This work explores the opportunity to reduce the cost and increase the stability of RuO
2-based electrocatalyst for oxygen evolution reaction by coating ternary oxide RuO
2-Sb
2O
5-SnO
2 on chemically stable titanium support. An active and stable type of
Ti/RuO
2-Sb
2O
5-SnO
2 dimensionally stable anodes (DSA) was studied with different
mole ratios of ruthenium prepared by using thermal deposition method. The metal
oxides coating layer was maintained around 15 g m
-2. In this ternary oxide coating,
RuO
2 serves as the catalyst, SnO
2 as the dispersing agent, and Sb
2O
5 as the dopant. The
morphology by SEM showed that the compact and uniform surface morphology that
indicates a favorable dispersion of species of 10%, 20% and 30% ruthenium samples.
Further increase of ruthenium content, surface...[
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This work explores the opportunity to reduce the cost and increase the stability of RuO
2-based electrocatalyst for oxygen evolution reaction by coating ternary oxide RuO
2-Sb
2O
5-SnO
2 on chemically stable titanium support. An active and stable type of
Ti/RuO
2-Sb
2O
5-SnO
2 dimensionally stable anodes (DSA) was studied with different
mole ratios of ruthenium prepared by using thermal deposition method. The metal
oxides coating layer was maintained around 15 g m
-2. In this ternary oxide coating,
RuO
2 serves as the catalyst, SnO
2 as the dispersing agent, and Sb
2O
5 as the dopant. The
morphology by SEM showed that the compact and uniform surface morphology that
indicates a favorable dispersion of species of 10%, 20% and 30% ruthenium samples.
Further increase of ruthenium content, surface structure with more agglomerated
particles of RuO
2 and the coating surface becomes less compact. The microstructure by
XRD indicates that 10%, 20% and 30% ruthenium samples well intermix with Sb
2O
5,
when ruthenium content exceeded 50% in the active coating layer, new and noticeable
peaks corresponding to ruthenium oxide appear.
Effects of ruthenium content on Ti/RuO
2-Sb
2O
5-SnO
2 anodes in terms of both catalyst
activity and the catalyst corrosion for oxygen evolution reaction were investigated. The
electrochemical characterization of these electrodes has been performed in acid
medium, and the reversibility, electrochemical porosity (related to voltammetric
charge), kinetic parameters (related to Tafel measurements) and electrochemical
resistance (related to electrochemical impedance spectroscopy) have been established.
The best activity performances were achieved by 75% nominal ruthenium content.
The value of q
aq
c-1
was approximately equal to 1, the porosity was 35.5%, the potential
at 1 mA cm
-2
was 1.426 V, which shows better electroactivity than pure RuO
2. Moreover,
the accelerated service lifetimes of the DSA could reach up to 429.3 hours in 3 M H
2SO
4
solution under a current density of 500 mA cm
-2 at 25℃, which is equivalent to more
than 5.8 years for normal electroflotation at 25℃. The electrode service lifetime for
high temperature condition test showed that this electrode with 30% ruthenium give an
average accelerated service lifetime as high as 167.3 hours at 70℃, which is estimated
to be over 2.3 years working at 70℃ under normal electroflotation conditions.
These results revealed overall good catalytic efficiency which could be explained by
the fact that Ti/RuO
2-Sb
2O
5-SnO
2 electrode has a) better electronic transport inside the
coating due to small crystallinity and particle size (electronic factor); b) higher
electrode charge (morphological effects); c) low Tafel slope (SnO
2 as an assisting
reagent can efficiently remove adsorbed hydroxyl species and increase the utilization
ratio of the active element.); d) good conductivity (SnO
2 is a good semiconductor with
high resistivity, and it can be further improved by incorporating antimony); and e)
longer operational lifetime (Sb
2O
5 as a dopant can well intermixed with RuO
2 and
effectively avoid RuO
4 which can be dissolved in electrolyte).
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