TiO₂-ZnO Binary Oxide Systems: Comprehensive Characterization and Tests of Photocatalytic Activity.

Katarzyna Siwińska-Stefańska,Stefan Jurga,Grzegorz Nowaczyk,Adam Piasecki,Teofil Jesionowski,Adam Kubiak,Joanna Goscianska

doi:10.3390/ma11050841

Katarzyna Siwińska-Stefańska, Stefan Jurga + Show 5 more

Open Access

https://doi.org/10.3390/ma11050841

Copy DOI

Abstract

A series of TiO2-ZnO binary oxide systems with various molar ratios of TiO2 and ZnO were prepared using a sol-gel method. The influence of the molar ratio and temperature of calcination on the particle sizes, morphology, crystalline structure, surface composition, porous structure parameters, and thermal stability of the final hybrids was investigated. Additionally, to confirm the presence of characteristic surface groups of the material, Fourier transform infrared spectroscopy was applied. It was found that the crystalline structure, porous structure parameters, and thermal stability were determined by the molar ratio of TiO2 to ZnO and the calcination process for the most part. A key element of the study was an evaluation of the photocatalytic activity of the TiO2-ZnO hybrids with respect to the decomposition of C.I. Basic Blue 9, C.I. Basic Red 1, and C.I. Basic Violet 10 dyes. It was found that the TiO2-ZnO material obtained with a molar ratio of TiO2:ZnO = 9:1 and calcined at 600 °C demonstrates high photocatalytic activity in the degradation of the three organic dyes when compared with pristine TiO2. Moreover, an attempt was made to describe equilibrium aspects by applying the Langmuir-Hinsherlwood equation.

Highlights

Photocatalysis is an effective process for creating minerals out of pollutants in the air and water such as simple inorganic compounds in the presence of a catalyst [1]
Dispersive analysis of the synthetic TiO2 -ZnO oxide systems showed that the molar ratio of the precursors significantly affects the particle sizes of the resulting materials
We studied how the TiO2 :ZnO molar ratio and calcination temperature affects the physicochemical and photocatalytic properties of synthetic TiO2 -ZnO oxide hybrids

Summary

Introduction

Photocatalysis is an effective process for creating minerals out of pollutants in the air and water such as simple inorganic compounds in the presence of a catalyst [1]. The most common and widely described heterogeneous photocatalysts are transition metal oxides and semiconductors such as TiO2 , ZnO, SnO2 , and CeO2 [2,3,4,5]. Titanium dioxide is the most active of the compounds that have been tested. It is relatively cheap, photochemically stable, non-toxic, UV-activated, and insoluble in most reaction environments [6,7]. Its application is limited because of its narrow photocatalytic region (α < 400 nm) and its ability to absorb only a small fraction (5%) of incident solar irradiation, which results from its relatively large band gap (anatase, ~3.2 eV) [8]. Many recent studies have focused on modifying the morphology and crystalline structure of TiO2 to improve its photocatalytic activity

Objectives

Results

Conclusion