Juanjuan Gao

Chemically edge-connected multilayer graphene-based architecture with enhanced thermal stability and dispersibility: experimental evidence of making the impossible possible

An edge-connected multilayer graphene-based architecture has been rationally designed for the first time by a covalent/noncovalent one-pot strategy. The novel nanohybrid exhibits enhanced thermal stability and dispersibility simultaneously, indicating the generation of increasing interfacial interactions. The successful fabrication demonstrated that the steric hindrance of each component plays an important role in synthetic reactions based on graphene oxide.

Highly-sensitive electrocatalytic determination for toxic phenols based on coupled cMWCNT/cyclodextrin edge-functionalized graphene composite

Highly-sensitive electrocatalytic determination of toxic phenol compounds is of significance in environmental monitoring due to their low degradation and high toxicity to the environment and humans. In this paper, a rapid and sensitive electrochemical sensor based on coupled carboxyl-multi-walled carbon nanotube (cMWCNT) and cyclodextrin (CD) edge-functionalized graphene composite was successfully employed towards trace detection of three typical phenols (4-aminophenol, 4-AP; 4-chlorophenol, 4-CP; 4-nitrophenol, 4-NP). The morphology studies from scanning electron microscope and transmission electron microscope analysis revealed that cMWCNTs as conductive bridges were successfully incorporated into CD edge-functionalized graphene layers. Further, The electrocatalytic detection performance of the 3D simultaneously reduced and self-assembled sensing architecture (GN-CD-cMWCNT) with trace amounts of CDs was evaluated. The electrochemical studies demonstrated that GN-CD-cMWCNT displays excellent electrocatalytic activity, high sensitivity and stability. Under optimal conditions, the current responses of 4-AP, 4-CP and 4-NP are linear to concentrations over two different ranges, with low detection limit of 0.019, 0.017 and 0.027μM (S/N=3), respectively. And, GN-CD-cMWCNT shows an excellent anti-interference ability against electroactive species and metal ions. In addition, validation of the applicability of the presented sensor was also performed for the determination of three phenols in tap water sample with satisfactory results.

Understanding room-temperature metastability of graphene oxide utilizing hydramines from a synthetic chemistry view

Owing to polydispersity and polyfunctionality, the chemically controlled heterogeneous synthesis of graphene-based compounds is a great challenge for synthetic chemists. Graphene oxide as significant precursor is playing an irreplaceable part in multiple applications. The external temperature stimuli-response process based on the chemistry of graphene oxide is not well understood. An improved fundamental understanding is a crucial prerequisite for their potential application in future. Here, a simple and efficient approach for the synchronized room-temperature surface and edge modification of hydramines (HA) on graphene oxide (GO) is reported. The chemical mechanism investigation of the simultaneous covalent/noncovalent functionalization demonstrates that GO is a metastable material, whose oxygen-containing functional groups could be regarded as active sites and involved in various reactions under such a low temperature. And the size and steric hindrance of substituent of organic molecules play a vital factor to affect the chemical activity. The accurate nanostructures of HA functionalized GO nanomaterials would effectively promote the controlled interfacial engineering of advanced graphene-based nanocomposites.

Hierarchical Self-Assembly of Cyclodextrin and Dimethylamino-Substituted Arylene–Ethynylene on N-doped Graphene for Synergistically Enhanced Electrochemical Sensing of Dihydroxybenzene Isomers

An electrochemically active sensing nanomaterial (denoted as CD-MPEA-NG) has been successfully constructed by an hierarchical self-assembly of cyclodextrin (CD) and N,N-dimethyl-4-(phenylethynyl)aniline (MPEA) on N-doped graphene (NG) in a low-temperature hydrothermal process. The unique nanostructure of the high-performance CD-MPEA-NG was confirmed by utilizing Fourier transform infrared spectra, an X-ray diffractometer, and differential pulse voltammetry (DPV), etc. In particular, the method of density functional theory with dispersion energy (DFT-D) of wB97XD/LanL2DZ was employed to optimize and describe the face-to-face packing structure of heterodimers of NG and MPEA. The CD-MPEA-NG sensor exhibits highly sensitive performance toward dihydroxybenzene isomers, without relying on expensive noble metal or a complicated preparation process. The experimental results demonstrate that given the synergistic effect of NG and MPEA as a coupled sensing platform, CD as a supramolecular cavity can significantly enhance the electrochemical response. The detection limits (S/N = 3) for catechol (CT), resorcinol (RS), and hydroquinone (HQ) are 0.008, 0.018, and 0.011 μM by DPV, respectively. Besides, the CD-MPEA-NG sensor shows a superb anti-interference, reproducibility, and stability, and satisfactory recovery aimed at detecting isomers in Nanjing River water. The encouraging performance as well as simplified preparation approach strongly support the CD-MPEA-NG sensor is a fascinating electrode to develop as a seamless and sensitive electroanalytical technique.