Tandem Synthesis of some Low and High Indexed Monometallic Nanoparticles in Polyols, Poly(Vinylpyrrolidone), Trisodium Citrate and Dodecanethiol Matrices

Sequential synthesis of some noble metal nanoparticles was successfully carried out by polyol/borohydride or hydrazine reduction in the presence of poly(vinylpyrrolidone), trisodium citrate and dodecanethiol in non-aqueous and aqueous solutions with concomitant precipitation of some high index faceted nanoparticles. The polyols afforded Pt NPs as small as 3.5 nm in diameter, which gradually (over a period of months) self-assembled into nanorods that were 5-6 nm in width and 20-30 nm in length. The formation of low indexed Pt NPs species occurred only at moderate temperature, but Pd high indexed face-centered cubic structures formed at 160 °C, while Co formed high indexed nanodiscs at 190 °C with an average diameter of 11.23 nm. The process could be monitored by UV absorption spectrophotometer, powder x-ray diffractometer and transmission electron microscopy (TEM). The polyol was indeed multifunctional: it reduced M+ (Co2+, Ni2+, Ru3+, Pd2+, Pt4+), stabilized the obtained M0 species and served as a template for the tandem formation of monometallic NPs of different morphology.