A series of ruthenium iron nitride phases with Ru:Fe ratios of ca. 1:3 were synthesized by ammonolysis. When the ammonolysis temperature was above 500°C, the obtained RuFeN materials had a ε-FeN (622) structure, while two similar phases were present when the ammonolysis was lower than 500°C. Powder neutron diffraction identified one phase as relating to the ε-FeN structure, while the other had a disordered NiAs-type (6/) structure. These ternary metal nitrides show ammonia synthesis activity at low temperature (200°C-300°C) and ambient pressure, which can be related to the loss of lattice nitrogen. Steady state catalytic performance at 400°C is associated with ruthenium-iron alloy. Additionally, density functional theory calculations were performed using an approximate model for the disordered hexagonal phase, revealing that this phase is more stable than a cubic anti-perovskite phase which has been previously investigated computationally, and corroborating the experimental findings of the present work.
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http://dx.doi.org/10.1016/j.isci.2024.110795 | DOI Listing |
J Phys Chem Lett
January 2025
School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China.
Electrochemical nitrogen conversion for ammonia (NH) synthesis, driven by renewable electricity, offers a sustainable alternative to the traditional Haber-Bosch process. However, this conversion process remains limited by a low Faradaic efficiency (FE) and NH yield. Although transition metals have been widely studied as catalysts for NH synthesis through effective electron donation/back-donation mechanisms, there are challenges in electrochemical environments, including competitive hydrogen evolution reaction (HER) and catalyst stability issues.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
Department of Chemistry, Malaviya National Institute of Technology, Jaipur, Jaipur 302017, India.
Herein, a simple ambient conditioned sunlight promoted photochemical reduction reaction is demonstrated for the of nitrate (NO) conversion to ammonia (NH) with the maximum conversion yield of ∼16 mM using iron filings (f-Fe) in the presence of HO. Based on a radical scavenging study of reactive species and the characterization of catalyst f-Fe before and after the reaction, a plausible mechanism has been proposed for the ambient conditioned synthesis of NH. The results associated with the NH synthesis have been verified using the N isotopic labeled nitrate (NO), which supports the simpler viability of the reported procedure.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853.
Ammonia oxidizing archaea (AOA) are among the most abundant microorganisms on earth and are known to be a major source of nitrous oxide (NO) emissions, although biochemical origins of this NO remain unknown. Enzymological details of AOA nitrogen metabolism are broadly unavailable. We report the recombinant expression, purification, and characterization of a multicopper oxidase, Nmar_1354, from the AOA .
View Article and Find Full Text PDFSmall Methods
January 2025
School of Mechanical and Aerospace Engineering, Gyeongsang National University, Jinju, 52828, South Korea.
In various applications, the pore structure of a porous medium must be controlled to facilitate heat and mass transfer, which considerably influence the system performance. Freeze-casting is a versatile technique for creating aligned pores; However, because of the complexity of the associated equipment and the energy inefficiency of liquid-nitrogen-based cooling in a room-temperature environment, limits scalability for industrial applications. This study is aimed at establishing a novel freeze-casting strategy with a simple mold design combining heat-conductive and insulating materials for long-range pore alignment via directional ice growth under deep-freezing conditions, rendering it feasible for large-scale production.
View Article and Find Full Text PDFMetab Brain Dis
January 2025
Institute of Liver and Biliary Sciences, New Delhi, India.
Hepatic encephalopathy (HE) is traditionally associated with hepatic parenchymal diseases, such as acute liver failure and cirrhosis. Its prevalence in non-cirrhotic portal hypertension (NCPH) patients, extrahepatic portal vein obstruction (EHPVO), and non-cirrhotic portal fibrosis (NCPF) is less well described. HE in NCPH allows one to study the effect of portosystemic shunting and ammonia without significant hepatic parenchymal injury.
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