Abstract
The present work reports the enhancement of the photoelectrochemical water splitting performance of in-situ silicon (Si)-doped nanotubular/nanoporous (NT/NP) layers. These layers were grown by self-organizing anodization on Fe-Si alloys of various Si content. The incorporation of Si is found to retard the layer growth rates, leads to a more pronounced nanotubular morphology, and most importantly, an improved photoelectrochemical behavior. By increasing Si content from 1, 2 to 5at.% in the iron oxide NT/NP photoanodes, the photocurrent onset potential shifts favorably to lower values. At 1.3V vs. RHE, hematite layer with 5at.% Si shows a 5-fold increase of the photocurrent, i.e. 0.5mAcm−2 in comparison to 0.1mAcm−2 for the undoped samples. The study also reveals that a suitable layer thickness is essential to achieve a beneficial effect of the Si doping.
•We grow anodically Si-doped Fe2O3 nanotubular/porous layers.•Si promotes the formation of a nanotubular morphology.•Si doping shifts the water splitting onset potential to a favorably lower value.