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Figure S3 GC spectrum using FID-Methanator for the (a) commercial pure CO, and (b) evolved gas from FA/SF system over Pd/C synthesized with citric acid at ...

Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate —Supplementary Information Zhi-Li Wang, Jun-Min Yan*, Hong-Li Wang, Yun Ping, and Qing Jiang Key Laboratory of Automobile Materials, Ministry of Education, Department of Materials Science and Engineering, Jilin University, Changchun 130022, China

1

0.20

0.15

0.10

(b)

(1) (2) (3) (4)

Absorbance (a.u.)

0.25

0.05

0.00

350

400

450

500

550

600

Wavelength (nm) Figure S1 (a) Color evolution of Na2PdCl4 aqueous solution (4.70×10-3 M) after addition of (1) SF (0.84 M), (2) FA (1.06 M), and (3) citric acid (0.03 M) for the given time at room temperature. (b) UV-vis spectra for aqueous solution of (1) pure Na2PdCl4, (2) Na2PdCl4 with FA, (3) Na2PdCl4 with citric acid , and (4) Na2PdCl4 with SF for 2 min.

It can be seen From Fig. S1a(1) that, after addition of SF into Na2PdCl4 aqueous solution for 2 min, the solution color changes from yellow to black, and the corresponding UV-vis absorption peak of [PdCl4]2- at 415 nmS1 (Fig. S1b(1)) disappears (Fig. S1b(4)). This indicates that Pd2+ cations have been reduced to Pd NPs by SF within 2 min. However, FA or citric acid can not reduce Pd2+ which is proved by the unchanged solution color after addition of FA (Fig. S1a(2)) or citric acid even for 300 min (Fig. S1a(3)). Moreover, the characteristic UV-vis absorption of [PdCl4]2- does not disappear after addition of FA (Fig. S1b(2)) or citric acid (Fig. S1b(3)). Thus, in the present H2 generation system, SF acts as a useful reducing agent for in situ formation of Pd NPs.

2

H2 2.00E-009

1.00E-009

Intensity

CO2 Ar

H2 O 0.00E+000

0

8

16

24

32

40

48

m (z) Figure S2 MS spectrum for the evolved gas from FA/SF system over Pd/C synthesized with citric acid at 298 K under Ar atmosphere.

300000

CO

Intensity

150000

CO2

(a)

(b) 0

0

5

10

15

20

Time (min) Figure S3 GC spectrum using FID-Methanator for the (a) commercial pure CO, and (b) evolved gas from FA/SF system over Pd/C synthesized with citric acid at 298 K .

3

1200000

H2

Intensity

800000

400000

CO2 0

2

4

6

8

10

12

14

16

Time (min)

Figure S4 GC spectrum using TCD for the evolved gas from FA/SF over Pd/C synthesized with citric acid 298 K. 100

Volume of gas (mL)

80 60 40 20 0 0

50

100

150

200

250

300

Time (min) Figure S5 Gas generation by decomposition of FA/SF (1.06 M/0.84 M, 5 mL) in THF catalyzed by in situ prepared Pd/C catalyst (nPd/n(FA+SF)=0.005) with citric acid at 298 K.

4

Volume of the gas (mL)

100 80 60 40 20 0 0

50

100

150

200

250

300

Time (min) Figure S6 Gas generation from citric acid aqueous solution (1.06M, 5 mL) catalyzed by Pd/C (nPd/ncitric acid = 0.009) at 298K. 350 56%

Volume of gas (mL)

300 250 200 25%

150 0%

100 75%

50 0

100%

0

100

200

300

400

500

600

700

Time (min) Figure S7 Gas generation by decomposition of FA/SF with different FA molar percents (n(FA+SF) = 9.5 mmol) catalyzed by in situ prepared Pd/C with citric acid (nPd/n(FA+SF) = 0.005) at 298K.

