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Other publication (non peer-review)

Book Charge carrier dynamics in semiconductor-electrolyte interface of hematite based per water-splitting cell
Publisher University of Pretoria, Pretoria

Open Access

Type of Open Access Repository (Green Open Access)


Photo-electrochemical water splitting is a front running technique for solar to chemical fuels technologies with Hematite (α - Fe2O3) constituting one of the most promising semiconductor materials for the job. The understanding of its drawbacks is still, however, very limited and would go a long way to making improvements to its efficiency. More specffically this present study focuses on the Hematite electrolyte interface and the dynamics of the photo-induced charge carriers through the interface under water splitting conditions. Cyclic Voltammetry and Impedance Spectroscopy were employed to determine the predominant steps in photocurrent production as well as the water oxidation under different voltage and illumination conditions as well as in the presence of a Cobalt ion based surface catalyst. An appropriate physical model in the form of an equivalent circuit was created that took into account surface states made up of water oxidation intermediaries, activity of the Cobalt catalyst and the depletion layer of Hematite. Chronoamperometric studies were also done and modeled using a novel mathematical model that aimed to extract at-band potentials, charge carrier densities and depletion layer width data in a simpler and as accurate way as the complex Impedance Spectroscopy. These findings demonstrate a holistic view of the complexities of the interface and an alternative way of studying it.