Fig. 1: Airborne sound-absorbing mechanism with triboelectric effect introduced in the porous fibrous triboelectric composite (TEC) foam absorber.

a Schematics representation of the fibrous TEC foam absorber, with a detailed zoom-in illustrating two intersecting fibers (Fiber 1 and Fiber 2). Interaction between these fibers is activated by incoming acoustic waves, inducing relative movements among fibers, and initiating the triboelectric effect within their overlapping contact region. Fiber 1 and Fiber 2 represent a complementary pair of positive and negative triboelectric materials, respectively. The triboelectric charges generated during this interaction are dissipated through conductive elements and eventually transformed into heat. b Schematic illustration of the sound absorption mechanisms of the fibrous TEC foam. c Contact electrification and electrostatic induction between the two fibers, prompted by the relative movement of adjacent fibers. d An overview of the mechano-electro-thermal conversion in fibrous TEC foam for sound absorption, emphasizing the energy conversion perspective: mechanical energy of sound waves undergoes transformation into electrical energy via the triboelectric effect, the charges are subsequently dissipated, culminating in the completion of electro-thermal conversion chain and facilitating effective noise attenuation.