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

CO2 capture via adsorptionhas been widelyexploredand is viewed as one of the most effective and green solutions toaddress the high CO2 concentration globally. However, theformation of intermediates during CO2 adsorption and thesynthesis of the adsorbent, activated carbon, still need to be resolved.In this study, potassium citrate-activated carbon (ACK) samples wereprepared. The synergistic effects of the potassium content and reactiontemperature (600 and 1000 degrees C) were examined. In the synthesisof potassium citrate-activated carbon, potassium citrate was convertedto KOH, K2CO3, and K2O and evaporatedas metallic potassium vapor followed by intercalation into the activatedcarbon lattice, forming a micro- and mesoporous nanostructure, whichis advantageous for CO2 capture and electrocatalytic reduction.In addition, trace potassium in the ACK sample acted as a reactivesite to redistribute and facilitate electron transfer, enabling enhancedCO(2) activation and reduction. The ACK samples exhibitedstrong dual-site bonding of CO2 to the Lewis basic sites,forming b-CO3 (2-) intermediates by thephysical adsorption through the abundant porous structure of the ACKsample and chemical adsorption by its strong Lewis basicity. In summary,our work presents detailed analyses to understand the mechanism ofCO(2) adsorption using activated carbon as an effective adsorbent.