Bimetallic Nanocatalysts in Glycerol for Applications in Controlled Synthesis. A Structure–Reactivity Relationship Study

Abstract

Small and well-dispersed zerovalent PdCu-A and PdCu-B bimetallic nanoparticles (mean diameter, ca. 3–4 nm) stabilized by polyvinylpyrrolidone (PVP) were synthesized by a coreduction process in neat glycerol under hydrogen pressure from Cu(II) and Pd(II) precursors. These BMNPs were fully characterized both at solid state and in glycerol solutions by different techniques (PXRD, FT-IR, XPS, cyclic voltammetry, HR(TEM), HAADF-STEM, EDX), thanks to the negligible vapor pressure of glycerol. Depending on the Pd:Cu ratio, different structures were observed. Thus, using a Pd:Cu ratio of 1:1, PdNPs coated by a nonuniform Cu-shell were formed, while for Pd:Cu = 1:2, a disordered alloy was obtained; Pd:Cu = 2:1 ratio mainly led to monometallic species. The as-prepared BMNPs were tested in catalytic semihydrogenation of alkynes and azide–alkyne cycloaddition (CuAAC) with the aim of establishing a correlation between structure and reactivity. Moreover, PdCu-A nanoparticles were applied in one-pot tandem processes inv...