,500 365nm 11.6 This

work

S16

14. Photocatalytic H2 production rates

Figure S15. Photocatalytic H2 production rates obtained from TiO2, NiTiO3, TiO2:Ni (1%),

NiOx/TiO2 (1%), NiTiO3/TiO2 ( 1%, 2%, 5%).

0

2

4

6

8

10

12

14

16

NiT

iO3/T

iO2 (

5%

)

NiT

iO3/T

iO2 (

2%

)

NiT

iO3/T

iO2 (

1%

)

NiT

iO3/T

iO2 (

0.5

%)

TiO

2

NiO

x/T

iO2 (

5%

)

NiO

x/T

iO2 (

2%

)

NiO

x/T

iO2 (

1%

)

NiO

x/T

iO2 (

0.5

%)

TiO

2:N

i (0

.5%

)

TiO

2:N

i (5

%)

TiO

2:N

i (2

%)

TiO

2:N

i (1

%)

0.2

2.0

0.50.1

1.9

0.50.2

3.4

11.6

2.5

4.4

1.42.1

3.1

NiT

iO3

H2 m

mol h

-1g

-1

S17

15. UV-vis analysis

Figure S16. Kubelka-Munk function for TiO2, NiTiO3/TiO2 (1, 2, 5%) and NiOx/TiO2 including a

linear fit (dashed lines) to determine the band gap energy.

1.5 2.0 2.5 3.0 3.5 4.0

NiTiO3/TiO2

NiTiO3

(1%)

(2%)

(5%)

NiOx/TiO2 (1%)

Energy (eV)

(h)1

/2 / (

eV

/m)1

/2

TiO2

1%, 2%, 5%

S18

References

S1. S. Hu, F. Li, Z. Fan and J. Gui, J. Power Sources, 2014, 250, 30–39. S2. J. Yu, Y. Hai and B. Cheng, J. Phys. Chem. C, 2011, 115, 4953–4958. S3. L. Li, B. Cheng, Y. Wang and J. Yu, J. Colloid Interface Sci., 2015, 449, 115–121. S4. Y. Wei, G. Cheng, J. Xiong, F. Xu and R. Chen, ACS Sustain. Chem. Eng., 2017, 5, 5027–5038. S5. W. Wang, S. Liu, L. Nie, B. Cheng and J. Yu, Phys. Chem. Chem. Phys., 2013, 15, 12033–12039. S6. L. Li, B. Cheng, Y. Wang and J. Yu, J. Colloid. Interf. Sci., 2015, 449, 115-121. S7. A. Rawool, M. R. Pai, A. M. Banerjee, A. Arya, R. Ningthoujam, R. Tewari, R. Rao, B. Chalke, P. Ayyub and A. Tripathi,

Appl. Catal. B Environ., 2018, 221, 443-458.