Possible influence of electrostatics in molecular bonding at supported metal nanoparticles

A mechanism is proposed for interaction between gas molecules and supported metal nanoparticles. Hot electrons that are formed via electron–hole pair excitations caused by exothermic reactions on the particles, enter into the insulating support, thereby leaving a positive charge that is distributed over the volume of the nanoparticle. The lifetime of the charge depends on the size of the metal particle and on the electronic and dielectric properties of the support, and may be too short for equilibrium to be established between the particle and its surroundings on the time scale of the chemical reaction. The electrostatic potential of the particle depends on its size, and therefore the position of the d-density of states of the particle, and thus the interaction with adsorbed molecules may be tuned by changing particle size. Thus, catalytic activity and selectivity may be affected for chemical reactions.