Laser driven exfoliation and in situ engineering of MoS₂/WS₂-Ag nanocomposites for high-performance electrochemical sensing and photonic applications

We reveal a new laser-mediated strategy for the simultaneous exfoliation and functionalization of molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂), producing few-layered TMD nanosheets directly decorated with silver nanoparticles (Ag NPs) in a one-step, reductant-free process. Employing nanosecond pulsed laser ablation in liquid, the process utilizes laser-induced localized defect generation as active nucleation sites for Ag, allowing for controlled morphologies without chemical stabilizers. Subsequent laser ablated MoS₂/WS₂-Ag nanohybrids exhibit ultrahigh electrochemical sensing sensitivity for dopamine and ascorbic acid with an unprecedented low limit of detection of 0.1 nM, better than the majority of the highest-ranked nanocomposite sensors. In-depth spectroscopic and microscopic characterization confirms that laser parameters play a pivotal role in determining nanosheet thickness and Ag NP size/distribution, permitting tunability of electrochemical output. In addition, the composites display significant nonlinear optical limiting behavior, confirming their multitasking ability. This research presents an environmentally friendly, scalable approach for engineering defect-rich 2D TMD platforms with built-in plasmonic functionality and establishes a new standard for next-generation sensor and optical nanodevice design.