Platinum Metal Catalysts of High-Index Surfaces: From Single-Crystal Planes to Electrochemically Shape-Controlled Nanoparticles

Nanoparticles of platinum group metals (PGM) supported on diverse substrate materials are widely used catalysts in many important fields such as modern chemical industry, petrochemical industry, automobile exhaust purification, and fuel cells. Due to the extremely high cost and rare reserve of the PGM on the earth, to further improve the catalytic activity, stability, and utility efficiency of PGM nanoparticles is the key issue in relevant industrial development as well as the challenge of basic research of science and technology. This feature article summarizes at first the relationship between surface structure and catalytic functionality gained by using metal single-crystal planes as model electrocatalysts, which reveals that high-index planes, i.e., the planes denoted by a set of Miller indices (hkl) with at least one index being larger than unit, with high density of atomic steps and kinks, exhibit generally high catalytic reactivity and stability. Next, guided by the knowledge acquired in model electrocatalysis, we put emphasis upon the electrochemically shape-controlled synthesis of Pt and Pd nanocrystals (NCs) bounded by high-index facets, including tetrahexahedral NCs with 24 {hk0} facets, trapezohedral NCs with 24 {hkk} facets, concave hexoctahedral NCs with 48 {hkl} facets, and multiple twinned nanorods with {hk0} facets. Finally, challenging issues and future prospects in this exciting field are outlined.