Structure-Dependent Selective Hydrogenation of α,β-Unsaturated Aldehydes over Platinum Nanocrystals Decorated with Nickel

The shape sensitivity of monometallic Pt and bimetallic Pt-Ni nanocrystals in alpha,beta-unsaturated aldehydes is studied by using a cubic shape enclosed by six {100} facets as well as an octahedral shape surrounded by eight {111} facets. Compared with monometallic Pt and bimetallic Pt-Ni cubic/octahedral shapes, Pt3Ni cubes enhanced the selective hydrogenation of the C=O double bond and suppressed the selective hydrogenation of the C=C double bond of the alpha,beta-unsaturated aldehyde. The Pt, Pt3Ni, or PtNi octahedral shape is an unfavorable structure for C=O hydrogenation and enables the activation of the whole conjugated system of the molecule, which leads to complete hydrogenation to form the saturated alcohol product. The synergistic effects of the surface structure and electronic properties of Pt or Pt-Ni nanocrystals play a key role in controlling the selective hydrogenation of C=C and C=O bonds of alpha,beta-unsaturated aldehydes.