Solid phase modification of carbon nanotubes with anthraquinone and nitrobenzene functional groups

Long-Chain Modification of the Tips and Inner Walls of MWCNTs and Their Nanocomposite Reverse Osmosis Membranes

Multi-walled carbon nanotubes (MWCNTs) were modified on the tips and inner walls by 12-chloro-12-oxododecanedioic acid-methyl ester groups and then added to the polyamide composite membranes to prepare MWCNT-CH₂OCOC₁₂H₂₃O₂ membranes for desalination. The characterization results of transmission electron microscopy, Fourier transform, infrared transform, and thermogravimetric analysis showed that the 12-chloro-12-oxododecanedioic acid-methyl ester group was successfully grafted to the entrances and inner walls of the MWCNTs. The performance of the MWCNTs' composite membranes was evaluated by scanning electron microscopy, contact angle, and filtration test. The modified membrane morphology is more uniform, and there is no structural damage. The grafting of carbon nanotubes with methyl 12-chloro-12-oxydodecyldicarboxylate could improve the hydrophilicity of the membrane. Under identical conditions, the water flux of MWCNT-CH₂OCOC₁₂H₂₃O₂ membranes was higher than that of the pristine carbon nanotube's membrane, and the desalination rate was also slightly improved.

Experimental and theoretical studies of electrochemical oxidation of nicotinamide adenine dinucleotide at the modified SWCNT and graphene oxide

In recent years, nicotinamide adenine dinucleotide (NADH) and its oxidized form (NAD⁺) have withdrawn a substantial attention since they possess a significant place in both biosensor and biofuel cell studies. However, the transformation of NADH to NAD⁺ brings about the surface passivation and fouling at the most of corresponding conductive materials; consequently, significant decrease takes place in the current. In order to overcome these drawbacks, we have performed the surface functionalization of single-walled carbon nanotube (SWCNT) and graphene oxide (GO) immobilized onto glassy carbon surface with dihydroxybenzene (di-HB) using solid-phase synthesis methodology. The di-HB-modified SWCNT and GO were found to exhibit great catalytic activity as they reduce required overpotential of electrochemical oxidation of NADH and lead to enhancement in the peak current, compared with unmodified carbon electrodes. Molecular docking simulation technique was also carried out to enlighten attained experimental findings in detail, and we have found that increase in the binding affinity of NAD⁺ to functionalized carbon surfaces with di-HB is related to formation of hydrogen bonding interactions Furthermore, our experimental and theoretical outputs were also found to be quite consistent in terms of reactivity of modified surfaces to NADH oxidation.

Functional Protection of Exfoliated Black Phosphorus by Noncovalent Modification with Anthraquinone

Few and monolayer black phosphorus (phosphorene) is currently an intensively researched material. Shear exfoliated black phosphorus (BP_SE) nanosheets were functionalized with the redox active antraquinone (AQ) that can provide additional charge storage capacity. The noncovalent interaction of BP with AQ occurs due to van der Waals interactions. X-ray photoelectron spectroscopy results show that AQ coverage of BP_SE nanosheets led to a stabilization against BP_SE degradation. Electrochemistry of the BP_SE-AQ shows that AQ is stably anchored onto BP_SE and exhibits redox peaks stable for more than 100 cycles. The surface coverage by AQ on BP_SE is estimated to be 1.25 nmol AQ/mg BP and electron-transfer rate constant ( k_ET) of 33 s^-1. Furthermore, the proposed modification greatly increases the gravimetric capacitance of BP_SE-AQ with respect to the starting BP_bulk. Such coating of BP not only protects BP from degradation but also brings electroactive functionality to this two-dimensionally layered material.