Controllable Regulation of MoS2 Surface Atomic Exposure for Boosting Interfacial Polarization and Microwave Absorption

Atomic-level surface design of 2D materials, which benefits from their ultra-high occupancy of surface atoms, has demonstrated significant potential for regulating electronic states. Despite efforts to explore heterojunctions on 2D surfaces, the stacking-dominated surface electronic structures and their influences on dielectric polarization remain unclear. Herein, a confined growth strategy is proposed to accurately adjust the surface atom occupancy of MoS2 nanoflakes and thereby boost the polarization-dominated microwave absorption (MA). By altering the stacking layer number from single layers to tens of layers of MoS2, the charge transfer from graphite substrate to MoS2 surface atoms, accompanied by the formation of local electric fields, reaches its highest intensity at two layers and then degrades dramatically with thicker MoS2 nanoflakes. The strengthened dielectric properties eventually enhance the MA performance, increasing the maximum absorption intensity (41.9 dB) by 346% and the effective absorption bandwidth (3 GHz) by 750%. These discoveries shed new light on the electronic modification of 2D materials and their electromagnetic functionalization.