Pillared-graphene structure (PGS) is a novel three-dimensional structure consists of parallel graphene sheets that are separated by carbon nanotube (CNT) pillars that is proposed for efficient thermal management of electronics. For microscale simulations, finite element analyses were carried out by imposing a heat flux on several PGS configurations using a Gaussian pulse. The temperature gradient and distribution in the structures was evaluated to determine the optimum design for heat transfer. The microscale simulations also included conducting a mesh-independent study to determine the optimal mesh element size and shape. For nanoscale simulations, Scienomics MAPS software (Materials And Processes Simulator) along with LAMMPS (Large-scale Atomic/ Molecular Massively Parallel Simulator) were used to calculate the thermal conductivity of different configurations and sizes of PGS. The first part of this research included investigating PGS when purely made of carbon atoms using non-equilibrium molecular dynamics (NEMD). The second part included investigating the structure when supported by a copper foil (or substrate); mimicking production of PGS on copper. The micro- and nano-scale simulations show that PGS has a great potential to manage heat in micro and nanoelectronics. The fact that PGS is highly tunable makes it a great candidate for thermal management applications. The simulations were successfully conducted and the thermal behavior of PGS at the nanoscale was characterized while accounting for phonon scattering the graphene/CNT junction as well as when PGS is supported by a copper substrate.

Unique layered structure with excellent electrical, mechanical, thermal, and optical properties gives graphene widespread application. Graphene based materials are extensively studied in the field of energy storage such as batteries, hydrogen storage and supercapacitors (SC’s). High surface area, electrical conductivity and mechanical flexibility are notable properties for the materials used in energy conversion systems. Porous spaced graphene oxide (PGO) structures were synthesized by hydrothermal and solvothermal reaction between GO and various pillaring molecules include Tetrakis (4-aminophenyl) methane (TKAm), Ethylenediamine (EDA), 2-Amino-5-diethylaminopentane (ADAP) and 2-Aminoethyl trimethylammonium chloride hydrochloride (ATA). Pristine GO shows interlayer distance of 7.2 Å. Characterisation techniques such as XRD, SEM, FTIR, BET and TGA were used understand the properties of these PGO. In contrast, these pillared structures show interlayer distance greater than of the pristine GO. Notably, GO/TKAm show interlayer distance of 14.30 Å. These pillared structures are considered to solve the restacking and aggregation issues found in 2D porous structures. Since these pillaring molecules help to achieve 3D porous network. Pristine GO shows only surface area of 14 m2/g whereas these materials also show excellent surface area as well. GO/TKAm shows high surface area of 450 m2/g. Followed it GO/ATA shows surface area of 106 m2/g. GO/pillared structures show low sheet resistance which means good electrical conductivity. Ultimately, these pillared structures not only solve the issues in 2D porous systems but also improve the surface area, mechanical stability, and electrical conductivity of those systems by means of 3D porous interconnected structures. All these excellent properties make them a great candidate for the energy conversion systems. / Unik skiktad struktur med utmärkta elektriska, mekaniska, termiska och optiska egenskaper ger grafen en utbredd tillämpning. Grafenbaserade material studeras omfattande inom området energilagring såsom batterier, vätelagring och superkondensatorer (SC). Hög yta, elektrisk ledningsförmåga och mekanisk flexibilitet är anmärkningsvärda egenskaper för de material som används i energiomvandlingssystem. Porösa grafenoxidstrukturer (PGO) syntetiserades genom hydrotermisk och solvotermisk reaktion mellan GO och olika pelarmolekyler inkluderar tetrakis (4-aminofenyl) metan (TKAm), etylendiamin (EDA), 2-amino-5-dietylaminopentan (ADAP) och 2 Aminoetyltrimetylammoniumkloridhydroklorid (ATA). Pristine GO visar mellanskiktsavstånd på 7,2 Å. Karakteriseringstekniker som XRD, SEM, FTIR, BET och TGA användes för att förstå egenskaperna hos dessa PGO. Däremot visar dessa pelarstrukturer mellanskiktsavståndet större än det för den orörda GO. Noterbart visar GO / TKAm mellanskiktsavstånd på 14.30 Å. Dessa pelarstrukturer anses lösa omstaplings- och aggregeringsproblemen som finns i 2D-porösa strukturer. Eftersom dessa pelarmolekyler hjälper till att uppnå 3Dporöst nätverk. Pristine GO visar endast en yta på 14 m2 / g medan dessa material också visar utmärkt yta också. GO / TKAm visar hög yta på 450 m2 / g. Följde den visar GO/ATA en yta på 106 m2/g. GO / pelarstrukturer visar lågt plåtmotstånd vilket innebär god elektrisk ledningsförmåga. I slutändan löser dessa pelarstrukturer inte bara problemen i 2D-porösa system utan förbättrar också ytarean, den mekaniska stabiliteten och den elektriska ledningsförmågan hos dessa system med hjälp av 3D-porösa sammankopplade strukturer. Alla dessa utmärkta egenskaper gör energiomvandlingssystem.