Conductive rGO interlayer enabling uniform Zn electrodeposition and enhanced corrosion resistance of biodegradable magnesium alloys

Abstract

Magnesium alloys have attracted increasing interest as biodegradable implant materials. However, their excessively rapid corrosion in physiological environments severely limits clinical applications. In this work, an rGO/Zn composite coating was successfully constructed on a magnesium alloy surface through a multi-step process involving electrophoretic deposition of GO, thermal reduction, and subsequent Zn electrodeposition. Reduced graphene oxide was introduced as an intermediate layer to improve surface conductivity and enable uniform Zn deposition, addressing the difficulty of directly depositing Zn on magnesium substrates. The effects of Zn 2+ concentration and deposition time on the coating microstructure, adhesion, and corrosion resistance were systematically investigated. The results demonstrate that the rGO interlayer significantly enhances the uniformity and compactness of the Zn coating. The rGO/Zn composite coatings effectively suppress hydrogen evolution, mitigate solution alkalization, and markedly improve the electrochemical stability of magnesium alloys in simulated body fluid. Among all samples, the rGO/Zn-0.1/20 coating exhibits the best overall corrosion resistance, with the corrosion rate reduced to 0.28 mm y −1 . XRD analysis after immersion reveals that the formation of stable corrosion products, including ZnO and Zn 5 (OH) 8 Cl 2 ·H 2 O, plays a critical role in enhancing the long-term protective performance of the composite coating.