1. Introduction
Themajor focus of researchers is on the development of one dimensional
semiconductor nanorods. This is due to their shape dependent
properties as well as potential applications in nanoscale electronic and
optoelectronic devices [1–4]. Azo dyes are widely used for the process
of dying in various industries like ceramics, cosmetics, textile, paper,
leather and food processing. These dyes have great hazards on human
health and the environment. Semiconductors are the commonly used
material in the degradation process of azo dyes [5–12].
Zinc oxide (ZnO) is a functional semiconducting material used for
various applications as it has a lot of advantages like, being environmental
friendly, chemically stable and less costly as compared to the other metal
oxides. Meanwhile one of the biggest disadvantages of ZnO is that it
absorbs only in the UV region because of its large band gap (3.2 eV).
A number of investigations on the photocatalytic activity of one dimensional
zinc oxide nanorods are studied under UV light [13–16]. Therefore,
there is a lot of interest to develop the photocatalytic activity of ZnO in the
visible light and to solve the above environmental issue. There are several
approaches to improve the photocatalytic activity of ZnO under visible
light such as dye sensitization, polymer sensitization, non-metal doping,
metal doping, and coupling of semiconductors. The enhancement of
visible light photocatalytic activity depends on various factors like surface
modification, band gap modification and the suppression of electron–hole
recombination [17–23]. Wang et al. explained that morphology is the
potential factor which influences the photocatalytic activity, and also
rod shaped ZnO has higher photocatalytic performance when compared
to the commercially available ones because of its large surface area [24].
Doping is a generally usedmethod to improve the various properties
of semiconductors. Already zinc oxide has been doped with various
metals and non-metals to improve its photocatalytic activity under