This finding can be attributed to three reasons. First is the strong redox ability of CdS in the nanocomposite with smallercrystal size. Second is the increase in specific surface area for more adsorbed MO. Third is the reductionin electron–hole pair recombination with the introduction of FGS. Based on their high photocatalyticactivity, the CdS NP/FGS composites can be expected to be a practical visible light photocatalyst.