1. Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON N6A 5B9, Canada
2. College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
3. Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L8, Canada
4. Ballard Power Systems Inc., 9000 Glenlyon Parkway, Burnaby, BC V5J 5J8, Canada