Enhancement of Water Oxidation Photocurrent for Hematite Thin Films Electrodeposited with Polyvinylpyrrolidone

Hematite photoanodes were prepared by anodic electrodeposition in the presence of polyvinylpyrrolidone (PVP). PVP has been shown to alter hematite nanoparticle morphology, but has not been used before for anodic electrodeposition of thin films. Significant improvement in the water oxidation photocurrent was observed with PVP, with greater charge-collection efficiency due to a finer nanostructured morphology, and higher quantum yields for photons absorbed throughout the thickness of the hematite film from its increased porosity. Different post-deposition treatments showed distinct effects with and without PVP. Compared to electrodes dried 48 hours before annealing under N-2, electrode performance was significantly reduced upon annealing in air, or annealing immediately after deposition when PVP was not used. A distinct wavelength dependence for front-versus back-side illumination, and a similar to 100-fold decrease in dopant density, was attributed to formation of a dead layer on the top of those electrodes with reduced photoactivity, and was avoided using PVP. (C) The Author(s) 2016. Published by ECS. All rights reserved.