Synthesis of highly transparent and fast-responding photochromic coating by template method with space-limited domains

The persistent global high-temperature weather warns us that improving energy efficiency and reducing CO 2 emissions are urgent. Controlling the solar energy input in buildings using photochromic smart coating can effectively reduce the energy consumption required for cooling. However, it remains a challenge to achieve high transparency and fast photoresponse in organic–inorganic hybrid photochromic smart coating. Herein, we utilize space-limited domains to design a template polymer that facilitates the formation of amorphous WO 3 nanodots, thereby enhancing the polymer network structure through hydrogen bonding and dipole–dipole interactions, which endow the smart coating with excellent adhesion strength up to 13 MPa. Notably, the photochromic smart coating with amorphous WO 3 nanodots exhibits higher transparency (96.8 %) than conventional glass (91 %), and a wide visible light modulation range of 96.8 %-4.8 %. Based on this, the cooling efficacy of the smart photochromic coating was assessed within a model residence under actual environmental conditions. The inner temperature of the model house was reduced by up to 13 °C, which decreased indoor heat absorption by 25.8 %, significantly improving energy efficiency. This work provides an important and attractive strategy for achieving energy-efficient building materials and addressing global climate warming.