Tailoring the morphology of hafnium zirconium oxide (Hf0.6Zr0.4O2) as a cocatalyst for photoelectrochemical water oxidation over a hematite (α‐Fe2O3) photoanode

We fabricated the hematite (α‐Fe2O3) photoanode with Hf0.6Zr0.4O2 (HZO)‐based cocatalysts prepared by two different types of the surface treatments, the overlayer coating, and the deposition of the nanoparticles. When the HZO nanoparticles were deposited, the current density at 1.23 VRHE was improved by about 31%, compared to that of the bare α‐Fe2O3 film, with the cathodic shift of the onset potential. On the other hand, in the case of the HZO overlayer, the PEC performance drastically decreased. In this study, we revealed that HZO nanoparticles could act as a cocatalyst, while the overlayer treatment accelerated the surface recombination. HZO nanoparticles acted as a cocatalyst, while the overlayer treatment accelerated the surface recombination