报告题目：Multi-doped Graphene and its Application in Clean Energy Conversion and Storage
报告人：Zhenhai Xia, Department of Materials Science and Engineering, University of North Texas
报告内容简介：A critical issue in the development of renewable energy production and storage technologies isthe discovery of efficient and cost-effective catalysts for use in electrochemical energy conversion processes such as the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), both of which are central to the efficiencies of direct-solar and electrolytic water-splitting devices, fuel cells and metal–air batteries. Doped carbon nanomaterials are attractive in principle for catalytic applications because their unique molecular structure facilitates the four-electron ORR. In addition, there are even more appeals because of their extreme flexibility, the large surface area, excellent mechanical and electrical properties, and highly stability in the extreme environment. A fundamental understanding of carbon-based catalyst design principle that links material structures to the catalytic activity can accelerate the search for highly active and abundant metal-free catalysts to replace platinum. In this talk, we present our recent work on nitrogen, boron and other element-doped graphene for catalytic application in fuel cells. We demonstrate that the catalytic activity primarily correlates to charge and spin densities of the graphene. The doping and defects introduce high positive spin and/or charge densities that facilitate the ORR on graphene surface. The identified active sites are closely related to doping cluster size and dopant-defect interactions. For four-electron transfer, the effective reversible potential ranges from 1.07~1.15 V/SHE, depending on the defects and cluster size. The catalytic properties of graphene could be optimized by introducing small doping clusters in combination with material defects.