Shape-Controlled Nanocrystals for Catalytic Applications

Abstract

The activity, selectivity, and long-term stability of catalyst nanoparticles can be enhanced by shape modulation. Such shaped catalytic nanocrystals have welldefined surface crystalline structures on which the cleavage and recombination of chemical bonds can be rationally controlled. Metal and metal oxide nanocrystals have been synthesized in various shapes using wet chemistry techniques such as reducing metal precursors in the presence of the surface-capping agents. The surface-capping agents should be removed prior to the catalytic chemical reaction, which necessitates clean catalytically active surface. The removal process should be performed very carefully because this removal often causes shape deformation.A few examples in which the surface-capping agents contribute positively to the chemical reactions have been reported. The examples described in this review include shaped metal, metal composite, and metal oxide nanocrystals that show enhanced catalytic activity, selectivity, and long-term stability for various gas-phase, liquid-phase, or electrocatalytic reactions. Although most of the studies using these shaped nanocrystals for catalytic applications have focused on low-index surfaces, nanocrystals with high-index facets and their catalytic applications have recently been reported. By bridging surface studies with nanoparticle catalysts using shape modulation, catalysts with improved properties can be rationally designed.

Surface Treatment Strategies on Catalytic Metal Nanoparticles

“…However, because the aim of this chapter is mainly focused on their surface structure-dependent (electro)catalytic properties of such nanostructures, some of the most relevant reviews dealing with the synthesis of such metal nanoparticles are just mentioned [8,[17][18][19][20].…”

“…These results clearly evidence the enormous advantage of using this kind of nanoparticles containing high-index facets for some electrocatalytic applications. Consequently, great efforts are being currently dedicated to develop methodologies to produce metal nanoparticles enclosed by highindex facets, which have high density of atomic steps/kinks and, thus, containing a high fraction of low-coordinated surface sites [18,[60][61][62][63][64][65].…”

Controlled Synthesis of Porous Platinum Nanostructures for Catalytic Applications

“…Generally, surface-capping agents play two important roles in shape-controlled preparation: stablizing the nanoparticles to avoid overgrowth and Ostwald ripening; selectively adsorbing on a certain facet to hinder the growth in a specific direction. 50 Various organic capping agents such as PVP (polyvinypyrrolidone), 49 citrate ions and various organic ammonium salts (CTAB, CTAC) 51 have successfully been applied to grow specific shapes. For instance PVP is known to preferentially bind to (111) and (100) planes.…”

An Overview of One-Dimensional Metal Nanostructures for Electrocatalysis

“…So far, various Pt-or other metal-based catalysts with novel nanostructures, such as faceted polyhedral nanocrystals, alloys, core-shell, porous or hollow, concave, and branched nanostructures etc. have been synthesized as alternative catalysts to replace the traditional nanoparticle catalysts [8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”