Mechanically strong multifunctional three-dimensional crosslinked aramid nanofiber/reduced holey graphene oxide and aramid nanofiber/reduced holey graphene oxide/polyaniline hydrogels and derived films

Abstract

To endow high mechanical strength and thermal stability aramid nanofibers (ANF) with novel functionality will lead to great applications. Herein, a strategy to generate covalent bonds among components towards obtaining uniform ANF/reduced holey graphene oxide (ANF/rHGO) and ANF/rHGO/polyaniline (ANF/rHGO/PANI) hydrogels with high mechanical properties is proposed through solvent exchange gelation and subsequent hydrothermal treatment. The as-prepared ANF/rHGO and ANF/rHGO/PANI hydrogels demonstrate excellent recoverability at high compressive strength of 20.2 and 13.8 kPa with a strain of 34.4% and 30.6%, respectively, compared to a recoverability of 92.5% at a strain of ∼20% for ANF hydrogels. Moreover, ANF/rHGO and ANF/rHGO/PANI aerogels possess fast and high oil absorption capacity of 38.9–64.1 g g⁻¹ and 24.5–44.0 g g⁻¹, respectively. ANF/rHGO and ANF/rHGO/PANI films obtained after vacuum-drying exhibit a high tensile strength of 121.4 and 95.5 MPa, respectively. Additionally, ANF/rHGO/PANI thin films present good selective absorption of visible light by controlling the doping level of PANI. ANF/rHGO/PANI aerogel films prepared by freeze-drying are assembled into flexible solid-state symmetric supercapacitors and deliver a favorable specific capacitance of 200 F g⁻¹, a desirable capacitance retention of 98.9% after 2500 mechanical bending cycles and an approximately 100% capacitance retention even after keeping tensile force for 15 h. The as-prepared hydrogels, aerogels and derived films with such excellent performances are promising for applications in oil pollution removal, optical filters and flexible load-bearing energy storage devices.