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Title: Wavelength-dependent ultrafast charge carrier separation in the WO 3/BiVO 4 coupled system

Due to its ~2.4 eV band gap, BiVO 4 is a very promising photoanode material for harvesting the blue portion of the solar light for photoelectrochemical (PEC) water splitting applications. In WO 3/BiVO 4 heterojunction films, the electrons photoexcited in BiVO 4 are injected into WO 3, overcoming the lower charge carriers’ diffusion properties limiting the PEC performance of BiVO 4 photoanodes. Here, we investigate by ultrafast transient absorption spectroscopy the charge carrier interactions occurring at the interface between the two oxides in heterojunction systems to directly unveil their wavelength dependence. Under selective BiVO 4 excitation, a favorable electron transfer from photoexcited BiVO 4 to WO 3 occurs immediately after excitation and leads to an increase of the trapped holes’ lifetime in BiVO4. However, a recombination channel opens when both oxides are simultaneously excited, evidenced by a shorter lifetime of trapped holes in BiVO 4. As a result, PEC measurements reveal the implication of these wavelength-dependent ultrafast interactions on the performances of the WO 3/BiVO 4 heterojunction.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [4] ; ORCiD logo [3] ; ORCiD logo [1]
  1. Univ. degli Studi di Milano, Milano (Italy)
  2. Queen's Univ., Kingston, ON (Canada)
  3. Univ. of Notre Dame, Notre Dame, IN (United States)
  4. Politecnico di Milano, Milano (Italy)
Publication Date:
Grant/Contract Number:
FC02-04ER15533
Type:
Published Article
Journal Name:
ACS Energy Letters
Additional Journal Information:
Journal Volume: 2; Journal Issue: 6; Journal ID: ISSN 2380-8195
Publisher:
American Chemical Society (ACS)
Research Org:
Univ. of Notre Dame, Notre Dame, IN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE
OSTI Identifier:
1356719
Alternate Identifier(s):
OSTI ID: 1372220