Electrodeposition of Superhydrophobic Cu Film on Active Substrate from Deep Eutectic Solvent

A hierarchical rough Cu film constructed by nanosheet-like clusters is electrodeposited on Fe and Mg alloy substrates from a deep eutectic solvent based electrolyte containing CuCl2 and NaH2PO2 at 75 degrees C (CuP-75 degrees C). After modifying by stearic acid for 5 min, the film turns from superhydrophilic to superhydrophobic with a water contact angle (CA) of 161. and a sliding angle of similar to 1.0 degrees. For comparison, the electrodeposited Cu film from the electrolyte only containing CuCl2 (Cu-75 degrees C) exhibits more hydrophilic. Smaller CA value is obtained at lower deposition temperature due to the decrease in surface roughness. The CA value of the CuP-75 degrees C film increases with increase of the surface modification time. Amazingly, only 3 min of stearic acid modification at room temperature can make the CuP-75 degrees C film superhydrophobic with a CA of 155 degrees. Such a fast process is attributed to the chemical reactions of the native CuO formed on the film surface with stearic acid and physical absorptions caused by larger specific surface area. The superhydrophobic CuP-75 degrees C film exhibits a positively shifted E-corr (-356 mV vs. Ag/AgCl) and a decreased icorr (7.07 mu A cm(-2)) compared with the hydrophilic counterpart film, thus providing effective protections for active substrates. (C) 2015 The Electrochemical Society. All rights reserved.