TiO₂ Photocatalysis–DESI-MS Rotating Array Platform for High-Throughput Investigation of Oxidation Reactions

We present a new high-throughput platform for studying titanium dioxide (TiO₂) photocatalytic oxidation reactions by performing reactions on a TiO₂-coated surface, followed by direct analysis of oxidation products from the surface by desorption electrospray ionization mass spectrometry (DESI-MS). For this purpose, we coated a round glass wafer with photocatalytically active anatase-phase TiO₂ using atomic layer deposition. Approximately 70 aqueous 1 μL samples can be injected onto the rim of the TiO₂-coated glass wafer, before the entire wafer is exposed to UV irradiation. After evaporation of water, the oxidation products can be directly analyzed from the sample spots by DESI-MS, using a commercial rotating sample platform. The method was shown to provide fast photocatalytic oxidation reactions and analysis with throughput of about four samples per minute. The feasibility of the method was examined for mimicking phase I metabolism reactions of amodiaquine, buspirone and verapamil. Their main photocatalytic reaction products were mostly similar to the products observed earlier in TiO₂ photocatalysis and in in vitro phase I metabolism assays performed using human liver microsomes

Atomic Layer Deposition of Spinel Lithium Manganese Oxide by Film-Body-Controlled Lithium Incorporation for Thin-Film Lithium-Ion Batteries

Lithium manganese oxide spinels are promising candidate materials for thin-film lithium-ion batteries owing to their high voltage, high specific capacity for storage of electrochemical energy, and minimal structural changes during battery operation. Atomic layer deposition (ALD) offers many benefits for preparing all-solid-state thin-film batteries, including excellent conformity and thickness control of the films. Yet, the number of available lithium-containing electrode materials obtained by ALD is limited. In this article, we demonstrate the ALD of lithium manganese oxide, Li_<i>x</i>Mn₂O₄, from Mn­(thd)₃, Li­(thd), and ozone. Films were polycrystalline in their as-deposited state and contained less than 0.5 at. % impurities. The chemical reactions between the lithium precursor and the film were found not to be purely surface-limited but to include a bulk component as well, contrary to what is usually found for ALD processes. In addition, we show a process for using Li­(thd)/ozone and LiO^<i>t</i>Bu/water treatments to transform ALD-MnO₂ and ALD-V₂O₅ into Li_<i>x</i>Mn₂O₄ and Li_<i>x</i>V₂O₅, respectively. The formed Li_<i>x</i>Mn₂O₄ films were characterized electrochemically and found to show high electrochemical capacities and high cycling stabilities