supporting informationsupporting information identification of bi 2wo6 as a highly selective visible...
TRANSCRIPT
Supporting Information
Identification of Bi2WO6 as a highly selective visible light photocatalyst
toward oxidation of glycerol to dihydroxyacetone in water
Yanhui Zhang,a Nan Zhang,a Zi-Rong Tang,b and Yi-Jun Xu*ab
aState Key Laboratory Breeding Base of Photocatalysis, College of Chemistry and Chemical Engineering, Fuzhou
University, Fuzhou 350002, P.R. China bCollege of Chemistry and Chemical Engineering, New Compus, Fuzhou University, Fuzhou 350108, P.R. China
To whom correspondence should be addressed. E-mail address: [email protected]
Contents list
Experimental Details
Fig. S1. The UV–visible diffuse reflectance spectra (DRS) of Bi2WO6(A), Bi2WO6(B), and Bi2WO6(C);
inset is the estimated energy band gap by the plot based on the Kubelka-Munk function versus the energy
of light.
Table S1. Photocatalytic selective oxidation of glycerol over Bi2WO6 (B) under the irradiation of visible
light for 4 h in different solvents.
Fig. S2. 13C nuclear magnetic resonance (NMR) spectra of glycerol and dihydroxyacetone (DHA).
Fig. S3. The photoluminescence (PL) spectra of samples of flower-like Bi2WO6(A), Bi2WO6(B), and
Bi2WO6(C) with an excitation wavelength of 340 nm.
Fig. S4. Photocurrent transient responses of the samples of Bi2WO6(A), Bi2WO6(B), and Bi2WO6(C)
under the irradiation of visible light at a 0 V bias condition.
Fig. S5. N2 adsorption–desorption isotherms of the samples of Bi2WO6(A), Bi2WO6(B), and Bi2WO6(C);
and the summary of surface area and pore volume. Inset is the pore size distribution curve.
Fig. S6. Electron spin resonance (ESR) spectra of superoxide radicals trapped by DMPO and
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corresponding g factor over Bi2WO6 suspension in methanol solution (a); no hydroxyl radicals trapped by
DMPO are detected by ESR over Bi2WO6 suspension in aqueous solution (b).
Fig. S7. The absorption spectra of the flower-like Bi2WO6(B) aqueous solution in the presence of
peroxidase (POD) and N, N-diethyl-p-phenylenediamine (DPD) after visible light irradiation for 2 h.
Fig. S8. The ●OH-trapping photoluminescence (PL) spectra of the sample of flower-like Bi2WO6(B)
aqueous solution.
Fig. S9. The potential of valence band (VB) and conduction band (CB) for Bi2WO6 photocatalyst.
Fig. S10. Remaining fraction of glycerol and dihydroxyacetone (DHA) after the adsorption-desorption
equilibrium in the dark is achieved over the samples of Bi2WO6 (A), Bi2WO6 (B), and Bi2WO6 (C).
Fig. S11. Stability photoactivity test of only DHA in water over Bi2WO6(B) photocatalyst under visible
light irradiation.
Fig. S12. Recycled photoactivity test for six times operational runs of the optimum sample Bi2WO6(B)
toward selective oxidation of glycerol to DHA in water under visible light irradiation for 5 h.
Fig. S13. XRD patterns of fresh Bi2WO6(B), and used Bi2WO6(B) after selective oxidation of glycerol to
DHA in water under visible light irradiation for 5 h.
Fig. S14. XPS spectra of fresh Bi2WO6(B), and used Bi2WO6(B) after selective oxidation of glycerol to
DHA in water under visible light irradiation for 5 h.
Fig. S15. The sample pictures of the suspension after the photocatalytic reaction under visible light
irradiation for 2h (a); the suspension after removing the catalyst particles via a centrifugation process (b);
the remaining solution after removing the solvent of water via a rotary evaporation process in a water-
bath at 328 K in vacuum (c); the two-layered solution in a 1.5 mL centrifugal tube after a centrifugation
process (d).
Fig. S16. The HPLC spectra to identify reactant glycerol and main product DHA for selective oxidation
of glycerol in water over Bi2WO6 (B) photocatalyst under the irradiation of visible light for 4 h in the
reaction system.
