Improved charge carrier dynamics through a type II staggered Ce MOF/mc BiVO4 n-n heterojunction for enhanced visible light utilisation

Abstract

3D heterostructure of varied compositions between monoclinic BiVO4 and Cerium (Ce) Metal Organic Framework (MOF), possessing donor-acceptor characteristic was synthesized through facile hydrothermal technique. Molecular modelling was performed to understand the electronic structure and chemical bonding environment of BiVO4. The composite showed a reduction in bandgap to 2.20 eV and enhanced the light absorption in visible region with enhanced light absorbance. Band edge position calculation revealed the formation of type II staggered heterojunction. Such junction resulted a built-in electric field that prevented the exciton recombination with a lifetime of 5.8 µs. Ce MOF acted as an electron sink that received the excited electrons from BiVO4 and reduced the luminescence and charge transfer resistance to 17.3 Ω. The reduction in Debye length and increase in the carrier density favored the electronic movement around the junction interface. The superiority of this 3:1 composition was evaluated against removing methylene blue, Rhodamine B, and methyl orange with 88.8%, 86.07% and 74.7% degradation ratio, respectively. Similar excellent catalytic performance was also achieved for the phenol of non-photosensitizing nature with 51.3% removal efficiency. Active species trapping showed the h+ played a dominant role amongst the Reactive Oxygen Species (ROS) for the removal of studied pollutant from water.