Synthesis and Electronic Applications of Particle-Templated Ti3C2Tz MXene-Polymer Films via Pickering Emulsion Polymerization.

MXene/polymer composites have gained widespread attention due to their high electrical conductivity and extensive applications, including electromagnetic interference (EMI) shielding, energy storage, and catalysis. However, due to the difficulty of dispersing MXenes in common polymers, the fabrication of MXene/polymer composites with high electrical conductivity and satisfactory EMI shielding properties is challenging, especially at low MXene loadings. Here, we report the fabrication of MXene-armored polymer particles using dispersion polymerization in Pickering emulsions and demonstrate that these composite powders can be used as feedstocks for MXene/polymer composite films with excellent EMI shielding performance. Ti3C2Tz nanosheets are used as the representative MXene, and three different monomers are used to prepare the armored particles. The presence of nanosheets on the particle surface was confirmed by X-ray photoelectron spectroscopy and scanning electron microscopy. Hot pressing the armored particles above Tg of the polymer produced Ti3C2Tz/polymer composite films; the films are electrically conductive because of the network of nanosheets templated by the particle feedstocks. For example, the particle-templated Ti3C2Tz/polystyrene film had an electrical conductivity of 0.011 S/cm with 1.2 wt % of Ti3C2Tz, which resulted in a high radio frequency heating rate of 13-15 °C/s in the range of 135-150 MHz and an EMI shielding effectiveness of ∼21 dB within the X band. This work provides a new approach to fabricate MXene/polymer composite films with a templated electrical network at low MXene loadings.

Mechanistic evaluation of heterocyclic aromatic compounds mineralization by a Cu doped ZnO photo-catalyst.

In this study, Cu doped ZnO photo-catalysts were used for the degradation of the heterocyclic compounds, pyridine and quinoline. Three ZnO based photo-catalysts with different amounts of Cu doping (1%, 5% and 10%) were synthesized by precipitation method. The characterization of the catalyst was done using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET), diffuse reflectance spectroscopy (DRS) and photo-luminescence (PL) techniques. The band gaps of the pure ZnO, and 1%, 5% and 10% Cu doped ZnO photo-catalysts were found to be 3.27 eV, 3.21 eV, 3.17 eV and 2.91 eV, respectively. The effects of pH, photo-catalyst dose and irradiation time were studied. Under optimum conditions (5% Cu doped ZnO, dose of 1.2 g L-1 for pyridine and 1.6 g L-1 for quinoline, pH = 11 and time = 5 h), the maximum pyridine and quinoline mineralization efficiencies were found to be 92.4% and 74.3%, respectively. The mineralization process followed first-order kinetics. The in situ formation of singlet oxygen, hydroxyl radicals and superoxide radicals was confirmed by reactive oxygen species (ROS) scavenger studies. Catalyst reusability studies showed excellent mineralization up to four consecutive cycles. The enhanced photo-catalytic mechanism was studied by comparing the band structure with respect to the potential of highly reactive species (˙OH and O2˙-). A possible mineralization pathway was proposed on the basis of the intermediates detected by gas chromatography coupled with mass spectrometry (GC-MS) analysis.