Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203, USA

Biography Professor Zhenhai Xia

Zhenhai Xia is a professor of Department of Materials Science and Engineering, and Department of Chemistry at University of North Texas, USA. His current research interests include multiscale and multi-physics modeling (finite element analysis, molecular dynamics, and DFT, etc.); catalytic materials for clean energy conversion and storage (fuel cell metal-air batteries and water-splitting, supercapacitors, etc.), biological and bioinspired materials (e.g., tunable adhesion and friction, dynamic self-cleaning, micromanipulation and assembly), and mechanics of materials (strengthening and toughening, nanocomposites, high-entropy alloys). His research has been funded by the National Science Foundation, Air Force Office of Scientific Research, the Army Research Laboratory, and industry. He has graduated over 10 Ph.D. students, and is active in teaching graduate and undergraduate courses in materials science and engineering at UNT. He has authored one book, 5 book chapters and over 170 publications in peer-reviewed journals, including 3 in Science and 4 in Nature series. His work has been cited over 13,000 citations (over 15 highly-cited papers/hot papers selected by Web of Science). He was the recipient of Humboldt Scholarship from Alexander von Humboldt Foundation, Germany in 1997, and Nanoscience Research Leader Award from Science Letters, USA in 2015. For more information, please visit https://Xiagroup.materials.engineering.unt.edu

Abstract

Guiding Principles of Carbon-Based Materials as High-Performance Catalysts for Clean Energy Conversion

Clean and sustainable energy technologies, such as fuel cells, metal-air batteries, water-splitting and solar cells, are currently under intensive research and development because of their high efficiency, promising large-scale applications, and virtually no pollution or greenhouse gas emission. At the heart of these energy devices, there are critical chemical reactions: oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO₂RR) that determine the efficiencies of energy conversion and storage. These reactions, however, are sluggish and require noble metals (e.g., platinum) or their oxides as catalysts. The limited resources and high cost of platinum have hampered the commercialization of these technologies. Therefore, it is necessary to search for alternative materials to replace Pt. Carbon nanomaterials, such as carbon nanotubes (CNTs) and graphene, are appealing as an alternative for metal-free catalytic applications because of their structures and excellent properties. Although the superior catalytic capabilities of heteroatom-doped carbon nanomaterials for ORR have been demonstrated, trial-and-error approaches are still used to date for the development of highly-efficient catalysts. To rationally design a catalyst, it is critical to understand which intrinsic material characteristics, or descriptors that control catalysis. Through first-principles calculations, we have identified a material property that serves as the activity descriptor for predicating ORR and OER activities, and established a volcano relationship between the descriptor and the bifunctional activities of the carbon-based nanomaterials. Such descriptor enables us to design new metal-free catalysts with enhanced ORR and OER activities, even better than those reported for platinum-based metal catalysts. The similar principles were applied to covalent organic framework (COF) single-atom catalysts for ORR, OER and CO₂RR. The design principles can be used as a guidance to develop various new carbon-based materials for clean energy conversion and storage.