Improving the Photoelectrochemical Performance of Hematite by Employing a High Surface Area Scaffold and Engineering Solid-Solid Interfaces

Herein, a high surface area electrode (HSE) consisting of indium tin oxide (ITO) as a scaffold and ultrathin Ti-doped hematite (α-Fe2O3) as the absorber material is developed. The HSE exhibits sixfold improvement in photoactivity over an analogous photoelectrode with a flat morphology. Interfacial recombination due to dopant impurities and shunting resulting from a high pinhole density in the hematite layer limit the device performance. These limitations are mitigated by introducing a tin oxide barrier layer, which reduces recombination at the solid–solid interface and mitigates shunting. Employing the HSE with an appropriate barrier layer improves charge separation efficiency and catalytic activity compared to conventional planar devices. This strategy can potentially be extended to other light absorber materials whose performance is affected by charge transport limitations.