A Titanium-Doped SiOx Passivation Layer for Greatly Enhanced Performance of a Hematite-Based Photoelectrochemical System

This study introduces an in situ fabrication of nanoporous hematite with a Ti‐doped SiOx passivation layer for a high‐performance water‐splitting system. The nanoporous hematite with a Ti‐doped SiOx layer (Ti‐(SiOx/np‐Fe2O3)) has a photocurrent density of 2.44 mA cm−2 at 1.23 VRHE and 3.70 mA cm−2 at 1.50 VRHE. When a cobalt phosphate co‐catalyst was applied to Ti‐(SiOx/np‐Fe2O3), the photocurrent density reached 3.19 mA cm−2 at 1.23 VRHE with stability, which shows great potential of the use of the Ti‐doped SiOx layer with a synergistic effect of decreased charge recombination, the increased number of active sites, and the reduced hole‐diffusion pathway from the hematite to the electrolyte. A nanoporous hematite with a Ti‐doped SiOx layer (Ti‐(SiOx/np‐Fe2O3)) has a photocurrent density of 2.44 mA cm−2 at 1.23 VRHE and 3.70 mA cm−2 at 1.50 VRHE. This is due to a synergistic effect of decreased charge recombination, the increased number of active sites, and the reduced hole‐diffusion pathway from the hematite to the electrolyte.