Reversible oxygen electrochemistry is vital to numerous future renewable energy technologies, such as fuel cells, metal-air batteries, and electrolyzers. Active electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are known, however they are typically expensive and based on rare materials such as Pt (for ORR) and Ir/IrOx (for OER). These benchmark catalysts can also suffer from reaction poisoning and poor electrochemical selectivity, further decreasing their utility. Therefore, catalyst materials that are highly active, stable, and cost-effective are needed. We will present on the synthesis, characterization and electrocatalytic evaluation of Nickel- and Copper-ion doped α-MnO2 (i.e. Cu-α-MnO2 and Ni-α-MnO2) nanowire electrocatalysts. Metal ion doping modifies the nanowire crystalline lattice, surface area and valence state of manganese ions at the surface of the nanowire, all of which yield improvements in catalytic activity. Improvements in terminal current densities, kinetic rate constants, and charge transfer resistances are obtained with Cu-α-MnO2 and Ni-α-MnO2, as compared to un-doped α-MnO2. In an effort to also understand the role of conductivity on the electrocatalytic process, we are also developing a methodology to obtain temperature-dependent, single-nanowire conductivity measurements. Such fundamental understanding of electrocatalysis for nanomaterials is required in order to develop improved catalysts suitable for next generation renewable energy technologies such as metal air batteries, fuel cells and water electrolyzers. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Cu- and Ni-doped α-MnO2 electrocatalysts for reversible oxygen electrochemistry

249th National Meeting (2015)

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