Nitrate and perchlorate have considerable use in technology, synthetic materials, and agriculture; as a result, they have become pervasive water pollutants. Industrial strategies to chemically reduce these oxyanions often require the use of harsh conditions, but microorganisms can efficiently reduce them enzymatically. We developed an iron catalyst inspired by the active sites of nitrate reductase and (per)chlorate reductase enzymes. The catalyst features a secondary coordination sphere that aids in oxyanion deoxygenation. Upon reduction of the oxyanions, an iron(III)-oxo is formed, which in the presence of protons and electrons regenerates the catalyst and releases water.

Lithium lanthanum zirconate (LLZO) is a promising ceramic solid electrolyte for all-solid-state lithium batteries with improved safety characteristics. However, the different phases of LLZO differ in lithium ionic conductivity by several orders of magnitude, with extrinsic dopants often required to stabilize the high conductivity cubic phase. Here we show that cubic LLZO can be stabilized at room temperature in nanostructured particles without the use of extrinsic dopants. LLZO nanowires were synthesized using electrospinning and formed cubic phase materials after only 3 h calcination at 700 °C. Bulk LLZO with tetragonal structure was transformed to the cubic phase using particle size reduction via ball milling. Heating conditions that promoted particle coalescence and grain growth induced a transformation from the cubic to tetragonal phases in both types of nanostructured LLZO. Detailed structural characterization with XRD and TEM were performed to understand the LLZO formation processes and phase transformations. This work demonstrates another strategy, namely the use of nanostructuring, as an alternative to extrinsic doping for obtaining cubic phase LLZO.

Cerium compounds have played vital roles in organic, inorganic, and materials chemistry due to their reversible redox chemistry between trivalent and tetravalent oxidation states. However, attempts to rationally access molecular cerium complexes in both oxidation states have been frustrated by unpredictable reactivity in cerium(III) oxidation chemistry. Such oxidation reactions are limited by steric saturation at the metal ion, which can result in high energy activation barriers for electron transfer. An alternative approach has been realized using a rare earth/alkali metal/1,1'-BINOLate (REMB) heterobimetallic framework, which uses redox-inactive metals within the secondary coordination sphere to control ligand reorganization. The rational synthesis of functionalized cerium(IV) products and a mechanistic examination of the role of ligand reorganization in cerium(III) oxidation are presented.

Lithium lanthanum zirconate (LLZO) is a promising Li+ ion conductor for applications as a ceramic solid electrolyte in all-solid-state lithium batteries. However, the tetragonal and cubic phases of LLZO differ in lithium ionic conductivity by several orders of magnitude with extrinsic dopants or nanostructuring often required to stabilize the high conductivity cubic phase at room temperature. Here, we show that nanostructured LLZO can be prepared by templating onto various cellulosic fibers, including laboratory Kimwipes, Whatman filter paper, and nanocellulose fibrils, followed by calcination at 700–800 °C. The effect of templating material, calcination temperature, calcination time, and heating ramp rate on the LLZO crystal structure and morphology were thoroughly investigated. Templating was determined to be an effective method for controlling the LLZO size and morphology, and low calcination times and ramp rates were found to favor the formation of small ligaments. Furthermore, it was verified that cubic phase stabilization occurred for LLZO with ligaments of size less than 1 μm on average without the use of extrinsic dopants. This work provides more information regarding the size dependence of cubic LLZO stabilization that was not previously investigated in detail, and cellulosic templating is shown to be a viable route toward the scalable, sustainable synthesis of LLZO solid electrolytes.

The derivatization of the imino-functionalized tris(pyrrolylmethyl)amine ligand framework, N(pi) (L; X = H, Br; R = cyclohexyl (Cy), phenyl (Ph), 2,6- diisopropylphenyl (DIPP)), is reported. Modular ligand synthesis allows for facile modification of both the primary and secondary coordination sphere electronics. The iron(II)-hydroxo complexes, N(pi)(afa)Fe(II)OH (LFeOH), are synthesized to establish the impact of the ligand modifications on the complexes' electronic properties, including their chemical and electrochemical oxidation. Cyclic voltammetry demonstrates that the Fe(II/III) redox couple spans a 400 mV range across the series. The origin of the shifted potential is explained based on spectroscopic, structural, and theoretical analyses of the iron(II) and iron(III) compounds.