Supporting Information. and Technology, 130 Meilong Road, Shanghai , China.

Transcription

1 Supporting Information Interfacial growth of TiO 2 -rgo composite by Pickering emulsion for photocatalytic degradation Shenping Zhang a, Jian Xu b, Jun Hu* a, Changzheng Cui* c, Honglai Liu a a. School of Chemistry and Molecular Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai , China. b. Shanghai Institute of Measurement and Testing Technology, 1500 Zhang Heng Road, Shanghai, , China c. Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai , China. junhu@ecust.edu.cn, cuichangzheng@ecust.edu.cn

2 Figure S1. Morphologies of TiO 2 -GO Pickering emulsions at different HCl dosages. (a) 40 µl, (b) 60 µl, (c) 80 µl, (d) 100 µl.

3 Figure S2. Morphology of TiO 2 -GO Pickering emulsions at different TBT dosages. (a) 1 ml, (b) 2 ml, (c) 3 ml.

4 Figure S3. Photographs of Pickering emulsions (a) as-prepared and (b) preserved for 30 days.

5 Figure S4. (a) XRD patterns and (b) FTIR spectra of GO before and after the hydrothermal process. FTIR spectra revealed that many strong absorption peaks of various oxygen-containing functional groups, such as, -OH stretching (3410 cm 1 ), carboxylates or ketones C=O stretching (1728 cm 1 ), -OH bending (1622 cm 1 ), carboxyl C-O stretching (1385 cm 1 ), epoxide C-O-C or phenolic C-O-H stretching (1223 cm 1 ), and C-O stretching (1058 cm 1 ) 1 in GO showed significant decreases in their intensity after the hydrothermal treatment. Therefore, GO was reduced to graphene, resulting in TiO 2 -rgo composites by the hydrothermal reduction.

6 Figure S5. XPS spectra of TiO 2 -rgo (a), Curve fits of Ti 2p(b), C 1s(c) and O 1s(d) Figure S5a shows the XPS survey spectrum of TiO 2 -rgo composite, where the chemical binding energies located at , 458.5, and eV are assigned to the characteristic peaks of C 1s, Ti 2p, and O1s, respectively. The C1s spectra of TiO 2 -rgo displays a predominant peak associated with C=C/C C ( ev), two relative weak peaks attributed to C O (285.6 ev) and C=O (289.5eV). 2 With respect to the XPS spectra of O1s in Fig S5d, three peaks of 529.7, , and eV have been fitted, which should be ascribed to Ti-O-Ti (lattice O), Ti-OH, and C-OH (and C-O-C) species, respectively. The core-level XPS signal shown in Fig S5b reveals two peaks at and ev, respectively, which are in good agreement with the reported XPS data of Ti 2p3/2 and Ti 2p1/2 in TiO 2. This indicates carbonaceous species here should be mainly deposited and bonded on the surface of

7 TiO 2, as neither Ti2p binding energy shift nor C1s binding energy around 282 ev (C Ti) 3 was observed, chemical C-Ti-O bond was not formed in this work. Figure S6. The TGA of TiO 2 -rgo composite.

8 Figure S7. Effects of (a) the dosage of TiO 2 -rgo and (b) the interfering ions of Ca 2+ and Mg 2+ on the degradation of TCH When we kept the initial concentration of TCH as 20 ppm, the effect of TiO 2 -rgo dosage on the photodegradation of TCH within a range from 0 to 0.5 g L -1 was investigated. As shown in Figure S7a, TCH is very stable under visible light without catalyst, when the TiO 2 -rgo dosage changed from 0.1 to 0.4 g L -1, with the concentrations of residual TCH as 39.6%, 22.3%, 15.5%, and 10.3%, respectively, the photodegradation efficiency significantly increased. Further increasing the TiO 2 -rgo dosage to 0.5 g L -1, the residual TCH concentrations was 8.6%, just a 1.7% decrease compared with 0.4 g L -1 dosage. So we selected 0.4 g L -1 as the optimal dosage for the following photodegradation experiments.

9 Figure S8. Characterizations of photocatalysts of TiO 2 -rgo composite by using Pickering emulsion approach, TiO 2 -rgo sol-gel composite and P25-rGO mixture. (a) XRD patterns, (b) N 2 adsorption-desorption isotherms, with the insert of the pore size distribution calculated by BJH model.

10 Figure S9. (a) Concentrations of residual TCH in solution after the adsorption on TiO 2 -rgo composite (b) Zeta potentials of TiO 2 -rgo at different ph As shown in Figure S9a, we studied the adsorption capacity of TCH on TiO 2 -rgo composite at different ph values by testing the concentration of residual TCH in the solution. When the solution ph is below the pk a1 value (3.30) of TCH (Scheme S1), 4 the dominant species of TCH in water was TCH 3+, while the hydroxyl moieties on the + surfaces of TiO 2 -rgo composite existed in the form of positively charged, TiOH 2 (Fig. S9b). The repulsion electrostatic interaction between TCH and TiO 2 -rgo led to the weak adsorption capacity of TCH at low ph. With increasing ph to around 6, the dominant TCH species was TCH 2, and the surface of TiO 2 -rgo composite was neutrally charged. Hence, the lowest electrostatic repulsion was experienced, resulting in the highest adsorption capacity. When ph was further increased, the dominant TCH species became TCH and TC 2, and the surface of TiO 2 -rgo composite also became negatively charged, which resulted in a stronger electrostatic repulsion, accordingly, a reduced adsorption capacities of TCH to TiO 2 -rgo composite.

