Co-precipitation synthesis of Cu2V2O7 nanoparticles and electrochemical investigation of the corrosion resistance of Zn–Cu2V2O7 composite coatings on mild steel in 3.5 wt% NaCl and 0.1 M HCl solutions

Abstract

The present work reports the synthesis of a novel brightener from the condensation of vanillin and L-isoleucine. The Cu₂V₂O₇ nanoparticles were synthesized by a simple co-precipitation method, and were characterized with the help of various techniques, such as XRD, FESEM, EDX, TEM, UV-visible spectra and FTIR. The XRD analysis confirmed the formation of monoclinic β-Cu₂V₂O₇ with an average particle size of 20 nm, while FESEM and TEM analysis revealed the uniform distribution of the nanoparticles. The UV spectra confirmed the optical band gap of 2.5 eV. The synthesized nanoparticles were utilized for co-deposition with zinc onto mild steel using the electroplating technique. Surface characterisation of the composite coating showed a compact, homogeneous coating with improved hydrophobicity (103.8°) compared to pure zinc (78.3°). Electrochemical studies in 3.5 wt% NaCl and 0.1 M HCl solutions showed that the composite coating has a higher corrosion resistance. The Zn–Cu₂V₂O₇ composite coating exhibited a higher charge transfer resistance (R_ct = 3427 Ω cm² and R_ct = 2472 Ω cm² in NaCl and HCl, respectively) and a lower corrosion current density (I_corr = 1.721 × 10⁻⁶ A cm⁻² and I_corr = 4.408 × 10⁻⁶ A cm⁻² in NaCl and HCl, respectively) than the pure Zn coating. These results confirmed that the inclusion of nanoparticles into the zinc matrices effectively inhibits the corrosion of mild steel compared to the bare zinc coating.