Etched titania nanoplates by both HF and HAc and the ...Etched titania nanoplates by both HF and HAc and the photocatalytic activities for degradation of pollutants Mengjiao Xu, Fei

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Supporting Information for

Etched titania nanoplates by both HF and HAc and the

photocatalytic activities for degradation of pollutants

Mengjiao Xu, Fei Teng,* Juan Xu, Tianyun Lu and Mindong Chen

Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control,

Innovative Research Laboratory of Environment and Energy, School of Environmental

Sciences and Engineering, Nanjing University of Information Sciences and Engineering,

Nanjing 210044, P. R. China

Corresponding author. Email: [email protected] (F. Teng); Phone/Fax: +86-25-58736689

Experimental Section

Chemicals: Titanium butoxide (TB, 98%), 40% hydrofluoric acid (40% HF), glacial

acetic acid (HAc, 99.5%) and Commercial TiO2 (Degussa P25) were purchased from

Shanghai Reagents Company (Shanghai, China). All chemicals were used as received

without further purification.

Synthesis of TiO2 nanoplates: In a typical procedure, 1.2 g of water, 5.35 g of 4% HF

and 30.03 g of HAc were mixed to form a clear solution, and then mixed with 5 mmol

of TB in a Teflon-lined stainless steel autoclave with a capacity of 50 mL, and finally

kept at 180 oC for 24 h. After being cooled to room temperature naturally, the resultant

white powder was separated by centrifugation, washed with ethanol and distilled water

for several times, and dried at 60 oC overnight. In the study, a series of TiO2 nanoplates

with different shapes and sizes were synthesized by varying the precursors ratios or

reaction temperature.

Characterizations: The phase compositions of the samples were determined by X-ray

diffractometer (Rigaku D/max-2550VB): using graphite monochromatized Cu Kα

Electronic Supplementary Material (ESI) for RSC AdvancesThis journal is © The Royal Society of Chemistry 2014

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radiation (λ=0.154 nm), operating at 40 kV and 50mA. The XRD patterns were scanned

in the range of 20-80◦ at a scanning rate of 5◦min-1. The images of the samples were

obtained by scanning electron microscope (SEM, Hitachi SU-1510) operated at 120 kV.

The samples were coated with 5-nm-thick gold layer before observation. The structure

of the samples was observed by high-resolution transmission electron microscopy

(HRTEM, JEM-2100) with an acceleration voltage of 200 kV. Nitrogen

adsorption-desorption isotherms were performed at 77 K on the NOVOE 4000

physicoadsorption apparatus.

Photocatalytic reactions: Photocatalytic activities of the samples were tested by the

photocatalytic decomposition of rhodamine B (RhB). Typically, 0.1 g of powders were

put into a solution of RhB (200 ml, 8 mg/L), which was irradiated with a 300W Xe arc

lamp equipped with an visible light cutoff filter to provide ultraviolet with λ<420 nm.

Before the light was turned on, the solution was continuously stirred for 30 min in the

dark to ensure the establishment of an adsorption-desorption equilibrium. The

concentration of RhB during the degradation was monitored by colorimetry using a

UV-vis spectrometer (Shimadzu UV-2500 PC) at the wavelength 550 nm.

Table S1 The sizes of the samples at different x values in the xH2O/100HAc/2HF/1TB

system synthesized at 180 oC for 24 h

x 50 60 70 100

Diameter (µm) 2.5 1 0.6 0.2

Thickness (nm) 200 100 100 50

Aspect ratio 12.5 10 6 4


3

10 20 30 40 50 60 70 80

inte

nsity

(a.u

.)

2 Theta(degree)

0 2 4 6 8 10

0

2

4

6

8

10

Fig.S1 XRD patterns of the typical TiO2 nanoplates synthesized at 180°C for 24 h: in

the 70H2O/100HAc/2HF/1TB (molar ratios) system. TB: Titanium butoxide; all the

ratios of the chemicals in the following data are molar ratios


4

A

B


5

0 10 20 30 40 50 60 70 80 90

inten

sity

2 Theta(degree)

A B C D

0 2 4 6 8 10

0

2

4

6

8

10

C

D

E


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Fig.S2 SEM images and XRD patterns of TiO2 nanoplates synthesized at different

reaction temperatures for 24 h in the 70H2O/100HAc/2HF/1TB system: (A)140 oC, (B)

160 oC, (C) 180 oC, (D) 200 oC, (E) XRD

A

B


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Fig.S3 TEM images of the as-synthesized TiO2 samples at different temperatures for 24 h in the 70H2O/100HAc/2HF/1TB system: (A, B) 160 oC, (C, D, E) 180 oC

C D

E


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Fig.S4 SEM images of the as-synthesized anatase TiO2 at 180 oC for 24 h: (A)

70H2O/100HAc/2HF/1TB; (B) 200H2O/100HAc/2HF/1TB

A

1 μm

B


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Fig.S5 SEM images of the anatase TiO2 synthesized at 180 oC for 24 h: (A) 70H2O/

2HF/ 1TB, without adding HAc; (B) 70H2O/100HAc/ 1TB, without adding HF

A

B


10

0 10 20 30 40 50 60 70 80 90

inten

sity

2 Theta

0 2 4 6 8 10

0

2

4

6

8

10

Fig.S6 SEM images (A) and XRD patterns (B) of the TiO2 nanoplates synthesized at

180°C for 24 h in the 70H2O/100HAc/4HF/1TB system

A

B


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Fig.S7 Schematic growth mechanism for TiO2 samples

Etch figure

Assembly

Packing

Etching

Ti:F=1:2

Oriented attachment

Nucleation Growth

Ti:F=1:4

Increasing the molar

ratio of HAc/H2O

1 um

At high temperatures

Etch figures

Etch pits


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Table S2 Sizes, thicknesses and aspect ratios of the plates at different H2O/HAc molar

ratios

H2O/HAc (molar ratio) Diameter (µm) Thickness (nm) Aspect ratio

50/100 2.5 200 12.5

60/100 1 100 10

70/100 0.6 100 25

100/100 0.2 50 4

Preparation: 180 oC/24 h

Table S3 Sizes, thicknesses and aspect ratios of the plates at different temperatures

Temperature/oC Diameter (nm) Thickness (nm) Aspect ratio

140 180 50 3.6

160 600 100 25

180 600 100 6

200 500 100 5

Preparation: H2O/HAc=70/100 (molar ratio)


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Etched titania nanoplates by both HF and HAc and the ...Etched titania nanoplates by both HF and HAc and the photocatalytic activities for degradation of pollutants Mengjiao Xu, Fei