Intramolecular orbital engineered hetero bimetallic Ce-Fe MOF with reduced transition energy and enhanced visible light property

A structurally stable, 3d-4f heterometallic coordination polymer has been solvothermally synthesised and evaluated for its accomplished materials properties. The light absorption activity in the visible band was higher for unique Ce-Fe MOF than that of the homometallic Ce-MOF or Fe- MOF. The intimate overlap of two different metal clusters in heterometallic environmental induced the formation of low line conduction orbital, which ultimately lowered the transition energy. The heterometallic acquired an additional sensitisation from a Fe-μ3-oxo cluster that had vibrantly enhanced the light uptake activity. The vacancy created in the 6s, 5d orbital of Ce in Ce-Fe MOF contributed to the photo-excitation of electrons and reduced the recombination time. This distinct intramolecular arrangement assisted the exciton trapping characteristic. Also, the presence of multiple metal cores in the framework aided to confine the increased number of excitons for a redox reaction. The solar photocatalysis study with acetaminophen revealed these improved materialistic features by degrading it 94.6% with a rate constant of 0.0137 min⁻¹. The recycle studies confirmed the robust stability of the synthesised MOF.     

Significance of rod shape transformation of tetrahedral TiO2 under thermal influence for enhanced solar photocatalysis

TiO₂ nanorods (NRs) have been successfully synthesized via simple hydrothermal technique utilizing TiCl₄ as precursor at varied temperature of 160 °C, 200 °C and 250 °C, respectively. Further, thermal treatment was done in the close system at calcinations temperature thrice of the synthesis temperature. The prepared NRs were well characterized for the various physio-chemical natures of the materials. Crystallographic and morphological investigations showed that the samples exhibited high crystallinity with diameter ranges from 300 to 400 nm and length in several micrometers. XPS analysis proved the existence of oxygen defects that were created during the synthesis. The solar photocatalysis showed 81.27%, 92.20% and 58.79% removal of color by NR1, NR2 and NR3, respectively, within 300 min of direct sun irradiation time. The first-order kinetic model fits the better curve with the correlation coefficients of 0.97509, 0.97608 and 0.98417, respectively. Trapping experiments shows the dominant of holes and superoxide as the primary reactive oxygen species.

Graphical abstract