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Experimental Details
Preparation of flower-like Bi2WO6 samples:
The procedures for synthesis of flower-like Bi2WO6 spherical superstructures in the present work are
based on a modified hydrothermal approach.S1 Typically, 0.98 g of Bi(NO3)3·5H2O was ultrasonicated in
40 mL of 0.3 M HNO3 aqueous solution to dissolve it evenly. Then, 20 mL of 0.05 M Na2WO4 solution
was added with vigorous stirring and a white precipitate was formed. Subsequently, 20 mL of 0.2 M
NaOH solution was added and the mixing solution was kept stirring for 24 h. After that, it was transferred
to 100 mL Teflon-sealed autoclave and maintained at 433 K for 4, 8 and 16 h, respectively. The resulting
sample was recovered by filtration, washed by water, and fully dried at 333 K in oven to get the final
flower-like Bi2WO6 samples.
Ref. S1: L. Zhang, W. Wang, Z. Chen, L. Zhou, H. Xu and W. Zhu, J. Mater. Chem., 2007, 17, 2526.
Characterization:
The morphology information was determined by a field-emission scanning electron microscope
(FESEM, FEI Nova NANOSEM 230). The crystalline structure of the catalysts was determined by
powder X-ray diffraction (XRD), using Ni-filtered Cu Kα radiation in the 2θ range from 5° to 80° with a
scan rate of 0.08° per second. The optical properties of the catalysts were analyzed by UV-vis diffuse
reflectance spectroscopy (DRS) using a Cary-500 spectrophotometer over a wavelength range of 200-800
nm, during which BaSO4 was employed as the internal reflectance standard. Nitrogen adsorption-
desorption isotherms and the Brunauer-Emmett-Teller (BET) surface area were collected at 77K using
Micromeritics ASAP 2010 equipment.
The photoluminescence (PL) spectra was measured on an Edinburgh FL/FS900 spectrophotometer.
For the PL analysis of solid samples of Bi2WO6, the excitation wavelength is 340 nm. The PL spectra are
often employed to study surface processes involving the electron-hole fate of semiconductor. With the
electron-hole pairs recombination after a semiconductor photocatalyst is irradiated, photons are emitted,
thus resulting in PL. Thus, the PL analysis of solid Bi2WO6 sample reflects the fate of electron-hole pairs
photogenerated from semiconductor Bi2WO6.
For the PL analysis of hydroxyl radicals photogenerated in solution, the terephthalic acid (TA) was
used as a probe molecule which can capture hydroxyl radicals photogenerated in Bi2WO6 aqueous
suspension to produce 2-hydroxyl terephthalic acid (TAOH) and the as-formed TAOH exhibits the
characteristic PL peak. Such a well-established PL-TA method is widely used to detect the hydroxyl
radicals photogenerated in an aqueous suspension of semiconductors.S2
In particular, for the PL analysis of hydroxyl radicals photogenerated in solution, the terephthalic acid
(TA) was used as a probe molecule which can react with hydroxyl radicals and the as-formed complex
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exhibits characteristic PL spectra. Typically, the as-prepared catalyst powder was dispersed in TA/NaOH
aqueous solution (1:2, mol/mol). The mixture was stirred for 1 h in the dark to blend well and allow the
adsorption-desorption equilibrium before the irradiation of visible light (λ>420 nm). The suspension was
magnetically stirred before and during the irradiation. A 3 mL sample solution was drawn form the
system at a certain time interval during the experiment, which was subject to the PL analysis with an
excitation wavelength of 312 nm.
The analysis of H2O2 generated in the photocatalytic reaction system was performed by a photometric
method. Typically, the measurement of H2O2 was carried out in a 10 mL Pyrex glass bottle under the
irradiation of visible light. In a typical process for measurement the concentration of H2O2 under visible
light irradiation, a mixture of 8 mg catalyst and 1.5 mL of water, which was saturated with pure molecular
oxygen. The above mixture was transferred into a 10 mL Pyrex glass bottle and stirred for 10 min to
make the catalyst blend evenly in the solution. The suspensions were irradiated by a 300 W Xe arc lamp
with a UV cutoff filter (λ>420 nm). After the reaction, the mixture was centrifuged at 12,000 rmp for 20
min to completely remove the catalyst particles, and then 10 μL of N, N-diethyl-p-phenylenediamine
(DPD) and 10 μL of peroxidase (POD) was added. The solution was analyzed on a Varian UV-vis
spectrophotometer (Cary-50, Varian Co.).
