Rational Cationic Disorder in Hexagonal Cesium Tungsten Bronze Nanoparticles for Infrared Absorption Materials

Hexagonal cesium tungsten bronze (Cs_0.33WO₃) nanoparticles (NPs) have attracted attention for their potential applications in near-infrared (NIR) absorbing materials. However, the insufficient Cs doping in Cs_0.33WO₃ NPs has limited their NIR absorbing capabilities and practical stability. In this study, we demonstrate the transition pathway from intermediate W-defective Cs_0.33WO₃ NPs synthesized by flame spray pyrolysis to cationic (Cs, W)-disordered Cs_0.33WO₃ NPs prepared through appropriate heat treatments. Direct atomic observations reveal the basal shear and prismatic (Cs, W)-defective planes, which contributed to the disorder of full Cs doping in Cs_0.33WO₃ NPs. The obtained Cs_0.33WO₃ NPs with cationic disorder exhibited enhanced practical performance compared with conventional Cs_0.33WO₃ NPs. Therefore, the developed approach that regulates cationic disorder enables the rational design of defective metal oxides for a variety of applications, including NIR absorbing materials.