title: Predicting Adsorbent and Electronic Properties of Graphene-Based Materials
creator: Piras, Anna
subject: ddc-540
subject: 540 Chemistry and allied sciences
description: Graphene-based materials (GBMs) represent one of the most promising and sustainable alterna-  tives to metal- and silicon-based systems in a plethora of practical applications, from sensing to  catalysis. However, the structural variability and lack of standard testing conditions make the  efficient development of candidates for specific applications challenging. Nowadays, computational  chemistry and materials science can aid experiments by providing crucial understanding of the be-  haviour of GBMs, but the choice of in silico models and theoretical methods is critical to achieve  reliable and insightful results. Furthermore, compositional and structural variety and a broad  range of sizes of GBMs and their molecular (nano-) variants challenge the applicability of highly  accurate ab initio methodologies. Clearly, better guidance is needed when deciding how to simulate  these functional organic materials accurately and efficiently.  The aim of this thesis is to address this need by studying how the choice of in silico model  and of the level of theory influence computed properties of GBMs, from adsorption energetics to  redox transformations. A large set of computational methods is employed, including semiempirical  tight-binding, hybrid, and range-separated density functional theory in finite and periodic settings,  symmetry-adapted perturbation theory and many other wavefunction theory implementations, as  well as several energy and density decomposition approaches. The results are used to benchmark  the performance of these methods, formulate the guidelines for the best-practice techniques, un-  derstand the chemical behaviour of the GBMs, and, ultimately, distil the design principles for new  and improved materials.  The results and discussion of this work are provided in three chapters:  • In Chapter 3 we present an extensive benchmarking of diverse theoretical approaches for  the adsorption of carbon dioxide on pristine graphene across model sizes and derive a simple yet  powerful extrapolation scheme for accurate estimates of the adsorption energies on infinite GBMs.  • In Chapter 4 we present a study on nitroaromatic compounds adsorbed on diverse graphene-  based sensing materials, highlighting the relationship between computed properties and experimen-  tally determined limits of detection, and analysing how the size-dependency of these properties  varies with the chemical nature of the adsorbent.  • In Chapter 5 we transfer the established extrapolation scheme to the redox properties of  GBMs, namely, ionisation energy, electron affinity, and redox potentials. Given complex electronic  structures of the systems involved, we probe the reliability of single-reference approaches. We also  show that, in contrast to adsorption energies, the size-dependencies of these properties are not  affected by the material’s functionalisation.  This works illustrates that choosing an appropriate theoretical methodology for modelling the  chemistry of graphene-based materials is defined by both the balance between cost and accuracy  and by the questions the simulations aim to answer.
date: 2024
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/34612/1/Piras_Anna_PhD_thesis_08_02_2024.pdf
identifier: DOI:10.11588/heidok.00034612
identifier: urn:nbn:de:bsz:16-heidok-346124
identifier:   Piras, Anna  (2024) Predicting Adsorbent and Electronic Properties of Graphene-Based Materials.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/34612/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng