Laser-Ablated ZnO Nanoparticles and Their Photocatalytic Activity toward Organic Pollutants.

Neli Mintcheva,Ali Aljulaih,Satoru Iwamori,Wilfried Wunderlich,Sergei Kulinich

doi:10.3390/ma11071127

Abstract

This work aimed to prepare nanostructures of ZnO with various lasers, testing them as photocatalysts, and comparing their morphology and activity in the degradation of organic pollutants in aqueous media. ZnO nanospheres (ns-ZnO) and ZnO nanorods (ms-ZnO) were prepared via the laser ablation of a Zn metal plate in water using nanosecond- and millisecond-pulsed lasers, respectively. The obtained materials were characterized using a set of optical, structural, and surface-science techniques, such as UV-vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Under visible-light irradiation, both nanostructures were found to be catalytically active toward the oxidation of methylene blue, which was used as a model compound. The ZnO nanorods fabricated with the millisecond laser showed better photocatalytic performance than their spherically shaped counterparts obtained by means of the nanosecond laser, which could be assigned to a larger number of defects on the ms-ZnO surface.

Highlights

Among various “top-down” approaches for the preparation of nanoparticles (NPs), laser ablation in liquid (LAL) is a sustainable, easy-to-use, and efficient laboratory method for the production of diverse nanomaterials with different chemistry, and various morphologies and shapes [1,2,3,4,5,6,7,8]
It is well known that the absorption peak of ZnO in the wavelength range of 300–400 nm is due to the intrinsic absorption of ZnO when electrons are promoted from the valence band to the conduction band of the semiconductor [5,25]
This study compared ZnO nanomaterials prepared via ablating Zn metal plates in water by means of nanosecond- and millisecond-long laser pulses

Summary

Introduction

Among various “top-down” approaches for the preparation of nanoparticles (NPs), laser ablation in liquid (LAL) is a sustainable, easy-to-use, and efficient laboratory method for the production of diverse nanomaterials with different chemistry (mainly metal oxides, sulfides, carbides, and metals), and various morphologies and shapes [1,2,3,4,5,6,7,8]. ZnO NPs with different morphology were reported by several groups to be generated via ablating a zinc metal plate in water (or some other solvents) using different types of lasers [2,3,5,6,7,10,11,12,13,14,15,16,17,18,19,20]. The most commonly used nanosecond pulsed lasers were applied to produce ZnO NPs with different sizes and photoluminescence (PL) properties [6,7,11,12,13,16,17,20]. The effect of medium pressure on the sizes and PL properties of the produced ZnO NPs was studied [7,20]

Objectives

Methods

Results

Conclusion