The Study Of Synthesis Of TiS₂ Nanosheets Via Hot Injected Method And Characteristics Of Their Localized Surface Plasmon Resonances

Localized surface plasmon resonance (LSPR) has many applications, especially in biological and optoelectronic fields, such as photothermal therapy and photodetecting communication, which require LSPRs matched to biological (650-1350 nm) and communication (1260-1675 nm) windows. However, for the classic noble metals (Au, Ag), tuning LSPRs from visible region to these two windows is still very hard due to their intrinsic limitations on charge density and dielectric function.Here, for the first time, we prepared high-quality TiS2 nanosheets (NSs) via a modified hot-injected method, with the virtues including well crystallinity, high dispersity, and high homogeneity. Moreover, both the thickness and planar size of obtained TiS2 NSs can be tuned well.We firstly observed a novel strong absorption peak located at near-infrared (NIR) wavelengths (1000-1400 nm) from the TiS2 NSs suspension, matched with both biological and communication windows, which can be tuned by changing their size or thickness. Then we confirmed the absorbance attributed to the LSPRs of TiS2 NSs by FDTD simulations and experiments, according to its dependence on particle shape and refractive index of solvents.With surface modification, TiS2 NSs were composited with F127 to form TiS2/F127 nanomicelles with wonderful hydrophily. When irradiated under excitations of 808 nm and 980 nm, the superiority of such LSPRs was demonstrated by the ～50℃ photothermal temperature rise after 30 min. Moreover, when TiS2/PMMA film was used to improve the NIR photodetection, the enhancement of photocurrents of PbS photodetectors under excitations of 1310 nm was more than two times. The TiS2 NSs with NIR LSPRs have important significances when applied under both biological and communication windows.