Organic-Inorganic Hybrid Material for Photocatalytic H₂ Evolution: Electron Shuttling between Photoresponsive Nanocomposite and Co(II) Redox Mediator

Abstract

In this report, a conductive polymer encapsulated metal oxide photocatalyst is developed through a straightforward insitu synthesis method wherein, polythiophene is incorporated with TiO₂ nanoparticles which imparts enhanced visible-light absorption to the samples and significantly improves the efficiency of charge transfer resulting due to the vacancy defects and high conductivity, ultimately leading to exceptional performance in H₂ production. Significantly, the rate of H₂ production was enhanced even further through the deposition of simple redox mediator. The introduction of Co²⁺ facilitates the transfer of photogenerated holes from the valence band by its conversion from +2 to +3 oxidation state which further enables the oxidation mechanism. The recombination rate of excitons has been significantly reduced due to the efficient transfer of photogenerated holes and the rate of photocatalytic H₂ production is improved. Interestingly, the valence states and local atomic structure of the Ti species in the synthesized sample were ascertained through the utilization of Ti K-edge XANES and EXAFS analysis, which validated the energy position.