Size Dependence Surface Activity of Metallic Nanoparticles

For fundamental research, manipulation of properties, or building functionalized smart nanomaterials via plasma-enhanced technologies, we need to understand and predict the behavior of materials at nanoscale, which is far different from their bulk properties. Here, we first review a simple thermodynamic-based theory for size dependency feature of total cohesion (binding) energy of metallic nanoparticles. Then, with regard to the size dependency of cohesion energy, a simple theory for size dependency of enthalpy and Gibbs free energy of formation of metallic nanoparticles will be developed. Moreover, to describe the relative activity of metallic nanoparticles, a hypothesis through the modified classical physicochemical formalism of activity of particles in a reactive medium will be presented. Series of computations for size dependency of Gibbs free energy of formation, relative reaction constant (nano to macro), and activity of Zn, Al, Ag, Ga, and W at nanoscale will be presented. Our computational results show that by decreasing the size of the particles to less than 100 nm, the equilibrium reaction constant, rate constant, and consequently the relative activity of particles increase. our predicted extreme activity at nanoscale confirms the tendency observed in the experiments so far.