Decoupling Feature Size and Functionality in Solution-Processed, Porous Hematite Electrodes for Solar Water Splitting

We introduce a simple solution-based strategy to decouple morphological and functional effects of annealing nanostructured, porous electrodes by encapsulation with a SiO2 confinement scaffold before high temperature treatment We demonstrate the effectiveness of this approach using porous hematite (alpha-Fe2O3) photoanodes applied for the storage of solar energy via water splitting and show that the feature size and electrode functionality due to dopant activation can be independently controlled This allows a significant increase in water oxidation photocurrent from 1 57 mA cm(-2) (in the control case) to 2 34 mA cm(-2) under standard illumination conditions in 1 M NaOH electrolyte the highest reported for a solution-processed hematite photoanode This increase is attributed to the improved quantum efficiency, especially with longer wavelength photons, due to a smaller particle size, which is afforded by our encapsulation strategy