In situ observation of the solid solution-induced sublimation of CuAg Janus nanoparticles

Abstract

Bimetallic Janus nanostructures (JNs) have attracted much interest because of their promising potential applications induced by unique interface effects, especially in catalysis. Catalytic stability acts a role as significant as catalytic efficiency in the potential applications of catalysts. However, the response of bimetallic JNs to high temperature has been poorly investigated due to their complex structure and sublimation kinetics. Herein, the thermal stability and sublimation mechanisms of CuAg JNs are studied through in situ annealing experiments performed in an aberration-corrected FEI Titan 80-300 transmission electron microscope operated at 300 kV. It is proven that CuAg JNs begin to sublimate until the temperature increases to 800 °C, although Ag nanostructures can always begin to sublimate at temperatures as low as 500 °C. Interestingly, Cu and Ag atoms sublimate simultaneously with a molar ratio likely to preserve at approximately 1 because Cu partially dissolves into the Ag phase at higher temperatures. Furthermore, a rational atomic motion mechanism is proposed to explain the phase transition in which the solid solution forms and the whole special sublimation process. These in situ observations promise to be helpful for understanding the evolutionary behaviors of bimetallic JNs under high temperatures arising in catalytic processes and other applications.