Natav Yatom, PhD. Candidate
In the search for photoanode materials for affordable, efficient, and stable photoelectrochemical (PEC) cells for solar water splitting, hematite (α-Fe2O3) is considered a leading candidate. Yet, hematite has some major drawbacks which hinder the development of high efficiency photoanodes. One of them is the charge transfer efficiency from the surface to the water.
In this research, we combine first principle calculations by density functional theory (DFT) together with experimental investigation of heteroepitaxial hematite films to gain insights into the water photo-oxidation mechanism. Firstly, the oxygen evolution reaction (OER) bottleneck intermediate was identified by resolving previous surface absorption spectra. Next, we investigated the relation between surface charging and the photocurrent by a preconditioned cyclic voltammetry (CV) measurements, analyzed by DFT and a revised charge transfer model. Finally, we conducted a DFT-based dynamic Monte Carlo (DMC) simulation to study the reaction order alteration due to potential/pH change.
The results of these studies yield new understanding on the OER on hematite electrodes, and provide new methods to analyze surface catalysis. These advances may pave the path to improve hematite’s solar to hydrogen fuel conversion efficiency.