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Uninterrupted galvanic reaction for scalable & rapid Synthesis of metallic and bimetallic sponges/dendrites for efficient catalyst for 4-nitrophenol reduction

Barun Kumar Barman and Karuna Kar Nanda*

Materials Research Centre, Indian Institute of Science, Bangalore-560012, India

The yield calculation:

Cu:

Mol. Wt. of CuSO4, 5H2O = 249.70, Mol. Wt. of Cu = 63.546

1000 ml of 1M CuSO4, 5H2O solution ≡ 63.546 gm. Cu

2.5 ml of 0.2M CuSO4, 5H2O solution ≡ 0.0317 gm. Cu

Experimentally, when we immersed ~26 mg (3cm) of Mg ribbon in 2.5 ml of 0.2M CuSO4, 5H2O solution + 0.5 ml of 5M

H2SO4 solution, we get ~26.4 mg of Cu.

The yield of Cu ≡ 83 %

For synthesis of 1 gm. of Cu spongy structures, accordingly, we increased the corresponding precursor. For this case, we

used 100 ml of 0.2 M of CuSO4, 5H2O solution + 20 ml of 5M H2SO4 solution along with 1.4 gm. of Mg ribbon. Then we

get around 0.96 gm. of Cu sponge. So, we can really predict the synthesized product.

Ag:

Mol. Wt. of AgNO3 = 169.87 Mol. Wt. of Ag =107.86

1000 ml of 1 M AgNO3 solution ≡ 107.86

2.5 ml of 0.05 M AgNO3 solution ≡ 0.0135 gm. of Ag

Experimentally, when we immersed ~26 mg (3cm) of Mg ribbon in 2.5 ml of 0.05 AgNO3 solution + 0.5 ml of 5M H2SO4

solution, we get ~10.93 mg of Ag.

The yield of Ag ≡ 81 %

Sn:

Mol. Wt. of SnCl2, 2H2O = 225.64 Mol. Wt. of Sn=118.17

1000 ml of 1M SnCl2, 2H2O solution ≡ 118.71 gm. of Sn

2.5 ml of 0.2 M SnCl2, 2H2O solution ≡ 0.059 gm. of Sn

Experimentally, when we immersed ~26 mg (3cm) of Mg ribbon in 2.5 ml of 2.5 ml of 0.2 M SnCl2, 2H2O solution + 0.5 ml

of 5M H2SO4 solution, we get ~ 47 mg of Sn.

Electronic Supplementary Material (ESI) for Dalton Transactions.This journal is © The Royal Society of Chemistry 2015

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The yield of Sn≡ 80%

Fig1. Photograph of ~2.5 cm of Mg ribbon and Sn, Cu and Ag sponge structures after complete etching of the Mg ribbon.

Fig.2 SEM images of Mg ribbon (A & B) and Cu (C &D) and Ag (E & F) nanostructures grown on the Mg ribbon (inset) in absence of acid.

A B

C D

E F

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Fig.3 (A-D) SEM images of different magnification of spongy Ag nanostructures obtained with 2.5 ml of 0.05 M AgNO3 and 0.6 ml of 5M H2SO4.

A B

C D

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Fig.4 SEM images of spongy Sn obtained with 2.5 ml of 0.1M SnCl2, 2H2O and 0.6 ml of 5 M H2SO4.

Fig.5 SEM images of spongy Sn obtained with 2.5 ml of 0.2 M SnCl2, 2H2O and 0.6 ml of 5M H2SO4.

A B

C D

A

B

C D

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Cu sponge:

Fig.6 SEM images of spongy Cu obtained with 2.5 ml of 0.2 M CuSO4, 5H2O solution and 0.5 ml of 5M H2SO4. No change in morphology was observed when 0.1 M CuSO4, 5H2O solution was used. However, the amount was half in quantity.

Fig.7 (A & B) SEM images of Mg(OH)2 nanostructures formation on Mg foil surfaces when we performed the experiment in absence of acid medium. (C) XPS spectrum of Mg 2p in Mg(OH)2

(corresponding of to the binding energy 49.6 eV).1

A B

C D

30 35 40 45 50 55

Inte

nsity

(a.u

.)

