Estudo dos efeitos da oxigenação e hidroxilação sobre as propriedades estruturais e eletrônicas do nitreto de boro hexagonal
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Data
2022-02-08
Autores
Dantas Filho, Reinaldo Vieira
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Universidade Estadual Paulista (Unesp)
Resumo
Materiais nanoestruturados têm recebido grande atenção por parte da comunidade acadêmica após a revolução nanocientífica, ocorrida em meados da década de 1980 com a descoberta de nanoestruturas com propriedades mecânicas e eletrônicas capazes de revolucionar a tecnologia moderna. Somado a isso, a chegada do grafeno com suas propriedades fascinantes, em 2004, acentuou a busca por novos materiais bidimensionais que compartilhassem essas características, e é neste cenário que estruturas alótropas do grafeno se tornaram foco de investigações, como o grafenileno, grafeno poroso e suas versões inorgânicas, compostas por átomos de boro e nitrogênio. É neste contexto em que, através de simulações computacionais, foram estudados sistemas de nitreto de boro hexagonal (h-BN), também conhecido como grafeno inorgânico. Para tal, foi utilizada a aproximação tight-binding da Teoria do Funcional Densidade, a DFTB - implementada através do código aberto DFTB+ -, para realizar otimizações geométricas, cálculos das estruturas de bandas eletrônicas e orbitais de fronteira (HOMO e LUMO) para uma folha de h-BN pura e para os casos onde há a adsorção de oxigênio e hidroxila em baixas concentrações. Foi verificado que para ambos os adsorbatos há a formação de ligações químicas com a rede 2D, alterando algumas propriedades estruturais e eletrônicas do sistema. Os resultados alcançados estão de acordo com aqueles relatados na literatura, obtidos através de métodos ab initio, indicando que a aproximação DFTB é válida para estudar propriedades de sistemas nanoscópicos a partir de uma perspectiva quântica.
Nanostructured materials have received great attention from the academic community after the nanoscientific revolution, which took place in the mid-1980s after the discovery of nanostructures with mechanical and electronic properties capable of revolutionizing modern technology. Added to this, the arrival of graphene with its fascinating properties, in 2004, accentuated the search for new two-dimensional materials that shared these characteristics, and it is in this scenario that graphene's allotrope structures became the focus of investigations, such as graphenylene, porous graphene and their inorganic versions, composed of boron and nitrogen atoms. It is in this context that, through computer simulations, hexagonal boron nitride (h-BN) systems were studied, also known as inorganic graphene. For this, the tight-binding approach of the Density Functional Theory, DFTB - implemented through the open source code DFTB+ -, was used to perform geometric optimizations, calculations of the electronic dispersions and frontier orbitals (HOMO and LUMO) for a pure h-BN sheet and for cases where there is adsorption of oxygen and hydroxyl at low concentrations. It was verified that for both adsorbates there is the formation of chemical bonds with the 2D lattice, changing some structural and electronic properties of the system. The results achieved are in agreement with those reported in the literature, obtained through ab initio methods, indicating that the DFTB approximation is valid to study properties of nanoscopic systems from a quantum perspective.
Nanostructured materials have received great attention from the academic community after the nanoscientific revolution, which took place in the mid-1980s after the discovery of nanostructures with mechanical and electronic properties capable of revolutionizing modern technology. Added to this, the arrival of graphene with its fascinating properties, in 2004, accentuated the search for new two-dimensional materials that shared these characteristics, and it is in this scenario that graphene's allotrope structures became the focus of investigations, such as graphenylene, porous graphene and their inorganic versions, composed of boron and nitrogen atoms. It is in this context that, through computer simulations, hexagonal boron nitride (h-BN) systems were studied, also known as inorganic graphene. For this, the tight-binding approach of the Density Functional Theory, DFTB - implemented through the open source code DFTB+ -, was used to perform geometric optimizations, calculations of the electronic dispersions and frontier orbitals (HOMO and LUMO) for a pure h-BN sheet and for cases where there is adsorption of oxygen and hydroxyl at low concentrations. It was verified that for both adsorbates there is the formation of chemical bonds with the 2D lattice, changing some structural and electronic properties of the system. The results achieved are in agreement with those reported in the literature, obtained through ab initio methods, indicating that the DFTB approximation is valid to study properties of nanoscopic systems from a quantum perspective.
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h-BN, Adsorção, Dispersão eletrônica, DFTB, Grafeno inorgânico, Propriedades estruturais, Adsorption, Electronic dispersion, Inorganic graphene, Structural properties