The photocatalytic ability of visible-light-responsive interfacial charge transfer complex between TiO2 and Tiron

Abstract

The surface modification of commercial TiO2 powder with catecholate-type ligand Tiron (TIR) leads to the formation of the interfacial charge transfer complex (ICT) absorbing in the visible spectral range. The estimated band gap energy of the ICT complex (Eg = 2.2 eV) by density functional theory (DFT) calculations agrees with experimental measurements. The surface-modified TiO2 with TIR has enhanced sorption capacity towards Pb2+ ions compared to the pristine one due to the presence of free sulfonate groups. Our attempt to reduce Pb2+ ions to metallic form failed. The TiO2-based ICT complex with TIR can serve as an efficient sorbent to remove Pb2+ ions from the solution without the ability to recover them in metallic form in a photo-driven catalytic process. The photocatalytic ability of the ICT complex to induce oxidation reactions is significantly improved since the complete degradation of organic dye methyl orange occurs under exclusive excitations with visible light photons.