10.1021/jacs.7b05184.s001
Camilo A. Mesa
Camilo A.
Mesa
Andreas Kafizas
Andreas
Kafizas
Laia Francàs
Laia
Francàs
Stephanie R. Pendlebury
Stephanie R.
Pendlebury
Ernest Pastor
Ernest
Pastor
Yimeng Ma
Yimeng
Ma
Florian Le Formal
Florian Le
Formal
Matthew T. Mayer
Matthew T.
Mayer
Michael Grätzel
Michael
Grätzel
James R. Durrant
James R.
Durrant
Kinetics
of Photoelectrochemical Oxidation of Methanol on Hematite Photoanodes
American Chemical Society
2017
rate law analysis
1 sun irradiation
α- Fe 2 O 3 photoanodes
metal oxide surfaces
anatase TiO 2 photoanodes
methanol oxidation
Kinetic isotope effect studies
α- Fe 2 O 3
photoinduced absorption spectroscopy
unity Faradaic efficiency
PEC methanol oxidation
2017-07-22 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Kinetics_of_Photoelectrochemical_Oxidation_of_Methanol_on_Hematite_Photoanodes/5303590
The kinetics of photoelectrochemical
(PEC) oxidation of methanol, as a model organic substrate, on α-Fe<sub>2</sub>O<sub>3</sub> photoanodes are studied using photoinduced absorption
spectroscopy and transient photocurrent measurements. Methanol is
oxidized on α-Fe<sub>2</sub>O<sub>3</sub> to formaldehyde with
near unity Faradaic efficiency. A rate law analysis under quasi-steady-state
conditions of PEC methanol oxidation indicates that rate of reaction
is second order in the density of surface holes on hematite and independent
of the applied potential. Analogous data on anatase TiO<sub>2</sub> photoanodes indicate similar second-order kinetics for methanol
oxidation with a second-order rate constant 2 orders of magnitude
higher than that on α-Fe<sub>2</sub>O<sub>3</sub>. Kinetic isotope
effect studies determine that the rate constant for methanol oxidation
on α-Fe<sub>2</sub>O<sub>3</sub> is retarded ∼20-fold
by H/D substitution. Employing these data, we propose a mechanism
for methanol oxidation under 1 sun irradiation on these metal oxide
surfaces and discuss the implications for the efficient PEC methanol
oxidation to formaldehyde and concomitant hydrogen evolution.