Electron spin resonance (ESR) signal of the radicals spin-trapped by 5,5-dimethyl-1-pyrroline-N-
oxide (DMPO) was measured using Bruker EPR A300 spectrometer. The settings for the ESR
spectrometer were as follows: center field=3507 G, microwave frequency=9.84 GHz and power=6.36
mW; the visible light irradiation source was a 300 W Xe arc lamp system equipped with a UV cutoff filter
(λ > 420 nm).
The electrochemical measurements were carried out in a three-electrode quartz cell. A Pt plate was
used as the counter electrode, and a Ag/AgCl electrode used as the reference electrode. The working
electrode was prepared in indium–tin oxide (ITO) conductor glass. A 5 mg sample was ultrosonicated in
0.5 mL of anhydrous ethanol to disperse it evenly to get slurry. The slurry was spreading onto ITO glass
whose side part was previously protected using scotch tape. The working electrode was dried overnight
under ambient conditions. A copper wire was connected to the side part of the working electrode using a
conductive tape. Uncoated parts of the electrode were isolated with epoxy resin. The electrolyte was 0.2
M aqueous Na2SO4 solution (pH=6.8) without additive. The photocurrent measurements were conducted
on a BAS Epsilon workstation without bias. The visible light irradiation source was a 300 W Xe arc lamp
system equipped with a UV cutoff filter (λ > 420 nm).
Ref. S2: N. Zhang, S. Liu, X. Fu and Y. J. Xu, J. Phys. Chem. C, 2011, 115, 9136.
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Photocatalytic activity
As previously done for photocatalytic oxidation of alcohols in the organic solvent of benzotrifluoride
(BTF), S3-S6 selective oxidation of glycerol in the solvent of water was carried out in a 10 mL Pyrex glass
bottle under the irradiation of visible light. In a typical process, a mixture of 8 mg catalyst and 0.1 mmol
of glycerol were dissolved in the solvent 1.5 mL of water, which was saturated with pure molecular
oxygen from a gas cyclinder. The above mixture was transferred into a 10 mL Pyrex glass bottle and
stirred for 10 min to make the catalyst blend evenly in the aqueous phase with a pH value ca. 6.7 (Notably,
without the catalyst, the pH value of glycerol solution in water is ca. 6.8). The suspensions were irradiated
by a 300 W Xe arc lamp with a UV cutoff filter (λ>420 nm). After the reaction, the mixture was
centrifuged at 12,000 rmp for 20 min to completely remove the catalyst particles. The remaining solution
was analyzed with a Shimadzu Liquid Chromatograph (DGU-20A3, equipped with a 512 Diode Array
Detector and a C18 analysis column). In order to confirm if the as-prepared Bi2WO6 photocatalyst is very
active and, in particular, highly selective toward oxidation of glycerol to DHA, we have also performed
the scale-up experiments by using five times the amount glycerol, i.e., 0.5mmol, while other reaction
conditions are the same as that described above.
Controlled photoactivity experiments using different radicals scavengers (ammonium oxalate as
scavenger for photogenerated holes,S7 tert-butyl alcohol as scavenger for hydroxyl radicals,S7 AgNO3 as
scavenger for electrons,S8,S9 and benzoquinone as scavenger for superoxide radical speciesS10,S11) were
performed similar to the above photocatalytic oxidation of glycerol except that radicals scavengers (0.1
mmol) was added to the reaction system.
Conversion of glycerol (GC), yield of dihydroxyacetone (DHA) and selectivity for dihydroxyacetone
(DHA) based on a GC analysis were defined as the follows:
100])([(%) 00 ×−= CCCConversion GC
100(%) 0 ×= CCYield DHA
100)]([(%) 0 ×−= GCDHA CCCySelectivit
Where C0 is the initial concentration of glycerol, CGC and CDHA are the concentration of glycerol and
dihydroxyacetone (DHA), respectively, at a certain time after the photocatalytic reaction. In order to
confirm the nature of product DHA by 13C NMR nucluear magnetic resonance (NMR) analysis, a post-
separation and purification process of DHA using the column chromotograph on silica get with acetone as
eluentS12 is performed, which is described in the Appendix in Supporting Information. The 13C NMR
nucluear magnetic resonance (NMR) spectra were performed using a Bruker Avance III 400 spectrometer.
Details for the separation of residual reactant glycerol and product DHA for 13C NMR analysis are
provided in the Appendix in Supporting Information.
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Ref. S3: Y. Zhang, Z. R. Tang, X. Fu and Y. J. Xu, ACS Nano, 2011, 5, 7426.
