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Understanding the chemical mechanisms at play in atomic layer deposition (ALD) is critical for effective process development and expansion of ALD into more complex classes of materials. In this work, a mechanistic study of iron oxide deposited by ALD using tert‐butylferrocene and ozone as reactants is performed. Iron oxide ALD using ozone is a useful model system for mechanistic studies due to the prevalence of ozone‐based ALD processes and the uses of iron oxide in ternary and quaternary metal oxides. Results show that saturation conditions require significantly greater exposures of both reactants than is typically reported in the literature, and growths per cycle of greater than one monolayer of Fe2O3 per cycle are observed and explained. A growth mechanism is proposed whereby increased ozone exposure results in uptake of superstoichiometric oxygen into the film. X‐ray characterizations reveal the presence of excess oxygen stored near the surface of films deposited with larger ozone exposures and show that increased ozone exposures cause crystalline domain rearrangement and conversion of the film from the γ‐maghemite phase to the α‐hematite phase. The mechanism described here has implications for the wider class of ozone‐based ALD processes, and potential applications of this growth phenomenon are discussed. [ABSTRACT FROM AUTHOR]

Electrochemical processes for ammonia synthesis could potentially replace the high temperature and pressure conditions of the Haber‐Bosch process, with voltage offering a pathway to distributed fertilizer production that leverages the rapidly decreasing cost of renewable electricity. However, nitrogen is an unreactive molecule and the hydrogen evolution reaction presents a major selectivity challenge. An electrode of electrodeposited lithium in tetrahydrofuran solvent overcomes both problems by providing a surface that easily reacts with nitrogen and by limiting the access of protons with a nonaqueous electrolyte. Under these conditions, we measure relatively high faradaic efficiencies (ca. 10 %) and rates (0.1 mA cm−2) toward NH3. We observe the development of a solid electrolyte interface layer as well as the accumulation of lithium and lithium‐containing species. Detailed DFT studies suggest lithium nitride and hydride to be catalytically active phases given their thermodynamic and kinetic stability relative to metallic lithium under reaction conditions and the fast diffusion of nitrogen in lithium. [ABSTRACT FROM AUTHOR]

Keywords: ammonia; catalysis; density functional calculations; electrochemistry; Haber-Bosch EN ammonia catalysis density functional calculations electrochemistry Haber-Bosch 1509 1509 1 04/20/20 20200401 NES 200401 B The Front Cover b shows the idealized lithium-containing species on an electrocatalyst surface for the reduction of nitrogen to ammonia at atmospheric pressure and temperature. The nitrogen activation occurs in non-aqueous electrolytes to achieve high faradaic efficiency on a complex reactive surface. Ammonia, catalysis, density functional calculations, electrochemistry, Haber-Bosch. [Extracted from the article]