Electrochemical behaviors and electrodeposition of single-phase Cu-Sn alloy coating in [BMIM]Cl

In this work, copper-tin (Cu-Sn) alloy coating was prepared in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) using electrodeposition method. The electrochemical behaviors of different electrolytes and the electrodeposition reversibility of Cu-Sn alloy were studied using cyclic voltammetry (CV). The electro-crystallization mechanism was investigated using chronoamperometry at different step potentials on glassy carbon (GC) electrode. The micromorphology and phase composition of Cu-Sn alloy coatings were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed a new reduction peak located at -0.50 similar to -1.00 V, which belonged to Cu-Sn co-deposition. The reduction of Cu-Sn alloy in this system was an irreversible process. The electro-crystallization of Cu-Sn alloy followed the three-dimensional instantaneous nucleation. The results for micro-morphologies showed that, when the potential is changed, different microstructures can be formed, whereas the morphology changed from snow-like to cypress leaf-like shape. The results for phase composition showed that Cu-Sn alloy coating at different electrodeposition potentials consisted of pure cubic system Cu13.7Sn phase. Additionally, the Cu-Sn alloy deposition from [BMIM]Cl system showed a preferred orientation on (220) crystallographic plane, which is different from the standard card. (C) 2018 Elsevier Ltd. All rights reserved.