MOF Templated Design of Hierarchical Nanoporous Photocatalyst for Water Detoxification and Microbial Photoinactivation

Abstract

Metal Organic Framework (MOF) materials are highly porous, functionally flexible and optically tunable photocatalytic material which has been widely studied for energy and environmental applications. However, the low chemical and skeletal stability of MOF limits its application under real conditions. A unique approach to counter these drawbacks is to use MOFs as sacrificial precursor to design various MOF derived functional nanomaterials1 . This study emphasizes in synthesizing hierarchical α-Bi2O3-BiVO4-CuFe2O4 ternary photocatalyst from Bi-trimesic acid MOF through a one pot self-assembly route2 . Initially, the Bi-MOF is used as a structural template to prepare α-Bi2O3-BiVO4 binary heterostructure with quasi-rod morphology with interconnecting porous architecture. The α-Bi2O3-BiVO4 quasi-rods were subsequently integrated with hexagonal CuFe2O4 nanosheets to prepare a hierarchical ternary composite for potential application in water remediation. The MOF derived heterostructure materials displayed higher surface area in comparison to the conventionally synthesized pristine materials. Comprehensive characterizations by using XRD, FTIR, BET, RAMAN, UV-Vis DRS, FESEM, TRPL and TEM revealed crystalline semiconductor phases, efficient photo garnering ability, improved dynamics of photoexcited state and enhanced charge migration dynamics. The synthesized photocatalyst displayed robust activity towards aqueous phase mineralization of mutagenic mesotrione herbicide with reaction rates 6-12 folds higher than parent semiconductors. The ternary heterostructure was also found to be highly effective in achieving complete microbial photo-inactivation (Escherichia coli) within 1h of light illumination. A conjugated S-scheme charge migration mechanism is postulated based on radical trapping experiments, ESR study and ROS analysis that accounted for the improved photocatalytic activity of the ternary MOF derived photocatalyst.