Erbium and Titanium Co‐Doped Hematite Nanorods: Structural, Optical, and Catalytic Properties for Enhanced Water Splitting

Abstract

Herein, hydrothermally synthesized hematite nanorods (NRs) co‐doped with erbium and titanium, using titanium tetrachloride and erbium(III) nitrate pentahydrate as the dopant sources, are presented. The effect of varied volumes of the erbium/titanium surface co‐dopants on the morphology, structural, optical, and photoelectrochemical (PEC) properties of hematite NRs is investigated. The pristine hematite, 40 ‐Er, and 40 ‐Er/20 ‐Ti‐doped NRs samples present a similar surface morphology of vertically aligned NRs. The NRs are randomly oriented with an increase in titanium dopant for the 40 ‐Er/30 ‐Ti‐doped NRs and later coalesced for the 40 ‐Er/40 ‐Ti‐doped NRs. The structural analysis based on X‐ray diffraction and Raman analysis present a uniform, pure hematite phase for all the prepared NRs. The samples exhibit high photon absorbance with peaks in the 400–450 nm wavelength range of the visible spectrum. The 40 ‐Er/40 ‐Ti‐doped NRs sample present the highest photocurrent density of 83.9 μA cm−2 at 1.4 V vs reversible hydrogen electrode (RHE) and is attributed to the lowest flat band potential (−0.76 V vs RHE) that enhances charge mobility at the electrode–electrolyte interface. These results reveal the facile erbium/titanium doping of hematite NRs as a viable strategy for enhancing their PEC water‐splitting performance.