Concave Nano-Octahedral Alloys: Wet Chemical Synthesis of Bimetallic Pt-Pd Nanocrystals with High-Index {hhl} Facets

Concave morphologies provide noble metal nanocrystals (NCs) with unique performances due to large specific surface areas, high curves, hot spots, and elevated energy facets. As a result, concave morphologies have attracted considerable attention in many areas. However, most NCs with concave shapes are currently made of a single metal, leaving plenty of room for easy wet chemical synthesis and structural analysis of unique concave structures, especially bimetallic compounds. In this work, concave octahedral Pt-Pd alloy NCs with high-index {hhl} faces were synthesized using glycine as a coordination molecule and polyvinylpyrrolidone as the surfactant and reducing agent. The high-index facets coupled with the synergistic and electronic effects between Pt and Pd provided concave octahedral Pt-Pd alloy NCs with excellent activity and stability toward the electrooxidation of formic acid when compared to their convex counterparts and commercial Pt black.