A method is disclosed. The method includes forming a mixture including nanorods with a first material having first ions, coordinating molecules, and second ions in a solvent, and forming composite nanorods in the solvent. Each composite nanorod has a linear body with a first region having the first material and a second region having a second material, where the second material has the second ions.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 The invention described and claimed herein was made in part utilizing funds supplied by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Government has certain rights in this invention.