For example,
To estimate number of electrons in oxygen reduction reaction
To compare voltage at 10 mV/cm2 in the case of oxygen evolution
Most of the articles have reported real surface area, however, to estimate above-mentioned values (or other calculations) geometric area is used.
For example, in case of Pt/C real surface area can be easily estimated by hydrogen adsorption and desorption but for RDE calculations most of the studies use geometric area and not real surface area.
Geometric area normally is used as a standard way of comparing sample in different studies, an un-written rule agreed among researchers. Why? Because then you can calculate the real surface area, like the Pt in your example, and then report it as a roughness factor. The roughness factor will be a more telling metric than just the geometric normalized current density.
So when you look at a reported value, by just comparing the geo based activity to your results, you'll be able to tell which one has a higher roughness factor. And researchers use the real surface area in many cases, that's what you see as the specific activity in the ORR paper. See papers below for more discussion:
http://pubs.rsc.org/-/content/articlehtml/2012/ee/c2ee02689a
http://www.sciencedirect.com/science/article/pii/S1388248116301060
Good luck
The area that matters in the model depends on the yardstick (scale) of the process. When measuring Pt surface area using H-UPD, the area that matters is the "real surface area" with the yardstick of the size on one atom. When describing the diffusion limited current on a RDE, the yardstick is the diffusion boundary layer thickness (DBLT). Surface roughness on the scale much smaller than DBLT plays not role in this model, and true surface area is an inadequate metrics for the diffudion -limited current on the RDE.
- Badges
- Science topic
- Similar topics
- Geoscience
- Atmospheric Sciences
- Atmosphere