THESIS
2022
1 online resource (xv, 115 pages) : illustrations (some color)
Abstract
Graphene, a single-atom-thick 2-dimensional sheet of carbon atoms densely arranged in a
hexagonal lattice, has captured much attention from scientists and engineers due to its unique
mechanical and electrical properties. Synthesis of graphene by catalytic chemical vapor
deposition (CVD) using gaseous hydrocarbons has been widely investigated. However,
researchers are still seeking for precursors which are sustainable and accessible to obtain a high
quality of graphene. This work delivers a comprehensive study on catalyst development for
graphene fabrication from the spent tea ground. Various kinds of catalysts were developed for
pyrolysis of spent tea grounds to produce methane, which is the carbon source for graphene
fabrication. The catalysts were characterized by analytical technique...[
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Graphene, a single-atom-thick 2-dimensional sheet of carbon atoms densely arranged in a
hexagonal lattice, has captured much attention from scientists and engineers due to its unique
mechanical and electrical properties. Synthesis of graphene by catalytic chemical vapor
deposition (CVD) using gaseous hydrocarbons has been widely investigated. However,
researchers are still seeking for precursors which are sustainable and accessible to obtain a high
quality of graphene. This work delivers a comprehensive study on catalyst development for
graphene fabrication from the spent tea ground. Various kinds of catalysts were developed for
pyrolysis of spent tea grounds to produce methane, which is the carbon source for graphene
fabrication. The catalysts were characterized by analytical techniques such as X-ray diffraction,
X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), and transmission
electron microscopy (TEM) to evaluate the metal/metal oxide crystallinity, metal oxidation
states, morphology, and crystallinity nature, correspondingly. Moreover, the effect of the
reaction temperature, catalyst dosage, catalyst calcination temperature and types of spent tea
grounds on the methane generation were studied.
With the optimized metal catalyst and pyrolysis reaction, the whole catalytic system was
practically applied in the graphene synthesis. The commercial spent tea grounds were used as
the sole carbon source for growing graphene monolayer on copper foil by catalytic CVD. This
method utilizes the optimized monometallic and bimetallic catalysts to efficiently catalyse the pyrolytic reaction of the spent tea ground and the generated fragments subsequently are
deposited on the copper foil substrate. Raman spectroscopy confirmed that the graphene was
successfully deposited on the copper foil substrate using either specifically designed
Ru/alumina, or bimetallic CoRu-based catalysts. This new approach not only demonstrates a
new route of transforming the spent tea grounds into useful graphene material, but also
promotes a concept of “waste-to-functional materials” to achieve the goal of “carbon-zero” by
Year 2050.
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