Modeling the electrooxidation of CO on the catalyst with heterogeneous sites

Abstract

The distribution and type of exposed surface sites are essential aspects of kinetics which should be considered together with mass transport in an electrochemical process, since multiple types of functional sites may coexist on electrocatalyst surfaces. In this study, we categorize the surface sites into active sites where the dissociation of water molecule and CO oxidation take place and nonactive sites where CO is adsorbed. By solving the bulk diffusion, adsorption, surface diffusion and reaction using the Fick’s diffusion law, reaction rate law, and Butler-Volmer equation, it is shown that the catalysts surface with a certain ratio of nonactive sites possesses high current rather than only with a type of active sites. More importantly, the high steady-state current can be obtained by balancing the micro-kinetics and mass transport. The findings provide a new strategy of catalyst design and electrochemical operation.