I am an undergraduate materials science student. I am currently preparing to conduct some research over the summer on alkaline electrolyte membrane fuel cells and have been reading some papers to get background information (this is a very new area to me). The surface chemistry section of the paper involves several cyclic voltammetry plots, and I am having trouble understanding a part of one of them. To preface the diagram, the author states:
For the Pd-black-coated electrode, a pair of symmetrical peaks is observed between −1.0 and −0.82 V and is assigned to the formation/ desorption of proton−palladium species...
The [proton−palladium species] formation/desorption peaks are smaller for the Pd−Ni or Pd−Ni−P electrodes compared with the Pd-coated electrode.
To my uneducated eyes, this appears to be incorrect, as at least the Pd-Ni-P peaks appear to be larger than the Pd-blk peaks. How should I go about correctly interpreting this diagram? The paper can be found here, and the diagram and statements in question are in section 3.3: Surface Electrochemistry of Catalyst-Coated Electrodes. Any guidance is greatly appreciated, and I am sorry if my question is repetitive or the answer is obvious. If additional information is needed, please let me know.