RESUMO
In this work, a heterogeneous photocatalysis system is fabricated for treating wastewater containing organic dyes and pharmaceutical substances. Double-heterojunction Janus photocatalysts are formed on the surface of size-tunable polydimethylsiloxane (PDMS) microparticles shaped via simple and low-cost coflow microfluidic devices. Ag0/Ag0-TiO2/TiO2 Janus-like photocatalysts are synthesized on the surface of porous PDMS microparticles as the support in which the metal-semiconductor heterojunction of Ag0/Ag0-TiO2 and the second heterojunction of Ag0-TiO2/TiO2 are created in situ, leading to the formation of Ag0/Ag0-TiO2/TiO2@PDMS photocatalysis systems. To form the heterojunctions on the PDMS surface, the polymer chain etching method is employed as a desired strategy to have half of the TiO2 nanoparticles on the surface of microparticles, which are treated by a Ag source. Using salt additives and the etching method, PDMS microparticles are made porous, providing more surface area for photoreactions. Surprisingly, the highest decomposition efficiencies of 94.4 and 91.1% are achieved for rhodamine B(RhB) and tetracycline (TC), respectively, under visible light for 60 min pH 11, a light source at a distance of 2 cm, 5 mM AgNO3, 10 wt % TiO2, 7 wt % NaCl, and 20 gm/L photocatalyst, which are conditions that result in the best performance for RhB degradation. Regarding the stability of the photocatalysts, no significant change is observed in the performance after five cycles.
RESUMO
In this work, size-tunable polydimethylsiloxane (PDMS) microparticles are fabricated from a high-viscosity oil phase using a facile coflowing capillary microfluidic device and optimized aqueous phase composition. The dispersity of the microparticle size is tuned by engineering of the viscosity of the continuous phase and flow rate ratio that leads us to achieve monodisperse microparticles. Regarding the high potential of the PDMS microparticles for optical applications, efficient environmentally durable perovskite-based UV sensors are fabricated employing the designed size-tunable microparticles. Surprisingly, the UV sensors comprising CH3NH3PbBr3 perovskite quantum dots as UV-sensitive nanocrystals embedded in transparent PDMS microparticles are water resistant because of the high hydrophobicity of PDMS. Remarkably, the UV sensors show a photoluminescence quantum yield as high as 75% that can be employed effortlessly as reusable leak detectors in different fluidic working systems.
