电化学原理Chaper 7 - Electrocatalysis.pdfVIP

Chapter 7 Electrocatalysis Heterogeneous electrocatalysis  “Catalysis” to promote or inhibit a reaction via modifying the reaction pathways (reaction activation energy ) by using catalysts;  “Heterogeous” not in a single, homogeneous phase, but at interfaces between two phases; adsorption of reactants, intermediates or products is mostly involved; the reaction rate depends on the nature and properties of the catalysts.  “ Electrocatalysis” electrochemical catalysis: electron transfer as well as adsorption are involved; the reaction rates depend not only on the nature and properties of the catalysts, but the properties of electrode/electrolyte interface. Electrocatalysis vs. Catalysis 0 (G0 ) (G ) reagents products reagents nFE products Electrocatalysis Heterogenous catalysis 3 The effects of surface structure of catalysts Chemical composition (bulk and surface) Geometric structure (surface atomic arrangement) Electronic structure The catalytic active sites Hydrogen Electrode Reactions Hydrogen evolution reaction (HER) H  H  H ad 2 Hydrogen oxidation reaction (HOR) Volmer reaction: M H  e M - H ad Tafel reaction: M - H M - H 2M H ad ad 2 Heyrovsky reac