Nitrous oxide production via enzymatic nitroxyl from the nitrifying archaeon .

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 .

Origin of Performance Decline in Carbonated Anion Exchange Membrane Fuel Cells.

Anion exchange membrane fuel cells (AEMFCs) have successfully eliminated anode carbonate precipitation through cation immobilization with the incorporation of alkaline polymer electrolytes (APEs). However, carbonation by CO in ambient air continues to induce significant AEMFC performance losses via mechanisms that remain unclear/elusive. In this multimodal investigation of AEMFC carbonation, we find that the increase in ionic resistance after carbonation accounts for only a small fraction of the cell voltage drop, especially at high current densities.

The Electrochemical Peroxydisulfate-Oxalate Autocatalytic Reaction.

Aqueous solutions containing both the strong oxidant, peroxydisulfate (SO), and the strong reductant, oxalate (CO), are thermodynamically unstable due to the highly exothermic homogeneous redox reaction: SO + CO → 2 SO + 2 CO (Δ = -490 kJ/mol). However, at room temperature, this reaction does not occur to a significant extent over the time scale of a day due to its inherently slow kinetics. We demonstrate that the SO/CO redox reaction occurs rapidly, once initiated by the Ru(NH)-mediated 1e reduction of SO to form SO, which rapidly undergoes bond cleavage to form SO and the highly oxidizing radical SO.

Colloidal Synthesis of Monodisperse High-Entropy Spinel Oxide Nanocrystals.

Synthesis of high-entropy oxide (HEO) nanocrystals has focused on increasing the temperature in the entropy term ((Δ)) to overcome the enthalpy term. However, these high temperatures lead to large, polydisperse nanocrystals. In this work, we leverage the low solubility product () of metal oxides and optimize the Lewis-acid-catalyzed esterification reaction for equal rate production of the cation monomers to synthesize HEO nanocrystals at low temperatures, producing the smallest (<4 nm) and most monodisperse (<15% size dispersity) HEOs to date.