Robust CA-GO-TiO2/PTFE Photocatalytic Membranes for the Degradation of the Azithromycin Formulation from Wastewaters.

We have developed an innovative thin-film nanocomposite membrane that contains cellulose acetate (CA) with small amounts of TiO2-decorated graphene oxide (GO) (ranging from 0.5 wt.% to 2 wt.%) sandwiched between two polytetrafluoroethylene (PTFE)-like thin films. The PTFE-like films succeeded in maintaining the bulk porosity of the support while increasing the thermal and chemical robustness of the membrane and boosting the catalytic activity of TiO2 nanoparticles. The membranes exhibited a specific chemical composition and bonding, with predominant carbon-oxygen bonds from CA and GO in the bulk, and carbon-fluorine bonds on their PTFE-like coated sides. We have also tested the membranes' photocatalytic activities on azithromycin-containing wastewaters, demonstrating excellent efficiency with more than 80% degradation for 2 wt.% TiO2-decorated GO in the CA-GO-TiO2/PTFE-like membranes. The degradation of the azithromycin formulation occurs in two steps, with reaction rates being correlated to the amount of GO-TiO2 in the membranes.

Fabrication of Hybrid Electrodes by Laser-Induced Forward Transfer for the Detection of Cu2+ Ions.

Composites based on poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS)-graphene oxide (GO) are increasingly considered for sensing applications. In this work we aim at patterning and prototyping microscale geometries of PEDOT:PSS: GO composites for the modification of commercially available electrochemical sensors. Here, we demonstrate the laser-induced forward transfer of PEDOT:PSS: GO composites, a remarkably simple procedure that allows for the fast and clean transfer of materials with high resolution for a wide range of laser fluences (450-750 mJ/cm2). We show that it is possible to transfer PEDOT:PSS: GO composites at different ratios (i.e., 25:75 %wt and 50:50 %wt) onto flexible screen-printed electrodes. Furthermore, when testing the functionality of the PEDOT:PSS: GO modified electrodes via LIFT, we could see that both the PEDOT:PSS: GO ratio as well as the addition of an intermediate release layer in the LIFT process plays an important role in the electrochemical response. In particular, the ratio of the oxidation peak current to the reduction peak current is almost twice as high for the sensor with a 50:50 %et PEDOT:PSS: GO pixel. This direct transfer methodology provides a path forward for the prototyping and production of polymer: graphene oxide composite based devices.

Polypyrrole-Tungsten Oxide Nanocomposite Fabrication through Laser-Based Techniques for an Ammonia Sensor: Achieving Room Temperature Operation.

A highly sensitive ammonia-gas sensor based on a tungsten trioxide and polypyrrole (WO3/PPy) nanocomposite synthesized using pulsed-laser deposition (PLD) and matrix-assisted pulsed-laser evaporation (MAPLE) is presented in this study. The WO3/PPy nanocomposite is prepared through a layer-by-layer alternate deposition of the PPy thin layer on the WO3 mesoporous layer. Extensive characterization using X-ray diffraction, FTIR and Raman spectroscopy, scanning electron microscopy, atomic force microscopy, and water contact angle are carried out on the as-prepared layers. The gas-sensing properties of the WO3/PPy nanocomposite layers are systematically investigated upon exposure to ammonia gas. The results demonstrate that the WO3/PPy nanocomposite sensor exhibits a lower detection limit, higher response, faster response/recovery time, and exceptional repeatability compared to the pure PPy and WO3 counterparts. The significant improvement in gas-sensing properties observed in the WO3/PPy nanocomposite layer can be attributed to the distinctive interactions occurring at the p-n heterojunction established between the n-type WO3 and p-type PPy. Additionally, the enhanced surface area of the WO3/PPy nanocomposite, achieved through the PLD and MAPLE synthesis techniques, contributes to its exceptional gas-sensing performance.