Synthesis and Characterization of Crystalline Ag_2Se Nanowires Through a Template-Engaged Reaction at Room Temperature

摘要

Single-crystalline Ag_2Se nanowires have been successfully synthesized through a template-engaged topotactic reaction in which nanowires of trigonal selenium were transformed into Ag_2Se by reacting with aqueous AgNO_3 solutions at room temperature (RT). An interesting size-dependent transition between two crystal structures has also been observed for this newly synthesized one-dimensional system: The Ag_2Se nanowires adopted a tetragonal structure when their diameters were less than ～40 nm; an orthorhombic structure was found to the more favorable as the diameter of these nanowires was increased beyong 40 nm. Since this reaction can be carried out at ambient pressure and temperature, it should be straightforward to scale up the entire process for the high-volume production of Ag_2Se nanowires with well-controlled sizes and crystal structures. These highly uniform nanowires of single-crystalline Ag_2Se are potentially useful as photosensitizers, superionic conductors, magnetoresistive compounds, or thermoelectric materials. This work also represents the first demonstration of a template-engaged process capable of generating single-crystalline nanowires from the solution-phase ad at RT.