Manufacturing of Platinum Nanocrystal-Embedded Nanoporous Metal Oxide Electrodes for High Performance Metal-Air Batteries

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Metal-air batteries with bifunctional catalysts as cathodes are emerging technologies for renewable energy storage owing to their very competitive energy densities compared to fossil fuels. Nanoporous metal oxide electrodes embedded with platinum nanocrystals are believed to deliver high performance for metal-air batteries. Current methods for manufacturing platinum-metal oxide electrodes are impeded by inhomogeneous material distribution and composition, high energy consumption and low yield, which limit their scalable manufacturing. This award supports fundamental research to provide needed knowledge for the development of a scalable, room temperature electrochemical process for manufacturing of metal-air battery electrodes. The new process enables manufacturing of electrodes with homogeneous composition and seamless interface. Such materials result in high-performance metal-air batteries with high energy efficiencies and long cyclability. Nanoporous electrodes made from a wide variety of bifunctional catalysts are increasingly preferred for applications in energy, healthcare, biomedical, aerospace, chemical or automotive industries. Therefore, results from this research benefit the U.S. economy and society. This research involves several disciplines including manufacturing, electrochemistry, and materials science. The multi-disciplinary approach helps broaden participation of underrepresented groups in research and positively impacts engineering education.The pulse electrochemical manufacturing process overcomes several limitations of current electrochemical manufacturing techniques, which are lack of morphology and composition control and difficulty in the control of selective growth and etching kinetics. However, some scientific barriers are yet to be overcome to realize the full application potential of pulse electrochemical deposition and anodization for scalable manufacturing. This research is to fill the knowledge gap on the mechanisms of platinum nanocrystal (Pt-NC) facet selective growth and nanoporous framework formation during electrochemical deposition and anodization. The objectives are (1) to explore the nucleation and bottom-up growth kinetics of Pt-NCs in complex electrochemical systems containing multiple cations by using pulse electrochemical deposition, (2) to understand the roles of dynamic O2 bubbles in selective metal oxidation, etching, and nanopore top-down growth processes by pulse anodization, and (3) to uncover the processing-microstructure-property relationships in designing, manufacturing, and applying Pt-embedded metal oxide electrodes for metal-air batteries. The research team plans to perform advanced electrochemical analyses and materials characterizations to understand the mechanism of nanopore formation in electrochemical deposition and anodization, test the hypothesis that pulse voltage and frequency are the determining factors for nanopores and selective facets of Pt-NCs in electrochemical manufacturing, and establish relationships between process parameters and porosity in electrochemical deposition and anodization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.