United States Department of Energy

About: United States Department of Energy is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Coal & Catalysis. The organization has 13656 authors who have published 14177 publications receiving 556962 citations. The organization is also known as: DOE & Department of Energy.

High-Throughput Models for Exposure-Based Chemical Prioritization in the ExpoCast Project

Abstract: The United States Environmental Protection Agency (U.S. EPA) must characterize potential risks to human health and the environment associated with manufacture and use of thousands of chemicals. High-throughput screening (HTS) for biological activity allows the ToxCast research program to prioritize chemical inventories for potential hazard. Similar capabilities for estimating exposure potential would support rapid risk-based prioritization for chemicals with limited information; here, we propose a framework for high-throughput exposure assessment. To demonstrate application, an analysis was conducted that predicts human exposure potential for chemicals and estimates uncertainty in these predictions by comparison to biomonitoring data. We evaluated 1936 chemicals using far-field mass balance human exposure models (USEtox and RAIDAR) and an indicator for indoor and/or consumer use. These predictions were compared to exposures inferred by Bayesian analysis from urine concentrations for 82 chemicals reported ...

Electrode assembly for use in a solid polymer electrolyte fuel cell

Abstract: A gas reaction fuel cell may be provided with a solid polymer electrolyte membrane. Porous gas diffusion electrodes are formed of carbon particles supporting a catalyst which is effective to enhance the gas reactions. The carbon particles define interstitial spaces exposing the catalyst on a large surface area of the carbon particles. A proton conducting material, such as a perfluorocarbon copolymer or ruthenium dioxide contacts the surface areas of the carbon particles adjacent the interstitial spaces. The proton conducting material enables protons produced by the gas reactions adjacent the supported catalyst to have a conductive path with the electrolyte membrane. The carbon particles provide a conductive path for electrons. A suitable electrode may be formed by dispersing a solution containing a proton conducting material over the surface of the electrode in a manner effective to coat carbon surfaces adjacent the interstitial spaces without impeding gas flow into the interstitial spaces.

Size-dependent photocatalytic reduction of CO2 with PbS quantum dot sensitized TiO2 heterostructured photocatalysts

Abstract: The photocatalytic reduction of CO2 to value-added chemicals, such as CH4, is a promising carbon management approach which can generate revenue from chemical sales to offset the cost of implementing CO2 capture technologies. To make photocatalytic conversion approaches efficient, economically practical, and industrially scalable, catalysts capable of utilizing visible and near infrared (IR) photons need to be developed. Here we investigate the sensitization of TiO2 catalysts using PbS quantum dots (QDs) which lead to the size dependent photocatalytic reduction of CO2 at frequencies ranging from the violet to the orange-red edge of the electromagnetic spectrum (λ ∼ 420 to 610 nm). Under broad band illumination (UV- NIR), the PbS QDs enhance CO2 photoreduction rates with TiO2 by a factor of ∼5 in comparison to unsensitized photocatalysts. X-ray photoelectron spectroscopy (XPS) is used to investigate the deactivation mechanism of the QD sensitizers after prolonged photoexcitation. The synthesis, characterization, and catalytic testing of these PbS sensitized TiO2 heterostructures will aid the development of more robust, visible light active photocatalysts for carbon management applications.

On the Flexibility of Metal–Organic Frameworks

Abstract: Occasional, large amplitude flexibility in metal–organic frameworks (MOFs) is one of the most intriguing recent discoveries in chemistry and material science. Yet, there is at present no theoretical framework that permits the identification of flexible structures in the rapidly expanding universe of MOFs. Here, we propose a simple method to predict whether a MOF is flexible, based on treating it as a system of rigid elements, connected by hinges. This proposition is correct in application to MOFs based on rigid carboxylate linkers. We validate the method by correctly classifying known experimental MOFs into rigid and flexible groups. Applied to hypothetical MOFs, the method reveals an abundance of flexibility phenomena, and this seems to be at odds with the proportion of flexible structures among experimentally known MOFs. We speculate that the flexibility of a MOF may constitute an intrinsic impediment on its experimental realization. This highlights the importance of systematic prediction of large ampli...