Synthesis of Microscopic 3D Graphene for High-Performance Supercapacitors with Ultra-High Areal Capacitance.

Despite graphene being considered an ideal supercapacitor electrode material, its use in commercial devices is limited because few methods exist to produce high-quality graphene at a large scale and low cost. A simple method is reported to synthesize 3D graphene by graphenization of coal tar pitch with a KCO catalyst. This produces 3D graphenes with high specific surface areas up to 2113 m g and exceptional crystallinity (Raman I/I as low as ≈0.

High-performance cementitious composites containing nanostructured carbon additives made from charred coal fines.

Carbon-based nanomaterials, such as carbon nanoplatelets, graphene oxide, and carbon quantum dots, have many possible end-use applications due to their ability to impart unique mechanical, electrical, thermal, and optical properties to cement composites. Despite this potential, these materials are rarely used in the construction industry due to high material costs and limited data on performance and durability. In this study, domestic coal is used to fabricate low-cost carbon nanomaterials that can be used economically in cement formulations.

Structural Basis of CO₂ Adsorption in a Flexible Metal-Organic Framework Material.

This paper reports on the structural basis of CO₂ adsorption in a representative model of flexible metal-organic framework (MOF) material, Ni(1,2-bis(4-pyridyl)ethylene)[Ni(CN)₄] (NiBpene or PICNIC-60). NiBpene exhibits a CO₂ sorption isotherm with characteristic hysteresis and features on the desorption branch that can be associated with discrete structural changes. Various gas adsorption effects on the structure are demonstrated for CO₂ with respect to N₂, CH₄ and H₂ under static and flowing gas pressure conditions.

Active sites of ligand-protected Au25 nanoparticle catalysts for CO2 electroreduction to CO.

Recent experimental studies have reported the electrochemical reduction of carbon dioxide (CO2) into CO at atomically precise negatively charged Au25 (-) nanoclusters. The studies showed CO2 conversion at remarkably low overpotentials, but the exact mechanisms and nature of the active sites remain unclear. We used first-principles density functional theory and continuum solvation models to examine the role of the cluster during electrochemical CO2 reduction and analyze the free energies of proposed intermediate species.

Efficient electrochemical CO2 conversion powered by renewable energy.

The catalytic conversion of CO2 into industrially relevant chemicals is one strategy for mitigating greenhouse gas emissions. Along these lines, electrochemical CO2 conversion technologies are attractive because they can operate with high reaction rates at ambient conditions. However, electrochemical systems require electricity, and CO2 conversion processes must integrate with carbon-free, renewable-energy sources to be viable on larger scales.

Plasmonic nanocomposite thin film enabled fiber optic sensors for simultaneous gas and temperature sensing at extreme temperatures.

Embedded sensors capable of operation in extreme environments including high temperatures, high pressures, and highly reducing, oxidizing and/or corrosive environments can make a significant impact on enhanced efficiencies and reduced greenhouse gas emissions of current and future fossil-based power generation systems. Relevant technologies can also be leveraged in a wide range of other applications with similar needs including nuclear power generation, industrial process monitoring and control, and aviation/aerospace. Here we describe a novel approach to embedded sensing under extreme temperature conditions by integration of Au-nanoparticle based plasmonic nanocomposite thin films with optical fibers in an evanescent wave absorption spectroscopy configuration.

Visible light plasmonic heating of Au-ZnO for the catalytic reduction of CO2.

Plasmonic excitation of Au nanoparticles attached to the surface of ZnO catalysts using low power 532 nm laser illumination leads to significant heating of the catalyst and the conversion of CO2 and H2 reactants to CH4 and CO products. Temperature-calibrated Raman spectra of ZnO phonons show that intensity-dependent plasmonic excitation can controllably heat Au-ZnO from 30 to ~600 °C and simultaneously tune the CH4 : CO product ratio. The laser induced heating and resulting CH4 : CO product distribution agrees well with predictions from thermodynamic models and temperature-programmed reaction experiments indicating that the reaction is a thermally driven process resulting from the plasmonic heating of the Au-ZnO.

Screening Hofmann compounds as CO2 sorbents: nontraditional synthetic route to over 40 different pore-functionalized and flexible pillared cyanonickelates.

A simple reaction scheme based on the heterogeneous intercalation of pillaring ligands (HIPLs) provides a convenient method for systematically tuning pore size, pore functionality, and network flexibility in an extended series of pillared cyanonickelates (PICNICs), commonly referred to as Hofmann compounds. The versatility of the approach is demonstrated through the preparation of over 40 different PICNICs containing pillar ligands ranging from ∼4 to ∼15 Å in length and modified with a wide range of functional groups, including fluoro, aldehyde, alkylamine, alkyl, aryl, trifluoromethyl, ester, nitro, ether, and nonmetalated 4,4'-bipyrimidine. The HIPL method involves reaction of a suspension of preformed polymeric sheets of powdered anhydrous nickel cyanide with an appropriate pillar ligand in refluxing organic solvent, resulting in the conversion of the planar [Ni2(CN)4]n networks into polycrystalline three-dimensional porous frameworks containing the organic pillar ligand.

