Facile preparation of Prussian blue electrochromic films for smart-supercapattery via an in-situ replacement reaction

Abstract

As an attractive electrochromic (EC) material, Prussian blue (PB) holds many praiseworthy merits such as environmental benignity, low cost, proper redox potential, and fast electrochemical kinetics, thanks to their unique open framework structure consisting of common elements. However, restricted by the available synthetic methods and the formation of crystallographic imperfects, facile fabrication of large areal and high performance PB EC layers is still challenging. In this article, we establish a simple yet effective protocol to prepare PB EC layers with the assistance of ITO nanoparticle (ITO-np). This preparation method involves just an interfacial precipitation reaction between Fe(CN)64- from the electrolyte and Fe3+ from the acid-etched sacrifice layers. The ITO-np, as a transparent conductive additive, is used to enhance not only electrical conductivity but also adhesion strength of the prepared PB EC layers. The whole processes can be completed under atmospheric pressure without requests of any sealed reaction spaces, and thus should be very friendly to scale up fabrication. The as-prepared PB layers demonstrate decent EC performances with a transmittance modulation of 59.9% at 633 nm, a bleaching/coloring time of 12 s/8s, a cycling lifetime with 77% transmittance modulating ability remained after 1200 cycles, along with a remarkable charge storage/release ability. This work provides an alternative approach for the facile preparation of PB-based films for applications of both EC devices and smart-supercapatteries.