Unveiling the Role of Hydrophobicity on Multilayer Carbon Nanosheets Enriched in sp-Carbon for Toluene Adsorption under Humid Conditions.

Carbon materials are regarded as a promising adsorbent for the adsorption of volatile organic compounds (VOCs). However, their adsorption behaviors are usually compromised at ambient conditions, attributed to the competitive VOCs adsorption with water vapor. In this study, we demonstrated that the selectivity for toluene than water of carbon can be effectively enhanced by introducing more sp-carbon with two-dimensional nanosheets stacked. The multilayer carbon nanosheets enriched with sp-carbon (CNS-MCA) exhibit a 151° HO-contact angle, indicating hydrophobicity. Dynamic adsorption behaviors revealed that CNS-MCA retain 71% of their toluene adsorption capacity (91 mg/g) even at 60% relative humidity. Density functional theory (DFT) calculations, static adsorption studies, in situ Raman spectroscopy, and time-resolved in situ nuclear magnetic resonance (NMR) spectroscopy collectively indicate that toluene exhibits enhanced adsorption and selectivity due to π-π* interactions between its aromatic rings and the sp-carbon. Conversely, water adsorption is attenuated, attributed to the reduced availability of surface-exposed hydrogen bonds associated with sp-carbon and the inherent hydrophobic nature of multilayer graphene. This study extends a novel solution for the enhancement of VOCs adsorption under humid conditions.