Shannon M. Mahurin

Dopamine as a Carbon Source: The Controlled Synthesis of Hollow Carbon Spheres and Yolk‐Structured Carbon Nanocomposites

A facile and versatile synthesis using dopamine as a carbon source gives hollow carbon spheres and yolk-shell Au{at}Carbon nanocomposites. The uniform nature of dopamine coatings and their high carbon yield endow the products with high structural integrity. The Au{at}C nanocomposites are catalytically active.

Water desalination using nanoporous single-layer graphene

By creating nanoscale pores in a layer of graphene, it could be used as an effective separation membrane due to its chemical and mechanical stability, its flexibility and, most importantly, its one-atom thickness. Theoretical studies have indicated that the performance of such membranes should be superior to state-of-the-art polymer-based filtration membranes, and experimental studies have recently begun to explore their potential. Here, we show that single-layer porous graphene can be used as a desalination membrane. Nanometre-sized pores are created in a graphene monolayer using an oxygen plasma etching process, which allows the size of the pores to be tuned. The resulting membranes exhibit a salt rejection rate of nearly 100% and rapid water transport. In particular, water fluxes of up to 10(6) g m(-2) s(-1) at 40 °C were measured using pressure difference as a driving force, while water fluxes measured using osmotic pressure as a driving force did not exceed 70 g m(-2) s(-1) atm(-1).

Soft‐Templated Mesoporous Carbon‐Carbon Nanotube Composites for High Performance Lithium‐ion Batteries

Mesoporous carbon with homogeneously dispersed multi-walled carbon nanotubes (MWNTs) are synthesized via a one-step brick and mortar soft-templating approach. Nanocomposites exhibit high rate capability and reversible lithium storage capacity of 900 mA h g-1 and good rate performance. Such homogeneous nanocomposites are ideal candidates for electric vehicle applications where high power and energy density are primary requirements.

Direct exfoliation of natural graphite into micrometre size few layers graphene sheets using ionic liquids

Stable high-concentration suspensions (up to 0.95 mg mL(-1)) of non-oxidized few layer graphene (FLG), five or less sheets, with micrometre-long edges were obtained via direct exfoliation of natural graphite flakes in ionic liquids, such as 1-butyl-3-methyl-imidazolium bis(trifluoro-methane-sulfonyl)imide ([Bmim]-[Tf(2)N]), by tip ultrasonication.

A Superacid-Catalyzed Synthesis of Porous Membranes Based on Triazine Frameworks for CO2 Separation

A general strategy for the synthesis of porous, fluorescent, triazine-framework-based membranes with intrinsic porosity through an aromatic nitrile trimerization reaction is presented. The essence of this strategy lies in the use of a superacid to catalyze the cross-linking reaction efficiently at a low temperature, allowing porous polymer membrane architectures to be facilely derived. With functionalized triazine units, the membrane exhibits an increased selectivity for membrane separation of CO(2) over N(2). The good ideal CO(2)/N(2) selectivity of 29 ± 2 was achieved with a CO(2) permeability of 518 ± 25 barrer. Through this general synthesis protocol, a new class of porous polymer membranes with tunable functionalities and porosities can be derived, significantly expanding the currently limited library of polymers with intrinsic microporosity for synthesizing functional membranes in separation, catalysis, and energy storage/conversion.

Reversible and robust CO2 capture by equimolar task-specific ionic liquid–superbase mixtures

Integrated sorption systems consisting of 1 : 1 mixtures of an alcohol-functionalized ionic liquid and a superbase were found to be effective for CO2 capture under atmospheric pressure, eliminating the use of volatile n-alkanols or water. Conversely, by using the current approach, there is no longer a requirement for maintaining scrupulously dry conditions. The effect of ionic liquid structure, choice of superbase, their relative ratios, the sorption temperature, and the reaction time on the absorption and release of CO2 were investigated. Our results demonstrate that (i) this integrated ionic liquid–superbase system is capable of rapid and reversible capture of nearly one mole of CO2 per mole of superbase, (ii) the captured CO2 can be readily released by either mild heating or bubbling with an insert gas (N2, Ar), and (iii) this novel CO2 chemisorption platform can be recycled with minimal loss of activity. This efficient and fully reversible catch-and-release process using non-volatile, task-specific ionic liquids provides an excellent alternative to current CO2 capture technologies, which are based largely around volatile alkanols or alkylamines. Furthermore, our integrated ionic liquid–superbase system can be used as a novel medium for supported liquid membranes, for which they demonstrate both good selectivity and permeability in model CO2/N2 gas separations.

Efficient CO2 capture by a task-specific porous organic polymer bifunctionalized with carbazole and triazine groups

A porous triazine and carbazole bifunctionalized task-specific polymer has been synthesized via a facile Friedel-Crafts reaction. The resultant porous framework exhibits excellent CO2 uptake (18.0 wt%, 273 K and 1 bar) and good adsorption selectivity for CO2 over N2.

Hierarchical ordered mesoporous carbon from phloroglucinol-glyoxal and its application in capacitive deionization of brackish water

Templated carbon materials have recently received tremendous attention due to energy storage and separations applications. Hierarchical structures are ideal for increased mass-transport throughout the carbon material. A new ordered mesoporous carbon material has been developed using glyoxal which exhibits a hierarchical structure with pore sizes up to 200 nm. The hierarchical structure arises from the cross linking reagent and not from the standard spinodal decomposition of a secondary solvent. The carbon material was studied for potential application as a capacitive deionization (CDI) electrode for brackish water. Results indicate that the hierarchical structure provides a pathway for faster adsorption kinetics when compared to standard resorcinol-formaldehyde CDI electrodes.

Efficient CO2 Capture by Porous, Nitrogen‐Doped Carbonaceous Adsorbents Derived from Task‐Specific Ionic Liquids

The search for a better carbon dioxide (CO(2) ) capture material is attracting significant attention because of an increase in anthropogenic emissions. Porous materials are considered to be among the most promising candidates. A series of porous, nitrogen-doped carbons for CO(2) capture have been developed by using high-yield carbonization reactions from task-specific ionic liquid (TSIL) precursors. Owing to strong interactions between the CO(2) molecules and nitrogen-containing basic sites within the carbon framework, the porous nitrogen-doped compound derived from the carbonization of a TSIL at 500 °C, CN500, exhibits an exceptional CO(2) absorption capacity of 193 mg of CO(2) per g sorbent (4.39 mmol g(-1) at 0 °C and 1 bar), which demonstrates a significantly higher capacity than previously reported adsorbents. The application of TSILs as precursors for porous materials provides a new avenue for the development of improved materials for carbon capture.

High CO2 solubility, permeability and selectivity in ionic liquids with the tetracyanoborate anion

Five different ionic liquids containing the tetracyanoborate anion were synthesized and evaluated for CO2 separation performance. Measured CO2 solubility values were exceptionally high compared to analogous ionic liquids with different anions and ranged from 0.128 mol L−1 atm−1 to 0.148 mol L−1 atm−1. In addition, CO2 permeability and CO2/N2 selectivity values were measured using a supported ionic liquid membrane architecture and the separations performance of the ionic liquid membranes exceeded the Robeson upper bound. These results establish the distinct potential of ionic liquids with the tetracyanoborate, [B(CN)4], anion for the separation of CO2.