Waste to wealth: Lightweight, mechanically strong and conductive carbon aerogels from waste tissue paper for electromagnetic shielding and CO2 adsorption

Carbon aerogels (CAs) have always shown great potential for multifunctional applications. However, simultaneous improvement of mechanical, electrical and thermal properties of CAs with low density is still a big challenge due to their structural defects, disordered microstructure, and colossal oxygen containing functional groups. Herein, a subtle approach is developed to prepare CAs from waste tissue paper (WTP) and poly(vinyl alcohol) (PVA) as the basic ingredients. The WTP-PVA CAs possessed a highly interconnected three-dimensional porous structure with low density (0.057 g cm(-3)), high porosity (similar to 97%) and specific surface area (1384 m(2) g(-1)). Albeit with low density, the resultant CA displayed superior mechanical properties (specific Young's modulus up to 1246.8 MPa cm(3) g(-1)) and thermal stability. Besides, they also featured high electrical conductivity (1.35 S cm(-1)) and low thermal conductivity (0.087 Wm(-1) K-1). These properties provided an opportunity for some advanced applications such as electromagnetic interference (EMI) shielding and CO2 gas capture. The highest shielding effectiveness (SE), specific SE and thickness-averaged specific SE of WTP-PVA in the X-band are 40 dB, 700 dB cm(3) g(-1) and 1818 dB cm(2) g(-1) respectively, with an absorption-dominant shielding mechanism. More importantly, the WTP-PVA CA with abundant ultramicropores showed great potential for CO2 adsorption (5.14 mmol g(-1) at 0 degrees C) with good selectivity and regeneration capability even without the aid of any chemical activation, functionalization or heteroatom doping.