Role of Hydrogen in Defining the n-Type Character of BiVO<sub>4</sub> Photoanodes [electronic resource].

Published:: Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2016.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description:: pages 5,761-5,771 : digital, PDF file
Additional Creators:: Lawrence Berkeley National Laboratory, United States. Department of Energy. Office of Basic Energy Sciences, United States. Office of Science, and United States. Department of Energy. Office of Scientific and Technical Information

Access Online

www.osti.gov

Availability

Finding items...

Restrictions on Access:

Free-to-read Unrestricted online access

Summary:

The roles of hydrogen impurity and oxygen vacancy defects on defining the conductivity, and hence photoelectrochemical (PEC) performance characteristics, of monoclinic scheelite bismuth vanadate (BiVO₄) are investigated using a combination of experiment and theory. We find that elemental hydrogen is present as an impurity in as-synthesized BiVO₄ and that increasing its concentration by annealing in H₂ at temperatures up to 290°C leads to near-complete elimination of majority carrier transport limitations, a beneficial shift in the photoanodic current onset potential, and improved fill factor. Magnetic resonance measurements reveal that hydrogen can be incorporated in at least two different chemical environments, which are assigned to interstitial and substitutional sites. Incorporation of hydrogen leads to a shift of the Fermi level toward the conduction band edge, indicating that n-type character is correlated with increased hydrogen content. This finding is in agreement with theory and reveals that hydrogen acts as a donor in BiVO₄. Sub-bandgap photoluminescence is observed from as-synthesized material and is consistent with deep electronic states associated with oxygen vacancies. Hydrogen treatment leads to reduced emission from these states. These findings support the conclusion that hydrogen, rather than oxygen vacancies, is dominant in determining the n-type conductivity of BiVO₄. These findings have important implications for controlling the electronic properties and functional characteristics of this promising photoanode material.

Report Numbers:

E 1.99:1393071

Subject(s):

Note:

Published through SciTech Connect.
07/19/2016.
"ark:/13030/qt2mc0q5db"
Chemistry of Materials 28 16 ISSN 0897-4756 AM
Jason K. Cooper; Soren B. Scott; Yichuan Ling; Jinhui Yang; Sijie Hao; Yat Li; Francesca M. Toma; Martin Stutzmann; K. V. Lakshmi; Ian D. Sharp.

Funding Information:

AC02-05CH11231

View MARC record | catkey: 24044568