Title：Engineering Graphene and Carbon Frameworks for Effective Energy Storage
Speaker： Prof. Zhengxiao Guo，University College London
Time：19th April，2018 (Thursday) 10:00 a.m
Place：Yuan wang lu，7th floor ，Building Chao Kuang Piu
Inviter： Prof. Hongge Pan
Abstract：
Carbon / graphene -based materials offer great scope for chemical / electrochemical /photochemical energy storage and catalysis, while the exceptional physical and mechanical properties are also utilised. Such functionalities can be effectively tuned by means of atomic doping, defect control, inter-layer spacing, porosity architecturing, and hybridisation with other nanostructures. The focus here is to demonstrate how those approaches can be effectively engineered to the development of storage materials for hydrogen, methane and CO2, and of electrochemical catalysts for oxygen reduction and/or evolution reactions (ORR or OER), which underpins the costs and stability of rechargeable metal�air batteries and regenerative fuel cells � the energy conversion / storage technologies for portable devices, electric vehicles and the smart grid. Currently, the commercial noble metal catalysts, such as Pt/C and Ir/C, only exhibit mono-functional activity for either ORR or OER. Non-noble metal or metal-free materials are increasingly considered as cost-effective alternatives, but their catalytic activities, especially OER performance, are yet to match their metallic counterparts. Our systematic development firstly demonstrates the enrichment of N-doping and graphene / graphitic carbon-nitride intercalation are effectively for enabling rapid four-electron transfer process in ORR, and then switching of ORR and OER by single heat-treatment of a metal-organic-framework. Finally by closely coupling theory and experiment, we show the most effective catalytic sites in phosphorus-nitrogen co-doped graphene frameworks (PNGF), and then engineered the synthetic formulations to enrich such sites. The developed electrocatalysts show highly efficient bifunctionality for both ORR and OER. The ORR/OER potential gap is reduced successively from the initial 1.252 mV, to 1.037 mV with P,N co-doping, then to 795 mV after PNGF optimisation, and finally to 705 mV after purposeful enrichment of the active P�N sites. This design strategy, synthesis approach and the efficient catalysts offer great opportunities for the development of highly cost-effective energy storage technologies on a large scale.
Bio：
Dr. Zhengxiao-Guo, Professor of Materials Chemistry at University College London (UCL). Prior to this, he was at Queen Mary, University of London as a Lecturer (1995-1998), Reader (1998-1999), and Professor (2000-2007). He was a research fellow at the Universities of Strathclyde (1988-1990) and Oxford (1990-1995), respectively. He obtained a BEng degree in Materials Science form Northeastern University/China in 1983; and then an MRes and a PhD from the University of Manchester in 1984 and 1988, respectively. Prof. Guo’s group focuses on integrated theoretical and experimental approaches for the design and development of highly functional atomic clusters, nanostructures and materials, as well as their synthesis processes. He has contributed ~ 300 high-quality journal publications and over 300 conference papers/presentations for energy, environmental, aerospace and biomedical applications. He was awarded the Beilby Medal 2000, jointly by the Society of Chemical Industry, the Royal Society of Chemistry, and the Institute of the Minerals, Metals and Materials. Quality outputs include Energy and Environmental Sciences (x6), Advanced (Energy/Functional) Materials (x7), Nano Letters (x2), Angewandte Chemie Inter Ed (x1), Chemical Science (x1), Chemistry of Materials (x1), and invited reviews in Progress in Materials Science (x2). The team has led research projects over ￡15 million, involving consortia grants over ￡70million in the past 10 years. Particular materials systems include molecules, 2D structures / graphenes, metal and ceramic nanostructures. Fundamental theories are coupled with ab initio, molecular dynamics, cellular automata and finite element simulations for materials discovery, while selected materials are synthesised and harnessed by polymerisation, sol-gel, mechano-chemical exfoliation, P/CVD/Atomic-Layer functionalization, co-precipitation, self-assembly, and 2D/3D printing and molecular architecturing.
