Laser-ablation synthesis of novel tungsten disulfide nanostructures in liquid and their charge transfer dynamics with gold nanoparticles.

In recent years, tungsten disulfide (WS₂), a type of 2D nanomaterial, has garnered significant attention as a promising new material due to its unique properties. Research efforts are underway to explore its various applications. In this study, we employed a liquid-phase laser ablation technique using two different pulse lasers, with a 10 ns or 130 fs pulse duration, to fabricate WS₂ nanostructures and conducted thorough evaluations of their physical properties. Additionally, we fabricated and evaluated WS₂-gold nanocomposites by decorating WS₂ with gold nanoparticles. Femtosecond transient absorption measurements revealed that in samples subjected to the shorter pulse width, the free carrier relaxation rate up to recombination was slower, with free carriers disappearing within tens of picoseconds, leaving only trapped species as long-lived entities. Furthermore, in gold-decorated samples, the interaction between gold nanoparticles and WS₂ suggested that excited electrons underwent interfacial charge transfer and formed charge separated states, resulting in a slower relaxation time before recombination.