Research output: Contribution to journal › Article › peer-review
Effect of the degree of inversion on the photoelectrochemical activity of spinel ZnFe2O4. / Granone, Luis I.; Nikitin, Konstantin; Emeline, Alexei; Dillert, Ralf; Bahnemann, Detlef W.
In: Catalysts, Vol. 9, No. 5, 434, 01.05.2019.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Effect of the degree of inversion on the photoelectrochemical activity of spinel ZnFe2O4
AU - Granone, Luis I.
AU - Nikitin, Konstantin
AU - Emeline, Alexei
AU - Dillert, Ralf
AU - Bahnemann, Detlef W.
PY - 2019/5/1
Y1 - 2019/5/1
N2 - Physicochemical properties of spinel ZnFe2O4 (ZFO) are known to be strongly affected by the distribution of the cations within the oxygen lattice. In this work, the correlation between the degree of inversion, the electronic transitions, the work function, and the photoelectrochemical activity of ZFO was investigated. By room-temperature photoluminescence measurements, three electronic transitions at approximately 625, 547, and 464 nm (1.98, 2.27, and 2.67 eV, respectively) were observed for the samples with different cation distributions. The transitions at 625 and 547 nm were assigned to near-band-edge electron-hole recombination processes involving O2- 2p and Fe3+ 3d levels. The transition at 464 nm, which has a longer lifetime, was assigned to the relaxation of the excited states produced after electron excitations from O2- 2p to Zn2+ 4s levels. Thus, under illumination with wavelengths shorter than 464 nm, electron-hole pairs are produced in ZFO by two apparently independent mechanisms. Furthermore, the charge carriers generated by the O2- 2p to Zn2+ 4s electronic transition at 464 nm were found to have a higher incident photon-to-current efficiency than the ones generated by the O2- 2p to Fe3+ 3d electronic transition. As the degree of inversion of ZFO increases, the probability of a transition involving the Zn2+ 4s levels increases and the probability of a transition involving the Fe3+ 3d levels decreases. This effect contributes to the increase in the photoelectrochemical efficiency observed for the ZFO photoanodes having a larger cation distribution.
AB - Physicochemical properties of spinel ZnFe2O4 (ZFO) are known to be strongly affected by the distribution of the cations within the oxygen lattice. In this work, the correlation between the degree of inversion, the electronic transitions, the work function, and the photoelectrochemical activity of ZFO was investigated. By room-temperature photoluminescence measurements, three electronic transitions at approximately 625, 547, and 464 nm (1.98, 2.27, and 2.67 eV, respectively) were observed for the samples with different cation distributions. The transitions at 625 and 547 nm were assigned to near-band-edge electron-hole recombination processes involving O2- 2p and Fe3+ 3d levels. The transition at 464 nm, which has a longer lifetime, was assigned to the relaxation of the excited states produced after electron excitations from O2- 2p to Zn2+ 4s levels. Thus, under illumination with wavelengths shorter than 464 nm, electron-hole pairs are produced in ZFO by two apparently independent mechanisms. Furthermore, the charge carriers generated by the O2- 2p to Zn2+ 4s electronic transition at 464 nm were found to have a higher incident photon-to-current efficiency than the ones generated by the O2- 2p to Fe3+ 3d electronic transition. As the degree of inversion of ZFO increases, the probability of a transition involving the Zn2+ 4s levels increases and the probability of a transition involving the Fe3+ 3d levels decreases. This effect contributes to the increase in the photoelectrochemical efficiency observed for the ZFO photoanodes having a larger cation distribution.
KW - Cation distribution
KW - Degree of inversion
KW - Photoelectrochemical activity
KW - ZnFeO
KW - PHOTOLUMINESCENCE
KW - TEMPERATURE-DEPENDENCE
KW - degree of inversion
KW - PHOTOANODES
KW - ZnFe2O4
KW - PHOTOCATALYTIC ACTIVITY
KW - FLUORESCENCE
KW - photoelectrochemical activity
KW - CATION DISTRIBUTION
KW - cation distribution
KW - WATER
UR - http://www.scopus.com/inward/record.url?scp=85067075341&partnerID=8YFLogxK
U2 - 10.3390/catal9050434
DO - 10.3390/catal9050434
M3 - Article
AN - SCOPUS:85067075341
VL - 9
JO - Catalysts
JF - Catalysts
SN - 2073-4344
IS - 5
M1 - 434
ER -
ID: 43904556