Assembling Highly Coordinated Pt Sites on Nanoporous Gold for Efficient Oxygen Electroreduction.

Pt with high coordination number (HCN) located in the defect surface sites is favorable for high oxygen reduction reaction (ORR) activity. But it is still a challenge to design and fabricate such a structure with high density of Pt HCN sites at minimum Pt usage. Here, using nanoporous Au (NPG) that intrinsically possesses higher proportion of HCN Au atoms over traditional nanoparticles, we epitaxially deposit Pt monolayer onto NPG to inherit the high-density HCN Pt sites. Among the NPG-Pt catalysts, the one with smaller ligament size possesses higher proportion of HCN Pt atoms, thus exhibiting a 5.2-fold specific activity and 18.7-fold mass activity enhancement than the commercial Pt/C catalyst. Moreover, depositing Au atoms on the NPG-Pt surface can further increase the HCN Pt surface exposure, which leads to a 6.9-fold specific activity and 19.1-fold mass activity increase as compared to Pt/C.