Microfluidic Laminar Flow‐Based Continuous Assembly of Nanosheets Toward Ultrathin Layered Nanocomposite Films

Assembling 2D nanosheets into layered nanocomposite films has attracted enormous interest due to their various promising applications in energy conversion, flexible electronics, and wastewater treatment. However, achieving efficient and convenient assembly of nanosheets for specific functions remains challenging. In this work, a microfluidic laminar flow-based strategy is proposed for the efficient alignment of 2D nanosheets into ultrathin, high-strength layered nanocomposite films. The microfluidic laminar flow in microchannels enables efficient alignment of graphene oxide (GO) nanosheets, which, in combination with aramid nanofibers (ANF), are converted into layered nanocomposite films via ANF re-protonation within seconds. The ANF/GO layered nanocomposite films achieve a high orientation order parameter of 0.93 with a thickness of 922 ± 12 nm, showing a high salinity gradient power generation of 29.73 ± 0.94 W m^-2. By introducing polyvinyl alcohol (PVA) and carbon nanotubes (CNT) to enhance interlayer interactions, the resulting ANF/GO/PVA/CNT layered nanocomposite films show a tensile strength of up to 670 ± 20 MPa. Moreover, such a microfluidic laminar flow-based strategy enables the continuous assembly of various 2D nanosheets, presenting a promising solution for layered nanocomposite films fabrication toward practical applications.