Boosting electrochemical stability of ultralow-Pt nanoparticle with Matryoshka-like structure in polymer electrolyte membrane fuel cells.

• Carbon-supported Pt-based materials with Matryoshka-like structure are proposed as ORR catalysts. • The catalyst has 3.4 times higher mass activity than commercial Pt/C in half-cell. • Pt@Cu IL Pd/C-based polymer electrolyte membrane fuel cells show high and stable performance. Electrochemical catalysts with a core-shell structure have received much attention because of their enhanced efficiency and activity. Among them, those with a CuPd alloy core exhibit better activity than the ones with a single metal Pd core, which is known to be an excellent core-material. However, the superior performance of previously reported Pt catalysts with CuPd core has only been observed in half-cells, and was not reflected or even expanded to single-cells. We report catalysts having a Matryoshka-like structure with a Pt outer-layer, Cu interlayer, and Pd core for oxygen reduction reaction. This catalyst has 3.4 times higher Pt mass activity than the commercial Pt/C in half-cells, and also performs better in single-cells at only 0.056 mg Pt cm−2. Particularly, the stability of this catalyst satisfies the 2020 DOE target, and electrochemical surface area loss during the stability test is only 40 % for this catalyst, while that of Pt/C is 80 %. [ABSTRACT FROM AUTHOR]