Scavenger-Supported Photocatalytic Evidence of an Extended Type I Electronic Structure of the TiO₂@Fe₂O₃ Interface.

Content Provider	Europe PMC
Author	Trenczek-Zajac, Anita Synowiec, Milena Zakrzewska, Katarzyna Zazakowny, Karolina Kowalski, Kazimierz Dziedzic, Andrzej Radecka, Marta
Copyright Year	2022
Abstract	Heterostructures of TiO2@Fe2O3 with a specific electronic structure and morphology enableus tocontrol the interfacial charge transport necessary for their efficientphotocatalytic performance. In spite of the extensive research, therestill remains a profound ambiguity as far as the band alignment atthe interface of TiO2@Fe2O3 is concerned.In this work, the extended type I heterojunction between anatase TiO2 nanocrystals and α-Fe2O3 hematitenanograins is proposed. Experimental evidence supporting this conclusionis based on direct measurements such as optical spectroscopy, X-rayphotoemission spectroscopy, scanning electron microscopy, high-resolutiontransmission electron microscopy (HRTEM), and the results of indirectstudies of photocatalytic decomposition of rhodamine B (RhB) withselected scavengers of various active species of OH•, h•, e–, and •O2–. The presence of small 6–8nm Fe2O3 crystallites at the surface of TiO2 has been confirmed in HRTEM images. Irregular 15–50nm needle-like hematite grains could be observed in scanning electronmicrographs. Substitutional incorporation of Fe3+ ionsinto the TiO2 crystal lattice is predicted by a 0.16% decreasein lattice parameter a and a 0.08% change of c, as well as by a shiftof the Raman Eg(1) peak from 143 cm–1 in pure TiO2 to 149 cm–1 in Fe2O3-modified TiO2. Analysis of O 1s XPSspectra corroborates this conclusion, indicating the formation ofoxygen vacancies at the surface of titanium(IV) oxide. The presenceof the Fe3+ impurity level in the forbidden band gap ofTiO2 is revealed by the 2.80 eV optical transition. Thesize effect is responsible for the absorption feature appearing at2.48 eV. Increased photocatalytic activity within the visible rangesuggests that the electron transfer involves high energy levels ofFe2O3. Well-programed experiments with scavengersallow us to eliminate the less probable mechanisms of RhB photodecompositionand propose a band diagram of the TiO2@Fe2O3 heterojunction.
ISSN	19448244
Journal	ACS Applied Materials & Interfaces
Volume Number	14
PubMed Central reference number	PMC9412959
Issue Number	33
PubMed reference number	35969717
e-ISSN	19448252
DOI	10.1021/acsami.2c06404
Language	English
Publisher	American Chemical Society
Publisher Date	2022-08-15
Access Restriction	Open
Rights License	Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/). © 2022 The Authors. Published by American Chemical Society
Subject Keyword	TiO2 Fe2O3 heterostructures band diagram interface electron transfer photocatalysis
Content Type	Text
Resource Type	Article
Subject	Nanoscience and Nanotechnology Medicine Materials Science