Ref. S4: M. Zhang, C. Chen, W. Ma and J. Zhao, Angew. Chem. Int. Ed., 2008, 47, 9730.
Ref. S5: N. Zhang, X. Fu and Y. J. Xu, J. Mater. Chem., 2011, 21, 8152.
Ref. S6: N. Zhang, S. Liu, X. Fu and Y. J. Xu, J. Phys. Chem. C, 2011, 115, 22901.
Ref. S7: W. Li, D. Li, Y. Lin, P. Wang, W. Chen, X. Fu and Y. Shao, J. Phys. Chem. C, 2012, 116, 3552.
Ref. S8: O. Carp, C. L. Huisman and A. Reller, Prog. Solid State Chem., 2004, 32, 33.
Ref. S9: A. Primo, T. Marino, A. Corma, R. Molinari and H. García, J. Am. Chem. Soc., 2011, 133, 6930.
Ref. S10: M. Stylidi, D. I. Kondarides and X. E. Verykios, Appl. Catal., B, 2004, 47, 189.
Ref. S11: P. Raja, A. Bozzi, H. Mansilla and J. Kiwi, J. Photochem. Photobio., A, 2005, 169, 271.
Ref. S12: R. M. Painter, D. M. Pearson and R. M. Waymouth, Angew. Chem. Int. Ed., 2010, 49, 9456.
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300 400 500 600 700 8000.0
0.3
0.6
0.9
1.2
1.5
2.1 2.4 2.7 3.0 3.3 3.6 3.9 4.20
100
200
300
400
500
600
2.81 eV2.79 eV
2.81 eV Bi2W O6(A) Bi2W O6(B) Bi2W O6(C)
hv (eV)
(ahv
)2Wavelength (nm)
Abs
orba
nce
(a.u
.)
Bi2WO6(A) Bi2WO6(B) Bi2WO6(C)
Fig. S1. The UV–visible diffuse reflectance spectra (DRS) of Bi2WO6(A), Bi2WO6(B), and Bi2WO6(C);
inset is the estimated energy band gap by the plot based on the Kubelka-Munk function versus the energy
of light.
Table S1. Photocatalytic selective oxidation of glycerol over Bi2WO6 (B) under the irradiation of visible light for 4 h in different solvents.
Selectivity (%) Solvent Conversion (%)
glycerol DHA glyceraldehyde
H2O 91 93 7
CH3CN 84 91 9
BTF 73 89 11
DMF 77 90 10
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Fig. S2. 13C nuclear magnetic resonance (NMR) spectra of glycerol and dihydroxyacetone (DHA).
Note: left column is the 13C NMR of standard samples of glycerol and DHA; right column is the 13C
NMR of sample glycerol and DHA after the photocatalytic reaction and separation process of reactant and
product.
The details for the separation of product DHA and purification of DHA by chromotograph column on
silica gel using acetone as eluent after photocatalytic reaction and 13C NMR analysis are provided in the
Appendix below.
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450 480 510 540 570 600Wavelength (nm)
Inte
nsity
(a.u
.)
Bi2WO6 (A) Bi2WO6 (B) Bi2WO6 (C)
Fig. S3. The photoluminescence (PL) spectra of samples of flower-like Bi2WO6(A), Bi2WO6(B), and
Bi2WO6(C) with an excitation wavelength of 340 nm.
0 40 80 120 160 200Time (sec)
Phot
ocur
rent
(a.u
.)
Bi2WO6(A) Bi2WO6(B) Bi2WO6(C)
off
on
Fig. S4. Photocurrent transient responses of the samples of Bi2WO6(A), Bi2WO6(B), and Bi2WO6(C)
under the irradiation of visible light at a 0 V bias condition.
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0.0 0.2 0.4 0.6 0.8 1.0
0
20
40
60
80
100
0 10 20 30 40 50 60 70 800
2
4
6
8
10
12
14
Bi2WO6(A) Bi2WO6(B) Bi2WO6(C)
Pore Width(nm)
Pore
Vol
ume(
x 1
0-3 c
m3 /g
)
Bi2WO6(A) Bi2WO6(B) Bi2WO6(C)
Vo
lum
e ad
sorb
ed(c
m3 /g
.STP
)
Relative Pressure(P/P0)
Sample Bi2WO6 (A) Bi2WO6 (B) Bi2WO6 (C)
surface area (m2/g)
pore volume (cm3/g)
30
0.16
31
0.16
31
0.16
Fig. S5. N2 adsorption–desorption isotherms of the samples of Bi2WO6(A), Bi2WO6(B), and Bi2WO6(C);
and the summary of surface area and pore volume. Inset is the pore size distribution curve.
