Systematic synthesis and analysis of change in morphology, electronic structure and photoluminescence properties of 2,2′-dipyridyl intercalated MoO3 hybrid nanostructures and investigation of their photocatalytic activity

Abstract

An organic–inorganic hybrid structure was synthesized by using 2,2′-dipyridyl and MoO₃ nanorods through a simple hydrothermal method. The as-prepared dipyridyl–MoO₃ hybrid samples looked like rod shaped micro crystals. The starting material used for this work was MoO₃ nanorods which had a width of 150 nm and a length of several microns, whereas the resulting hybrid structure had a width of one micron and a length of 10 to 30 microns. Here, dipyridyl has acted as a stretching molecule and bonded the MoO₃ nanorods together along their length to form hybrid micro crystals. By calcinating the hybrid sample at 400 °C, intercalated dipyridyl was removed, while maintaining the microscale morphology. These deintercalated MoO₃ samples looked like micro slabs having a width of 5 micrometers. The presence and intercalation of dipyridyl was confirmed by the change in the XRD [0 k 0] peak positions. As the cross sectional size of the dipyridyl is close to the van der Waals gap of the orthorhombic MoO₃ crystal, this space was effectively used for this intercalation process. The deintercalation process, i.e. the removal of dipyridyl was confirmed by TGA, and XRD measurements. The influence of dipyridyl in the valence band electronic density of states (DOS) of MoO₃ was also analyzed by XPS and XES methods. A photoluminescence study was also conducted, reflecting the intercalation effect on the emission characteristics of the MoO₃ nanostructures. A photodegradation study on Procion Red MX 5B was also carried out, showing that the dipyridyl deintercalated MoO₃ micro slab like samples had the highest photodegradation efficiency.