Research article

Comparative synthesis of ZnO nanorods and nanoflowers as photocatalysts for the photodegradation of 4-chlorophenol

¹Manriquez  Ramirez  ME, ¹Wang JA, ²Gómez Romero JR, ¹Reza San Germán CM, ³Hernandez Cortez JG, ¹Zuniga Moreno A and  ^{1, 4}Estrada Flores M

¹Escuela Superior de Ingeniería Química e Industriales Extractivas, Instituto Politécnico Nacional, UPALM, Col. Zacatenco, 07738 México D.F., Mexico.

²Depto. Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, 09340 México D.F. Mexico

³Programa de Ingeniería Molecular, Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas 152, A.P. 14-805, 07730 México, D.F., Mexico.

⁴Instituto de Investigaciones en Materiales, Circuito Exterior S/N, Zona de Institutos, Ciudad Universitaria, C.P. 04510, México, D.F.

*Corresponding Author E-mail: mestradaf7@hotmail.com 

Accepted 12 October 2014

Abstract

Nanostructured ZnO materials were comparatively synthesized via three different methods: precipitation, ultraviolet irradiation, and hydrothermal synthesis. ZnO with different morphologies such as flower-like androds were obtained, depending on the synthetic method. XRD analysis indicates that ZnO single-crystallite particularly grows along the [002] direction in all samples. The photocatalytic activity in the photodegradation of 4-chlorophenol appears to be correlated with the surface oxygen deficiency, the band gap energy, and the morphologies of the samples. ZnO nanorods prepared by the precipitation method show higher activity in comparison with that achieved by the samples synthesized by ultraviolet irradiation and hydrothermal methods; in the latter shows higher band energy and there exists a great extent of lattice oxygen deficiency in the surface that is unfavorable in the formation of surface active oxygen species like superoxide radicals, thus exhibiting the lower photoactivity.

Keywords: ZnO synthesis, photoactivity, 4-chlorophenol, surface oxygen deficiency.