Photocatalytic hollow TiO2 and ZnO nanospheres prepared by atomic layer deposition

Nóra Justh,Imre Miklós Szilágyi,Bence Parditka,Zoltán Erdélyi,Gabriella Kiss,László Péter Bakos,Klára Hernádi,Balázs Réti

doi:10.1038/s41598-017-04090-0

Abstract

Carbon nanospheres (CNSs) were prepared by hydrothermal synthesis, and coated with TiO2 and ZnO nanofilms by atomic layer deposition. Subsequently, through burning out the carbon core templates hollow metal oxide nanospheres were obtained. The substrates, the carbon-metal oxide composites and the hollow nanospheres were characterized with TG/DTA-MS, FTIR, Raman, XRD, SEM-EDX, TEM-SAED and their photocatalytic activity was also investigated. The results indicate that CNSs are not beneficial for photocatalysis, but the crystalline hollow metal oxide nanospheres have considerable photocatalytic activity.

Highlights

Photocatalysis using solar energy has been acknowledged as an environment friendly method to degrade pollutants and to treat wastewater[1]
Metal oxides can be deposited onto the carbon carriers with numerous techniques[24], from which atomic layer deposition (ALD) is an outstanding method to prepare carbon-metal oxide composites, since it allows the coating of the surface of nanostructures in a conformal and homogeneous way, with nanoscale precise control of the thickness of the deposited film
The carbon nanospheres, the carbon-metal oxide composites and the hollow metal oxide nanospheres were characterized by thermogravimetry/differential thermal analysis coupled with mass spectrometry (TG/DTA-MS), Fourier-transformation infrared spectroscopy (FTIR), Raman spectroscopy, powder X-ray diffraction (XRD), scanning electron microscope - energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscope - selected area electron diffraction (TEM-SAED), and the photocatalytic activity of the samples was investigated

Summary

Introduction

Photocatalysis using solar energy has been acknowledged as an environment friendly method to degrade pollutants and to treat wastewater[1]. In addition ZnO and TiO2 they have narrow light response range limited to UV due to the large bandgap of TiO2 (3.2 eV) and ZnO (3.3 eV) These limitations interfere with achieving maximum activity of the photocatalysts; it is desirable to use a co-catalyst to synthesize photocatalysts with improved charge separation, low recombination rates and wider response ranges[4, 7,8,9]. Carbon-based nanomaterials (e.g. nanotubes, nanospheres, fullerenes, graphene) are very attractive due to their high surface area, good thermal and electrical conductivity, mechanical as well as chemical stability, and they can be ideal co-catalysts in carbon-metal oxide composites[10, 11]. The carbon nanospheres, the carbon-metal oxide composites and the hollow metal oxide nanospheres were characterized by thermogravimetry/differential thermal analysis coupled with mass spectrometry (TG/DTA-MS), Fourier-transformation infrared spectroscopy (FTIR), Raman spectroscopy, powder X-ray diffraction (XRD), scanning electron microscope - energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscope - selected area electron diffraction (TEM-SAED), and the photocatalytic activity of the samples was investigated

Objectives

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Results

Conclusion