A Model for the pH-Dependent Selectivity of the Oxygen Reduction Reaction Electrocatalyzed by N-Doped Graphitic Carbon

摘要: Nitrogen-doped graphitic carbon materials have been extensively studied as potential replacements for Pt-based electrocatalysts the oxygen reduction reaction (ORR). However, little is known about catalytic mechanisms, including parameters that determine selectivity of reaction. By comparing theoretical calculations ORR at a well-defined graphene nanostructure with experimental results, we propose model based on interfacial solvation to explain observed preference four-electron pathway in alkaline electrolytes. The hydrophobic environment around active sites, enzymatic catalysis, restricts access water and destabilizes small ionic species such peroxide, product two-electron pathway. This model, when applied acidic electrolytes, shows preferring pathway, consistent well-known pH-dependent catalyzed by materials. Because similarity between more compl...