ABSTRACT
X-ray-radiolysis-induced photochemical reaction of a liquid solution enables the direct synthesis and immobilization of nano/micro-scale particles and their aggregates onto a desired area. As is well known, the synthesis, growth and aggregation are dependent on the pH, additives and X-ray irradiation conditions. In this study, it was found that the topography and composition of synthesized particles are also dependent on the types of substrate dipped in an aqueous solution of Cu(COOCH3)2 in the X-ray-radiolysis-induced photochemical reaction. These results are attributed to the fact that a secondary electron induced by the X-ray irradiation, surface or interface on which the particles are nucleated and grown influences the particle shape and composition. This study will shed light on understanding a novel photochemical reaction route induced under X-ray irradiation. The development of this process using the X-ray-radiolysis-induced photochemical reaction in aqueous liquids enables us to achieve the rapid and easy operation of the synthesis, growth and immobilization of special nano/micro-scale complex materials or multifunctional composites.
ABSTRACT
Synthesis and immobilization of caltrop cupric particles onto a Si substrate using X-ray radiolysis directly from a liquid solution of Cu(COOCH3)2 is demonstrated. Caltrop cupric oxide particles are formed in the X-ray radiolysis of aqueous solutions of Cu(COOCH3)2, which also contain methanol, ethanol, 2-propanol or 1-propanol as ^\bulletOH scavenger. The blade lengths of the caltrop particles are dependent on the alcohol chain length. In particular, it was found that an alkyl alcohol whose chain length is longer than four is unable to synthesize any particles in aqueous solutions of Cu(COOCH3)2 in X-ray radiolysis. These results are attributed to the alkyl alcohol chain length influencing the rate of reaction of radicals and determines the solvable ratio of its alcohol into water. In addition, it was found that the synthesized particle geometric structure and composition can also be controlled by the pH of the aqueous solution in the X-ray radiolysis. This study may open a door to understanding and investigating a novel photochemical reaction route induced under X-ray irradiation. The development of the X-ray radiolysis process enables us to achieve the rapid and easy process of synthesis and immobilization of higher-order nano/microstructure consisting of various materials.
ABSTRACT
X-ray radiolysis of a Cu(CH3COO)2 solution was observed to produce caltrop-shaped particles of cupric oxide (CuO, Cu2O), which were characterized using high-resolution scanning electron microscopy and micro-Raman spectrometry. X-ray irradiation from a synchrotron source drove the room-temperature synthesis of submicrometer- and micrometer-scale cupric oxide caltrop particles from an aqueous Cu(CH3COO)2 solution spiked with ethanol. The size of the caltrop particles depended on the ratio of ethanol in the stock solution and the surface of the substrate. The results indicated that there were several synthetic routes to obtain caltrop particles, each associated with electron donation. The technique of X-ray irradiation enables the rapid synthesis of caltrop cupric oxide particles compared with conventional synthetic methods.
