Fluctuation analysis of an organic semiconductor-insulator interface.

The space-charge region of an organic semiconductor (OS)-insulator interface is probed by analyzing the spontaneous, thermally driven drain current fluctuations of a field-effect transistor in which the OS forms the gate electrode. This so called "excess drain current noise" is the outcome of local fluctuations of the Fermi level, resulting from stochastic exchange of electrons between traps near the Fermi level. The power spectral density of this noise is characteristic of a Lorentzian process with a distribution of time constants, which is attributed to the disorder in the OS film.

γ-Valerolactone ring-opening and decarboxylation over SiO2/Al2O3 in the presence of water.

γ-Valerolactone (GVL) has been identified as a promising, sustainable platform molecule that can be produced from lignocellulosic biomass. The chemical flexibility of GVL has allowed the development of a variety of processes to prepare renewable fuels and chemicals. In the present work involving a combination of computational and experimental studies, we explore the factors governing the ring-opening of GVL to produce pentenoic acid isomers, as well as their subsequent decarboxylation over acid catalysts or hydrogenation over metal catalysts.

Integrated catalytic conversion of gamma-valerolactone to liquid alkenes for transportation fuels.

Efficient synthesis of renewable fuels remains a challenging and important line of research. We report a strategy by which aqueous solutions of gamma-valerolactone (GVL), produced from biomass-derived carbohydrates, can be converted to liquid alkenes in the molecular weight range appropriate for transportation fuels by an integrated catalytic system that does not require an external source of hydrogen. The GVL feed undergoes decarboxylation at elevated pressures (e.

Catalytic conversion of renewable biomass resources to fuels and chemicals.

Lignocellulosic biomass is renewable and cheap, and it has the potential to displace fossil fuels in the production of fuels and chemicals. Biomass-derived carboxylic acids are important compounds that can be used as platform molecules for the production of a variety of important chemicals on a large scale. Lactic acid, a prototypical biomass derivative, and levulinic acid, an important chemical feedstock produced by hydrolysis of waste cellulosic materials, can be upgraded using bifunctional catalysts (those containing metal and acid sites), which allows the integration of several transformations (e.

Catalytic conversion of biomass to monofunctional hydrocarbons and targeted liquid-fuel classes.

It is imperative to develop more efficient processes for conversion of biomass to liquid fuels, such that the cost of these fuels would be competitive with the cost of fuels derived from petroleum. We report a catalytic approach for the conversion of carbohydrates to specific classes of hydrocarbons for use as liquid transportation fuels, based on the integration of several flow reactors operated in a cascade mode, where the effluent from the one reactor is simply fed to the next reactor. This approach can be tuned for production of branched hydrocarbons and aromatic compounds in gasoline, or longer-chain, less highly branched hydrocarbons in diesel and jet fuels.

Liquid alkanes with targeted molecular weights from biomass-derived carbohydrates.

Liquid transportation fuels must burn cleanly and have high energy densities, criteria that are currently fulfilled by petroleum, a non-renewable resource, the combustion of which leads to increasing levels of atmospheric CO(2). An attractive approach for the production of transportation fuels from renewable biomass resources is to convert carbohydrates into alkanes with targeted molecular weights, such as C(8)-C(15) for jet-fuel applications. Targeted n-alkanes can be produced directly from fructose by an integrated process involving first the dehydration of this C(6) sugar to form 5-hydroxymethylfurfural, followed by controlled formation of C-C bonds with acetone to form C(9) and C(15) compounds, and completed by hydrogenation and hydrodeoxygenation reactions to form the corresponding n-alkanes.