Pulsed Laser Ablation-Induced Green Synthesis of TiO2 Nanoparticles and Application of Novel Small Angle X-Ray Scattering Technique for Nanoparticle Size and Size Distribution Analysis.

Leo Hyvärinen,Jorma Vihinen,Erkki Levänen,Erkka Frankberg,Mari Honkanen,Amandeep Singh

doi:10.1186/s11671-016-1608-1

Leo Hyvärinen, Jorma Vihinen

Open Access

https://doi.org/10.1186/s11671-016-1608-1

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Journal: Nanoscale research letters	Publication Date: Oct 5, 2016
Citations: 38	License type: CC BY 4.0

Affiliation: Tampere University

Abstract

This paper aims to introduce small angle X-ray scattering (SAXS) as a promising technique for measuring size and size distribution of TiO2 nanoparticles. In this manuscript, pulsed laser ablation in liquids (PLAL) has been demonstrated as a quick and simple technique for synthesizing TiO2 nanoparticles directly into deionized water as a suspension from titanium targets. Spherical TiO2 nanoparticles with diameters in the range 4–35 nm were observed with transmission electron microscopy (TEM). X-ray diffraction (XRD) showed highly crystalline nanoparticles that comprised of two main photoactive phases of TiO2: anatase and rutile. However, presence of minor amounts of brookite was also reported. The traditional methods for nanoparticle size and size distribution analysis such as electron microscopy-based methods are time-consuming. In this study, we have proposed and validated SAXS as a promising method for characterization of laser-ablated TiO2 nanoparticles for their size and size distribution by comparing SAXS- and TEM-measured nanoparticle size and size distribution. SAXS- and TEM-measured size distributions closely followed each other for each sample, and size distributions in both showed maxima at the same nanoparticle size. The SAXS-measured nanoparticle diameters were slightly larger than the respective diameters measured by TEM. This was because SAXS measures an agglomerate consisting of several particles as one big particle which slightly increased the mean diameter. TEM- and SAXS-measured mean diameters when plotted together showed similar trend in the variation in the size as the laser power was changed which along with extremely similar size distributions for TEM and SAXS validated the application of SAXS for size distribution measurement of the synthesized TiO2 nanoparticles.

Highlights

Nanotechnology has eminently transformed the technology sector in the last few decades
The process of pulsed laser ablation in liquids (PLAL) can be divided into five stages: (i) irradiation of target with pulsed laser to form plasma, (ii) relaxation of plasma and formation of a cavitation bubble, (iii) nucleation and growth of nanoparticle in the cavitation bubble, (iv) collapse of the cavitation bubble to release nanoparticles in surrounding liquid, and (v) irradiation of synthesized nanoparticles by laser pulses
We propose small angle X-ray scattering (SAXS) for size and size distribution measurement of these nanoparticles, we still propose the use of transmission electron microscopy (TEM) for determination of shape and appearance of nanoparticles, as we do not obtain this information from SAXS

Summary

Introduction

Nanotechnology has eminently transformed the technology sector in the last few decades. It includes the atomic level analysis and manipulation of materials. The prevailing methods for the production of nanomaterials such as graphene are chemical vapor deposition and chemical exfoliation that are toxic and batch-type processes [1]. As these processes use toxic chemicals, they are precarious and potentially detrimental for the environment. Ogale et al in 1992 discovered formation of nanoparticles when materials immersed in water were ablated by a pulsed laser [2].

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