Single-crystalline metal nanorings and methods for synthesis thereof

In various embodiments, methods for synthesizing single-crystalline zero-valent metal nanorings, such as single-crystalline copper nanorings, are described herein. The methods include providing a solution containing a metal cation, a complexing agent bound to the metal cation, thereby forming a metal complex that is at least partially soluble in the solution, and a reducing agent operable for reducing the metal complex to a zero-valent metal and then heating the solution for a sufficient time and at a sufficient temperature until zero-valent metal nanorings form. The solution may be an aqueous solution in an embodiment. Single-crystalline metal nanorings produced by the methods described herein may have a diameter less than about 100 μm and a wall thickness between about 10 nm and about 500 nm