Conformal formation of physically cross-linked dual-network hydrogels on porous surface for excellent electrochemical performance and self-healing behavior

Abstract

Despite significant advances in multilayer hybrid composite structures for exceptionally promising applications, controlling their chemisorption and growth on stationary platforms for excellent anti-corrosion and self-healing properties remains challenging. In this study, we coated porous MgO on magnesium substrate, and alginic acid sodium salt (ALG) with hydroxypropyl methylcellulose (HMC; layer-forming agent) and sodium calcium (CaCl₂; self-healing agent), respectively, via a combination of interfacial plasma electrolysis (I-PE) and dip chemical coating (DCC). The HMC-ALG layer grew on the platform surface via robust physical and chemical bonds, affording HMC-ALG mats with two-dimensional morphologies. Polarization analysis and electrochemical impedance spectroscopy (EIS) measurements of HMC-ALG/MgO in a 3.5 wt% NaCl solution demonstrated its excellent electrochemical performance (inhibition efficiency of 98.79 %), due to the electron donor effect of the hydroxyl group and cross-linking behavior between ALG and CaCl₂. This elucidates the anti-corrosive mechanism of the additional layer with chemically adsorbed Mg–O bonds on the inorganic layer. This dual-network hydrogel offers good self-healing abilities, with healing efficiencies reaching up to 86 % within 45 min, owing to robust hydrogen bonding and aggregation during stretching. These results highlight the promise of the hydroxyl group's electron donor effect and cross-linking behavior for enhancing electrochemical performances with self-healing ability.