Synergetic effect of MXene/MoS2 heterostructure and gradient multilayer for highly sensitive flexible piezoelectric sensor

In this study, we proposed a flexible piezoelectric sensor made of gradient multilayer polyacrylonitrile (PAN) MXene/Molybdenum disulfide (MoS2) nanocomposites prepared by layer-by-layer electrospinning technology. Each layer of the composite film was formed by adding different mass ratios of MXene and MoS2 (MXene: MoS2 = 4:1, 2:1, 1:1) as filler materials, with a constant content of MXene (2% of the PAN matrix), and the concentration of MoS2 increases progressively from the inner layer to the outer layer. In addition, a heterojunction structure was formed using MXene and MoS2, which formed hydrogen bonds with -CN on PAN, thereby enhancing their interaction. By employing this novel concept of gradient multilayer and 2D/2D heterostructure, the interface coupling effect could be effectively promoted, and more 31-helical conformations could be transformed into planar zigzag conformations, significantly improving the dielectric, ferroelectric, and piezoelectric properties of the multilayer composite fiber films, thereby enhancing its output performance. With the gradient multilayer structure, the piezoelectric sensor exhibited excellent voltage sensitivity (14.9 V/N). The piezoelectric sensor detected body movement during basketball shooting and offered excellent breathability for enhanced comfort. It shows promise for use in health monitoring, electronic skin, and human-computer interaction.