Structure-Defect-Interface Correlations in Cs _x WO₃/MWCNT Nanocomposites: Implications for Broadband NIR Absorption...

Cs _x WO₃/multiwalled carbon nanotube (MWCNT) nanocomposites were synthesized via a time-controlled solvothermal process to investigate how synthesis duration influences crystallinity, oxygen-related structural features, and oxide-carbon interfacial characteristics. Structural and spectroscopic analyses indicate that lattice ordering and defect-associated features evolve systematically with the reaction time, while MWCNTs serve as conductive scaffolds that promote dispersion, thermal transport, and interfacial coupling. Optical and thermal measurements reveal a clear correlation between oxygen-related states and photothermal behavior. The composites exhibit broad UV-Vis-NIR absorption, which is discussed in terms of localized surface plasmon resonance (LSPR), polaronic transitions, and interfacial interactions. Under NIR irradiation (0.8 W cm^-2 for 300 s), surface temperatures of up to ∼112 °C were achieved, reflecting efficient light-to-heat conversion under concentrated illumination. Overall, this study provides qualitative insight into how the synthesis duration mediates the interplay between structural order, oxygen-related features, and photothermal response in Cs _x WO₃/MWCNT hybrids, offering guidance for the rational design of oxide-carbon photothermal materials.