Size control of semimetal bismuth nanoparticles and the UV-visible and IR absorption spectra

Abstract

We introduced a simple chemical rnethod to synthesize semimetal bismuth nanoparticles in N,N-dimethylformamide (DMF) by reducing Bi3+ with sodium borohydride (NaBH4) in the presence of poly(vinylpyrroldone) (PVP) at room temperature. The size and dispersibility of Bi nanoparticles can be easily controlled by changing the synthetic conditions such as the molar ratio of PVP to BiCl3 and the concentration of BiCl3. The UV-visible absorption spectra of Bi nanoparticles of different diameters are systematically studied. The surface plasmon peaks broaden with the increasing molar ratio of PVP to BiCl3 as the size of bismuth nantoparticles decreases. Infrared (IR) spectra of the complexes with different molar ratios of PVP/BiCl3 show a strong interaction between the carboxyl oxygen (C=O) of PVP and Bi3+ ion and a weak interaction between the carboxyl oxygen (C=O) of PVP and the Bi atom in nanoparticles. This indicates that PVP serves as an effective capping ligand, which prevents the nanoparticles from aggregation.