Adsorption of molecular iodine on the surface of sulfur-doped carbon nanotubes: theoretical study on their interactions, sensor properties, and other applications

Synergistic mechanism of formaldehyde adsorption by intrinsic defects and carboxyl groups on the surface of carbon materials

The adsorption of formaldehyde on the original carbon material is limited. Determining the synergistic adsorption of formaldehyde by different defects on the carbon material is necessary for comprehensively understanding the mechanism of formaldehyde adsorption on the surface of the carbon material. The synergistic effect of intrinsic defects and oxygen-containing functional groups on formaldehyde adsorption on the surface of carbon materials was simulated and verified by experiments. Based on the density functional theory, the adsorption of formaldehyde on different carbon materials was simulated by quantum chemistry. The synergistic adsorption mechanism was studied by energy decomposition analysis, IGMH, QTAIM, and charge transfer, and the binding energy of hydrogen bonds was estimated. The results showed that the energy for the adsorption of formaldehyde adsorbed by the carboxyl group on the vacancy defect was the highest, at -11.86 kcal/mol, the hydrogen bond binding energy was -9.05 kcal/mol, and a larger charge transfer was recorded. The mechanism of synergy was studied comprehensively, and the simulation results were verified at multiple scales. This study provides valuable insights into the effect of carboxyl groups on the adsorption of formaldehyde by activated carbon.

Carbon Nanotube Chemical Sensors

Carbon nanotubes (CNTs) promise to advance a number of real-world technologies. Of these applications, they are particularly attractive for uses in chemical sensors for environmental and health monitoring. However, chemical sensors based on CNTs are often lacking in selectivity, and the elucidation of their sensing mechanisms remains challenging. This review is a comprehensive description of the parameters that give rise to the sensing capabilities of CNT-based sensors and the application of CNT-based devices in chemical sensing. This review begins with the discussion of the sensing mechanisms in CNT-based devices, the chemical methods of CNT functionalization, architectures of sensors, performance parameters, and theoretical models used to describe CNT sensors. It then discusses the expansive applications of CNT-based sensors to multiple areas including environmental monitoring, food and agriculture applications, biological sensors, and national security. The discussion of each analyte focuses on the strategies used to impart selectivity and the molecular interactions between the selector and the analyte. Finally, the review concludes with a brief outlook over future developments in the field of chemical sensors and their prospects for commercialization.

Computational screening of iodine uptake in zeolitic imidazolate frameworks in a water-containing system

Iodine capture is of great environmental significance due to the high toxicity and volatility of I2. Here we conduct a systematic computational investigation of iodine adsorption in zeolitic imidazolate frameworks (ZIFs) by adopting the grand canonical Monte Carlo (GCMC) simulation and the density functional theory (DFT) method. The results confirm the vital structural factors for iodine adsorption at 298 K and moderate pressures including metal sites, organic linkers, symmetry, and topology types. The uptake will be enhanced by active metal sites, the simple imidazolate linker and single asymmetric linkers with polar functional groups. The symmetry effect is stronger than the surface properties. Meanwhile low steric hindrance is more beneficial than polar functional groups to iodine adsorption. The specific topology types like mer bringing large surface areas and large diameter cages result in high iodine capacities. Iodine molecules tend to locate in cages with large diameters and aggregates along the sides of cages. In contrast, water prefers small diameter cages. In hydrophilic materials, water has a negative impact on iodine uptake due to its similar adsorption sites to iodine. The selectivity of iodine over water increases with increasing water content due to the large diameter cages of ZIFs. This work proves that ZIFs can be identified as efficient and economical adsorbents with high diversity for iodine in a water-containing system. Furthermore, it provides comprehensive insights into key structural factors for iodine uptake and separation in silver-free porous solids.

A simple synthesis of sulfur-doped graphene using sulfur powder by chemical vapor deposition

S-doped graphene has synthesized by CVD, using Fe/CaCO₃ as a catalyst, acetylene as a carbon resource and sulfur powder as a sulfur resource.

A sulfur doped carbon nanotube as a potential catalyst for the oxygen reduction reaction

The catalytic ability of SCNT in a four-electron oxygen reduction reaction (ORR) of fuel cells was studied by DFT calculations.

Different Interaction Mechanisms of Eu(III) and (243)Am(III) with Carbon Nanotubes Studied by Batch, Spectroscopy Technique and Theoretical Calculation

Herein the sorption of Eu(III) and (243)Am(III) on multiwalled carbon nanotubes (CNTs) are studied, and the results show that Eu(III) and (243)Am(III) could form strong inner-sphere surface complexes on CNT surfaces. However, the sorption of Eu(III) on CNTs is stronger than that of (243)Am(III) on CNTs, suggesting the difference in the interaction mechanisms or properties of Eu(III) and (243)Am(III) with CNTs, which is quite different from the results of Eu(III) and (243)Am(III) interaction on natural clay minerals and oxides. On the basis of the results of density functional theory calculations, the binding energies of Eu(III) on CNTs are much higher than those of (243)Am(III) on CNTs, indicating that Eu(III) could form stronger complexes with the oxygen-containing functional groups of CNTs than (243)Am(III), which is in good agreement with the experimental results of higher sorption capacity of CNTs for Eu(III). The oxygen-containing functional groups contribute significantly to the uptake of Eu(III) and (243)Am(III), and the binding affinity increases in the order of ≡S-OH < ≡S-COOH < ≡S-COO(-). This paper highlights the interaction mechanism of Eu(III) and (243)Am(III) with different oxygen-containing functional groups of CNTs, which plays an important role for the potential application of CNTs in the preconcentration, removal, and separation of trivalent lanthanides and actinides in environmental pollution cleanup.

Theoretical investigation of rare gas adsorption on and inside B-doped carbon nanotubes by DFT, QTAIM and NBO

Structures and intramolecular interactions of complexes formed by 1–2 boron atom doped CNTs with rare gases were studied.

An exceptional functionalization of doped fullerene observed via theoretical studies on the interactions of sulfur-doped fullerenes with halogens and halides

Interactions of sulfur-doped fullerenes with halogens and halides have been explored for possible applications such as sensor fabrication and adsorption processes.