Activation energy of tribochemical and heterogeneous catalytic reactions

The relationship between the activation energy and enthalpy, either in the presence or absence of a catalyst, is of particular importance. If a catalyst is present, the energy required for a given chemical reaction to go into transition state decreases, thereby decreasing the energy required to initiate the reaction. The dynamics of heterogeneous catalysis is still under discussion. The same applies to tribochemistry and/or tribocatalysis. It has been assumed that heterogeneous solid catalysts decrease the activation energy, reflected as apparent activation energy. The model presented elsewhere has been theoretically evidenced for the first time by reviewing the existing literature data concerning anisotropy features of the angular distribution of exoelectrons emitted from perturbed surfaces. Metal-insulator-metal thin film sandwich structures are of particular interest in this paper. Other evidence supporting the model is also discussed such as the anisotropic desorption emission from a surface during catalytic processes. The conclusions of this work have been applied in practice to design specific measurement techniques and devices for estimating the angular distribution of electrons triboemitted from solid catalyst materials under sliding contact in a high-vacuum tribometer.