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Ultra‐Narrow Depletion Layers in a Hematite Mesocrystal‐Based Photoanode for Boosting Multihole Water Oxidation
Author(s) -
Zhang Zhujun,
Nagashima Hiroki,
Tachikawa Takashi
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202001919
Subject(s) - hematite , photocurrent , materials science , water splitting , electrode , nanoparticle , optoelectronics , charge carrier , mesoporous material , chemical engineering , nanotechnology , chemistry , photocatalysis , catalysis , metallurgy , biochemistry , engineering
Significant charge recombination that is difficult to suppress limits the practical applications of hematite (α‐Fe 2 O 3 ) for photoelectrochemical water splitting. In this study, Ti‐modified hematite mesocrystal superstructures assembled from highly oriented tiny nanoparticle (NP) subunits with sizes of ca. 5 nm were developed to achieve the highest photocurrent density (4.3 mA cm −2 at 1.23 V vs. RHE) ever reported for hematite‐based photoanodes under back illumination. Owing to rich interfacial oxygen vacancies yielding an exceedingly high carrier density of 4.1×10 21 cm −3 for super bulk conductivity in the electrode and a large proportion of ultra‐narrow depletion layers (<1 nm) inside the mesoporous film for significantly improved hole collection efficiency, a boosting of multihole water oxidation with very low activation energy ( E a =44 meV) was realized.