Unraveling Oxygen Evolution Reaction on Carbon-Based Electrocatalysts: Effect of Oxygen Doping on Adsorption of Oxygenated Intermediates

Carbon-based nanomaterials have been widely studied as promising electrocatalysts for energy conversion and storage. Understanding the oxygen evolution and reduction reactions on carbon-based nanomaterials is of critical importance for development of highly active metal-free electrocatalysts. Here, the adsorption of oxygenated intermediates during oxygen evolution reaction (OER) on carbon nanotubes (CNTs) was examined by ex-situ X-ray photoelectron spectroscopy and in situ electrochemical impedance spectroscopy. The results demonstrate that the carbon atoms on CNTs near the C=0 functional groups are active for OER. On the basis of this result, we further revealed the origin of the enhanced intermediate adsorption on surface-oxidized CNTs and the relationship between surface groups and apparent activation energy. Our study gained new understanding of OER on oxygen-doped carbon nanomaterials and provided an effective approach for investigating electrocatalysis on heteroatom-doped carbon electrocatalysts.