WO3 Nanorod Array-Modified Prussian Blue with Long Cycling Stability for High-Performance Dual-Band Electrochromic Materials

Dual-bandelectrochromic (EC) smart windows are a promising energy-savingtechnology because they can control indoor temperature by modulatingthe transmitted light in visible and near-infrared (NIR) regions.The key to smart windows is the preparation of well-performed dual-bandEC materials (ECMs). Prussian blue (PB) is a typical anodic ECM withmultiple colors, high capacity, and excellent electrochemical activity.However, due to the lattice expansion and low electron density ofPB, the poor cycling stability and tedious modulation in the NIR regionseverely limit its wide application. Herein, we proposed a stabilizationstrategy to construct a one-dimensional WO3 array-modifiedPB with porous core-shell structures (named PB@WO3). Because of the porous structure and the heterostructure betweenWO(3) and PB, the PB@WO3 showed excellent stability(the current density did not exhibit obvious changes after 1000 cycles)and high coloring efficiency (62.3 cm(2)/C). Besides, themodification of WO3 also provided PB@WO3 witha dual-band modulation ability under low voltages (35.14% at 633 nm,60.55% at 1200 nm, and 67.18% at 1800 nm). Simultaneously, the combinationof WO3 and PB rendered PB@WO3 with three colors,i.e., white, blue, and green. Furthermore, the one-dimensional arraystructure and the interaction between WO3 and PB impartedPB@WO3 with fast switching speed (0.5 and 0.5 s per eachcoloration and bleaching cycle, respectively).