Enhanced Photoelectrochemical Performance of Hydrogen Treated Hematite Thin Films Decorated with a Thin Akaganéite (β‐FeOOH) Layer

Abstract

AbstractPoor oxygen evolution reaction (OER) on the surface of hematite is the limiting factor for overall photoactivity of hematite photoanode in the photoelectrochemical (PEC) cell for water oxydation. Herein, we effectively suppress the bulk carrier recombination by enhancing the propensity of surface‐reaching holes by dual modification, hydrogen treatment and β‐FeOOH loading in rf‐sputtered hematite (α‐Fe2O3) thin films. Hydrogen treatment in α‐Fe2O3 (H:α‐Fe2O3) improves the flat band potential and donor density thereby activating the α‐Fe2O3 photoanode for water splitting. However, the thin coating of FeOOH, an oxygen evolution catalyst (OEC), on the surface of α‐Fe2O3 photoanode reduces the interface recombination at the junction. The resulting β‐FeOOH/H:α‐Fe2O3 photoanode achieve a considerably higher photocurrent density (Jp ∼1.55 mA/cm2 at 1.23 V vs RHE) and more negative shift in the onset potential (‐0.60 V vs RHE) with respect to the pristine α‐Fe2O3 (0.60 V vs RHE) and exhibit long term stability under visible light illumination (λ > 420 nm). This work offer a simple but advance strategy of improving the performance of visible light active photocatalysts by hydrogen treatment and β‐FeOOH coating and open‐up the door for other applications such as dye degradation, solar water splitting, CO2 reduction etc under visible light illumination.