ABSTRACT
The solar spectrum is constituted of nearly 7% or even less of ultraviolet (UV) light, while the rest is visible light and infrared (IR) radiation. Therefore, the harvesting and utilization of sunlight from the UV-vis to near-infrared (NIR) regions and preferably the full solar light spectrum in the photocatalysis process is gaining increasing popularity (Sang et al. 2015) and has attracted the extensive attention of researchers (Baruah et al. 2012). Metal chalcogenides, in general, and metal oxides, in particular, are the most investigated photocatalysts in the contemporary material sciences. But their large band gap is one of the major drawbacks in their widespread use, which increases sensitivity of the metal oxides in the UV part of the solar spectrum and not in the visible and/or IR range. Therefore, an active research area these days is to synthesize a narrow band gap semiconductor that absorbs longer wavelengths of the solar spectrum. A semiconductor can be used successfully and efciently for environmental remediation such as degradation and decontamination of organic pollutant on a large scale if it can harness solar energy through an electron transfer. There are many shortcomings such as a wide band gap, colorless metal oxide, high recombination rate, and so on, which restrict the wide usage of these photocatalysts. Therefore, a search is being made to nd some amicable solution to these problems. Many methods have been tried from time to time to overcome these issues. One of the approaches that has attracted the attention of material scientists is doping of a semiconductor with metal and nonmetals (Nah et al. 2010).
