Highly Stable and Active Pt/Nb-TiO₂ Carbon-Free Electrocatalyst for Proton Exchange Membrane Fuel Cells

Figure 4

High-resolution XPS spectra of (a) Pt 4f; (b) Ti2p; (c) Nb3d; (d) O1S. Inset in (a) shows the corresponding deconvolution of Pt 4f spectrum.

(a)

(b)

(c)

(d)