Spectroscopic in situ Measurements of the Relative Pt Skin Thicknesses and Porosities of Dealloyed PtMn (Ni, Co) Electrocatalysts

X-ray adsorption near edge structure (XANES) data at the Co or Ni K-edge, analyzed using the Δμ difference procedure, are reported for dealloyed PtCox and PtNix catalysts (six different catalysts at different stages of life). All catalysts meet the 2017 DOE beginning of life target Pt mass activity target (>0.44 A mgPt–1), but exhibit varying activities and durabilities. The variance factors include different initial precursors, dealloying in HNO3 vs H2SO4, if a postdealloying thermal annealing step was performed, and different morphologies (some with a multi PtMx core and porous Pt skin, some single core with nonporous skin). Data are obtained at the initial beginning of life (BOL, ∼200 voltage cycles) and after 10k and 30k (end of life, EOL) voltage cycles following DOE protocol (0.6–1.0 V vs reversible hydrogen electrode). The Δμ data are used to determine at what potential (Vpen) the Pt skin is penetrated by O. The durability, related to a drop in the electrochemical surface areas (ECSAs) after extens...