Question

Calculate the number of atoms in a 1.4 nm diameter platinum nanoparticle using the total number of unit cells present. Consider a FCC unit cell with a lattice constant of a = 3.91 Å. Explain the interest in small platinum or palladium nanoparticles for catalysis.

Answer 1

tHe csit coll tate で一下. 2 4

The catalytic properties of metal nanoparticles are generally regarded as size- and shape-dependent. Attention has been given to the electronic effects induced by surface organic modifiers (stabilizers) on metal NP catalysts. Demonstrated that an interfacial electronic effect induced by ethylenediamine ligands adsorbed on Pt nanowires was able to control the selectivity of metal nanocatalysts during catalytic hydrogenation. A sulfur-containing polymer was demonstrated to be an efficient modifier for Pd catalysts controlling the selectivity in semihydrogenation of alkynes to alkenes.

The ligand-assisted method for the preparation of supported metal nanoparticles offers a versatile and convenient approach to obtain catalysts with a strong metal–support interaction, which result in (1) higher loading when compared with nonmodified silica, (2) negligible metal leaching, and (3) higher stability upon recycling. However, the ligands grafted on the silica surfaces influence the catalytic activity of supported PVA-stabilized Pd. NPs and have to be carefully selected. Those ligands that are detrimental to the catalytic activity can be removed by the thermal treatment to recover activity. The addition of excess of these ligands to supported Pd NPs suppressed the alkene-to-alkane reaction and therefore was used as a strategy to tune the selectivity of Pd in the semihydrogenation of alkyne to alkene. Although we demonstrated the successful utilization of ligand modifiers in combination with metal nanoparticles.