Effects of atom arrangement and thickness of Pt atomic layers on Pd nanocrystals for electrocatalysis

Depositing ultrathin Pt layer on less expensive substrates is an effective way to increase the catalytic activity and utilization efficiency of Pt catalyst in direct alcohol fuel cells. In this study, electrocatalytic properties of Pt atomic layer on Pd nanocrystals (NCs) was studied by changing the thickness of Pt layers and the surface structure of Pd NCs. We prepared 1–5 atomic Pt layers on {730}-faceted tetrahexahedral Pd nanocrystals (THH Pd@Pt_n NCs) and on {111}-preferential Pd NCs. For both cases, Pt monolayer has a strong electronic effect from Pd NCs, while Pt bilayers have a moderate effect. In comparison with the {111}-preferential Pd@Pt_n NCs, the THH Pd@Pt_n NCs exhibit about 3 times higher catalytic activity towards ethanol electrooxidation. It has measured that the THH Pd@Pt₂ NCs exhibit the highest catalytic activity amongst all THH Pd@Pt_n (n = 1–5) NCs and THH Pt NCs, which is interpreted by a synergy of electronic effect and surface atom arrangement effect.