11 Scheme S1. Chemical structure and acid dissociation constants of TCH.

12 Table S1. Porosity of each samples determined by the N 2 adsorption isotherms Samples GO p-tio 2 TiO 2 -rgo-300 TiO 2 -rgo-400 TiO 2 -rgo-500 A BET [m 2 g -1 ] [a] V total [cm 3 g -1 ] [b] [a] Calculated by BET method. [b] Calculated at the point of P/P 0 =0.99.

13 Table S2. Comparison of the photocataltic efficiency of various TiO 2 -carbon-based composites in organic pollutant degradations Composite BET (m 2 g -1 ) Pore size (nm) Pollutant amount (mg) Catalyst amount (mg) Light Removal rate Ref TG (MB) 100 Visible 120 min 42.5% 5 Ti/RGO(H 2 ) (MO or RhB) 30 Xenon lamp MO 140 min 100% RhB 120 min 100% 6 TiO 2-2wt%RGO (RhB) 30 Visible 80 min 98.8% 7 TOG (MB) 10 UV 30 min 90% 8 1C/2TiZr (Antipyrine) 50 Solar light 360 min 90% 9 TiO 2 -(20mg)GR (RhB) 50 Xenon lamp(>400nm) 120 min 100% 10 30%C 3 N 4 /F-TiO 2 1 (MB) 100 LED light 60 min 89% 11 TiO 2 /CNSAC 89 1 (MB) 20 Sunlight(with partial UV light) 120 min 96.35% 12 TiO 2 -rgo (MB) 4 (TCH) Xenon lamp(>400nm) 120 min 76% 120 min 90.49% this work

14 REFERENCES (1) Yan, W. Y.; Zhou, Q.; Chen, X.; Yang, Y.; Zhang, Y.; Huang, X. J.; Wu, Y. C. Size-Controlled TiO 2 Nanocrystals with Exposed {001} and {101} Facets Strongly Linking to Graphene Oxide via P-Phenylenediamine for Efficient Photocatalytic Degradation of Fulvic Acids. J. Hazard. Mater. 2016, 314, (2) Wu, Y.; Xing, M.; Zhang, J.; Chen, F. Effective Visible Light-Active Boron and Carbon Modified TiO 2 Photocatalyst for Degradation of Organic Pollutant. Appl. Catal. B Environ. 2010, 97 (1 2), (3) Chen, L. C.; Ho, Y. C.; Guo, W. S.; Huang, C. M.; Pan, T. C. Enhanced Visible Light-Induced Photoelectrocatalytic Degradation of Phenol by Carbon Nanotube-Doped TiO 2 Electrodes. Electrochim. Acta 2009, 54 (15), (4) Hopkins, Z. R.; Blaney, L. A Novel Approach to Modeling the Reaction Kinetics of Tetracycline Antibiotics with Aqueous Ozone. Sci. Total Environ. 2013, , (5) Ni, Y.; Wang, W.; Huang, W.; Lu, C.; Xu, Z. Graphene Strongly Wrapped TiO 2 for High-Reactive Photocatalyst: A New Sight for Significant Application of Graphene. J. Colloid Interface Sci. 2014, 428, (6) Xie, Y.; Hu, D.; Liu, L.; Zhou, P.; Xu, J.; Ling, Y. Oxygen Vacancy Induced Fast Lithium Storage and Efficient Organics Photodegradation over Ultrathin TiO 2 Nanolayers Grafted Graphene Sheets. J. Hazard. Mater. 2016, 318, (7) Sher Shah, M. S. A.; Park, A. R.; Zhang, K.; Park, J. H.; Yoo, P. J. Green Synthesis of Biphasic TiO 2 -Reduced Graphene Oxide Nanocomposites with Highly Enhanced Photocatalytic Activity. ACS Appl. Mater. Interfaces 2012, 4 (8), (8) Hu, C.; Chen, F.; Lu, T.; Lian, C.; Zheng, S.; Hu, Q.; Duo, S.; Zhang, R. Water-Phase Strategy for Synthesis of TiO 2 -Graphene Composites with Tunable Structure for High Performance Photocatalysts. Appl. Surf. Sci. 2014, 317, (9) Belver, C.; Bedia, J.; Rodriguez, J. J. Zr-Doped TiO 2 Supported on Delaminated Clay Materials for Solar Photocatalytic Treatment of Emerging Pollutants. J. Hazard. Mater. 2015, 322, (10) Yang, X.; Qin, J.; Li, Y.; Zhang, R.; Tang, H. Graphene-Spindle Shaped TiO 2 Mesocrystal Composites: Facile Synthesis and Enhanced Visible Light Photocatalytic Performance. J. Hazard. Mater. 2013, 261, (11) Dai, K.; Lu, L.; Liang, C.; Liu, Q.; Zhu, G. Heterojunction of Facet Coupled G-C 3 N 4 /surface-fluorinated TiO 2 Nanosheets for Organic Pollutants Degradation

15 under Visible LED Light Irradiation. Appl. Catal. B Environ. 2014, , (12) Ragupathy, S.; Raghu, K.; Prabu, P. Synthesis and Characterization of TiO 2 Loaded Cashew Nut Shell Activated Carbon and Photocatalytic Activity on BG and MB Dyes under Sunlight Radiation. Spectrochim. Acta - Part A Mol. Biomol. Spectrosc. 2015, 138,