Facile Formation of Anatase/Rutile TiO2 Nanocomposites with Enhanced Photocatalytic Activity.

Jing He,Jing An,Yang Bai,Xiaojing Yang,Xuemei Cai,Yi-En Du,Qi Feng,Pengfei Wang,Yongqiang Chen

doi:10.3390/molecules24162996

Abstract

Anatase/rutile mixed-phase TiO2 nanoparticles were synthesized through a simple sol-gel route with further calcination using inexpensive titanium tetrachloride as a titanium source, which effectively reduces the production cost. The structural and optical properties of the prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis adsorption. The specific surface area was also analyzed by Brunauer–Emmett–Teller (BET) method. The anatase/rutile mixed-phase TiO2 nanocomposites containing of rod-like, cuboid, and some irregularly shaped anatase nanoparticles (exposed {101} facets) with sizes ranging from tens to more than 100 nanometers, and rod-like rutile nanoparticles (exposed {110} facets) with sizes ranging from tens to more than 100 nanometers. The photocatalytic activities of the obtained anatase/rutile mixed-phase TiO2 nanoparticles were investigated and compared by evaluating the degradation of hazardous dye methylene blue (MB) under ultraviolet light illumination. Compared to the commercial Degussa P25-TiO2, the mixed-phase TiO2 nanocomposites show better photocatalytic activity, which can be attributed to the optimal anatase to rutile ratio and the specific exposed crystal surface on the surface. The anatase/rutile TiO2 nanocomposites obtained at pH 1.0 (pH1.0-TiO2) show the best photocatalytic activity, which can be attributed to the optimal heterojunction structure, the smaller average particle size, and the presence of a specific exposed crystal surface. The enhanced photocatalytic activity makes the prepared anatase/rutile TiO2 photocatalysts a potential candidate in the removal of the organic dyes from colored wastewater.

Highlights

Water pollution resulting from textile dyes and other industrial dyestuffs has become an overwhelming problem worldwide [1,2]
Patterns of pH0.5-TiO2 and pH1.0-TiO2 show the same diffraction peaks, which can be ascribed to the tetragonal anatase phase (JCPDs file no. 21-1272, space groupI41 /amd) and the tetragonal rutile phase (JCPDs file no. 21-1276, space groupP42 /mnm), and rutile TiO2 is the major phase because it is the most stable among the three polymorphs under strong acidic conditions [26]
Anatase/rutile mixed-phase TiO2 nanocomposites have been successfully synthesized through a simple sol-gel route with further calcinations by using titanium tetrachloride as the titanium source, analytical ethanol and deionized water as the solvent, and ammonium fluoride as the capping agent

Summary

Introduction

Water pollution resulting from textile dyes and other industrial dyestuffs has become an overwhelming problem worldwide [1,2]. The colored wastewater discharged into the environment during the dying process is considered to the main source of environmental hazards, such as nonaesthetic pollution and eutrophication. The dangerous byproducts formed as a result of oxidation, hydrolysis, or other chemical reactions taking place in the wastewater are considered to endanger human health [1,2]. Removing above the organic dyes from the colored wastewater has attracted. Titanium dioxide (TiO2 ) has been extensively used as the photocatalyst for degradation of the organic contaminants in the environment under ultraviolet (UV) or visible light irradiation, because of its high stability, strong redox ability, nontoxicity, good corrosion resistance, and low cost [3,4]. TiO2 has three kinds of phases, anatase (tetragonal, space group I41 /amd), rutile (tetragonal, space group P421 /mmm), and brookite

Methods

Results

Conclusion