Abstract
In this work, commercial IrO2-Ta2O5 anodes with a certain composition calcined at three different temperatures were investigated. The results show that the calcination temperature has a significant influence on the electrocatalytic activity for the oxygen evolution reaction (OER). This is attributed to the influence of the calcination temperature on the surface microstructure including the crystallinity and the preferred orientation of IrO2 crystallites of the IrO2-Ta2O5 binary oxide formed. The surface morphology of the anodes was revealed as mud-cracks surrounded by flat areas containing several scattered IrO2 nanocrystallites. The size of these nanocrystallites, which in turn contribute to the electrochemical active surface area, is dependent on calcination temperature. The (101)-surfaces of the IrO2 were found to have higher catalytic activity than (110) IrO2 with respect to the OER. The (101) IrO2 planes were dominating at low or moderate calcination temperatures, whereas the (110) IrO2 orientation was preferred at the highest calcination temperature. Accelerated lifetime tests of the investigated samples indicate that the (101) IrO2 is more stable (110) IrO2 during electrolysis. A moderate temperature is suggested as the best calcination temperature for this type of anode regarding the electrochemical active surface area, electrocatalytic activity and stability for OER in acidic aqueous electrolytes at operating conditions.
Highlights
Calcination Temperature Dependent Catalytic Activity and Stability of IrO2 –Ta2O5 Anodes for Oxygen Evolution Reaction in Aqueous Sulfate Electrolytes
The sluggish reaction kinetics of the oxygen evolution reaction (OER) in low-pH sulfate electrolytes lead to rather high anode overpotential at industrial relevant current densities, being a significant contributor to an increased cell voltage.[1]
They reported that the 70 mol% IrO2 – 30 mol% Ta2O5 catalyst coating on Ti substrate gave by far the best electrocatalytic activity toward the OER
Summary
To obtain reproducible electrochemical measurements, some pretreatment of the anodes was found to be necessary as the porous coating combined with destructive gas evolution could lead to large changes in the active surface area with time.[6] Preconditioning the anodes with 200 potential cycles at 100 mV/s was found to give satisfying reproducibility and was run on all anode samples before recording the reported E-I curves. This preconditioning must be distinguished from the stabilization stage during operation of an industrial electrolysis cell. The Ir losses of the coatings during the test were measured by X-ray fluorescence (XRF)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
