Highly Reactive Graphene Dispersant and Its Effective Reinforcement for Phase Change Coatings.

High efficient dispersant that meanwhile possesses additional functions is highly desirable for the fabrication of graphene-based composite. In this paper, a new reactive dispersant, multi-silanols grafted naphthalenediamine (MSiND), is synthesized, which shows superiority compared with conventional dispersants. It can not only stabilize graphene in water at a high concentration of up to 16 mg mL-1 , but also simultaneously be applicable for ethanol medium, in which the graphene concentration can be as high as 12 mg mL-1 at the weight ratio of 1:1 (MSiND:graphene). The dispersion is compatible with multi-matrixes and affinity to various substrates. In addition, MSiND exhibits excellent reactivity due to the existence of high-density silanol groups. Tough graphene coatings are constructed on glass slides and non-woven fabric simply by direct painting and dip-coating. Moreover, with the assistance of MSiND, graphene-doped phase-change coatings on hydrophobic non-woven fabric (e.g., functional mask) are prepared via the spray method. The composite coatings show enhanced mechanical strength and excellent energy storage performance, exhibiting great potential in heat preservation and thermotherapy.

Adenine derived reactive dispersant and the enhancement of graphene based composites.

HYPOTHESIS: Homogeneous dispersion of graphene is the precondition for constructing high performance graphene based composites. However, most of the current dispersants reported in literature still suffer excess usage to reach a desired graphene concentration. Residual of dispersant in composite may seriously affect its properties. Hence, it is expected to obtain effective dispersant with high reactivity to diminish its adverse impacts on graphene composites. EXPERIMENTS: A highly reactive graphene dispersant (DSiA) was synthesized by grafting silanol groups (Si-OH) onto adenine. Molecular structure and the performance of the dispersant were systematically characterized. Composites were fabricated by direct writing of the graphene dispersion on various substrates, and their features were evaluated by resistance, solvent erosion and tensile testing. FINDINGS: Graphene concentration can reach up to 6 mg mL-1 in the presents of DSiA at the weight ratio of 1:1 (DSiA: graphene). DSiA also exhibited good performance for stabilizing multi-walled carbon nanotubes (MWCNTs). Moreover, the dispersant is highly reactive. The graphene based composites showed good mechanical strength and excellent solvent resistance. Overall, the new dispersant provides an ideal choice to uniformly disperse graphene and suitable for fabricating high performance nanocarbon based composites.

Graphene dispersant-assisted in situ growth of Re-doped MoS2 nanosheets on carbon cloth and their performance for hydrogen evolution reaction.

Uniform distribution of electrochemically active transition metal compounds on carbon cloth can effective improve their hydrogen evolution reaction (HER) performance, however, harsh chemical treatment of carbon substrates is always unavoidable during this process. Herein, a hydrogen protonated polyamino perylene bisimide (HAPBI) was used as interface active agent for the in situ growth of rhenium (Re) doped MoS2 nanosheets on carbon cloth (Re-MoS2/CC). HAPBI contains a large conjugated core and multiple cationic groups and has been shown to be an effective graphene dispersant. It endowed the carbon cloth excellent hydrophilicity through simple noncovalent functionalization and, meanwhile, provided sufficient active sites to anchor MoO42- and ReO4- via electrostatic interaction. Uniform and stable Re-MoS2/CC composites were facilely obtained by immersing carbon cloth in HAPBI solution followed by hydrothermal treatment in the precursor solution. The doping of Re induced the formation of 1 T phase MoS2, which reached about 40% in the mixture with 2H phase MoS2. Electrochemical measurements showed an overpotential of 183 mV at a current density of 10 mA cm-2 in 0.5 mol L-1 H2SO4 when the molar ratio of Re to Mo is 1:100. This strategy can be further extended to construct other electrocatalysts that using graphene, carbon nanotubes, etc. as conductive additives.

CTAB assisted evaporation-induced self-assembly to construct imidazolium-based hierarchical porous covalent organic polymers for ReO4-/TcO4- removal.

Evaporation-induced self-assembly method (EISA) was a facile and reliable method to synthesize porous materials. Herein, we report a kind of hierarchical porous ionic liquid covalent organic polymers (HPnDNH2) under cetyltrimethylammonium bromide (CTAB) assisted by EISA for ReO4-/TcO4- removal. Unlike covalent organic frameworks (COFs), which usually needed to be prepared in a closed environment or with a long reaction time, HPnDNH2 in this study was prepared within 1 h in an open environment. It was worth noting that CTAB not only served as a soft template for forming pore, but also induced ordered structure, which was verified by SEM, TEM, and Gas sorption. Benefit from its hierarchical pore structure, HPnDNH2 exhibited higher adsorption capacity (690.0 mg g-1 for HP1DNH2 and 808.7 mg g-1 for HP1.5DNH2) and faster kinetics for ReO4-/TcO4- than 1DNH2 (without employing CTAB). Additionally, the material used to remove TcO4- from alkaline nuclear waste was seldom reported, because combining features of alkali resistance and high uptake selectivity was not easy to achieve. In this study, in the case of HP1DNH2, it displayed outstanding adsorption efficiency toward aqueous ReO4-/TcO4- in 1 mol L-1 NaOH solution (92%) and simulated Savannah River Site High-level waste (SRS HLW) melter recycle stream (98%), which could be a potentially excellent nuclear waste adsorbing material.

Potassium promoted Gd0.06Co catalysts for highly efficient catalytic N2O decomposition in presence of impurity gases at low temperature.

In order to enhance the catalytic performance of the Gd-modified Co3O4 catalyst (Gd0.06Co) for the N2O decomposition, alkali metal K was introduced as the promoter by impregnating the Gd0.06Co powder with an aqueous solution of KNO3 (with K/Co ratios 0.01-0.05). With the doping of K, the catalytic activity over Gd0.06Co was significantly improved and the temperature of N2O complete decomposition was decreased from 350 °C to 300 °C. Combining the results of XPS and O2-TPD, the superior catalytic performance of the optimum catalyst K0.025Gd0.06Co was mainly owing to the synergistic effect of Gd and K, which weakened the Co-O bond and endowed the catalyst surface with much more amount of oxygen vacancies. Even under the coexist of the impurity gases, such as 5 vol% O2, 100 ppmv NO and 2 vol% H2O, the K0.025Gd0.06Co catalyst exhibited prominently better catalytic activity than Gd0.06Co and K0.025Co catalysts.