Microlandscaping of Au Nanoparticles on Few-Layer MoS sub(2) Films for Chemical Sensing

Surface modification or decoration of ultrathin MoS sub(2) films with chemical moieties is appealing since nanointerfacing can functionalize MoS sub(2) films with bonus potentials. In this work, a facile and effective method for microlandscaping of Au nanoparticles (NPs) on few-layer MoS sub(2) films is developed. This approach first employs a focused laser beam to premodify the MoS sub(2) films to achieve active surface domains with unbound sulfur. When the activated surface is subsequently immersed in AuCl sub(3) solution, Au NPs are found to preferentially decorate onto the modified regions. As a result, Au NPs can be selectively and locally anchored onto designated regions on the MoS sub(2) surface. With a scanning laser beam, microlandscapes comprising of Au NPs decorated on laser-defined micropatterns are constructed. By varying the laser power, reaction time and thickness of the MoS sub(2) films, the size and density of the NPs can be controlled. The resulting hybrid materials are demonstrated as efficient Raman active surfaces for the detection of aromatic molecules with high sensitivity. "On-demand" self-assembly of Au nanoparticles on few-layer MoS sub(2) films is achieved by means of a focused laser beam technique. The location, size, and number density of the Au nanoparticles can be controlled by the combined effects of laser scanning, laser power, reduction reaction time, and MoS sub(2) film thickness. The fabricated hybrids are demonstrated as superior surface enhanced Raman scattering substrates with high sensitivity.