L1 2 Atomic Ordered Substrate Enhanced Pt-Skin Cu 3 Pt Catalyst for Efficient Oxygen Reduction Reaction.

Constructing Pt skin on L1 intermetallic substrate has been confirmed as an efficient approach to improve the catalytic efficiency of Pt for oxygen reduction reaction (ORR). While, as for the influence of L1 intermetallic substrate, it is still indistinct. Here, we constructed Pt skin encapsulated CuPt nanoparticles (NPs) with atomic disordered (denoted as Pt- d-CuPt/C) and ordered (denoted as Pt- o-CuPt/C) substrate to study the effect of substrate atomic ordering. Electrochemical results indicate that after the formation of Pt skin, the catalytic activities of CuPt catalysts go through a rapid increase and present at a considerably high level among Pt-Cu catalysts. In contrast to the disordered substrate, the L1 ordered substrate can further enhance the catalytic activity and durability of Pt-skin structure. The mass and specific activity of Pt- o-CuPt/C are 5.2 and 8.2 times greater than those of commercial Pt/C. Moreover, after 5k of potential cycles, Pt- o-CuPt/C only shows 12.5% loss in mass activity. Density functional theory (DFT) calculations suggest that the L1 substrate can further modify the electronic structure of surface Pt atoms and endow Pt skin with more optimal adsorption energy of oxygen atoms (E(O)). Furthermore, the superior durability can be attribute to the lower formation energy of L1 CuPt which makes Pt- o-CuPt/C more resistant to the leaching of Cu atoms. Thereby, it is suggested that Pt skin on L1 atomic ordered structure is a promising candidate for building high-performance catalysts toward ORR.