Green synthesis of copper oxide/nanographene nanocomposite as a novel adsorbent for enhanced CO₂ capture

The present study examined the carbon dioxide (CO₂) capture capabilities of copper oxide/nanographene (CuO/NG) nanocomposites, representing a novel generation of eco-friendly adsorbents. In addition to CuO/NG nanocomposites prepared using conventional methods, CuO/NG-green nanocomposites were developed using a “green synthesis” method involving hemp (Cannabis sativa L.) stalk bio-extract. The nanomaterials were characterized using a range of techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) method. Greater homogeneity in morphology and particle size distribution was revealed in the nanocomposites obtained by green synthesis. It has been indicated by BET analysis that a surface area of 644 m² g⁻¹ and an average pore diameter of 4.28 nm are possessed by the CuO/NG-green nanocomposite. Experiments involving CO₂ adsorption were carried out at temperatures of 273 K and 298 K within a pressure range of 0–1 bar. The results showed that the CuO/NG-green nanocomposite had the best performance, with CO₂ uptake capacities of 4.21 mmol g⁻¹ at 273 K and 3.62 mmol g⁻¹ at 298 K under 1 bar. The values obtained for this material are higher than those of the CuO/NG nanocomposite that was synthesized using the conventional method. Additionally, it was indicated by the isosteric heat of adsorption (Q_st) values that stronger interactions with CO₂ were exhibited by the CuO/NG-green nanocomposite. Additionally, after 10 cycles of reuse testing, the CuO/NG-green nanocomposite exhibited excellent reusability, maintaining 93% of its CO₂ uptake capacity. The findings indicate that synthesized CuO/NG-green nanocomposites have the potential to be utilized as sustainable, high-performance CO₂ adsorbents, positioning them as promising candidates for environmentally friendly carbon management technologies.