Hematite photoanodes prepared by particle transfer for photoelectrochemical water splitting

Abstract

A hematite (α-Fe₂O₃) photoanode for O₂ evolution is usually prepared as a thin film on a conductive substrate like a fluorine-doped tin oxide/glass. Such a conductive substrate is not resistive to a temperature as high as 800 °C, while this temperature is required to remove the surface states on α-Fe₂O₃. In this study, we solved this issue by preparing α-Fe₂O₃ particles at first and then applying them to photoanodes by particle transfer. The optimized particulate α-Fe₂O₃ photoanode showed a photocurrent of only ∼0.3 mA cm⁻² at 1.23 V (versus a reversible hydrogen electrode), but it showed a surprisingly low onset potential at 0.6 V_RHE at pH 7.2. It was therefore combined with a particulate Ga-doped La₅Ti₂Cu_0.9Ag_0.1O₇S₅ photocathode in a parallel cell for unbiased water splitting, showing a solar-to-hydrogen conversion efficiency of 0.07%. Our study presents an alternative approach for preparing a α-Fe₂O₃ photoanode and verifies its potential for cost-effective unbiased water splitting.