การควบคุมโครงสร้างพื้นผิวระดับนาโนของซิงค์ออกไซด์สำหรับเร่งปฏิกิริยาการสลายตัวโดยแสงของสารอินทรีย์ปนเปื้อนในน้ำ

Abstract

This work focuses on the studies of nanostructures of zinc oxide (ZnO) semiconductor as photocatalyst for degradation of phenol and benzene contaminants in water. Size and shape controlled ZnO nanostructure were first prepared by hydrothermal method. Flower-like ZnO nanorod and hexagonal ZnO nanoplate were obtained via different reaction conditions. In order to improve surface properties, Ag-modified flower-like ZnO nanorods (Ag- ZnO nanord) with various Ag contents were prepared by different methods, namely, a single-step method: continuous heating the mixture of Zn2+, Ag+ precursors in NaOH solution and two-step method: a flower-shaped of ZnO nanorod was synthesized followed by Ag+ precursor deposition and reduction on the ZnO surface. Particle size, shape, structure and compositions of the obtained ZnO and Ag/ ZnO nanostructure were characterized by transmission electron microscopy (TEM), scanning electron microscopy combined with Energy dispersive X-ray analysis (SEM/EDX), and X-ray powder diffraction (XRD). The relationship between exposed surfaces of ZnO nanostructures and their optical properties was explored by photouminesence spectroscopy. The catalytic performance of ZnO and Ag/ZnO nanostructure with different shapes and surface compositions was explored via photocatalytic degradation of phenol and benzene. ZnO hexagonal nanoplates presented 2 times higher in catalytic activity than flower-like rod structure. Different methods for metal deposition on the surface of ZnO showed different surface structures and compositions, leading to different in photocatalytic activity. 0.5%Ag-modified ZnO nanoplate prepares by two-step method resulted in high photodegradation activity. From the present study, more than 90% decomposition of phenol and benzene was achieved within 60 min.