Speaker
Ms
Ashley Roberts
(Monash University)
Description
Engineered membranes that are selectively ion-, gas-, or liquid- permeable are key aspects of emerging technology especially in the fields of gas separation (1), water purification (2), and energy storage (3). Recent reports have shown that graphene-based membranes consisting of graphene, chemically converted graphene (CCG), graphene oxide (GO), or partially reduced GO sheets have unique membrane properties and exhibit responsive behavior and tunable structures. Currently, no definitive models exist to describe the structure of these multi-layer graphene-based materials and initial results presented here are discussed in relation to a disordered lamellar system. The two-dimensional sheets are not rigid, and specific material properties of the membrane are determined by the pore size and pore size distribution arising from the disorder induced by corrugation (Figure 1). The graphene-based lamellar systems contain features such as wrinkles, buckles, curves, and corrugation along with defects and/or functional groups – all of which can be more or less controlled during the fabrication process.
Accurate characterization of the structure of these materials is of importance and the field could benefit from more widespread information on crystallography methods as applied to more disordered systems seen in soft matter. A typical XRD curve for these graphene-based systems has a broad peak attributed the shift in lamellar spacing from that of pure graphite. This broadening can be attributed to wrinkling and distributed bonding which is strain within the lattice: thus, both strain and crystallite size should be incorporated into the interpretation of peak broadening. Without higher order peaks, the line profile alone is not enough to distinguish between these properties and other methods can be used to extract useful information from the peaks. Further, advances in 2D detectors allow for more detailed analysis of orientation within the material (Figure 2), and *in-situ* studies of hydration have shown interesting information about the dynamic behaviour of these materials, showing a need for soft-matter focused sample environments.
![XRD Line Profiles for GO and CCG Membranes][1]
![Area Detector Image Through the Edge of CCG Membrane][2]
1. Li, H., et al. Science, 2013, 342, 95-98; Kim, H.W., et al. Science, 2013, 342, 91-95.
2. Joshi, RK, et al. Science, 2014, 343, 752-754; Shih, CJ, et al. Nat. Mater. 2013, 12, 866-869.
3. Yang, X.W., Li, D., et al. Adv. Mater. 2011, 23, 2833-2838.
[1]: http://Desktop/AbstractFig1.jpg
[2]: http://Desktop/AbstractFig2.jpg
Primary author
Ms
Ashley Roberts
(Monash University)
