Pham Van Viet1*, Tran Hong Huy1, Nguyen Xuan Sang2, Cao Minh Thi3 and Le Van Hieu1

One-step hydrothermal synthesis and characterization of SnO2 nanoparticle-loaded TiO2 nanotubes with high photocatalytic performance under sunlight

Pham Van Viet1*, Tran Hong Huy1, Nguyen Xuan Sang2, Cao Minh Thi3 and Le Van Hieu1

1Nanomaterials for Environmental Applications Laboratory, Faculty of Materials Science, University of Science, VNU–HCMC, 227 Nguyen Van Cu Street, District 5, Ho Chi Minh City, 700000, Vietnam.

2Faculty of Electronics–Telecommunication, Saigon University, 273An Duong Vuong Street, District 5, Ho Chi Minh City, 700000, Vietnam

3CM Thi Laboratory, Ho Chi Minh City University of Technology (HUTECH), 475A Dien Bien Phu Street, Binh Thanh District, Ho Chi Minh City, 700000, Vietnam

*Corresponding author:

Summary: There are 06 pages including 03 figures and 01 table

Table Caption

Table S1: Specific surface area (SBET), pore volume, and pore size of the materials

Figure Captions

Figure S1.EDS mapping image of 2% SnO2/TNTs synthesized by a one-step hydrothermal method

Figure S2.UV-vis diffuse reflectance spectra (a) and representative plot of Kubelka function versus energy of SnO2, TNTs and 2% SnO2/TNTs

Figure S3. The absorption spectra of MB and 2% SnO2/TNTs at different time under sunlight irradiation

Surface area analysis

Table S1: Specific surface area (SBET), pore volume, and pore size of the materials

The BET results showing specific surface area (SBET), pore volume, and pore size of TNTs and 2% SnO2/TNTs materials were displayed in Table 1. Clearly, the combination of TNTs with SnO2 NPs results in the elevation of SBET, and a twofold increase was obtained from BET result.The BET results could explain for the superior photocatalytic performance of 2% SnO2/TNTs owing to the enhanced surface area. Besides, the 2% SnO2/TNTs has a pore size smaller 2 nm, demonstrating as a micropores material[1].

EDS mapping Analysis

Figure S1shows the EDS mapping of the 2% SnO2/TNTs material. As expected, the existence of Ti, O, and Sn atoms was obtained with 47.49%, 51.93%, and 0.59% of weight%, respectively. These results strongly confirmed the appearance of SnO2 in the material.

Figure S1.EDS mapping image of 2% SnO2/TNTs synthesized by a one-step. hydrothermal method

Figure S2.UV-vis diffuse reflectance spectra (a) and representative plot of Kubeka function versus energy of SnO2, TNTs and 2% SnO2/TNTs.

Figure S2 (a) shows that the absorption edge of the 2% SnO2/TNTs is shifted to the long-wavelength region revealing the combination with SnO2has widened absorption wavelength of the TNTs. In particular, the Kubeka function versus energy is used to estimate the bandgap of these samples. Figure S2 (b) shows that the bandgap of SnO2, TNTs, and 2% SnO2/TNTs is 3.17 eV, 3.10 eV, and 3.05 eV, respectively, which indicates the bandgap of the TNTs decreased when SnO2NPs loaded TNTs. The reduction of band gapoccurs owing to the presence of intermediate defect energy levels in the bandgap of TNTs when form heterojunction with SnO2. The major factor inducing the narrowing bandgap of TNTs is oxygen vacancies acting as electron traps to yield Ti3+ and/or F-type color center[2].

Figure S3. The absorption spectra of MB and 2% SnO2/TNTs at different time under sunlight irradiation.

Figure S3 exhibits the absorption spectra of MB and 2% SnO2/TNTs for 180 min under sunlight irradiation. The result showed that the absorption spectrum of MB negligible changedafter 180 minutes under sunlight irradiation. Meanwhile, the absorption spectrum of 2% SnO2/TNTs drastically changed, particularly, the typical absorption peak of MB at 664 nm strongly decreased after 180 minutesunder sunlight irradiation. This result confirmed that the abasement of MB absorption peak was caused by the photodegradation of catalyst but not by photolysis of MB. These results showed the MB photodegradation ability under sunlight condition of 2% SnO2/TNTs was superior.

REFERENCES

[1]Sing KSW (1985) Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984).Pure Appl Chem 57: 603-619

[2]Xiong LB, Li JL, Yang B, Yu Y (2012) Ti3+ in the Surface of Titanium Dioxide: Generation, Properties and Photocatalytic Application. J Nanomater. 2012:831524.

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