Improving the Stability of Polymer Electrolyte Membrane Fuel Cells via Atomic Layer-Deposited Cerium Oxide

Figure 4

XPS spectra of Ce 3d according to ALD cycles: (a) 10 cycles, (b) 20 cycles, and (c) 30 cycles. (d) Survey spectra.

(a)

(b)

(c)

(d)