Laser-Induced photothermal activation of multilayer MoS₂ with spatially controlled catalytic activity

This study investigates the effects of high-power laser irradiation on multilayer MoS₂, a promising material for catalysis, optoelectronics, and energy applications. In addition to previously reported sculpting of MoS₂ layers, we discovered a novel effect of laser-induced photothermal heating that drives the chemical activation of MoS₂. The photothermal effect was confirmed by temperature-dependent experiments, in situ temperature measurements with nanolocalized probes, and simulations. Remarkably, we observed the reduction of Ag⁺ ions on laser-irradiated MoS₂ layers, forming plasmonic nanostructures without external stimuli such as photons or chemical reducing agents. We attribute this phenomenon to the significant defect density within the laser-carved region and the surrounding area induced by photothermal effects. Further functionalization of the laser-modified MoS₂ with 4-nitrobenzenethiol self-assembled monolayers demonstrated a significant increase in photocatalytic activity, close to 100% yield compared to the negligible activity of pristine material. Our findings contribute to a deeper understanding of the light-induced modification of MoS₂ properties and introduce a novel method for spatially controlling the chemical activation of MoS₂. This advancement holds significant potential in developing high-performance 2D semiconductors as nano-engineered catalytic materials.