Photomediated Oxidation of Atomically Precise Au25(SC2H4Ph)18(-) Nanoclusters.

The anionic charge of atomically precise Au25(SC2H4Ph)18(-) nanoclusters (abbreviated as Au25(-)) is thought to facilitate the adsorption and activation of molecular species. We used optical spectroscopy, nonaqueous electrochemistry, and density functional theory to study the interaction between Au25(-) and O2. Surprisingly, the oxidation of Au25(-) by O2 was not a spontaneous process.

Experimental and computational investigation of Au25 clusters and CO2: a unique interaction and enhanced electrocatalytic activity.

Atomically precise, inherently charged Au(25) clusters are an exciting prospect for promoting catalytically challenging reactions, and we have studied the interaction between CO(2) and Au(25). Experimental results indicate a reversible Au(25)-CO(2) interaction that produced spectroscopic and electrochemical changes similar to those seen with cluster oxidation. Density functional theory (DFT) modeling indicates these changes stem from a CO(2)-induced redistribution of charge within the cluster.

Carbon nanotube nanoreservior for controlled release of anti-inflammatory dexamethasone.

On demand release of anti-inflammatory drug or neurotropic factors have great promise for maintaining a stable chronic neural interface. Here we report the development of an electrically controlled drug release system based on conducting polymer and carbon nanotubes. Drug delivery research using carbon nanotubes (CNTs) has taken advantage of the ability of CNTs to load large amounts of drug molecules on their outer surface.

In situ observation of water dissociation with lattice incorporation at FeO particle edges using scanning tunneling microscopy and X-ray photoelectron spectroscopy.

The dissociation of H2O and formation of adsorbed hydroxyl groups on FeO particles grown on Au(111) were identified with in situ X-ray photoelectron spectroscopy (XPS) at water pressures ranging from 3 × 10(-8) to 0.1 Torr. The facile dissociation of H2O takes place at FeO particle edges, and it was successfully observed in situ with atomically resolved scanning tunneling microscopy (STM).

Permanent Trapping of CO(2) in Single-Walled Carbon Nanotubes Synthesized by the HiPco Process.

Infrared spectroscopy is used to study trapped and physisorbed CO2 in single-walled carbon nanotube bundles (SWNTs) synthesized by the HiPco process. CO2 is entrapped within the SWNTs by acid oxidation of the unpurified sample followed by vacuum heating to 700 K. The trapped CO2 has a single nu3 mode at 2327 cm-1, is stable during temperature cycling from 77 to 700 K, and remains after venting to room air.

Hydrogen-bonded and physisorbed CO in single-walled carbon nanotube bundles.

Fourier transform infrared spectroscopy is used to study CO adsorption in single-walled carbon nanotubes. Evidence for adsorption in endohedral and groove/external surface sites is presented through displacement studies involving both CO and CO2. Blue-shifted CO stretching frequencies also indicate that CO hydrogen bonds to hydroxyl functionalities created on the nanotubes by acid purification steps.

Controlled confinement and release of gases in single-walled carbon nanotube bundles.

A simple procedure is described that locks small quantities of SF6, CO2, and 13CO2 into opened single-walled carbon nanotube (SWNT) bundles and keeps the gas in the SWNTs above the desorption temperature of these molecules. The technique involves opening the SWNTs with ozonolysis at 300 K followed by vacuum-annealing at 700 K. Gases are then cryogenically adsorbed into the opened SWNTs and locked into the SWNT pores by functionalizing the sample with a low-temperature ozone treatment.

Hydrogen storage properties of metal nitroprussides M[Fe(CN)5NO], (M = Co, Ni).

The volumetric hydrogen adsorption isotherms of two isostructural dehydrated cubic metal nitroprussides M[Fe(CN)5NO] (M = Co2+, Ni2+) have been measured up to a pressure of 760 Torr at 77 and 87 K. These materials are among the most efficient H2 sorbents based on porous coordination polymers reported to date. The H2 uptake in both materials is approximately 1.

Raman spectroscopic investigation of gas interactions with an aligned multiwalled carbon nanotube membrane.

Raman spectroscopy has been used to investigate ethane, propane, and SF6 interactions with an aligned multiwalled carbon nanotube (MWNT) membrane. Pressures of 7.5-9.