Interfacial growth of 2D bimetallic metal-organic frameworks on MoS2 nanosheet for reinforcements of polyacrylonitrile fiber: From efficient flame-retardant fiber to recyclable photothermal materials

Abstract The application of polyacrylonitrile (PAN) fiber in textile and industrial fields faces two important concerns: flammability and fiber waste. Herein, to address these concerns, novel sandwich-type Co-Zn ZIF/MoS2 hybrid nanosheets are synthesized by interfacial growth of 2D bimetallic zeolitic-imidazolate frameworks (Co-Zn ZIF) on the surface of molybdenum disulfide (MoS2) nanosheets, and employed as efficient nanofillers for reinforcing PAN fibers. On the one hand, the incorporation of 2 wt% Co-Zn ZIF/MoS2 hybrid nanosheets imparts excellent flame-retardancy and toxic volatiles (e.g., CO, HCN and aliphatic C–H compounds) elimination performance to PAN composite fibers. Moreover, it is observed that Co-Zn ZIF/MoS2 can catalyze the generation of carbon nanotubes (CNTs) during the burning of PAN fiber, which provides good contributions for flame-retardant enhancement. Simultaneously, the tensile strength and thermal stability (T5%) of 2 wt% Co-Zn ZIF/MoS2/PAN composite fiber are improved by 57.1% and 28.6 °C, respectively. On the other hand, through a facile carbonization, the flame-retardant 2 wt% Co-Zn ZIF/MoS2/PAN composite fibers are converted into CNTs/MoS2-containing carbon materials, which shows high absorption in full-range solar spectrum, endowing it with a high evaporation rate of 1.394 kg/m2/h under 1 sun irradiation and an energy conversion efficiency of 85.3% for solar steam generation.