5

6.00E-009

H2 Ar

Intensity

4.00E-009

2.00E-009

H2O 0.00E+000

0

8

16

24

32

40

48

m (z) Figure S8 MS spectrum for the evolved gas from SF aqueous solution (1.9 M, 5 mL) over Pd/C synthesized with citric acid (nPd/nSF=0.005) at 298 K under Ar atmosphere.

(a)

30

30

Frequency (%)

Frequency (%)

40

20

10

(b)

20

10

0

0 1

2

3

4

Size (nm)

5

6

6

7

8

9

10

11

12

13

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15

size (nm)

Figure S9 Size distributions of Pd NPs prepared (a) with citric acid and (b) without citric acid.

6

35

2000

(a)

C (002)

400

Frequency (%)

800

25

Intensity (a. u.)

1200

(c)

30

Pd (111)

1600

Pd (200) Pd (220) Pd (311)

20 15 10 5

0

0

20

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50

60

70

80

2

90

3

2 (degree)

4

Size (nm)

Figure S10 (a) XRD pattern and (b) TEM image, and (c) size distribution of Pd/C synthesized with citric acid after the catalytic reaction.

350

Volume of gas (mL)

300 250 st

200

1 nd 2 rd 3 th 4

150 100 50 0 0

100

200

300

400

500

600

700

800

Time (min) Figure S11 Recycle test of Pd/C synthesized with citric acid toward H2 generation from FA/SF with different run numbers.

7

Frequency (%)

30

(b)

20

10

0 3

4

5

6

7

8

9

10

Size (nm)

Figure S12 (a) TEM image and (b) size distribution of in situ synthesized Pd/C in the presence of L-ascorbic acid.

Frequency (%)

40

(b)

30

20

10

0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

Size (nm)

Figure S13 (a) TEM image and (b) size distribution histograms of in situ synthesized Pd/C in the presence of PVP.

8

350 (a) (b) (c)

Volume of gas (mL)

300 250 200 150 100 50 0 0

100

200

300

400

Time (min) Figure S14 Gas generation by decomposition of FA/SF (1.06 M/0.84 M, 5 mL) catalyzed by Pd/C (nPd/n(FA+SF)=0.005) synthesized (a) with PVP, (b) with PVP after washing, and (c) with citric acid at 298 K.

Table S1 Conversion and TOF values for decomposition of FA/SF system catalyzed by various heterogeneous catalysts.

Catalyst

HCOOH+HCOONa

Tem.

CO

Reaction

H2 volume

ncatalyst

Conversion

TOF

Ref.

(mmol)

(K)

generation

time (min)

(mL)

(mmol)

(%)

(mol H2. mol catalyst-1. h-1)

PdAu/C-CeO2

49.7+16.65

365

Yes

AuPd/ED-MIL-101

120

625

0.113

39

113.1

24

3.04+1.02

363

Yes

65

73

0.026

74

106.0

29

Pd/C with citric acid

5.3+4.2

298

No

160

196

0.047

85

64.0

This work

PdAg/C-CeO2

49.7+16.65

365

Yes

120

210

0.113

13

38.0

24

[email protected]/C

33.2+33.2

365

Yes

360

712

0.227

44

21.4

27

[email protected]

10+0

293

No

240

100

0.200

41

5.1

28

Calculation methods: xa =

PatmVH 2 / RT n( FA SF )

(S1)

Where xa is conversion, Patm is the atmospheric pressure, VH 2 is the final generated volume of H2 gas, R is the universal gas constant, T is the room temperature (298 K), 9

n( FA SF ) is the total mole number of reactants of FA and SF. TOF =

PatmVH 2 / RT nPd t

(S2)

Where npd is the mole number of Pd catalyst and t is the reaction time in hour. Rm =

n( FA  SF ) n FA

(S3)

Where the Rm is the theoretical molar ratio of H2 to CO2 based on equations (1) and (2), nFA is the mole number of FA.

References: S1. Lim, B., Jiang, M., Tao, J., Camargo, P. H. C., Zhu, Y. & Xia, Y. Shape-controlled synthesis of Pd nanocrystals in aqueous solutions. Adv. Funct. Mater. 19, 189-200 (2009).

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