Synthesis, Characterization and Enhanced Photocatalytic Activity of Iron Oxide/Carbon Nanotube/Ag-doped TiO2 Nanocomposites

José Marques Neto,Carlos De Souza,Renê Da Silva,Carlos Bellato,Pablo Rocha

doi:10.21577/0103-5053.20170081

José Marques Neto, Carlos De Souza + Show 3 more

Open Access

https://doi.org/10.21577/0103-5053.20170081

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Abstract

A novel magnetically recoverable catalyst (Fe/MWCNT/TiO2-Ag) was prepared in this study by a process that involves few steps. Titanium dioxide doped with silver and iron oxide was deposited on support of multi-walled carbon nanotubes (MWCNT). The synthesized catalysts were characterized by inductively coupled plasma mass spectrometry (ICP-MS), N2 adsorption/desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), infrared spectroscopy (IR) and UV-Vis diffuse reflectance spectra (DRS). Phenol in aqueous solution (50 mg L-1) was used as a model compound for evaluation of UV-Vis (filter cut off for l > 300 nm) photocatalytic activity. The composite catalyst has a high photocatalytic activity, destroying ca. 100% of phenol and removing 85% of total organic carbon in an aqueous solution after 180 min. The Fe/MWCNT/TiO2-Ag catalyst remained stable, presenting an 8% decrease in phenol degradation efficiency after ten consecutive photocatalytic cycles.

Highlights

Among the semiconductors used in heterogeneous photocatalysis, titanium dioxide is that most used due to specific properties, including high photosensitivity, non‐toxic nature, chemical stability and relatively low cost.[1,2] One inherent problem to the use of this catalyst is the electron‐hole recombination and its high band-gap value of 3.2 eV, limiting its photoactivity at low wavelengths and preventing the use of TiO2 in applications with visible light.[3,4]Doping of TiO2 with metals such as gold, platinum, rhodium and silver increases the spectrum of radiation absorption by TiO2, allowing for its use with visible light.[5]
The photocatalysts were used in UV-Vis photodegradation of phenol in aqueous solution and presented high photocatalytic activity
The 10-Fe/multi-walled carbon nanotubes (MWCNT)/TiO2-Ag-9 composite photocatalyst resulted in approximately 100% phenol and 85% Total organic carbon (TOC) removal from an aqueous phenol solution of initial concentration equal to 50 mg L-1, after 180 min

Summary

Introduction

Among the semiconductors used in heterogeneous photocatalysis, titanium dioxide is that most used due to specific properties, including high photosensitivity, non‐toxic nature, chemical stability and relatively low cost.[1,2] One inherent problem to the use of this catalyst is the electron‐hole recombination and its high band-gap value of 3.2 eV, limiting its photoactivity at low wavelengths and preventing the use of TiO2 in applications with visible light.[3,4]Doping of TiO2 with metals such as gold, platinum, rhodium and silver increases the spectrum of radiation absorption by TiO2, allowing for its use with visible light.[5]. The increase of the intensity ratio is due to disturbances in the structure of the nanotubes by interaction with the TiO2-Ag and iron oxide nanoparticles.[48] The presence of the TiO2-Ag bands of the magnetite-maghemite and the shifts of the D and G bands of the carbon nanotubes (Figure 3f) indicated that there was a strong interaction between the catalyst components.

Results

Conclusion