Nanoparticlecatalysts with high energy surfaces and enhanced activity synthesized by electrochemical method

Abstract

Electrochemical shape-controlled synthesis of metal nanocrystal (NC) catalysts bounded by high-index facets with high surface energy was achieved by developing a square-wave potential route. Tetrahexahedral Pt NCs with 24 {hk0} facets, concave hexoctahedral Pt NCs with 48 {hkl} facets, and multiple twinned Pt nanorods with {hk0} facets were produced. The method was employed also to synthesize successfully trapezohedral Pd NCs with 24 {hkk} facets, and concave hexoctahedral Pd NCs with 48 {hkl} facets. It has been tested that, thanks to the high-index facets with high density of atomic steps and dangling bonds, the tetrahexahedral Pt NCs exhibit much enhanced catalytic activity for equivalent Pt surface areas for electrooxidation of small organic fuels such as ethanol. These results demonstrate that the developed square-wave potential method has surmounted the limit of conventional chemical methods that could synthesize merely metal nanocrystals with low surface energy, and opened a new prospect avenue in shape-controlled synthesis of nanoparticle catalysts with high surface energy and enhanced activity.

Shape‐Dependent Electrocatalysis: Oxygen Reduction on Carbon‐Supported Gold Nanoparticles

“…However, as shown in previous studies, [64][65][66] shape is expected to be a prerequisite for a particular surface structure. Thus, quasi-spherical nanoparticles can be considered as polyoriented, non-specificallysurface-structured catalyst materials, as no preferred facets are exposed.…”

Recent Development of Pd-Based Electrocatalysts for Proton Exchange Membrane Fuel Cells

“…With a square-wave potential method Tian et al [13] electrodeposited tetrahexahedral Pd nanocrystals with {730} high-index facets. With similar technique, Zhou et al [14] prepared the Pd NCs not limited to the tetrahexahedral crystals. Shen et al [15] used a sonoelectrochemical method to prepare Pd spherical nanoparticles, multitwinned particles, and spherical spongelike particles.…”

“…It still needs a correlation between crystallographic structure, morphological evolution and resultant shape of the nanocrystals. Zhou et al [14] proposed the correlation between crystalline planes and nanocrystalline shape. There is a triangle relationship between the unit stereographic of fcc single-crystal and the surface atomic arrangement.…”

Synthesis and Electrocatalytic Properties of H2SO4‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

“…In this regard, it is important to recall that, by simple analogy with the unit stereographic triangle of a fcc metal, a stereographic triangle with shaped fcc metal nanoparticles can be made in which the three apexes represent the coordinates of polyhedral nanocrystals bounded by basal facets (a cube, octahedron and rhombic dodecahedron enclosed by (100), (111) and (110) faces, respectively). [16][17][18] Thus, a preferential (100) surface structure is the expected orientation from cubic Pt nanoparticles. Figure 2 shows representative TEM images of the nanoparticles prepared in the presence of different amounts of H2SO4.…”