Morphology, Photocatalytic and Antimicrobial Properties of TiO2 Modified with Mono- and Bimetallic Copper, Platinum and Silver Nanoparticles.

Izabela Wysocka,Jacek Ryl,Ewa Kowalska,Anna Zielińska-Jurek,Grzegorz Nowaczyk

doi:10.3390/nano9081129

Abstract

Noble metal nanoparticles (NMNPs) enhanced TiO2 response and extended its activity under visible light. Photocatalytic activity of TiO2 modified with noble metal nanoparticles strongly depends on the physicochemical properties of NMNPs. Among others, the differences in the size of NMNPs seems to be one of the most important factors. In this view, the effect of the metal’s nanoparticles size, type and amount on TiO2 photocatalytic and biocidal activity was investigated. TiO2 modified with mono- and bimetallic nanoparticles of Pt, Cu and Ag were prepared using chemical and thermal reduction methods. Obtained nanocomposites were characterized using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and diffuse-reflectance spectroscopy (DR/UV-Vis) techniques. The photocatalytic activity was examined in 2-propanol oxidation and hydrogen generation processes. The mechanism of modified TiO2 excitation was evaluated in action spectrum measurements during phenol oxidation. A possibility of using less energy-consuming light sources as a set of light-emitting diodes (LEDs) selected based on action spectrum results was examined. It was found that the differences in NMNPs size were the result of the reduction method. Moreover, coupling with a second metal strongly affected and differentiated the photocatalytic and biocidal activity of the obtained TiO2-based photocatalysts.

Highlights

Noble metal nanoparticles (NMNPs) have attracted much attention due to their unique properties in comparison to bulk metals
Diffraction patterns of metal-modified TiO2 are shown in Figure S2a–c All obtained photocatalysts revealed a high level of crystallinity and consist of an anatase phase
Thermal reduction of silver ions resulted in a crystallite size that was two times larger, while for platinum ions thermal reduction led to a reduction of crystallite size from 34 nm to 24 nm

Summary

Introduction

Noble metal nanoparticles (NMNPs) have attracted much attention due to their unique properties in comparison to bulk metals. They possess exceptional optical, electrical and magnetic properties and are applied in various branches of industry, such as electronics, pharmacy, catalysis, cosmetics, optoelectronics and medicine [1,2,3]. Metal nanoparticles of d block (Ag, Au, Cu, Pt and Pd) possess the ability to absorb light from the visible to the near-infrared range due to the occurrence of localized surface plasmon resonance (LSPR). The term localized surface plasmon resonance (LSPR) describes the oscillation of metal particle-free electrons. The irradiation of nanoparticles with radiation of resonant frequency results in the oscillations of free electrons. The electron can be transferred as either interband or intraband, initiating local changes in the electric field in the surrounding environment [4,5,6,7,8,9,10,11,12,13]

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Results

Conclusion