Iron-doped TiO2 nanorods coupled with naphthalenediimide (NDI) and 3,4-ethylenedioxythiophene (EDOT)-based donor-acceptor-donor type small organic molecule for visible-light water oxidation

Abstract

The present article reports an inorganic/organic type of nano-heterostructure (NHs)—Fe-TiO2/NDIHEDOT) as a photoanode with good photoelectrochemical (PEC) water splitting efficiency driven by visible light. This heterostructured photoanode consists of iron (Fe)-doped TiO2 nanorods (NRs) as inorganic part and a donor-acceptor-donor (D-A-D) type organic molecule—N,N-bis(2-hexyl)-2,6-(3,4-ethylenedioxythiophene)-1,4,5,8-naphthalenediimide (NDIHEDOT)—as an organic part. The 10% iron (Fe)-doped TiO2 (Fe–TiO2) nanorods (NRs) were grown hydrothermally on fluorine-doped tin oxide (FTO) substrates. The consequence of heterostructure formation on optical and PEC properties of the Fe–TiO2 and Fe–TiO2/NDIHEDOT photoanode were explored through PEC responses under visible light irradiation. The result shows that photocurrent densities of Fe–TiO2 and Fe–TiO2/NDIHEDOT photoanodes measured at 1 V vs. Ag/AgCl are 0.25 μA cm–2 and 0.49 μA cm–2, respectively, increase in the photocurrent density by Fe–TiO2/NDIHEDOT concerning photocurrent density shown by Fe–TiO2. The hybrid photoanode also exhibits high photostability and faradaic efficiency for water splitting. This work paves the way to develop a new inorganic/organic heterostructure for high-performance water splitting.