A Grazing-Incidence SEM Strategy for High-Contrast Imaging of Multiscale Nanomaterials. MoS2, a Case Study

Scanning electron microscopy (SEM) is a powerful tool for the morphological characteri-zation of multiscale nanomaterials, including two-dimensional (2D) systems such as graphene and molybdenum disulfide (MoS₂). However, conventional SEM imaging often struggles to resolve nanoscale features due to limited contrast and depth sensitivity, espe-cially when dealing with ultrathin layers. In this work, we propose and demonstrate a simple yet effective strategy to overcome these limitations by exploiting grazing-incidence (radent) observation, achieved through a controlled tilting of the sample close to 90°. This approach significantly enhances the emission of secondary electrons from near-surface regions, thereby increasing image contrast and revealing morphological details, such as edges, ripples, defects, and overlapping layers, that remain hidden under standard imag-ing conditions. Optical characterization of the prepared MoS₂ colloids further supports the formation of monolayer and few-layer sheets, validating the structural information ob-tained from SEM. Interestingly, this approach recalls natural strategies observed in living organisms, where grazing-angle vision improved edge perception and surface recognition and therefore it can be considered as bio-inspired. Beyond its application to MoS₂, this biomimetic methodology offers a versatile and broadly applicable solution for improving morphological analysis of 2D nanomaterials and thin films, providing deeper insights into their structural characterization.