Size-dependent Electrochemical Properties of Binary Solid Solution Nanoparticles

Abstract

The electrochemical properties have different or reverse trend with decreasing radius dependent on the synthetic methods and thermodynamic states of nanoparticles. Here, a size-dependent thermodynamic model was derived to describe the thermodynamic equilibrium state of binary solid solution nanoparticles. This model combined the capillary equation with the Gibbs-Duhem equation and the Butler-Volmer equation, can simultaneously analyze nanoparticle size, stresses, solute segregation and electrochemical properties in solid solution nanoparticles. Then, spherical nanoparticles of CuZn binary solid solution were studied. With decreasing CuZn nanoparticle radius, the anodic current density decreased, whereas the equilibrium potential increased, meaning that the stability was enhanced. With increasing apparent Zn concentration, the anodic current density and the equilibrium potential difference between the CuZn nanoparticle components increased, implying that the selective corrosion of Zn atoms enhanced. These results were qualitatively consistent with some experimental observations.