Composition-Dependent Morphology of Bi- and Trimetallic Phosphides: Construction of Amorphous Pd-Cu-Ni-P Nanoparticles as a Selective and Versatile Catalyst.

Amorphous materials have been widely researched in heterogeneous catalysis and for next-generation batteries. However, the well-defined production of high-quality (e.g., monodisperse and high surface area) amorphous alloy nanomaterials has rarely been reported. In this work, we investigated the correlations among the composition, morphology, and catalysis of various Pd-M-P nanoparticles (NPs) (M = Cu or Ni), which indicated that less Cu (≤20 atom %) was necessary for the formation of an amorphous morphology. The amorphous Pd-Cu-Ni-P NPs were fabricated with a controllable size and characterized carefully, which show excellent selective catalysis in the semihydrogenation of alkynes, hydrogenation of quinoline, and oxidation of primary alcohols. The uniqueness of the catalytic performance was confirmed by control experiments with monometallic Pd, amorphous Pd-Ni-P NPs, crystalline Pd-Cu-P NPs, and a crystalline counterpart of Pd-Cu-Ni-P catalyst. The catalytic selectivity likely arose from improved Pd-M (M = Cu or Ni) synergistic effects in the amorphous phase and the electron deficiency of Pd. The model reactions proceeded under H2 or O2 gas without any additives, bases, or metal oxide supports, and the catalyst could be reused several times. This report is expected to shed light on the design of amorphous alloy nanomaterials as green and inexpensive catalysts for atom-economic and selective reactions.