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3460 3480 3500 3520 3540 3560
Hellolamp
Xe arc lamp
160 s
120 s
80 s
40 s
Magnetic Field(G)
Inte
nsity
(a.u
.)
(a)
1.99 2.00 2.01 2.02
2.0172.0132.010
2.0052.0021.998
Inte
nsity
(a.u
.)
g factor
3480 3500 3520 3540
(b)in the light
in the dark
Magnetic Field(G)
Inte
nsity
(a.u
.)
Fig. S6. Electron spin resonance (ESR) spectra of superoxide radicals trapped by DMPO and
corresponding g factor over Bi2WO6 suspension in methanol solution (a); no hydroxyl radicals trapped by
DMPO are detected by ESR over Bi2WO6 suspension in aqueous solution (b).
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420 450 480 510 540 570 6000.00
0.04
0.08
0.12
0.16
0.20
Wavelenght (nm)
Abs
orba
nce
(a.u
.)
Bi2WO6(B) irradiation 5 h Bi2WO6(B) irradiation 4 h Bi2WO6(B) irradiation 3 h Bi2WO6(B) irradiation 2 h Bi2WO6(B) irradiation 1 h without catalyst irradiation 5 h
Fig. S7. The absorption spectra of the flower-like Bi2WO6(B) aqueous solution in the presence of
peroxidase (POD) and N, N-diethyl-p-phenylenediamine (DPD) after visible light irradiation for 2 h.S13
Note: the appearance of absorption peaks located at ca. 510 nm and 551 nm indicates the presence of
H2O2 formation in our photocatalytic reaction system.
Ref. S13: H. Bader, V. Sturzenegge and J. Hoigné, Wat. Res., 1988, 22, 1109.
350 400 450 500 550 600
Wavelength (nm)
Inte
nsity
(a. u
.)
50 min 40 min 30 min 20 min 10 min 0 min
Fig. S8. The ●OH-trapping photoluminescence (PL) spectra (excitation wavelength, 312 nm) of the
sample of flower-like Bi2WO6(B) aqueous solution.
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E/V
vs.N
HE 0
1
2
3
-1
Bi2WO6
e
h
e
h
e
hVB +1.77 eV
CB -1.04 eVO2/O2·- -0.28 eV
H2O/·OH +2.30 eV
2.81eV
Fig. S9. The potential of valence band and conduction band for Bi2WO6 photocatalyst.
0.6
0.7
0.8
0.9
1.0 DHA glycerol
Bi2WO6(C)Bi2WO6(B)Bi2WO6(A)
R
emai
ning
frac
tion
of o
rgan
ic c
ompo
und
(a.u
.)
Initial
Fig. S10. Remaining fraction of glycerol and dihydroxyacetone (DHA) after the adsorption-desorption
equilibrium in the dark is achieved over the samples of Bi2WO6 (A), Bi2WO6 (B), and Bi2WO6 (C).
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1 2 3 4 50
20
40
60
80
100
C
onve
rsio
n (%
)
Irradiation Time (h)
Fig. S11. Stability photoactivity test of only DHA in water over Bi2WO6(B) photocatalyst under visible
light irradiation.
0
20
40
60
80
100
120
6th run5th run3rd run
Bi2WO6 (B)4th run2nd run1st runfresh
Sele
ctiv
ity(%
)
C
& Y
(%)
Selectivity Coversion Yield
0
20
40
60
80
Fig. S12. Recycled photoactivity test for six times operational runs of the optimum sample Bi2WO6(B)
toward selective oxidation of glycerol to DHA in water under visible light irradiation for 5 h.
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10 20 30 40 50 60 70 80
fresh Bi2WO6 (B)
used Bi2WO6 (B)
Bi2WO6
2 Theta (degree)
Inte
nsity
(a.u
.)
Fig. S13. XRD patterns of fresh Bi2WO6(B), and used Bi2WO6(B) after selective oxidation of glycerol to
DHA in water under visible light irradiation for 5 h.
