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 dramatically improve the electrochromic performance. Unambiguous evidence of performance enhancement 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.