Vicioxite: carbon material with adjacent OH groups for CO₂ and H₂O capture

Abstract

Developing efficient carbon-based adsorbents for CO₂ and H₂O capture is critical for mitigating climate change. Although functionalization of carbon materials is essential for efficient adsorption, the structural control of carbon materials remains challenging. While oxygen functional groups can enhance surface polarity, conventional oxidation methods lack control over group arrangement and often degrade the carbon framework. This study successfully synthesized “Vicioxite”, a carbon material with controlled structures and adjacent oxygen sites (especially OH groups) via catalysts-free synthesis to elucidate the effective configurations for CO₂ and H₂O capture. We synthesized model materials using coronene-coated activated carbon fibers (ACFs) via a regioselective two-step bromination and hydrolysis process. This method successfully introduced adjacent OH groups while preserving the π-conjugated basal plane. Computational analyses revealed that the specific edge topology of coronene energetically favors the formation of adjacent OH pairs, whereas steric hindrance restricts their formation on armchair edges. Experimental characterization, including ¹³C nuclear magnetic resonance, confirmed these structures. Crucially, CO₂ temperature-programmed desorption demonstrated that samples rich in adjacent OH groups exhibited superior CO₂ adsorption capacity compared to untreated ACF. These results suggest that adjacent OH groups induce interactions, demonstrating that controlling the local spatial arrangement of functional groups is essential for designing high-performance adsorbents.