Nb2CTx Mxene—Pistachio Shell-Filled Chitosan Coatings on Zn Biomaterial for In Vitro Corrosion and Bioactivity Improvement

This study aims to enhance the corrosion resistance and bioactivity of zinc surfaces through the development of chitosan–pistachio shell (CPM) coatings reinforced with Nb2CTx MXene. The approach introduces a sustainable pathway by incorporating waste pistachio shells as a natural, eco-friendly additive within a biopolymer matrix. Comprehensive structural and surface characterizations confirmed the homogeneous dispersion of Nb2CTx and the successful fabrication of the hybrid coating. Electrochemical analyses in simulated body fluid demonstrated that the CPM coatings markedly improved the corrosion protection of zinc by shifting the corrosion potential to more noble values, reducing current density and increasing polarization resistance. Impedance results further indicated enhanced charge transfer resistance and stable diffusion-controlled behavior. The coatings also exhibited stronger adhesion, higher hydrophilicity, and improved surface compatibility. After immersion in simulated body fluid, the formation of a dense apatite layer on the CPM surface confirmed the coating’s excellent bioactivity. These findings demonstrate that Nb2CTx-reinforced CPM coatings significantly enhance the functional performance of zinc, combining corrosion resistance, biocompatibility, and mechanical stability. Moreover, the use of pistachio shell waste underscores the potential of sustainable biomaterials in developing environmentally friendly coatings for biomedical applications.