Enhanced electrochromic performance by anodic polarization in nickel oxide films

Abstract

Nickel oxide (NiO) is considered to be the best candidate for the compensatory layer of WO3-based smart windows. In this article, we demonstrate that a facile anodic polarization can dra-matically improve the electrochromic performance. Unambiguous evidence of performance en-hancement was demonstrated by both in situ optical response and cyclic voltammetry. Benefiting from this treatment, the quantity of voltammetric charge increased by ∼43.8% under the same test conditions, enhancing the corresponding electrochromic modulation by ∼17.6 %. The improved performance is due to the newly exposed high-valence Ni3+ ions during anion-dependent anodization. These results offer a novel strategy for the preparation of high-performance NiO films and provide valuable insights into the underlying mechanism in the electrochromic process.