Ultrathin nanowires with diameters less than 10 nm, especially less than 3 nm, are of great interest for materials scientists, because such a small size may make the materials generate unique properties due to the quantum confinement effect.However, it is still a great challenge to produce uniform single-crystalline ultrathinnanowires with high aspect ratio.In addition, in order to apply the nanowires in devices, it is necessary to assemble them into ordered patterns over a large scale.