Time: May 28th, 2019, 9:00 am
Venue: No.2 Conference Room, Conference Center
Lecturer：XIE Jian, PhD，Department of Mechanical and Energy Engineering，Purdue School of Engineering and Technology，Purdue University at Indianapolis
Two of the major challenges for development of polymer electrolyte membrane fuel cell (PEMFC) systems, especially for automotive applications, are cost and durability of the precious metal group (PGM) based cathode electrocatalysts. The durability, to a large extent, depends on the PGM catalyst and support stabilities. We have been developed different catalyst supports ranging from functionalized carbon blacks (i.e. attaching SO3H and COOH groups, and steam etching to increase graphitization), steaming etched carbon blacks, nanoscale graphite particles, to graphenes. It has been demonstrated that higher graphitic structure of the support is, the stronger the support stability is. The graphene is the ultimate carbon support due to its highest graphitic structure. However, application of graphene supported catalysts in membrane electrode assembly (MEA) remains a huge challenge due to the restacking of the graphene sheets during the synthesis of the supports, the preparation of the catalyst, and the fabrication of the MEA. We have taken the approaches of (1) using our functionalized graphene methodology to transform the pure graphene into functional materials with enhanced H+ conductivity, improved Pt particle dispersion, and enhanced anchoring of Pt nanoparticles on the support, and (2) using our “spacer” approach to transform the 2 D graphene sheet into 3 D structured graphene with pores/channels for facile reactant/product transfer. Using these approaches, we have developed 3 D-structured, functionalized graphene-based (f-G) catalyst supports combined with PtxNi alloy catalysts in a membrane electrode assembly with excellent performance: ≤ 18% and 29% mass activity loss after 5K support cycles (0.5V/s, 1.0-1.5 V ) and 30K catalyst cycles (0.05V/s, 0.6-1.0 V ), respectively, which exceeds the DOE 2020 target (≤ 40%). This talk will cover the development of graphene supported catalysts for PEMFC applications with whole process characterization; catalyst ink using small angle x-ray scattering (USAXS) combined with cryogenic TEM, catalyst and support using identical location TEM for Pt nanoparticle stability, x-ray absorption (XAS) and x-ray photoelectron spectroscopy (XPS), and ionomer/catalyst interface using TEM and porosimetry of catalyst layers using Hg porosimetry, TEM tomography and Nano-CT.
Dr. XIE is an professor of Mechanical and Energy Engineering at the Purdue School of Engineering Indianapolis (IUPUI campus). He has published more than 55 journal papers, 11 patents applications, 2 book chapters and he has been awarded more than $4.86 million research grants within 8 years. He served as review board members for more than 12 journals including the well known Nature. He also serves as the panelist of the review panel for US National Science Foundation (NSF), Advanced Research Project Agency-Energy (ARPA-E) of US Department of Energy (DOE), Canadian National Science Foundation (CNSF) for grant proposal review and evaluation. He has been served as the session chair for Polymer Electrolyte Fuel Cells Symposium in the Electrochemical Society Meeting for more than 5 years. Before joining the university, he was a principal research scientist at Battelle Memorial Institute and worked on fuel cell R&D as well as Li-ion batteries and artificial lung. Prior to Battelle, as the program manager and senior electrochemical engineer at Cabot Corp, Dr. XIE worked extensively on catalyst development for fuel cells. Dr. XIE spent four years at Los Alamos National Laboratory on fuel cell research covering from membrane electrolytes, catalysts, membrane electrode assembly (MEA) to durability of fuel cells. As a system engineer, Dr. XIE was in charge of developing electric propulsion system for Electric Vehicle (EV) and Hybrid EV at General Motors Advanced Technology Vehicle, Indianapolis Technical Center. Dr. XIS received his PhD in chemistry from Miami University, U.S.A. and BS in chemical engineering (emphasis on electrochemical engineering) from Tianjin University, China.
Contact: SHAO Zhigang