Hydrothermal and sol-gel low-temperature synthesis of tin, silver co-doped TiO2 nanoparticles with enhanced photocatalytic efficiency: artificial neural network modelling

Robab Mohammadi ,Mohammad Isazadeh

doi:10.33945/sami/ajgc.2019.4.2

Abstract

Pure anatase TiO2 nanoparticles with various Ag and Sn contents were synthesized by hydrothermal and sol-gel low-temperature methods. Structural and morphological characterizations of synthesized nanoparticles were performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and N2 adsorption/desorption isotherm and brunauer-emmett-teller (BET) techniques. The effect of synthesis procedure on the crystalline structure, crystal size, surface area, pore size distribution and photocatalytic activity of synthesized samples were studied. The photocatalytic activity was tested vs. degradation of methylene blue (MB) under black light radiation. Ag/Sn-TiO2 nanoparticles synthesized by hydrothermal method showed higher photoactivity during the degradation of MB under black light irradiation because of being enhanced in the specific surface area, total pore volume, and its reduction in the crystallite size. An artificial neural network (ANN) comprising four input variables (mol% of dopant ions, photocatalyst dosage, initial dye concentration, and pH of the solution), eight neurons and an output variable (degradation efficiency %) was optimized, tested and validated for MB degradation by Ag/Sn-TiO2 nanoparticles synthesized via hydrothermal method. The results showed that the predicted data from the designed ANN model are in good agreement with the experimental data with a correlation coefficient (R2) of 0.979. A 98.9% photodegradation efficiency of MB was achieved by utilizing 0.07 mol% Ag and 0.03 mol% Sn co-doped TiO2 at pH = 12.

Highlights

During the last decade, application of photocatalysts to control environmental pollution has attracted significant attention from the scientific community as a new environmental purification technique
The crystallite size obtained using Debye-Scherrer’s formula for Ag/Sn-TiO2 nanoparticles prepared by hydrothermal method and Ag/Sn-TiO2 nanoparticles prepared by sol-gel low-temperature method are 7.2 nm and 9.3 nm, respectively
The results implied that photocatalytic activity of Ag/Sn-TiO2 nanoparticles synthesized via hydrothermal method was higher than that of the Ag/SnTiO2 nanoparticles synthesized by sol-gel low-temperature method

Summary

Introduction

Application of photocatalysts to control environmental pollution has attracted significant attention from the scientific community as a new environmental purification technique. TiO2 has its own disadvantage including the relatively high speed in recombination of photogenerated electron–hole pairs [5]. To reduce the electron–hole recombination, many studies have been conducted, such as transition metals doping and coupling semiconductors [6]. An effective method for increasing the photocatalytic activity of titanium dioxide is to explore the cooperative influence via doping more than one ion metal into TiO2 network [7]. Li et al [10] studied the structural and electronic properties of (Fe–F) and (Fe–S) codoped TiO2. They conclude that the photocatalytic activity of Fe/S TiO2 is greater than that of the Fe/F TiO2

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