Atomistic and Multi-scale Modelling of Functionalized Graphene and Hydrogen Diffusion in Advanced Materials

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In 2016, the Meta Council of Emerging Technologies of World Economic Forum identified two-dimensional (2D) materials as one of the top ten emerging technologies of the world. 2D materials such as graphene consist of single-layer atom sheets that can be used to build new materials and devices. They are proposed for a wide range of applications, such as sensor technology, composite materials, energy storage, environmental filters, drug delivery systems, and optoelectronics. Graphene is an important 2D material and its significance was recognized by the 2010 Nobel Prize in Physics. Application of graphene requires homogeneous dispersion in host materials and creation of strong bonds with other materials. Chemical functionalization is used to improve dispersion of graphene and form strong interfaces. Graphene-oxide (GO) is used for cost-effective mass production of functionalized graphene. GO can be produced from bulk graphite. It is dispersive and has hydroxyl and other functional bonds that can facilitate better interaction with materials. Currently, very limited research exists on the mechanical and interfacial properties of functionalized graphene and GO. The first part of the proposed research program examines the mechanics and mechanical properties of functionalized graphene and GO and their interfaces to support novel material and device design. A computer-based atomistic and multi-scale modeling approach will be used and comparisons with experiments will be made in selected cases. Two PhD students, two MSc students and three undergraduates will be trained on this research. The second part of the proposed research program aims to obtain a fundamental understanding of diffusion of hydrogen in Zirconium and Lead Zirconate Titanate (PZT). Zirconium pressure tubes are key elements of nuclear power plants, and PZT actuators are used in modern fuel injectors. Experimental studies confirm hydride formation in pressure tubes, and the resulting hydride-driven cracking as a major safety concern. Experiments also confirm the loss of polarization of PZT due to hydrogen, which is a barrier for the use of PZT-based injectors in hydrogen technology applications. The exact mechanism of hydride-driven cracking is not fully understood, and little is known about the interaction of PZT with hydrogen. The proposed program involves comprehensive computer-based atomistic modeling of hydrogen interaction and diffusion in zirconium and PZT lattices and a multi-scale model for diffusion. The findings will support safe design of pressure tubes and development of injectors for hydrogen technology. Two PhD students and two undergraduates will be trained on this research. The trainees will disseminate the research findings through peer-reviewed publications, conferences, and interaction with industry. High-performance computing facilities of WestGrid/Compute Canada will be used in this project.