Table 4. Intrinsic OER Activities for IrO2 and RuO2 in KOH Electrolytes.
| catalyst | electrolyte | jinta (μA/cm2) | low-η Tafel slopea (mV/dec) | high-η Tafel slopea (mV/dec) | ref |
|---|---|---|---|---|---|
| IrO2 (100)b | 0.1 M KOH | 3 | 55 | 93 | (205) |
| IrO2 (110)b | 0.1 M KOH | 5 | 61 | 85 | (205) |
| IrO2 powder | 1 M KOH | 171c | n.r.d | 106 | (112) |
| RuO2 (100)b | 0.1 M KOH | 182 | 54 | 144 | (205) |
| RuO2 (110)b | 0.1 M KOH | 65 | 56 | 141 | (205) |
| RuO2 powder | 1 M KOH | 43c | n.r.d | 83 | (205) |
a
The intrinsic activities (jint) and Tafel slopes are measured at 23.5 °C in the case of the two powder catalysts. The temperature is presumably the same and/or within 3 °C for the single-crystal electrodes. Furthermore, double layer (Cdl) measurements were used to estimate the surface area of the commercial IrO2 and RuO2 powders. All jint and Tafel slopes values shown in Table 4 seem to have been measured from nonsteady-state measurements.
b
All of the IrO2 and RuO2 single crystals were thin films in the rutile form.
c
The jint values were measured at a η value of 0.35 V.
d
n.r. stands for not reported.