Fabrication of functionalized coating with a unique flowery-flake structure for an effective corrosion performance and catalytic degradation

Abstract

• Inorganic coating layers are hybridized with organic corrosion inhibitors. • Flowery-flake structures are formed by heterogeneous nucleation. • Crystal growth is formed via Layer by Layer self-assembly process. • Formation of stable coordination complexes via molecular orbital interactions. • Functionalized coating with catalytic activity and corrosion protection. The hybridization of organic compounds with inorganic layers would lead to the discovery of novel organic–inorganic hybrid materials with desired functional properties, which could open new avenues toward their state-of-the-art applications. In the present work, therefore, a hybrid organic–inorganic functionalized coating with unique flowery-flake structures was successfully deposited on the defective surface of plasma electrolysis (PE) coating via layer-by-layer self-assembly process of 1-azanaphthalene-8-ol molecules. Herein, two types of defective coatings obtained via PE treatments of AZ31 Mg alloy using either silicate or phosphate-based electrolyte systems were sealed additionally by ethanoic solution of 1-azanaphthalene-8-ol for 24 h. Although the formation level of unique flowery-flake structures has relied on the composition of the defective surface of PE coating, an organic–inorganic hybrid functionalized coating exhibiting high corrosion stability with a trade-off catalytic activity has been successfully obtained. Detailed analysis of the surface morphology of this coating suggested that the formation of stable coordination complexes, due to the molecular orbital interactions of azanaphthalene-8-ol molecules with the PE coating layer, would be the main reason for such performance. The roles of lone pairs and net charges of heteroatoms within 1-azanaphthalene-8-ol molecules during initial physisorption and chemisorptions are computationally analyzed. The mechanism underlying the heterogeneous nucleation and crystal growth of unique flowery-flake structures was discussed by impedance and computational analyses.