Constructing Reversible Zn/MnO₂ Dual‐Electrodeposition‐Based Smart Window with Wide Modulation Range by an Iodide Mediator in Near‐Neutral Electrolyte

Abstract Conventional reversible manganese dioxide (MnO 2 ) electrodeposition‐based smart windows typically endure the constraints of narrow light modulation range, non‐neutral color, and highly acidic electrolytes. Herein, novel Zn/MnO 2 dual‐electrodeposition‐based smart windows are constructed utilizing near‐neutral electrolytes (pH = 5.74). The devices broaden the light modulation range of MnO 2 by reversible Zn electrodeposition, achieving a remarkable color change between transparent and neutral dark brown (chroma C * = 9.48). Furthermore, an iodide (I − ) as a redox mediator is used to significantly prolong the devices’ cycling durability by promoting the dissolution of MnO 2 and Zn. I − chemically reduces MnO 2 to form Mn 2+ and is oxidized to triiodide (I 3 − ), I 3 − then spontaneously oxidizes Zn to form Zn 2+ and is reduced back to I − , thus completing one mediator cycle. Consequently, the devices with the I − mediator exhibit impressive cycling durability (1,000 vs 60 cycles). Finally, the significant potential difference between the Zn and MnO 2 electrodes endows the devices with excellent energy storage performance. The study offers a line of thought for developing novel multifunctional devices.