Dual Deposition Dynamic Windows Based on Reversible Bismuth and Manganese Oxide Electrodeposition

Dynamic windows are electronically controlled devices with tunable opacity that can reduce the energy consumption of buildings. Within the past decade, reversible metal electrodeposition (RME) techniques have been researched for use in such devices. Most RME research focuses on reduction processes to metal films, however much less explored is the reversible oxidation of metal ions to form thin films of metal oxides. In this manuscript, we study the fundamental electrochemistry of reversible MnO2 electrodeposition for dynamic window applications. The electrolyte and transparent conducting electrode are optimized through various control experiments. Furthermore, the spectroelectrochemical compatibility of MnO2 with Zn, Cu, and Bi is investigated through deliberate electrolyte design. The Bi/MnO2 electrolyte demonstrates compatible functionality within the same electrolyte and is engineered into a dual tinting dynamic window device. From this device, an optical modulation of 70% at 600 nm is observed with a tinting time of 60 s and a subsequent clearing time of 10 s. This study presents a foundational analysis of Mn2+/MnO2 for application in dynamic windows and a promising outlook for the development of dual tinting reversible electrodeposition devices utilizing this chemistry.