156 159 162 165 168 171
0
5
10
15
20
25
Inte
nsity
(cou
nts
x 10
3 )
Bi 4f5/2
Bi 4f7/2
Binding Energy (eV)
(a) fresh Bi2WO6
32 34 36 38 40 42
0
2
4
6
Binding Energy (eV)
W 4f5/2
W 4f7/2
Inte
nsity
(cou
nts
x 10
3 )
(a) fresh Bi2WO6
156 159 162 165 168 171
0
5
10
15
20
25
Bi 4f5/2
Bi 4f7/2
Binding Energy (eV)
(b) used Bi2WO6
Inte
nsity
(cou
nts
x 10
3 )
32 34 36 38 40 42
0
2
4
6
Binding Energy (eV)
W 4f5/2
W 4f7/2
Inte
nsity
(cou
nts
x 10
3 )
(b) used Bi2WO6
Fig. S14. XPS spectra of fresh Bi2WO6(B), and used Bi2WO6(B) after selective oxidation of glycerol to
DHA in water under visible light irradiation for 5 h.
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Appendix.
It is well known that the melting point and boiling point of DHA are about 75-80 ℃ and 213.7 ℃,
whereas the melting point and boiling point of glycerol are about 17.8 ℃ and 210 ℃. However, the
boiling point of water is 100 ℃. Therefore, the suspension of glycerol and DHA after photocatalytic
reaction can be easily separated from the solvent of water by a simple rotary evaporation process.
Typically, after the reaction by visible light irradiation by a 300 W Xe arc lamp with a UV-cutoff filter
(λ>420 nm) for 2 h, the mixture suspension (panel a, Fig. S15) was centrifuged to completely remove the
catalyst particles. And then, the as-obtained solution was transferred into a Round-bottom glass flask
(panel b, Fig. S15). The solution was then evaporated in a rotary evaporator with water-bath at 328 K in
vacuum, by which the solvent of water was separated and removed. Consequently, the products and
reactants were left in the round bottom flask (panel c, Fig. S15 ). This mixture solution was then
transferred into a 1.5 mL centrifugal tube; followed by a centrifugation process, a two-layer separated
solution was obtained (panel d, Fig. S15 ). The upper layer solution is primarily the remaining reactant
glycerol while the lower layer solution with a slight yellow color is primary product DHA. The upper
layer solution was then extracted from the centrifugal tube, which was subject to the 13C nuclear magnetic
resonance (13C NMR) analysis. On the other hand, the lower solution was quickly transferred to a filter
paper, which turns into a solid sample at room temperature because the melting point of DHA are about
75-80 ℃.
To further purify the product dihydroxyacetone (DHA), we further apply the column chromatography
on silica gel using acetone as the eluent.S12 The as-obtained product DHA after this purification process
was subject to the 13C nuclear magnetic resonance (13C NMR) analysis. Typically, the sample (1 mmol)
was dispersed in the solvent deuterated oxide (D2O, 0.6 mL). 13C NMR was recorded using a Bruker
Avance III 400 spectrometer. The corresponding 13C NMR spectra of samples are displayed in the right
column in Fig. S2.
Ref. S12: R. M. Painter, D. M. Pearson and R. M. Waymouth, Angew. Chem. Int. Ed., 2010, 49, 9456.
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Fig. S15. The sample pictures of the suspension after the photocatalytic reaction under visible light
irradiation for 2h (a); the suspension after removing the catalyst particles via a centrifugation process (b);
the remaining solution after removing the solvent of water via a rotary evaporation process in a water-
bath at 328 K in vacuum (c); the two-layered solution in a 1.5 mL centrifugal tube after a centrifugation
process (d).
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0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 min
-500
0
500
1000
1500
2000
2500
3000
3500
4000
mAU
HO OHO
HO OHOH
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 min
-100
0
100
200
300
400
500
600
700
800
900
1000
mAU
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 min
-500
0
500
1000
1500
2000
2500
3000
3500
4000
mAU
Visible light irradiation 4 hDHA
glycerol
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 min
-500
0
500
1000
1500
2000
2500
3000
3500
4000
mAU
HO OHO
HO OHOH
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 min
-100
0
100
200
300
400
500
600
700
800
900
1000
mAU
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 min
-500
0
500
1000
1500
2000
2500
3000
3500
4000
mAU
Visible light irradiation 4 hDHA
glycerol
Fig. S16. The HPLC spectra to identify reactant glycerol and main product DHA for selective oxidation of glycerol in water over Bi2WO6 (B) photocatalyst under the irradiation of visible light for 4 h in the reaction system.
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