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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Plastic from CO 2 , Water, and Electricity: Tandem Electrochemical CO 2 Reduction and Thermochemical Ethylene-CO Copolymerization

Converting CO 2 into industrially useful products is an appealing strategy for utilization of an abundant chemical resource. Electrochemical CO 2 reduction (eCO 2 R) offers a pathway to convert CO 2 into CO and ethylene, using renewable electricity. Here, these products can be efficiently copolymerized by organometallic catalysts to generate polyketones. However, the conditions for these reactions are very different, presenting the challenge of coupling microenvironments typically encountered for the transformation of CO 2 into highly complex but desirable multicarbon products. Herein, we present a system to produce polyketone plastics entirely derived from CO 2 and water, where both the CO and C 2 H 4 intermediates are produced by eCO 2 R. In this system, a combination of Cu and Ag gas diffusion electrodes is used to generate a gas mixture with nearly equal concentrations of CO and C 2 H 4 , and a recirculatory CO 2 reduction loop is used to reach concentrations of above 11% each, leading to a current-to-polymer efficiency of up to 51% and CO 2 utilization of 14%.

carbon storage↗
DOE OSTI2021

Gallium‐Doping Effects on Structure, Lithium‐Conduction, and Thermochemical Stability of Li 7‐3 x Ga x La 3 Zr 2 O 12 Garnet‐Type Electrolytes

Abstract One of the most promising electrolytes for all‐solid‐state lithium batteries is Li 7 La 3 Zr 2 O 12 . Previously, their thermodynamic stability, Li‐ion conductivity, and structural features induced by Ga‐doping have not been empirically determined or correlated. Here, their interplay was examined for Li 7−3 x Ga x La 3 Zr 2 O 12 with target x Ga=0, 0.25, 0.50, 0.75, and 1.00 atoms per formula unit (apfu). Formation enthalpies, obtained with calorimetry and found to be exothermic at all compositions, linearly decreased in stability with increased x Ga. At dilute x Ga substitution, the formation enthalpy curve shifted stepwise endothermically, and the conductivity increased to a maximum, coinciding with 0.529 Ga apfu. This correlated with percolation threshold analysis (0.558 Ga apfu). Further substitution (0.787 Ga apfu) produced a large decrease in the stability and conductivity due to a large increase in point defects and blocked Li‐migration pathways. At x Ga=1.140 apfu, a small exothermic shift was related to defect cluster organization extending the Li hopping distance and decreased Li‐ion conductivity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Evaluating the potential of plastic waste upcycling using thermochemical technologies: A case study in Spain

A plastic waste upcycling value chain model has been applied to assess the potential of processing packaging waste in Spain using thermo-chemical technologies to produce low-density polyethylene (LDPE) and polypropylene (PP), which are highly valuable materials. The model projects an annual profit of 120.6 M$\$$/yr, with a capital investment of 789.3 M$\$$, generating 3285 jobs and contributing 65.5 M$\$$/yr to Spain’s economy. The achieved circularity rate of the waste processing infrastructure exceeds 40 %, incorporating recycled HDPE and PET. Despite these advantages, regulatory gaps and market hesitancy toward recycled materials due to quality concerns hinder adoption. Additionally, economies of scale remain underutilized in Spain due to lower plastic waste collection levels compared to countries such as the United States. This network, while less profitable, is environmentally superior, yielding upcycled products with a Global Warming Potential 20–35 % lower than their virgin, fossil-fuel counterparts, confirming this as a viable and sustainable alternative.

Chemical upcycling↗
DOE OSTI2021

Transition metal carbides and nitrides as catalysts for thermochemical reactions

Transition metal carbides and nitrides (TMCs and TMNs) have attracted much attention due to their unique physical and chemical properties brought by the incorporation of interstitial carbon and nitrogen into the crystal lattice of the parent metals. Recent advances in utilizing TMCs and TMNs have revealed their intriguing catalytic properties in many industrially important reactions, including heteroatom removal, CO 2 activation, alcohol reforming, and water–gas shift reactions. The promising activity, selectivity, and stability of TMCs and TMNs, either as catalysts or as supports for other metals, are often attributed to their strong interactions with the adsorbates, tunable surface properties, as well as the synergy with supported metals. This review summarizes the synthesis and characterization of TMC and TMN model surfaces and powder catalysts, and uses several case studies to demonstrate their unique catalytic properties in these important reactions. Finally, a discussion is also provided regarding the challenges and opportunities associated with the utilization of TMCs and TMNs in thermocatalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Thermochemically-informed mass transport model for interdiffusion of U and Zr in irradiated U-Pu-Zr fuel with fission products

A new formulation for redistribution of constituents in metallic U-Pu-Zr nuclear fuel is presented that can incorporate the contributions from fission products. The formulation is based on the thermodynamic driving forces derived from the generalized chemical potential that includes effects of composition and temperature. As a result, the redistribution model can readily account for the composition changes due to the generation of fission products while using only a limited set of transport coefficients. The thermodynamic model for the metallic fuel and thermochemistry solver Thermochimica were coupled with the nuclear fuel performance code BISON to implement the redistribution model. The simulations reproduce an experimentally observed Zr-depletion zone in the mid-radius region of an irradiated fuel slug. The generation of fission products during burnup is shown to have a stabilizing effect on the fuel chemistry, slowing the rate of U-Zr interdiffusion and reducing the size of the Zr-depleted zone. Here, the overall objective of the work is to advance predictive capabilities of fission product behaviour in U-Zr metallic fuel in the context of fuel performance and safety.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