How Density Functional Theory Surface Energies May Explain the Morphology of Particles, Nanosheets, and Conversion Films Based on Layered Double Hydroxides

abstract

Conversion films based on layered double hydroxides constitute an important and environmentally friendly technology for the corrosion protection of aeronautical structures. Unfortunately, the morphology of layered double hydroxide (LDH) conversion films is still not well understood. In the present work, the structure and driving forces behind the morphology of zinc aluminum LDH conversion films on aluminum alloy 2024 (AA2024) are explained from the perspective of molecular modeling. Since LDH particles are the core structures of LDH conversion films, the first step in this work was to understand the relation between structure and morphology of the particles themselves and the single-layer nanosheets that constitute them. Results regarding LDH's crystallites, particles, and conversion films obtained using X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) are interpreted using periodic model density functional theory (DFT) calculations. On the basis of the understanding of the formation of LDH particles and their exfoliation to obtain single-layer nanosheets, for the first time, LDH conversion films have been modeled using periodic model DFT. The results point to a preferential orientation of the cationic layers perpendicular to the surface, thus explaining the film morphology (SEM and AFM) and providing a rational for their crystallization process.

keywords

ACTIVE CORROSION PROTECTION; HYDROTALCITE-LIKE COMPOUNDS; OXYGEN EVOLUTION CATALYSIS; FORMATION MECHANISM; LDH; ALUMINUM; NANOCONTAINERS; INSIGHTS; COMBINATION; EXFOLIATION

subject category

Chemistry; Science & Technology - Other Topics; Materials Science

authors

Galvao, TLP; Neves, CS; Zheludkevich, ML; Gomes, JRB; Tedim, J; Ferreira, MGS

Groups

G3 - Electrochemical Materials, Interfaces and Coatings
G6 - Virtual Materials and Artificial Intelligence

Projects

CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)

Unveiling the self-healing mechanisms associated with smart nanocontainers (SELMA)

Multifunctional nanostructured conversion films based on Layered Double hydroxides for corrosion protection of aeronautical structures (PTDC/CTM-MAT/1515/2012)

Development of smart nano and microcapsulated sensing coatings for improving of material durability/performance (SMARCOAT)

MULTI-functional metallic SURFaces via active Layered Double Hydroxide treatments (MULTISURF)

NanoBarrier - Extended shelf-life biopolymers for sustainable and multifunctional food packaging solutions (NanoBarrier)

acknowledgements

This work was developed in the scope of the project CICECO Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable cofinanced by FEDER under the PT2020 Partnership Agreement. Financed in the framework of project reference PTDC/QEQ-QFI/4719/2014, funded by Project 3599 - Promover a Producao Cientifica e Desenvolvimento Tecnologico e a Constituicao de Redes Tematicas (3599-PPCDT) and FEDER funds through COMPETE 2020, Programa Operacional Competitividade e Internacionalizagab (POCI). The authors also thank financial support from FCT and COMPETE (PTDC/CTM-MAT/1515/2012 and Programa Investigador FCT). J.T. thanks FCT for the research grant IF/00347/2013. This work has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreements No 645662 and No 645676. This work has also received funding from the European Union's Seventh Framework Programme (FP7/ 2012-2016) under the grant agreement no. 280759.