Potassium Citrate-Activated Porous Carbon Nanostructures for CO₂ Adsorption and Electroreduction

Abstract

CO 2 capture via adsorption has been widely explored and is viewed as one of the most effective and green solutions to address the high CO 2 concentration globally. However, the formation of intermediates during CO 2 adsorption and the synthesis of the adsorbent, activated carbon, still need to be resolved. In this study, potassium citrate-activated carbon (ACK) samples were prepared. The synergistic effects of the potassium content and reaction temperature (600 and 1000 °C) were examined. In the synthesis of potassium citrate-activated carbon, potassium citrate was converted to KOH, K 2 CO 3 , and K 2 O and evaporated as metallic potassium vapor followed by intercalation into the activated carbon lattice, forming a microand mesoporous nanostructure, which is advantageous for CO 2 capture and electrocatalytic reduction. In addition, trace potassium in the ACK sample acted as a reactive site to redistribute and facilitate electron transfer, enabling enhanced CO 2 activation and reduction. The ACK samples exhibited strong dual-site bonding of CO 2 to the Lewis basic sites, forming b-CO 3 2− intermediates by the physical adsorption through the abundant porous structure of the ACK sample and chemical adsorption by its strong Lewis basicity. In summary, our work presents detailed analyses to understand the mechanism of CO 2 adsorption using activated carbon as an effective adsorbent.

Effects of Potassium-Based Activating Agents on the Biochar Derived from Coconut Tree Husk for Enhancing the Surface Area and Supercapacitor Performance

“…The carbonyl groups (OCO) have the peak position at the binding energy of 532.1 eV; the carboxylic groups (CO) have the peak at the binding energy of 533.2 eV; and the hydroxyl groups (COH) have the peak at the binding energy of 534.3 eV. The above results suggest that, at a high temperature, the KMnO 4 activator strongly oxidizes the carbon materials to boost the oxygen content and etch out the non-oxygen atoms. , It has been established that adding oxygen-functional groups to carbon materials makes them more hydrophilic, maximizing the use of their large specific surface areas and improving their capacity for energy storage …”

“…34,41 It has been established that adding oxygen-functional groups to carbon materials makes them more hydrophilic, maximizing the use of their large specific surface areas and improving their capacity for energy storage. 42 Electrochemical Performances of AC. The electrochemical and energy storage characteristics of pure AC1, AC2, AC3, AC4, AC5, and AC6 are investigated using a threeelectrode system before building the supercapacitor device.…”