Highly Efficient Surface Charge Transfer in Fe2TiO5 Epitaxial Thin Film Photoanodes

Pseudobrookite (Fe2TiO5) has attracted significant attention as an emerging photoanode for water oxidation due to reports of enhanced performance in polycrystalline heterostructures with alpha-Fe2O3 or TiO2. However, the specific properties and contribution of Fe2TiO5 remain unknown. Here, we present the first photoelectrochemical characterization of epitaxial thin film Fe2TiO5, an ideal platform for probing the inherent response of this earth-abundant photoanode for solar water splitting. Moreover, by using an electrolyte containing a hole scavenger, we find highly efficient charge transfer at the Fe2TiO5-electrolyte interface. This notable surface property is exploited in the form of an Fe2TiO5/alpha-Fe2O3 heterostructure photoanode, for which we observe a photocurrent density increase by 1 order of magnitude and an onset potential improvement by similar to 300 mV. Establishing these fundamental properties elucidates the nature of reaction mechanisms on Fe2TiO5 and informs the design of highly efficient water photo-oxidation devices by incorporating this material with other photoanodes.

Automated summary

The research presents the first photoelectrochemical characterization of epitaxial thin film Fe2TiO5, revealing highly efficient charge transfer at the Fe2TiO5-electrolyte interface. This notable surface property is exploited in the form of an Fe2TiO5/alpha-Fe2O3 heterostructure photoanode, leading to a significant increase in photocurrent density and improvement in onset potential.