Construction of unique heterojunction photoanodes through in situ quasi-epitaxial growth of FeVO4 on Fe2O3 nanorod arrays for enhanced photoelectrochemical performance

Abstract

A unique FeVO₄–Fe₂O₃ heterojunction photoanode was successfully constructed through a so-called in situ quasi-epitaxial growth process of FeVO₄ on Fe₂O₃ nanorod arrays, and applied in photoelectrochemical (PEC) water splitting. This structural design involved the formation of a smooth phase interface between FeVO₄ and Fe₂O₃ components, which facilitated charge transfer at the junction area and effectively optimized the migration route of photogenerated electrons and holes. The charge separation efficiency of the heterojunction photoanode was significantly higher than that of pristine Fe₂O₃, from 41% to 86%, which was expected to improve the photoelectrochemical performance. As a result, the FeVO₄–Fe₂O₃ photoanode demonstrated an enhanced PEC performance for water oxidation, with a photocurrent density of 3.84 mA cm⁻² at 1.23 V vs. RHE (without an AM1.5G filter). The applied bias photon-to-current efficiency (ABPE) of the FeVO₄–Fe₂O₃ photoanode reached 0.27%. The incident photon-to-electron conversion efficiency (IPCE) of FeVO₄–Fe₂O₃ measured at 405 nm was 2.5 times higher than that of Fe₂O₃. In addition, the photocurrent density of the FeVO₄–Fe₂O₃ photoanode also showed a weak attenuation in the stability test of 12 h. The present in situ quasi-epitaxial fabrication strategy of the heterojunction photoelectrode might provide an effective and practical route for enhancing photoelectrochemical water oxidation on heterogeneous structures.