Novel synthesis and characterization of bismuth nano/microcrystals with sodium hypophosphite as reductant

In this paper, we report on the low temperature solution reduction method employed in the synthesis of large quantities of nano/micro-sized bismuth (Bi) crystals with sodium hypophosphite (NaH2PO2·H2O) as reductant in acidic solutions. The achieved Bi crystals exhibited plate-like (100 nm in size and few nanometers in thickness) or polyhedral (500 nm in size) shapes. Bi nanocrystals transformed to octahedron-like Bi microcrystals only by prolonging the reaction time. The assembly and oriented growth should be the reason. To understand the growth mechanism, we also discussed the possible growth of the Bi nanocrystals exhibits influence of experimental parameters such as reaction time, NaH2PO2·H2O concentration, and pH value. The resulting Bi crystals were characterized by using scanning electron microscopy, X-ray powder diffraction and differential thermal analysis and thermogravimetry. Optical properties of the samples were studied by ultraviolet–visible spectroscopy.

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► Bi particles have been mildly synthesized via a solution reduction method.
► The pH value plays an important role for the formation of Bi nano/micro-structures.
► The reaction time has a key role for the formation and shape evolution of Bi samples.
► The optical properties changed with varied shapes of Bi structures.