Highly Efficient Catalytic Reductive Degradation of Various Organic Dyes By

SUPPLEMENTARY INFORMATION

Highly efficient catalytic reductive degradation of various organic dyes by Au/CeO2-TiO2nano-hybrid

PRANJAL SAIKIA,*,a ABU T MIAHa and PARTHA P DASb

a Department of Applied Sciences (Chemical Science Division), GUIST, Gauhati University, Guwahati 781 014, Assam, India

b Department of Physics, NIT Karnataka, Surathkal, Mangalore 575025, Karnataka, India

Email: ;

*For correspondence

Table of contents

Table S1. Comparison of metal nanoparticles catalyzed reduction of MB by NaBH4 with the present work.

Figure S1.(a) Ce 3d, (b) Ti 2p, and (c) O1s XP spectrum of Au/CeO2-TiO2nano-hybrid.

Figure S2. UV-Vis absorption spectra for aqueous MB (30 mL, 48.14× 10−6 M) with2 mL, 0.2 M NaBH4 and 0.433g/L of (a) Au/CeO2and (b) Au/CeO2-ZrO2nano-hybrid.

Figure S3. Plausible mechanism for Au/CeO2-TiO2nano-hybrid catalyzed reductive degradation of MB.

Figure S4. UV-Vis absorption spectra for degradation of MB (48.14× 10−6 M, 30 mL) with different catalyst loading: (a) 0.183 g/L, (b) 0.233 g/L, (c) 0.333 g/L, and (d) 0.433 g/L.

Figure S5. UV-Vis absorption spectra for Au/CeO2-TiO2nano-hybrid catalyzed degradation of MB with different MB concentration: (a) 48.14× 10−6 M, (b) 58.84 × 10−6 M, (c) 66.86 × 10−6 M, and (d) 74.89× 10−6 M.

Figure S6. UV-Vis absorption spectra for Au/CeO2-TiO2nano-hybrid catalyzed degradation of MB with different NaBH4 concentration: (a) 0.125 M, (b) 0.150 M, (c) 0.175 M, and (d) 0.200 M. (e) ln(At/Ao) vs. time plot of pseudo-first-order reaction kinetics for degradation of MB with 2 mL of different NaBH4 concentrationswith Au/CeO2-TiO2nano-hybrid.

Figure S7.ln(At/Ao) vs. time plot for degradation of MB with 0.2 M, 2 mL of NaBH4(a) and with 13 mg of Au/CeO2-TiO2nano-hybrid (b).

Figure S8. UV-Vis absorption spectra of (a) MO (61.10 × 10−6 M, 30 mL) and NaBH4 (0.2 M, 2 mL), (b) Congo red (28.71 × 10−6 M, 30 mL) and NaBH4 (0.2 M, 2 mL), (c) RhB (10.44 × 10−6M, 30 mL) and NaBH4 (0.2 M, 2 mL), and (d) MG (54.81 × 10−6 M, 30 mL) and NaBH4 (0.01 M, 0.3 mL).

Figure S9. UV-Vis absorption spectra for the reduction of (a) MO, (b) CR, (c) RhB, and (d) MG, catalyzed by Au/CeO2-TiO2nano-hybrid in the presence of NaBH4.

Figure S10.(a) % degradation of MB obtained after successive cycles for reuse of Au/CeO2-TiO2nano-hybrid. Reaction conditions: 30°C, 13 mg Au/CeO2-TiO2nano-hybrid, 30 mL of 48.14 x 10−6 M aqueous MB solution, 2 mL, 0.2 mol/L NaBH4. (b) & (c) are, respectively, the XRD and TEM patterns of recovered Au/CeO2-TiO2nano-hybrid after performing 5th cycle.

Calculation of particle size: Debye Scherrer’s equation

Table S1. Comparison of metal nanoparticles catalyzed reduction of MB by NaBH4 with the present work.

Catalysta / Reductant/Template used for catalyst synthesisb / MB concentration / Catalyst loadingc (mg) / MNP loadingd (wt%) / Amount of NaBH4 / kapp(10−3 min−1) / Ref.
Au/CT / Urea / (48.14 ×10−6 M) × 30 ml / 13.0 mg / 1.00 / 0.2 M × 2 ml / 333.6 / Our work
CoO NWs / 2,7-DHN/CTAB, MW heating / (8 × 10−6 M) × 8 mL / 0.25 mL / n.a. / 0.1M × 1.75 mL / 38.3 / 51
Au NPs / SMG / (1 mM + 7.5 mL H2O) × 1.5 mL / n.m. / n.a. / 10 mM × 1 mL / 241 / 52
Au/LCG / Laser ablation / 10−5 M × 2.5 mL / 50 μL / 9.06 / 0.1 M × 0.5 mL / 384 x 102 / 53
Au/sa-GH / TETA, hydrothermal treatment
(180 ̊ C) / 0.1 mM × 2.8 mL / 0.1 mg / 2.26 / 0.1 M × 0.20 mL / 237 / 54
Au/TiO2 / UV light/Sodium citrate / (34.76 × 10−6 M) × 20 mL / 2 mg / 123.24 / 0.1 M × 2 mL / 156 / 8
Ag/PEI-SiO2 / PEI / (9.4 × 10-5 M) × 1 mL / 1/10.5
(MB/Ag, molar ratio) / 1.33 / 1/1700 (MB/NaBH4, molar ratio)
x 2 ml / 46 x 102 / 55
Cu/SBA-15 / NaBH4/Pluronic P-123 / 22.5 mL of 9 x 10−2mM MB + 12.5 mL H2O / 1 mg / 12.5 / 0.2 M × 5 mL / 510 / 2
Ag/GO / PQBAE / 1 μM × 1.50 mL / 0.50 mL / 41.35 / 0.01 M × 1.00 mL / 38 / 46
Au@PPy/Fe3O4 / PDDA/NH3.H2O/THF / (64.18 x 10−6 M) × 2.5 mL / 0.1 mg / 4.6 / 15 mg/mL × 1.0 mL / 266 / 56
Ag NPs / D-maltose/PAA / (1 × 10−5 M) × 1 mL / 3 × 10−8 M Ag / n.a. / 0.01 M × 1 mL / 141.4 / 57
Ag/PAGs / Amidodiol/PAA / 160 mg/L × 20 mL / 20 mg / n.m. / 10 mM× 2 mL / 222 / 58
Pd/
Fe3O4-PEI-RGO / NaBH4/PEI / 50 μM / 0.8 mg/mL / 1.90 / 1μM / 441.5 / 50
Au/Fe3O4@C / K2CO3/NaBH4/PDDA / 0.01 mM× 15 mL / 5 mg / 1 / 5 mM / 331 / 45

