Hollow porous nanoparticles with Pt skin on a Ag-Pt alloy structure as a highly active electrocatalyst for the oxygen reduction reaction

Aiming to reduce the dosage of the noble metal Pt and improve the catalytic activity of the catalyst in fuel cells, hollow porous Ag-Pt alloy nanoparticles with Pt coating are prepared via a facile controlled galvanic replacement reaction. Ag is used as the substrate to build a hollow porous structure and alloyed with Pt to minimize the tensile effect of the Ag on the deposited Pt skin which would significantly lower the catalytic performance of the Ag-Pt bimetallic catalyst. This hollow porous Ag/Pt bimetallic catalyst exhibits a long catalytic durability and a mass activity of 0.438 A mg(Pt)(-1) at 0.9 V (vs. RHE) towards the oxygen reduction reaction (ORR), which is ca. 3 times higher than that of the commercial Pt/C catalyst. The significant enhancement over the state-of-the-art Pt catalysts can be attributed to (1) the high surface area of the nanoparticles, (2) the more suitable d-band center of the Pt skin deposited on the Ag-Pt alloy substrate, and (3) the high thermal stability of the Ag-Pt alloy. Therefore, this work provides a new strategy for designing high-performance catalysts with low cost. In addition, the synthetic chemistry involved can possibly be extended for fabricating versatile catalysts with a similar structure.