L12 Atomic Ordered Substrate Enhanced Pt-Skin Cu3Pt Catalyst for Efficient Oxygen Reduction Reaction

Constructing Pt skin on intermetallics has been confirmed as an efficient strategy to boost oxygen reduction reaction (ORR) kinetics. However, there still lacks a systematic study on revealing the influence of low-Pt-content intermetallic substrates (L12-PtM3). In this paper, Pt skin-encapsulated low-Pt-mole-fraction L12 Cu3Pt has been constructed (denoted as Pt-o-Cu3Pt/C) and compared with its disordered analogue (denoted as Pt-d-Cu3Pt/C). The L12 substrate shows a contracted lattice structure and provides Pt-o-Cu3Pt/C with an excellent specific activity of 1.73 mA cm-2, which is 1.4- and 8.4-fold higher than that of Pt-d-Cu3Pt/C and commercial Pt/C, respectively. Density functional theory calculations reveal that this superior performance is attributed to the more favorable oxygen adsorption energy of surface Pt atoms. Furthermore, the lower formation energy of L12 Cu3Pt combined with the enhanced antioxygenation of Pt provide Pt-o-Cu3Pt/C with a superior durability, showing only a 12.5% loss in mass activity after 5000 potential cycles. Therefore, it is suggested that L12 atomic ordered structure with a low Pt fraction is a promising substrate for building high-performance Pt-skin catalysts for ORR.