Modification of Hematite Electronic Properties with Trimethyl Aluminum to Enhance the Efficiency of Photoelectrodes.
The electronic properties of hematite were investigated by means of synchrotron radiation photoemission (SR-PES) and X-ray absorption spectroscopy (XAS). Hematite samples were exposed to trimethyl aluminum (TMA) pulses, a widely used Al-precursor for the atomic layer deposition (ALD) of Al2O3. SR-PES and XAS showed that the electronic properties of hematite were modified by the interaction with TMA. In particular, the hybridization of O 2p states with Fe 3d and Fe 4s4p changed upon TMA pulses due to electron inclusion as polarons. The change of hybridization correlates with an enhancement of the photocurrent density due to water oxidation for the hematite electrodes. Such an enhancement has been associated with an improvement in charge carrier transport. Our findings open new perspectives for the understanding and utilization of electrode modifications by very thin ALD films and show that the interactions between metal precursors and substrates seem to be important factors in defining their electronic and photoelectrocatalytic properties.
†Applied Physics-Sensors, Brandenburg University of Technology, Konrad Wachsmann Allee, 17, 03046, Cottbus, Germany.
Massimo
M
Tallarida
†Applied Physics-Sensors, Brandenburg University of Technology, Konrad Wachsmann Allee, 17, 03046, Cottbus, Germany.
Chittaranjan
C
Das
‡Institut Universitari d'Electroquímica i Departament de Química Física, Universitat d'Alacant, Apartat 99, E-03080 Alicante, Spain.
Dejan
D
Cibrev
§Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.|∥Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu, Estonia.
Kaupo
K
Kukli
∥Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu, Estonia.
Aile
A
Tamm
§Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
Mikko
M
Ritala
‡Institut Universitari d'Electroquímica i Departament de Química Física, Universitat d'Alacant, Apartat 99, E-03080 Alicante, Spain.
Teresa
T
Lana-Villarreal
‡Institut Universitari d'Electroquímica i Departament de Química Física, Universitat d'Alacant, Apartat 99, E-03080 Alicante, Spain.
Roberto
R
Gómez
§Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
Markku
M
Leskelä
†Applied Physics-Sensors, Brandenburg University of Technology, Konrad Wachsmann Allee, 17, 03046, Cottbus, Germany.
Dieter
D
Schmeisser
ALD; XAS; charge carrier transport; hybridization; photoemission; polaron; resonant photoemission; water splitting