Dealloyed PdAg core Pt monolayer shell electrocatalyst for oxygen reduction reaction

A core-shell nanostructure (Pt-PdAg/C-D) with dealloyed PdAg nanoparticles (PdAg/C-D) as the core and a Pt monolayer as the shell is prepared and employed as an electrocatalyst toward oxygen reduction reaction (ORR). Compared with its counterpart alloyed PdAg core-Pt monolayer shell catalyst (Pt-PdAg/C), the Pt-PdAg/C-D catalyst shows significantly higher catalytic activities for ORR. The half wave potential (E-1/2) on Pt-PdAg/C-D is located at -0.17 V, which is comparable to that on the commercial Pt/C catalyst and ca. 30 mV more positive than that on Pt-PdAg/C. The MSA of Pt in Pt-PdAg/C-D is 171.8 A g(Pd+Pt)(-1), which is 3.2 and 2.4 times higher than those of Pt-PdAg/C and commercial Pt/C catalysts, respectively. The Pt monolayer shell on the surface of the nanoparticles would induce much higher utilization of Pt atoms, and the dealloying process would result in a nanostructured PdAg core with a rough surface and a Pt shell with a numbers of low-coordinated atoms. It is concluded that the change in the electronic and geometric structure of Pt in the Pt-PdAg/C-D catalyst may contribute to the increase in catalytic performance for ORR.