Self‐Assembled Construction of Robust and Super Elastic Graphene Aerogel for High‐Efficient Formaldehyde Removal and Multifunctional Application

Simultaneously achieving exceptional mechanical strength and resilience of graphene aerogel (GA) remains a challenge, while GA is an ideal candidate for formaldehyde removal. Herein, flexible polyethyleneimine (PEI) is grafted chemically onto carbon nanotube (CNT) surface, and CNT‐PEI@reduced GA (rGA) is fabricated via hydrothermal self‐assembly, pre‐frozen, and hydrazine reduction process. Introducing CNT‐PEI contributes to well‐interconnected/robust 3D network construction by connecting reduced graphene oxide (rGO) nanosheets through enhancing cross‐linking, while entangled CNT‐PEI is intercalated into rGO layers to avoid serious restacking of sheets, producing larger surface area and more formaldehyde adsorption sites. Ultralight CNT‐PEI@rGA exhibits extreme high strength (276.37 kPa), reversible compressibility at 90% strain, and structural stability, while FA adsorption capacity reached 568.41 mg g‐1, ≈3.28 times of rGA, derivable from synergistic chemical‐physical adsorption effect. Furthermore, CNT‐PEI@rGA is ground into powder for first preparing polyoxymethylene (POM)/CNT‐PEI@rGA composite, while formaldehyde emission amount is 69.63%/73.96% lower than that of POM at 60/230 °C. Moreover, CNT‐PEI@rGA presents outstanding piezoresistive‐sensing and thermal insulation properties, exhibiting high strain sensitivity, wide strain detection range, and long‐term durability. Introducing carbon nanotube (CNT)‐polyethyleneimine (PEI) into reduced graphene oxide layers contributes to well‐interconnected/robust 3D network construction reduced graphene aerogel (rGA) through enhancing cross‐linking/support effect, simultaneously achieving exceptional strength and super‐elasticity, while entangled CNT‐PEI avoids sheets restacking, presenting significant formaldehyde removal capacity and outstanding piezoresistiv‐sensing and thermal insulation properties.