cs5b01748_si_001.pdf (323.61 kB)
Download fileA First-Principles Study on the Role of an Al2O3 Overlayer on Fe2O3 for Water Splitting
journal contribution
posted on 2015-12-04, 00:00 authored by Ofer Neufeld, Natav Yatom, Maytal Caspary TorokerUnderstanding
the role of an overlayer material on a catalyst is
crucial for improving catalytic activity. Iron(III) oxide (α-Fe2O3) is a widely studied catalyst commonly used
for solar water splitting. Recently, the water splitting efficiency
with α-Fe2O3 was enhanced by deposition
of an α-Al2O3 overlayer. In order to understand
the origin of this improvement, we perform first-principles calculations
with density functional theory + U on the α-Fe2O3(0001) surface with an α-Al2O3 surface overlayer. We find catalysis is unfavorable
directly over α-Al2O3 and rather takes
place over α-Fe2O3 exposed areas. In agreement
with experiment, we find that α-Al2O3 coverage
decreases the overpotential required for water oxidation on α-Fe2O3. We explain this improvement through the decrease
in the work function of α-Fe2O3 upon α-Al2O3 coverage that aids in extracting electrons during
the water oxidation reaction. We suggest that selecting an overlayer
with a smaller work function than that of the catalyst as a strategy
for future development of better catalysts.