A concentration gradient core-shell Pd-Ir-Ni/C electrocatalyst is facilely synthesized.
The Pd-Ir-Ni/C catalyst exhibits high activity for oxygen reduction reaction (ORR).
This catalyst possesses excellent ORR selectivity in the presence of methanol.
The enhanced ORR activity is ascribed to the optimal compressive lattice strain.
The underlying alloy core induces the lattice strain on the outer surface.