Mechanism of accelerated zinc electrodeposition in confined nanopores, revealed by x-ray absorption fine structure spectroscopy

Abstract

Recent studies have revealed that electrochemistry at the nanometer scale is profoundly different from its conventional framework. We reported that the combination of a hydrophobic nanoporous electrode and low-charge-density metal ions resulted in a drastic acceleration in the electrodeposition reaction. In the present study, we analyzed Zn embedded in nanoporous silicon by X-ray absorption fine structure spectroscopy. As a precursor to Zn electrodeposition, Zn(II) chelate was used under different pH conditions. The spectroscopy results clearly suggest that the accumulation of Zn(II) chelate occurred at pH conditions where the Zn(II) chelate had zero charge. The accumulation resulted in the promotion of Zn electrodeposition within confined nanopores. Based on this spectroscopic investigation, we propose a model for the accelerated electrodeposition of Zn in confined nanopores.