Hydrodynamic synthesis of Fe2O3@MoS2 0D/2D-nanocomposite material and its application as a catalyst in the glycolysis of polyethylene terephthalate.

We report a fast and simple synthesis of Fe2O3@MoS2 0D/2D-nanocomposite material using a Taylor-Couette flow reactor. A Taylor-Couette flow with high shear stress and mixing characteristics was used for fluid dynamic exfoliation of MoS2 and deposition of uniform Fe2O3 nanoparticles, resulting in a Fe2O3@MoS2 in the form of 0D/2D-nanocomposite material. Using Taylor-Couette flow reactor, we could synthesize Fe2O3@MoS2 0D/2D-nanocomposite material at a rate higher than 1000 mg h-1 which is much higher than previously reported production rate of 0.2-116.7 mg h-1. The synthesis of Fe2O3@MoS2 nanocomposite was achieved in an aqueous solution without thermal or organic solvent treatment. Exfoliated MoS2 nanosheets show an average thickness of 2.6 ± 2.3 nm (<6 layers) and a lateral size of 490 ± 494 nm. Fe2O3 nanoparticles have an average size of 7.4 ± 3.0 nm. Fe2O3 nanoparticles on chemically and thermally stable MoS2 nanosheets show catalytic activity in the glycolysis of polyethylene terephthalate (PET). High conversion of PET (97%) and a high yield (90%) for bis(hydroxyethyl) terephthalate (BHET) were achieved in a reaction time of 3 h at the reaction temperature of 225 °C.

Fast and Scalable Hydrodynamic Synthesis of MnO2/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life.

The integration of metal oxides and carbon materials provides a great potential for enhancing the high energy and power densities of supercapacitors, but the rational design and scalable fabrication of such composite materials still remain a challenge. Herein, we report a fast, scalable, and one-pot hydrodynamic synthesis for preparing ion conductive and defect-free graphene from graphite and MnO2/graphene nanocomposites. The use of this hydrodynamic method using Taylor-Couette flow allows us to efficiently fast shear-exfoliate graphite into large quantities of high-quality graphene sheets. Deposition of MnO2 on graphene is subsequently performed in a fluidic reactor within 10 min. The prepared MnO2/graphene nanocomposite shows outstanding electrochemical performances, such as a high specific capacitance of 679 F/g at 25 mV/s, a high rate capability of 74.7% retention at an extremely high rate of 1000 mV/s, and an excellent cycling characteristic (∼94.7% retention over 20 000 cycles). An asymmetric supercapacitor device is fabricated by assembling an anode of graphene and a cathode of MnO2/graphene, which resulted in high energy (35.2 W h/kg) and power (7.4 kW/kg) densities (accounting for the mass of both electrodes and the electrolyte) with a high rate capability and long cycle life.