Rapid, Selective Surface Oxygenation of Activated Carbon Via Microwave Air Oxidation Toward Advanced Organic Pollutant Adsorption and Energy Storage

Oxidation is a common-used strategy to enhance the surface functionality of activated carbon. Disappointingly, previous oxidation routes always enrich high-polarity poor-capacitance O-C=O groups (i.e., carboxyl/lactone) on the carbon material surface, which is a double-edged sword for its application in organic pollutant adsorption and electrochemical energy storage. Herein, microwave air oxidation (MWAO) was proposed as a facile, rapid strategy to selectively oxygenate the surface of activated carbon (AC). Characterization results suggested that the surface of the pristine AC was substantially oxygenated in a rapid microwave radiation process (e.g., 800 W for 15 S), and the pore structure was also preserved after MWAO. More importantly, unlike other oxidation routes, MWAO was not favorable for the formation high-polarity poor-pseudocapacitance O-C=O groups, resulting in higher bulk pH, zeta potential and thermal stability after MWAO of AC. Batch adsorption results indicated that MWAO remarkably increased the adsorption of various organic pollutants (dyes and antibiotics) by AC. Electrochemical analysis suggested that the specific capacitance for the AC was increased by 250% (from 60 to 208 F/g at 1A/g after MWAO at 800 W for 15 s), attributed to the reduced electrical resistance and the enhanced ion transport after MWAO. The results of this study might pave a new way for the engineering of surface functionality of AC for advanced application in organic pollutant adsorption and electrochemical energy storage