Engineering defects in 2D g-C3N4 for wideband, efficient electromagnetic absorption at elevated temperature

Abstract

Metal-free 2D nanomaterials such as graphitic carbon nitride (g-C₃N₄) nanosheets have attracted enormous attention due to their ultralow mass density, excellent chemical stability, high specific surface area, unique electronic structure and permittivity. However, the electromagnetic (EM) wave absorption performance of g-C₃N₄ cannot satisfy the requirements for addressing the ever-increasing occurrence of EM pollution. Herein, we demonstrate that the creation of pores in g-C₃N₄ nanosheets, combined with subsequent doping with phosphorus (P) and sulphur (S) atoms, give rise to a continuous frequency dispersive behaviour along with an enhanced conductive loss capability. As a result, the S/P-doped nanoporous g-C₃N₄ exhibit an efficient EM absorption over a wide frequency region (e.g., 6.0 GHz of >90% of absorption effectiveness at a sample thickness of 1.8 mm) at elevated temperatures (e.g., >4.0 GHz of >90% of absorption effectiveness at a thickness of 1.2 mm at 150 °C). Overall, our results reported in this work unmask new principles by which metal-free 2D nanomaterials can be modified to enable a significant enhancement in their EM absorption performance.