Femtosecond Laser Carburization of WS2 Flakes to W2C for Enhanced Photothermal Conversion Efficiency

Abstract

Photothermal therapy is a new, promising approach for treating cancer in a noninvasive way. Herein, a photothermally efficient nanomaterial is synthesized by exposing bulk WS2 powder, dispersed in carbon‐rich acetonitrile, to high‐intensity femtosecond laser pulses. The photothermal measurements show a significantly higher rise in temperature and enhance photothermal efficiency for the laser‐treated material. The attribution is on the enhancement to the formation of tungsten semi‐carbide (W2C), which is verified by morphological and structural characterization. The tungsten semi‐carbide is formed by laser‐induced carburization; intense laser pulses knock S atoms out of the WS2 lattice and dissociate the acetonitrile molecules, resulting in the formation of W2C. Interestingly, the hexagonal W2C has a two‐dimensional (2D) layered morphology like that of the WS2, suggesting its morphology is not random and might be determined by the morphology of the parent material. The study provides a simple route to transform a 2D transition‐metal dichalcogenide into a 2D transition‐metal carbide, which is useful for applications including photothermal therapy.