Screening of Novel Li–Air Battery Catalyst Materials by a Thin Film Combinatorial Materials Approach

A combinatorial synthesis and high-throughput screening process was developed for the investigation of potential oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts for use as Li–air battery cathode materials. Libraries of discrete ternary metal alloy compositions were deposited via thin-film sputtering. The samples were electrochemically tested in parallel using cyclic voltammetry in O₂-saturated KOH electrolyte. Compositions were ranked by ORR and OER onset potentials with respect to an internal Pt reference. Results from the Pt–Mn–Co, Cr–Mn–Co, Pd–Mn–Co, and Pd–Mn–Ru systems are reported. Many alloy compositions showed marked improvement in catalytic activity compared to pure Pt. Among the systems considered, Pt₁₂Mn₄₄Co₄₄, Pd₄₃Co₅₇ and Pd₃₆Mn₂₈Ru₃₆ in particular exhibited lower overpotentials for oxygen reactions, which occur at the cathode in Li–air batteries

Microwave-Assisted Solution–Liquid–Solid Synthesis of Single-Crystal Copper Indium Sulfide Nanowires

Chalcopyrite copper indium sulfide (CuInS₂) is an important semiconductor with a bandgap optimal for terrestrial solar energy conversion. Building photovoltaic and microelectronic devices using one-dimensional CuInS₂ nanowires can offer directional conduits for rapid and undisrupted charge transport. Currently, single-crystal CuInS₂ nanowires can be prepared only using vapor-based methods. Here, we report, for the first time, the synthesis of single-crystal CuInS₂ nanowires using a microwave-assisted solution–liquid–solid (MASLS) method. We show that CuInS₂ nanowires with diameters of less than 10 nm can be prepared at a rapid rate of 33 nm s^–1 to more than 10 μm long in less than 10 min, producing a high mass yield of 31%. We further show that the nanowires are free of structural defects and have a near-stoichiometric composition. The success of MASLS in preparing high-quality tertiary nanowires is explained by a eutectic growth mechanism involving an overheated alloy catalyst