Surface-Enriched Single-Bi-Atoms Tailoring of Pt Nanorings for Direct Methanol Fuel Cells with Ultralow-Pt-Loading.

Single-atom decorating of Pt emerges as a highly effective strategy to boost catalytic properties, which can trigger the most Pt active sites while blocking the smallest number of Pt atoms. However, the rational design and creation of high-density single-atoms on Pt surface remain as a huge challenge. Herein, a customized synthesis of surface-enriched single-Bi-atoms tailored Pt nanorings (SE-Bi1/Pt NRs) toward methanol oxidation is reported, which is guided by the density functional theory (DFT) calculations suggesting that a relatively higher density of Bi species on Pt surface can ensure a CO-free pathway and accelerate the kinetics of *HCOOH formation. Decorating Pt NRs with dense single-Bi-atoms is achieved by starting from PtBi intermetallic nanoplates (NPs) with intrinsically isolated Bi atoms and subsequent etching and annealing treatments. The SE-Bi1/Pt NRs exhibit a mass activity of 23.77 A mg-1 Pt toward methanol oxidation in alkaline electrolyte, which is 2.2 and 12.8 times higher than those of Pt-Bi NRs and Pt/C, respectively. This excellent activity endows the SE-Bi1/Pt NRs with a high likelihood to be used as a practical anodic electrocatalyst for direct methanol fuel cells （DMFCs） with high power density of 85.3 mW cm-2 and ultralow Pt loading of 0.39 mg cm-2.