Methane and carbon dioxide adsorption on carbon nano-onions synthesized by the submerged arc-discharge method

A top priority for the scientific community is reducing the greenhouse effect. Developing new materials for gas storage is a critical aspect, and new materials suitable for the adsorption of greenhouse gases such as carbon dioxide and methane are being investigated. Carbon Nano-Onions (CNOs) are one of the most recently discovered carbon allotropes, which can be synthesized by several methods, including submerged arc-discharge in water (SADW). Although the SADW method is well known, the properties of CNOs synthesized by this method as gas adsorbents have not yet been studied. Therefore, the aim of this work is to study these properties. For this purpose, CNOs were synthesized by SADW and characterized by different methods (XRD, TEM, Raman spectroscopy, and TGA) to determine their structural defects, size, morphology, and thermal stability. Their surface area, volume, and average pore size were also determined by nitrogen adsorption at 77 K measurement. Subsequently, their adsorption capacities of methane and carbon dioxide were obtained from adsorption/desorption isotherms and compared with other adsorbents found in the literature, with promising results. The predominant adsorption mode was also studied from isotherm models, and possible interaction mechanisms were provided.