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Magnetic Multifunctional Nanostructures as High-efficiency Catalysts for Oxygen Evolution Reactions Umanga De Silva, W. P. R. Liyanage, Manashi Nath* Department of Chemistry, Missouri University of Science and Technology, Rolla, MO 65409. *Email: [email protected] Abstract The search for high-efficiency and environmentally benign water splitting catalysts has been on the rise since this process is a source of renewable, clean energy. However the process is inherently slow, especially for the production of O2 from H2O (water oxidation) due to the high electron count and energy intensive bond formation of the reaction. Hence the search for novel catalysts for oxygen evolution reactions (OER) has led researchers to focus on various families of compounds including oxides and recently selenides. Multifunctional nanostructures containing the semiconductor electrocatalyst grafted onto an optically active metallic component might boost the catalytic activity even further due to efficient charge injection. Magnetically active catalysts will also be lucrative since that might induce better adhesion of the oxygenated species at the catalytically active site. In this report we introduce multifunctional, magnetic Au3Pd–CoSe nanostructures as high-efficiency OER electrocatalysts. These multifunctional nanostructures were synthesized by a chemical vapor deposition (CVD) reaction with cobalt acetylacetonate and elemental selenium on Au-Pd sputter coated silica substrate at 800°C. The morphology of these multifunctional nanostructures were mostly bifunctional Janus-like nanoparticles as seen through scanning and transmission electron microscopy. They also showed soft ferromagnetic behavior. These bifunctional nanoparticles were coated on the anodes of a water oxidation cell and it was observed that these nanoparticles showed a higher OER activity with lower onset potential for O2 evolution as compared to the conventional oxide-based OER electrocatalysts. INTRODUCTION Water splitting is a vital topic of interest in present days since it offers a solution for alternative energy generation without depleting fossil fuel. Water splitting can utilize both solar and/or electric energy for a cleaner, recyclable, and cheaper production of hydrogen and oxygen. The water-splitting reaction has two half-reactions: the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), both of which are fundamental for the overall efficiency of water splitting [1, 2]. Currently OER has been a prime area of research for energy generation from water oxidation, because of the inherently sluggish rate of the reaction. The OER process is inherently slow, due to the high electron count (4e) and energy intensive bond formation. Typically, catalysts are required to reduce the activation energy barrier for this uphill reaction. Some of the commonly used catalysts for OER in electrolysis cells are state-of-the-art noble metals of Pt, Ru, and Ir and their oxides.[3,4] However, there are some critical problems with the noble metal electrocatalysts including