Improved charge transfer performance of eosin Y-sensitized anatase TiO2 by anchoring group modification: from theoretical design to experiment

Abstract

Theoretical design and experimental proof of photocatalytic performance of eosin Y (EY) on anatase TiO₂ with a pyridine linker were obtained for increasing the photobiocatalytic activity of water splitting using visible light. Comparative studies on the hybrid interface of anatase and EY with carboxyl and pyridine anchors were performed by using density functional theory (DFT), time-dependent density functional theory (TD-DFT) calculations and experimental photoreduction of methyl viologen (MV). The geometries, binding interactions between dyes and anatase, electronic structures and electron transfer as well as the effect of isomers (ortho, meta, and para) on the dye/anatase systems were investigated. Theoretical results indicated that EY with carboxyl and pyridine anchors had visible absorption and electron transfer from the dye to the anatase titania. Compared to carboxyl-para, which had the best optical performance among carboxyl groups, the adsorption strength of pyridine-ortho was close to that of carboxyl-para, while the oscillator strength increased significantly, which was more than 10 times higher than that of carboxyl-para. Corresponding with the theoretical estimation, EY pyridine linked TiO₂ is active to MV reduction under visible light irradiation by fast charge transfer, in particular, pyridine-ortho and para. Furthermore, high stability is also achieved for pyridine-para. An apparent quantum yield higher than 2.00% and 0.67% under 520 nm light was experimentally achieved in biocatalytic H₂ and NH₃ formation, respectively, for EY pyridine linked TiO₂, which was correctly predicted by the DFT calculations.