The role of electrolyte ratio in electrodeposition of nanoscale Fe-Cr alloy from choline chloride-ethylene glycol ionic liquid: A suitable layer for corrosion resistance

Nanoscale Fe-Cr alloy is successfully electrodeposited in choline chloride-ethylene glycol (ChCl-EG, mole ratio 1:3) deep eutectic solvent (DES) at two-electrode system by optimizing concentration ratio c(Fe(II))/c(Cr (III)). ESI-MS analyses indicate [Fe(H2O)(3)(Cl)(3)] and [Cr(H2O)(2)Cl-4] are the dominant species of Fe(II) and Cr(III) in ChCl-EG DES, respectively. Linear sweep voltammetry demonstrates that with the increase of c(Fe (II))/c(Cr(III)) from 1:5 to 1:1, the reduction potential difference between Fe(II) and Cr(III) will become smaller, which is conducive to the electrodeposition of Fe-Cr alloy deposit with a higher Cr content. The reduction of Fe(II) or Cr(III) on glassy carbon electrode is a quasi-reversible process controlled by diffusion with a diffusion coefficient of 5.34 x 10(-6) cm(2).s(-1)and 2.22 x 10(-6) cm(2).s(-1). FE-SEM observation shows that as the cFe(II)/cCr(III) decreases from 1:2 to 1:5, the microstructure becomes uneven with the morphology transform from homogeneous particles to scaly blocks. At 1:2, the prepared nanocrystalline Fe-Cr alloy has a symmetrical element distribution with a mean coating thickness of 120.3 lm and a mean diameter of X1.56 nm. Corrosion resistance test manifests the prepared Fe-Cr alloy possesses good corrosion resistance. All the above studies provide a theoretical foundation for Fe-Cr alloy production by varying electrolyte ratios. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Nanoscale Fe-Cr alloy is electrodeposited in a Choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES) successfully. The concentration ratio of Fe(II) to Cr(III) affects the reduction potential difference and enables control over the Cr content of the alloy deposit.