Graphene modified anatase/titanate nanosheets with enhanced photocatalytic activity for efficient degradation of sulfamethazine under simulated solar light

Xiaona Liu; Haodong Ji; Si Li; Wen Liu

doi:10.1016/j.chemosphere.2019.05.229

Graphene modified anatase/titanate nanosheets with enhanced photocatalytic activity for efficient degradation of sulfamethazine under simulated solar light

Chemosphere. 2019 Oct:233:198-206. doi: 10.1016/j.chemosphere.2019.05.229. Epub 2019 May 29.

Authors

Xiaona Liu¹, Haodong Ji², Si Li², Wen Liu³

Affiliations

¹ Institute of Environmental Science, Taiyuan University of Science and Technology, Taiyuan, Shanxi, 030024, China.
² The Key Laboratory of Water and Sediment Science, Ministry of Education, College of Environment Sciences and Engineering, Peking University, Beijing, 100871, China.
³ The Key Laboratory of Water and Sediment Science, Ministry of Education, College of Environment Sciences and Engineering, Peking University, Beijing, 100871, China; The Beijing Innovation Center for Engineering Science and Advanced Technology (BIC-ESAT), Peking University, Beijing, 100871, China. Electronic address: wen.liu@pku.edu.cn.

PMID: 31173957
DOI: 10.1016/j.chemosphere.2019.05.229

Abstract

Graphene modified anatase/titanate nanosheets (G/A/TNS) synthesized through hydrothermal treatment were used for solar-light-driven photocatalytic degradation of a typical pharmaceutically active compound, sulfamethazine (SMT). The optimal material was synthesized with 0.5 wt% of graphene loading (G/A/TNS-0.5), which could efficiently degrade 96.1% of SMT at 4 h. G/A/TNS-0.5 showed enhanced photocatalytic activity compared with the neat anatase and unmodified anatase/titanate nanosheets (A/TNS). UV-vis diffuse reflection spectra indicated that G/A/TNS-0.5 had a lower energy band gap (E_g) of 2.8 eV than A/TNS (3.1 eV). The grafted graphene acted as an electron transfer mediator after photoexcitation, resulting in inhibition on rapid recombination of electron-hole pairs. More importantly, architecture of graphene and titanate nanosheets both with two-dimensional structures greatly facilitated the photoexcited electron transfer. •OH and ¹O₂ were the primary reactive oxygen species (ROS) to SMT degradation. Fukui index (f^-) derived from density functional theory (DFT) calculation predicted the active sites on SMT molecule, and then SMT degradation pathway was proposed by means of intermediates identification and theoretical calculation. Furthermore, G/A/TNS-0.5 could be well reused and 90.5% of SMT was also degraded after five runs. The developed new photocatalysts show great potential for degradation of emerging organic contaminants through photocatalysis under solar light.

Keywords: DFT calculation; Graphene; Pharmaceuticals; Photocatalysis; Titanium nanomaterials.

MeSH terms

Catalysis
Graphite / chemistry*
Nanostructures / chemistry*
Photochemical Processes
Reactive Oxygen Species / chemistry
Sulfamethazine / chemistry*
Sunlight
Titanium / chemistry*
Water Pollutants, Chemical / chemistry

Substances

Reactive Oxygen Species
Water Pollutants, Chemical
titanium dioxide
Sulfamethazine
Graphite
Titanium