Bismuth nanowires (Bi
NWs) were prepared from BiCl3 solution by an aqueous reduction
procedure with NaH2PO2 as reducing reagent and PVP as morphology
director. In a typical synthesis, 0.05 g of PVP K13 dissolved in 5 mL of
distilled water was first placed in a three-neck flask, and then 10 mL of
0.5 mol L−1 BiCl3 solution (with 1.44 mol L−1 of HCl in the solution)
and 40 mL of 2.5 mol L−1 of a NaH2PO2 solution were successively
added to the reaction system. Afterward, the reaction began at 80 °C
with constant stirring with the appearance of white precipitates. With
longer time, the precipitates underwent color changes from white to light gray (30 s), dark brown (3 min), and finally black (8 min). The
black precipitates are related to the bismuth product. After the reaction
proceeded for 1 h, a certain amount of NaOH solution was supplied to
the reaction system to manipulate the pH value to 7, and the reaction
was performed for an additional 2 h. The black precipitates obtained
were separated from the mother liquid and washed with distilled water
and alcohol several times to remove the residual reactants. The final
samples were obtained by drying the wet black precipitates at room
temperature in a desiccator for 20 h and subsequently in air oven of 60
°C for 1 h