Bismuth vanadate (BiVO4) with a band gap of similar to 2.4 eV has emerged as one of the visible photocatalysts that can absorb light below 520 nm. The electron/hole pairs that are generated following BiVO4 band gap excitation are effective for water splitting, especially when BiVO4 is combined with other metal oxides such as WO3. We report a solution processed method for designing transparent WO3/BiVO4 heterojunction electrodes and observe a synergistic effect on the photoelectrochemical activity of WO3/BiVO4, with the combined system performing dramatically better than either individual component. Using ultrafast transient absorption spectroscopy, we elucidated the electronic interaction between WO, and excited BiVO4. Moreover, the photocatalytic reduction of thionine by WO3/BiVO4 as well as by each individual oxide component is used to track electron injection processes and determine the energetics of the studied systems. In the composite WO3/BiVO4 film a shifted quasi-Fermi level results, due to electronic equilibration between the two materials. The better performance of WO3/BiVO4 heterojunction electrodes is thus a consequence of the electron injection from BiVO4 into WO3, followed by back electron transfer from WO3 to the holes in BiVO4.
Dynamics of Photogenerted Charge carriers in WO3/BiVO4 Heterojunction Photoanodes / I. Grigioni, K.G. Stamplecoskie, E. Selli, P.V. Kamat. - In: JOURNAL OF PHYSICAL CHEMISTRY. C. - ISSN 1932-7447. - 119:36(2015 Sep 10), pp. 20792-20800.
|Titolo:||Dynamics of Photogenerted Charge carriers in WO3/BiVO4 Heterojunction Photoanodes|
GRIGIONI, IVAN (Primo)
SELLI, ELENA (Corresponding)
|Settore Scientifico Disciplinare:||Settore CHIM/02 - Chimica Fisica|
|Data di pubblicazione:||10-set-2015|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1021/acs.jpcc.5b05128|
|Appare nelle tipologie:||01 - Articolo su periodico|