Surface State of Sacrificial Copper Electrode by Electropolishing in Hydrophobic Ionic Liquid 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

Anodic dissolution of natural surface-oxidized, air-annealed, cathodically reduced, and cathodically deposited copper in hydrophobic ionic liquid 1-buthyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide under galvanostatic conditions by means of gravimetric measurements was studied. The resulting samples were mirror-like oxide-free copper pattern. The mechanism of the electropolishing of oxidized copper surface was considered. The consequent anodic reactions Cu2O - 1e = Cu(+) + CuO, CuO - 2e = Cu(2+) + O, and Cu - 1e = Cu(+) take place. The electropolishing itself occurs over oxygen-free copper surface due to competitive residual water discharge in the pits and copper dissolution on the roughness.