aCT = ceria-titania, NWs = nanowires, LCG = laser converted graphene, sa-GH = self-assembled graphene hydrogel, PEI = polyethyleneimine, GO = graphene oxide, PPy = polypyrrole, PAGs = polyacrylic acid-amidodiol hydrogels (amidodiol = 1,6-bis(hydroxybutyramido) hexane), rGO = reduced graphene oxide,

b2,7-DHN = 2,7-dihydroxy naphthalene, CTAB = cetyltrimethylammonium bromide, MW = microwave, TETA = Triethylenetetramine, SMG = salmaliamalabarica gum, PQBAE=Picrasmaquassioides bark aqueous extract, PDDA = poly(diallyldimethylammonium chloride), THF = Tetrahydrofuran, PAA = Poly(acrylic acid), PEI = polyethyleneimine.

cn.m. = not mentioned,

dMNP = Metal nanoparticle, n.a. = not applicable, n.m. = not mentioned.

Figure S1.(a) Ce 3d, (b) Ti 2p, and (c) O1s XP spectrum of Au/CeO2-TiO2nano-hybrid.

Figure S2.UV-Vis absorption spectra for aqueous MB (30 mL, 48.14× 10−6 M) with 2 mL, 0.2 M NaBH4 and 0.433g/L of (a) Au/CeO2 and (b) Au/CeO2-ZrO2nano-hybrid.

Figure S3.Plausible mechanism for Au/CeO2-TiO2nano-hybrid catalyzed reductive degradation of MB.

Figure S4.UV-Vis absorption spectra for degradation of MB (48.14× 10−6 M, 30 mL) with different catalyst loading: (a) 0.183 g/L, (b) 0.233 g/L, (c) 0.333 g/L, and (d) 0.433 g/L.

FigureS5.UV-Vis absorption spectra for Au/CeO2-TiO2nano-hybrid catalyzed degradation of MB with different MB concentration: (a) 48.14× 10−6 M, (b) 58.84 × 10−6 M, (c) 66.86 × 10−6 M, and (d) 74.89× 10−6 M.

FigureS6.UV-Vis absorption spectra for Au/CeO2-TiO2nano-hybrid catalyzed degradation of MB with different NaBH4concentration: (a) 0.125 M, (b) 0.150 M, (c) 0.175 M, and (d) 0.200 M.(e) ln(At/Ao) vs. time plot of pseudo-first-order reaction kinetics for degradation of MB with2 mL of different NaBH4 concentrationswith Au/CeO2-TiO2nano-hybrid.

FigureS7.ln(At/Ao) vs. time plot for degradation of MB with 0.2 M, 2 mL of NaBH4(a) and with 13 mg of Au/CeO2-TiO2nano-hybrid (b).

FigureS8.UV-Vis absorption spectra of (a) MO (61.10 × 10−6 M, 30 mL) and NaBH4 (0.2 M, 2 mL), (b) Congo red (28.71 × 10−6 M, 30 mL) and NaBH4 (0.2 M, 2 mL), (c) RhB(10.44 × 10−6 M, 30 mL) and NaBH4 (0.2 M, 2 mL), and (d) MG (54.81 × 10−6 M, 30 mL) and NaBH4 (0.01 M, 0.3 mL).

Figure S9.UV-Vis absorption spectra for the reduction of (a) MO, (b) CR, (c) RhB, and (d) MG, catalyzed by Au/CeO2-TiO2nano-hybrid in the presence of NaBH4.

Figure S10.(a) % degradation of MB obtained after successive cycles for reuse of Au/CeO2-TiO2nano-hybrid. Reaction conditions: 30 °C, 13 mg Au/CeO2-TiO2nano-hybrid, 30 mL of48.14 x 10−6 M aqueous MB solution, 2 mL, 0.2mol/L NaBH4. (b) & (c) are, respectively, the XRD and TEM patterns of recovered Au/CeO2-TiO2nano-hybrid after performing 5th cycle.

Calculation of particle size: The average particle size of CeO2 nano-crystals were calculated with the help of Debye Scherrer’s equation: d = kλ/βcosθ, where d is the crystal size, k is a constant whose value is often taken as 1, λ is X-ray wavelength (0.15406 nm for Cu Kα radiation), β is the full width at half maximum of the (111) peak of the cubic CeO2 and θ is the diffraction angle.