Mechanistic insight of structural and optical properties of BiOCl in the presence of CNTs and investigating photodegradation of phenol by BiOCl/CNT composites

In this work, we have synthesized composites of BiOCl with carbon nanotubes (CNTs) via a hydrothermal method. Different compositions of CNTs were used to study their influence on the physicochemical properties of BiOCl. Based on the interesting results obtained, various significant correlations were made. This study explored how use of CNTs and different hydrothermal crystallization conditions can influence the photocatalytic activity of composites. The CNTs have an impact on the primary crystallite size and morphology of BiOCl. Also, a higher degree of crystallization was obtained in the case of samples containing CNTs. However, in some cases, the synthesis parameters such as high temperature and longer duration also promoted crystallinity in BiOCl/CNT samples. Further, the samples were investigated for their photocatalytic activity to study the photodegradation of RhB and phenol, as model pollutants, under visible and UV light, respectively. The maximum degradation efficiency of 83% for RhB under visible light and almost 40% for phenol under UV light was obtained using BiOCl/CNT composites. Surprisingly, pure BiOCl showed higher performance for the removal of both the pollutants. This is why some comparisons and correlations between the structural and optical properties of BiOCl and CNTs were made. Finally, this study illustrates how a nanostructure like conductive multiwalled carbon nanotubes can sometimes have detrimental effects on the overall photocatalytic properties of a photocatalyst like BiOCl under certain conditions. Therefore, understanding the synergy between physico-chemical properties of BiOCl and nanostructured-modifiers like CNTs could help in designing a photocatalyst system which could benefit wastewater treatment.