Surface
Passivation of TiO<sub>2</sub> Nanowires Using
a Facile Precursor-Treatment Approach for Photoelectrochemical Water
Oxidation
- Publication date
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Abstract
We
developed a facile precursor-treatment approach for effective
surface passivation of rutile TiO<sub>2</sub> nanowire photoanode
to improve its performance in photoelectrochemical (PEC) water oxidation.
The approach was demonstrated by treating rutile TiO<sub>2</sub> nanowires
with titanium precursor solutions (TiCl<sub>4</sub>, Ti(OBu)<sub>4</sub>, or Ti(OiP)<sub>4</sub>) followed by a postannealing process, which
resulted in the additional deposition of anatase TiO<sub>2</sub> layer
on the nanowire surface. Compared to pristine TiO<sub>2</sub>, all
the precursor-treated TiO<sub>2</sub> nanowire electrodes exhibited
a significantly enhanced photocurrent density under white light illumination.
Among the three precursor-treated samples, Ti(OBu)<sub>4</sub>-treated
TiO<sub>2</sub> nanowires achieved the largest enhancement of photocurrent
generation, which is approximately a 3-fold increase over pristine
TiO<sub>2</sub>. Monochromatic incident photon-to-electron conversion
efficiency (IPCE) measurements showed that the improvement of PEC
performance was dominated by the enhanced photoactivity of TiO<sub>2</sub> in the UV region. The photovoltage and electrochemical impedance
spectroscopy (EIS) measurements showed that the enhanced photoactivity
can be attributed to the improved charge transfer as a result of effective
surface state passivation. This work demonstrates a facile, low-cost,
and efficient method for preparing highly photoactive TiO<sub>2</sub> nanowire electrodes for PEC water oxidation. This approach could
also potentially be used for other photoconversion applications, such
as TiO<sub>2</sub> based dye-sensitized solar cells, as well as photocatalytic
systems