Binding Energy (eV)

6

OCu

Cu

Cu

0 2 4 6 8 10 12 14 16 18 20keVFull Scale 557 cts Cursor: 0.022 (2840 cts)

Fig.8 Photograph and SEM images of spongy structures of gram scale synthesis of Cu. The scale bar corresponds to 9 cm.

Fig. 8. (A and B) EDS spectra of spongy Ag and Cu nanostructures .

Element Weight% Atomic%Ag L 100.00 100.00

Totals 100.00 100

Element Weight% Atomic%O K 3.31 11.98Cu K 96.69 88.02Totals 100.00 100

A B C

B

A

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Cu-Ag bimetallic dendritic nanostructures:

Fig. 9 SEM images with different magnifications and EDS spectra of Ag33Cu67.

Element Weight% Atomic%Cu K 67.28 77.73Ag L 32.72 22.27Totals 100.00 100

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:

Fig. 10 SEM images with different magnifications and EDS spectra of Ag50Cu50.

Element Weight% Atomic%Cu K 50.24 63.64Ag L 49.76 36.36Totals 100.00 100

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Fig. SEM images with different magnifications and EDS spectra of Ag65Cu35.

Element Weight% Atomic%Cu K 35.20 47.98Ag L 64.80 52.02Totals 100.00 100

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Fig. 12 SEM images with different magnifications and EDS spectra of Ag92Cu8.

Element Weight% Atomic%Cu K 8.00 12.87Ag L 92.00 87.13Totals 100.00 100

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Fig. 13 EDS spectra of various kind of bimetallic nanostructures with the Au, Pt and Pd.

Au Au Au AuAuAuCuAu

Cu

Cu

0 2 4 6 8 10 12 14 16 18 20keVFull Scale 498 cts Cursor: 0.071 (17 cts)

Spectrum 11

Cu90Au10

Pd CuPdO

Cu

Cu

0 2 4 6 8 10 12 14 16 18 20keVFull Scale 862 cts Cursor: 0.071 (18 cts)

Spectrum 9

Cu91Pd9

PtPtPtPt

PtPtPt CuPt

Cu

Cu

0 2 4 6 8 10 12 14 16 18 20keVFull Scale 547 cts Cursor: 0.071 (20 cts)

Spectrum 8

Cu91Pt9

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Fig. 14 (A-D) High resolution XPS spectra of individual Cu, Pd, Au and O in CuPdAu dendritic nanostructures.

Fig.15 UV-vis spectra of 4-nitrophenol before and after adding NaBH4 solution.

250 300 350 400 450 5000.0

0.5

1.0

1.5

2.0

2.5

3.0

4-nitrophenolate ions (400 nm)

Abso

rban

ce

Wavelength (nm)

4-nitrophenol (317 nm)

92 90 88 86 84 82 80

Au4f7/2

Inte

nsity

(a.u

.)

Binding Energy (eV)

Au4f5/2

A

970 960 950 940 930 920

Inte

nsity

(a.u

.)

Binding Energy (eV)

Cu 2p

B

350 345 340 335 330

C

Inte

nsity

(a.u

.)

Binding Energy (eV)

Pd 3d

540 536 532 528

Intse

nsity

(a.u

.)

A

O 1s

D

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Fig. 16 (A and B) 4-NP reduction by commercially available bulk Cu powder (10 ml of 1 mM 4-

NP and 10 ml of 50 mM NaBH4 solution and 5 mg of catalyst) and its pseudo first order rate

kinetics plot. (C and D) 4-NP reduction by Cu35Ag65 and its pseudo first order rate kinetics plot.

Reference

1. Y. Zhua, G. Wub, Y. H. Zhanga, Q. Zhaoa, Applied Surface Science, 2011, 257, 6129–6137.

200 250 300 350 400 450 5000.0

0.5

1.0

1.5

2.0

2.5

3.0

Abso

rban

ce

Wavelength (nm)

0 min 3 min 5 min 7 min 9 min 11 min 13 min 15 min

A

200 250 300 350 400 450 500

Abso

rban

ce (a

.u.)

Wavelength (nm)

0 min 3 min 5 min

C

0 2 4 6 8 10 12 14 16

-3

-2

-1

0

ln(A

t/A0)

Time (min)

B

0 1 2 3 4 5-5

-4

-3

-2

-1

0

ln (A

t/A0)

Time (min)

D