Surface passivation of undoped hematite nanorod arrays via aqueous solution growth for improved photoelectrochemical water splitting

• HAuCl4 in precursor solution leads to surface passivation of hematite.
• Surface passivation effectively improves photoelectrochemical performance of hematite nanorods.
• A reduction in electron–hole recombination occurs in surface passivated hematite nanorods.

A facile solution-based strategy was found to be effective for surface passivation of undoped hematite nanorod photoanodes by adding noble-metal chlorides such as HAuCl4 and H2PtCl6 in the Fe3+ precursor solution. XPS and Raman spectra revealed that noble-metal ions would not be doped into, but lead to surface disorder of hematite. Incident photon to current efficiency (IPCE) of the hematite photoanode grown in HAuCl4 and H2PtCl6 contained precursor solution was increased from 3.6% to 11.5% and 12.9%, respectively, at 365 nm and 1.23 V vs. RHE (reversible hydrogen electrode). This photoelectrochemical (PEC) enhancement was ascribed to the surface passivation, which resulted in a reduced recombination of photogenerated carriers, as confirmed by ultrafast transient absorption spectroscopy.

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