A novel dual-functional layer exhibiting exceptional protection and photocatalytic activity by organic functionalization of plasma electrolyzed layer

Abstract

The formation of inorganic-organic hybrids (IOH) on the metallic substrates would play a decisive role in improving their structural and functional features. In this work, the growth of organic coating (OC) consisting of coumarin-3-carboxylic acid (3-CCA) and albumin (ALB) on the inorganic layer (IC), produced by plasma electrolysis of AZ31 Mg alloy, led to enabling organically synergistic reactions on the porous inorganic surface, forming a flake-like structure sealing the structural defects of IC. Synergistic actions between OC and IC endow the flake-like structures with chemical protection and photocatalytic performance. Upon contact with a corrosive solution, the IOH layer possesses stable morphologies that delay the corrosive degradation of the whole structure. The electrochemical stability of the sample produced by immersion IC in the organic solution for 10 h (IOH2 sample) was superior to the other samples as it had the lowest corrosion current density (1.69×10−10 A.cm−2) and the highest top layer resistance (1.2 × 107 Ω.cm2). Moreover, the IOH layer can photodegrade the organic pollutants in model wastewater, where the highest photocatalytic efficiency of 99.47% was found in the IOH2 sample. Furthermore, computational calculations were performed to assess the relative activity of different parts of the ALB and 3-CCA structures, which provide helpful information into the formation mechanism of the IOH materials.