FeOCl as a bifunctional co-catalyst on hematite: Heterojunction and charge transfer acceleration

FeOCl acts as a bifunctional co-catalyst on the Ti-Fe 2 O 3 photoanode for PEC water splitting. • FeOCl cocatalyst forms a type-II heterojunction with Ti-Fe 2 O 3 and boosts OER kinetics. • FeOCl can activate the lattice oxygen-mediated mechanism for accelerated OER. • AlOOH interlayer works synergistically with FeOCl to improve charge separation. • FeOCl/Al/Ti-Fe 2 O 3 photoanode achieves a photocurrent density 3.32 times that of bare Ti-Fe 2 O 3 . The photoelectrochemical water splitting performance of hematite photoanodes is limited by both poor charge separation and sluggish surface reaction kinetics. Herein, FeOCl is in situ deposited on Ti-doped Fe 2 O 3 (Ti-Fe 2 O 3 ) as an efficient co-catalyst with a bifunctional role. FeOCl forms a type-II heterojunction with Ti-Fe 2 O 3 that enhances bulk charge separation and accelerates charge transfer, potentially due to the activation of the lattice oxygen-mediated mechanism (LOM) to accelerate oxygen evolution reaction kinetics. Furthermore, an AlOOH interlayer introduced between FeOCl and Ti-Fe 2 O 3 reinforces the built-in electric field and works synergistically with FeOCl to further improve charge separation. The FeOCl/Al/Ti-Fe 2 O 3 photoanode delivers an optimized photocurrent density of 2.85 mA cm −2 at 1.23 V vs. RHE and 3.88 mA cm −2 at 1.50 V vs. RHE, outperforming both single-modifier photoanodes. This work demonstrates a dual-function design strategy that couples heterojunction formation with LOM activation, guiding the development of multi-component photoanodes. Download: Download high-res image (331KB) Download: Download full-size image