Carbon sphere templates for TiO 2 hollow structures: Preparation, characterization and photocatalytic activity

Abstract

TiO 2 hollow structures (HS) were synthesized by carbon sphere template removal method. Nanometer sized carbon spheres (CS) were prepared by mild hydrothermal treatment of ordinary table sugar (sucrose). The size of these spheres can be controlled by the parameters of the hydrothermal treatment (e.g. time and pH). The obtained CSs were characterized by scanning electron microscopy (SEM), Raman spectroscopy, infrared spectroscopy (IR), X-ray diffraction (XRD) and thermogravimetry (TG). CSs were successfully coated with TiO 2 via sol-gel method. The phase composition of the TiO 2 hollow spheres were controlled by the annealing temperature during crystallization and CSs template removal. TiO 2 hollow structures (HSs) were characterized by SEM, XRD, Raman spectroscopy, TG and energy-dispersive X-ray spectroscopy (EDX). Photocatalytic performance of the TiO 2 HSs was evaluated by phenol degradation in a batch-type foam reactor under low powered UV-A irradiation. The degradation reaction was followed by high-performance liquid chromatography (HPLC) and total organic carbon (TOC) measurement techniques. Photocatalytic activity test results pointed out that increased rutile content up to a certain extent (resulting mixed phase anatase-rutile TiO 2) effects advantageously the photocatalytic performance of TiO 2 HSs and the unique morphology proved to enhance the photocatalytic activity (six times) as well as TOC removal efficiency (twelve times) compared to the sample which was prepared by the same method without the CSs.

Wet-Chemical Preparation of TiO2-Based Composites with Different Morphologies and Photocatalytic Properties

“…Due to high specific surface area and low density, hollow structured materials have been widely used in many fields [ 54 ]. TiO 2 hollow spheres with a well-defined crystal phase are highly desirable for photocatalysis use [ 55 , 56 , 57 ]. Hollow structured TiO 2 can be feasibly synthesized by hard template and soft template methods.…”

Graphitic Carbon Nitride and Titanium Dioxide Modified with 1 D and 2 D Carbon Structures for Photocatalysis

“…[29,30] The main shortcomingo fT iO 2 that hinders its practical application is its wide band gap (E g % 3.2 eV = 388 nm and E g % 3.0 eV = 413 nm for anatasea nd rutile,r espectively).Therefore, the photoexcitation wavelengths essential to the initiatedp hotoreactions are associated with UV light. [29,30] The main shortcomingo fT iO 2 that hinders its practical application is its wide band gap (E g % 3.2 eV = 388 nm and E g % 3.0 eV = 413 nm for anatasea nd rutile,r espectively).Therefore, the photoexcitation wavelengths essential to the initiatedp hotoreactions are associated with UV light.…”

“…TiO 2 is one of the most prominentp hotocatalystso wing to its excellentcatalytic properties, nontoxicity,and long-term stability.M oreover,i ti sa na bundant component on earth,b yw hich it gains an advantage over other commercially availableh eterogeneousc atalysts. [29,30] The main shortcomingo fT iO 2 that hinders its practical application is its wide band gap (E g % 3.2 eV = 388 nm and E g % 3.0 eV = 413 nm for anatasea nd rutile,r espectively).Therefore, the photoexcitation wavelengths essential to the initiatedp hotoreactions are associated with UV light. [31] The photoactivity of TiO 2 is substantially suppressed by fast electron-hole recombination.…”

Photocatalytically Active Amorphous and Crystalline TiO2 Prepared by Atomic Layer Deposition

“…It has long been an important issue how the energy of the sunlight can be effectively converted into chemical energy [1], and in recent years the interest in semiconductor oxide photocatalysts such as WO 3 , ZnO, and TiO 2 has grown exponentially [2]. These photocatalysts are widely used in water purification [3,4], decomposition of organic contaminants [5][6][7] or in the preparation of self-cleaning surfaces [8,9]. TiO 2 is the most widespread out of the semiconductor oxides in these fields, due to its low cost, good physical and chemical stability and being environmentally friendly.…”