A Model System for Photocatalysis: Ti-Doped α-Fe2O3(11Ì
02) Single-Crystalline Films.
Chem Mater
; 32(9): 3753-3764, 2020 May 12.
Article
em En
| MEDLINE
| ID: mdl-32421058
ABSTRACT
Hematite (α-Fe2O3) is one of the most investigated anode materials for photoelectrochemical water splitting. Its efficiency improves by doping with Ti, but the underlying mechanisms are not understood. One hurdle is separating the influence of doping on conductivity, surface states, and morphology, which all affect performance. To address this complexity, one needs well-defined model systems. We build such a model system by growing single-crystalline, atomically flat Ti-doped α-Fe2O3(11Ì
02) films by pulsed laser deposition (PLD). We characterize their surfaces, combining in situ scanning tunneling microscopy (STM) with density functional theory (DFT), and reveal how dilute Ti impurities modify the atomic-scale structure of the surface as a function of the oxygen chemical potential and Ti content. Ti preferentially substitutes subsurface Fe and causes a local restructuring of the topmost surface layers. Based on the experimental quantification of Ti-induced surface modifications and the structural model we have established, we propose a strategy that can be used to separate the effects of Ti-induced modifications to the surface atomic and electronic structures and bulk conductivity on the reactivity of Ti-doped hematite.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Chem Mater
Ano de publicação:
2020
Tipo de documento:
Article