报告题目：Surface and Interface Engineering of Advanced Materials for Energy and Sustainability
报 告 人：Prof. Yang Yang, University of Central Florida
研究方向：Energy materials, energy conversion and storage
报告地点：Zoom meeting ID: 918 8452 0565
Safety and durability concerns caused by surface and interface instabilities of high-surface-activity energy materials are challenging modern electrochemical energy conversion and storage systems. These concerns pose formidable barriers to reliable power sources for electric vehicles (EVs), personal electronics, and other applications. In order to stabilize the surface and interface of energy materials used under hash electrochemical conditions, some surface and interface (strain, gradient, defect, confinement, etc.) engineerings at the nano/atomic scale are under consideration. However, the commonly used approaches to stabilize energy materials are still in their early infancy. It is critical to explore more efficient and universal strategies for addressing the issues of interfacial instabilities.
In this presentation, I will present our most recent representative works on the surface and interface engineering of functional materials for energy devices including aqueous batteries and direct ethanol fuel cells. In the first part of the presentation, I will introduce a new strategy to resolve the interfacial instability issues of battery materials using novel three-dimensional (3D) Zn-Mn alloys. In this work, we designed an in-situ visualized protocol that can exactly mimic the actual electrochemical environments used in aqueous batteries. Using this novel protocol, we observed the dynamic processes of metal plating/stripping on the alloys in aqueous batteries. Comprehensive and systematic studies based on experimental, theoretical, spectroscopic, and microscopic approaches prove that absolute reversibility can be achieved by using the proposed 3D alloys because of the significantly improved Zn diffusion and successfully suppressed dendrite growth. As a proof-of-concept, the novel alloy structures deliver unprecedented stability with nearly 100% Coulombic efficiency over thousands of cycles even under harsh electrochemical conditions, including testing in seawater-based aqueous electrolytes and using a high current density of 80 mA cm-2. In the second part of the presentation, I will discuss a new strategy to controllably regulate the local bonding states and local coordination environment (LCE) in the classic carbon-supported metal catalysts for direct ethanol fuel cells. Particularly, we use F-doped Pd-X-C (X = N, P, S, B) as model systems to study the LCE effects on oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR). The N-rich Pd surface with regulated LCE not only boosts the activity of Pd but also enhances the catalyst stability by inhibiting the migration and agglomeration of Pd as well as endowing carbon support with long-term anti-corrosion properties. As a result, an unbeatable power density of 0.57 W cm-2 with more than 5,900 hours of operation was achieved in direct ethanol fuel cells using the proposed LCE-regulated catalysts, remarkably outperforming benchmarking catalysts. In an extended study, the concept of F-induced LCE regulation can be applied to other Pd-X-C catalysts (X = P, S, B) with drastically improved activities and stabilities.
Dr. Yang Yang is an associate professor at the University of Central Florida (UCF) and studies surface and interface engineering of advanced materials for energy and sustainability. He obtained his Ph.D. from Tsinghua University in 2010. From 2010 to 2012 he was the Alexander von Humboldt Postdoctoral Fellow and worked with Prof. Patrik Schmuki at the University of Erlangen-Nuremberg, Germany. From 2012 to 2015 he was the Peter M. & Ruth L. Nicholas Postdoctoral Fellow and worked with Prof. James Tour at Rice University. Since 2015 he has started his independent research at the NanoScience Technology Center, Department of Materials Science & Engineering, Department of Chemistry, Renewable Energy and Chemical Transformation Cluster, UCF. His current research interests cover materials science, nanomanufacturing of metallic and carbon materials, interface engineering of energy materials, energy conversion and storage devices with a particular focus on aqueous electrochemical systems such as aqueous batteries, fuel cells, electrolyzers for H2 production and CO2 reduction. He has published almost 130 peer-reviewed articles, including Nature Energy, Nature Communications, Joule, Advanced Materials, JACS, Angewandte Chemie, Energy & Environmental Science, etc., with a total citation of over 11,000+ and H-index of 57. His lab website is http://www.yangyanglab.com.