Ultrasonic treatment duration: A nuanced parameter in synthesis affecting structural properties and ORR performance of KOH-activated carbon

In this study, we investigate the effects of the duration of ultrasonic treatment during the impregnation process of a carbon precursor with an aqueous alkaline solution on the structural and electrochemical properties of KOHactivated carbon materials. Our findings using polyacrylonitrile (PAN)-derived carbon materials reveal that extended ultrasonic treatment leads to a more consistent distribution of the activating agent, promoting more uniform surface activation. This leads to notable shifts in the material's structure and surface chemistry, thereby influencing its functionality as an electrode material in supercapacitors and its electrocatalytic activity in the oxygen reduction reaction (ORR). Our results indicate a 6 % difference in the specific surface area and an 8 wt% rise in oxygen content when comparing samples without ultrasonic treatment to those treated for 10 min. Moreover, the specific capacitance increases from 133.9 to 163.5 F g-1, and the ORR activity ascends from 1.88 to 2.23 mA cm-2. This research highlights the potential of ultrasonic treatment duration as a variable to fine-tune the structure and properties of porous carbon materials, emphasizing its scientific and technological significance in the production of stable porous carbon materials.