Photoelectrochemical solar energy conversion offers a way to directly store light into energy-rich chemicals. Photoanodes based on the WO3/BiVO4 heterojunction are most effective mainly thanks to the efficient separation of photogenerated charges. The WO3/BiVO4 interfacial space region in the heterojunction is investigated here with the increasing thickness of the BiVO4 layer over a WO3 scaffold. On the basis of X-ray diffraction analysis results, density functional theory simulations show a BiVO4 growth over the WO3 layer along the BiVO4 {010} face, driven by the formation of a stable interface with new covalent bonds, with a favorable band alignment and band bending between the two oxides. This crystal facet phase matching allows a smooth transition between the electronic states of the two oxides and may be a key factor ensuring the high efficiency attained with this heterojunction. The photoelectrochemical activity of the WO3/BiVO4 photoanodes depends on both the irradiation wavelength and the thickness of the visible-light-Absorbing BiVO4 layer, a 75 nm thick BiVO4 layer on WO3 being best performing.
Grigioni, I., Di Liberto, G., Dozzi, M., Tosoni, S., Pacchioni, G., Selli, E. (2021). WO3/BiVO4Photoanodes: Facets Matching at the Heterojunction and BiVO4Layer Thickness Effects. ACS APPLIED ENERGY MATERIALS, 4(8), 8421-8431 [10.1021/acsaem.1c01623].
WO3/BiVO4Photoanodes: Facets Matching at the Heterojunction and BiVO4Layer Thickness Effects
Di Liberto G.;Tosoni S.;Pacchioni G.;
2021
Abstract
Photoelectrochemical solar energy conversion offers a way to directly store light into energy-rich chemicals. Photoanodes based on the WO3/BiVO4 heterojunction are most effective mainly thanks to the efficient separation of photogenerated charges. The WO3/BiVO4 interfacial space region in the heterojunction is investigated here with the increasing thickness of the BiVO4 layer over a WO3 scaffold. On the basis of X-ray diffraction analysis results, density functional theory simulations show a BiVO4 growth over the WO3 layer along the BiVO4 {010} face, driven by the formation of a stable interface with new covalent bonds, with a favorable band alignment and band bending between the two oxides. This crystal facet phase matching allows a smooth transition between the electronic states of the two oxides and may be a key factor ensuring the high efficiency attained with this heterojunction. The photoelectrochemical activity of the WO3/BiVO4 photoanodes depends on both the irradiation wavelength and the thickness of the visible-light-Absorbing BiVO4 layer, a 75 nm thick BiVO4 layer on WO3 being best performing.
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