Chromophores assisted phytochemicals and pheromones coatings on porous inorganic layers for enhancing anti-corrosion and photocatalytic properties

Abstract

This work aims to enhance the anti-corrosion and photocatalytic activity of porous inorganic layers through a novel approach involving the exploitation of chromophores derived from phytochemicals and pheromones. Herein, organic acid (carminic acid) and organic salt (indigo carmine) obtained from pheromones and phytochemicals, respectively, are utilized to modulate the porous surface of inorganic layers produced on AZ31 Mg alloy via plasma electrolytic oxidation. Such pheromones and phytochemicals coatings have a double link inside them along with negatively charged functional groups, which enabled the sealing of the sponge-like structure of the inorganic layer through a couple of bonding mechanisms, such as hydrogen bonding, π-π interaction, as well as electrostatic interactions between polar parts of such organic molecules and cationic species generated from the inorganic layer. The phytochemical coating exhibited superior electrochemical stability compared to other samples, as demonstrated by its high polarization resistance (1.27 × 10+8 Ω.cm+2). Additionally, the phytochemical coating demonstrated the ability to photodegrade methylene blue, achieving a photocatalytic efficiency of 99.47 %. The stacked and parallel interactions of the phytochemical and/or phermonic layer on the surface of inorganic layers were explored with the aid of density functional theory.