Digital 3D Local Growth of Iron Oxide Micro- and Nanorods by Laser-Induced Photothermal Chemical Liquid Growth

We introduce laser growth of iron oxide micro and nanorods by the photothermal chemical liquid growth method at low temperature, ambient pressure, and solution environment. By focusing a 532 nm continuous-wave laser on a Pt substrate immersed in iron oxide precursor solution, vertically aligned iron oxide micro- and nanorods are successfully fabricated with the length up to >100 μm, whereas the length can be easily controlled by changing the laser power or the illumination time. It is also found that the direction of the laser ray determines the growth direction of the iron oxide micro- and nanorods, which is the property that makes this process suitable for the fabrication of complex 3D structures as confirmed by making an iron oxide junction and kinked iron oxide microrod structure. Moreover, the resultant iron oxide microrod is applied as a microtemplate for the growth of nanostructure to show that this process can be further integrated to other 3D structures to achieve trans-scale hierarchical structures.