PAN-based activated carbon nanofiber/metal oxide composites for CO₂ and CH₄ adsorption: influence of metal oxide

In the present study, we successfully prepared two different electrospun polyacrylonitrile (PAN) based-activated carbon nanofiber (ACNF) composites by incorporation of well-distributed Fe₂O₃ and Co₃O₄ nanoparticles (NPs). The influence of metal oxide on the structural, morphological, and textural properties of final composites was thoroughly investigated. The results showed that the morphological and textural properties could be easily tuned by changing the metal oxide NPs. Even though, the ACNF composites were not chemically activated by any activation agent, they presented relatively high surface areas (S_BET) calculated by Brunauer-Emmett-Teller (BET) equation as 212.21 and 185.12 m²/g for ACNF/Fe₂O₃ and ACNF/Co₃O₄ composites, respectively. Furthermore, the ACNF composites were utilized as candidate adsorbents for CO₂ and CH₄ adsorption. The ACNF/Fe₂O₃ and ACNF/Co₃O₄ composites resulted the highest CO₂ adsorption capacities of 1.502 and 2.166 mmol/g at 0 °C, respectively, whereas the highest CH₄ adsorption capacities were obtained to be 0.516 and 0.661 mmol/g at 0 °C by ACNF/Fe₂O₃ and ACNF/Co₃O₄ composites, respectively. The isosteric heats calculated lower than 80 kJ/mol showed that the adsorption processes of CO₂ and CH₄ were mainly dominated by physical adsorption for both ACNF composites. Our findings indicated that ACNF-metal oxide composites are useful materials for designing of CO₂ and CH₄ adsorption systems.