Photocatalytic activity of Hemin (Fe(iii) porphyrin) anchored BaTiO3 under the illumination of visible light: synergetic effects of photosensitization, photo-Fenton & photocatalysis processes

Abstract

The photocatalytic activity of Hemin (Fe(III) porphyrin) anchored BaTiO₃ (HBTO) under the illumination of visible light was studied. The average crystallite sizes obtained from PXRD were 42.88 nm and 40.32 nm for BaTiO₃ (BTO) and HBTO, respectively. The higher lattice strain values for the HBTO photocatalyst confirms the anchoring of hemin on BTO. The interaction of carboxylate groups of the hemin molecule with –OH groups, which are invariantly present on the surface of BTO through O–C–O–Ti bond, was confirmed by FTIR study. The observed XPS shift in the binding energy values of HBTO can be attributed to the anchoring of the hemin molecule to metal ions as well as due to the interaction with delocalized π-electrons of the porphyrin moiety. HBTO showed 33% decrease in the photoluminescence emission, implying less recombination of photogenerated charge carriers. This could be due to the efficiency of non-radiative electron-transfer through ISC from the excited singlet to the triplet state in the case of HBTO. The synergetic effects of various processes like photosensitization, formation of reactive singlet oxygen and the redox reactions involving iron in the +2 and +3 oxidation states were responsible for the extensive photonic efficiency of HBTO particularly in the presence of H₂O₂.