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In Operando Photoelectrochemical Femtosecond Transient Absorption Spectroscopy of WO3/BiVO4 Heterojunctions
journal contribution
posted on 2019-08-23, 14:46 authored by Ivan Grigioni, Lucia Ganzer, Franco V. A. Camargo, Benedetto Bozzini, Giulio Cerullo, Elena SelliThe
WO3/BiVO4 heterojunction is a promising
photoanode architecture for water splitting applications. Here, the
photoinduced charge carrier dynamics occurring in this system in operando
photoelectrochemical conditions, i.e., under an applied anodic potential,
are studied through femtosecond transient absorption spectroscopy
to unveil the effects of an applied bias on the early charge carrier
dynamics following WO3/BiVO4 excitation. Electrochromic
measurements on BiVO4 suggest the presence of intraband
gap (IBG) states in this oxide, which play an important role in the
charge carrier dynamics in the heterojunction. The differences observed
in WO3/BiVO4 with respect to individual BiVO4 electrodes are rationalized in terms of the electron equilibration
between the two oxides at the heterojunction, dominated by the WO3/BiVO4 interfacial electric field arising from
their band energy offset, and the bias-dependent alteration of the
IBG states, both determining the rate of hole transfer and accumulation
at the BiVO4 surface.
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WOband energycharge carrier dynamicsoperando photoelectrochemical conditionshole transferBiVO 4bias-dependent alterationheterojunctionphotoanode architectureIBG statesElectrochromic measurementsBiVO 4 electrodesOperando Photoelectrochemical Femtosecond Transient Absorption Spectroscopyphotoinduced charge carrier dynamicsintraband gapabsorption spectroscopyBiVO 4 surfaceelectron equilibrationwater splitting applications
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