Synchrotron X-ray-induced Synthesis of Copper Hydroxide Nitrate Nanoplates on Cu Thin Films in an Ambient Atmosphere

Synchrotron X-rays are widely used for material characterizations. However, they can also ionize atoms and molecules to damage and manipulate probed materials. We report here an X-ray-induced growth of copper hydroxide nitrate, Cu₂(OH)₃NO₃, on copper thin films in the ambient atmosphere without solvents and thermal treatment. In situ synchrotron X-ray diffraction measurements showed that the time-dependent growth process of the Cu₂(OH)₃NO₃ is accompanied by the consumption of Cu metal and can be described by a sigmoidal model. The growth rate was reduced after the initial fast growth period. Scanning electron microscopy (SEM) images show that the isolated islands of Cu₂(OH)₃NO₃ nanoplates formed in the beginning, which grew together with new nanoplates formed under continued X-ray irradiation. The result demonstrated that high-flux synchrotron X-rays may provide an unconventional approach to synthesizing and manipulating materials, which will inspire future investigation both experimentally and theoretically.