Thesis
Influence of functional groups on direct and indirect photolysis of graphene
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/100464
Abstract
Graphene, a two dimensional (2D) carbon-based nanomaterial, has various functional groups on its basal plane and edges. In this study, we investigated the influence of these functional groups on the degradation of graphene nanomaterials under simulated direct and indirect photolysis. The degradation of graphene nanomaterials was achieved by simulating sunlight in an Atlas Suntest controlled power system (CPS). Materials used in this study were graphene oxide (GO), graphene oxide reduced by a solvothermal reduction process for 2 hours (rGO 2hr) and 5 hours (rGO 5hr). For indirect photolysis, hydrogen peroxide (H2O2) was used to produce hydroxyl radicals. Analysis from different characterization techniques indicated that graphene nanomaterials undergo degradation by creating holes in basal planes where functional groups like hydroxyl groups reside. In the case of direct photolysis, graphene nanomaterial itself acts as chromophore. In the case of indirect photolysis, photosensitizers like natural organic matter (NOM), nitrate etc., that produce hydroxyl radicals, act as chromophores and initiate degradation process. FT-IR spectra showed disappearance of hydroxyl functional groups in direct photolysis but no change in indirect photolysis. However, in indirect photolysis, carboxyl functional groups were formed due to the presence of hydroxyl radical. Thus, degradation of graphene nanomaterial will be strongly influenced by the type of functional groups on the surface. Overall results indicate that hydroxyl functional group (-OH), present in the basal plane, was the major contributor for initiating the degradation in both processes. However, the rate of photolysis was much faster for indirect photolysis than direct photolysis. Moreover, samples in indirect photolysis undergo complete mineralization to CO2. Among the tested materials, GO photodegraded quicker than rGO. Results of this study will help understand the fundamental mechanisms of degradation process of graphene. Moreover, the results will be useful in designing graphene nanomaterials for sustainable applications.
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Details
- Title
- Influence of functional groups on direct and indirect photolysis of graphene
- Creators
- Mehnaz Shams
- Contributors
- Indranil Chowdhury (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525041701842
- Language
- English
- Resource Type
- Thesis