TiO2/PDMS nanocomposites for use on self-cleaning surfaces

AbstractIn this study, polydimethylsiloxane (PDMS)/TiO2 nanocomposite was processed by the spray method. TiO2 nanoparticles were synthesized by microwave-assisted hydrothermal method. Varying the proportion of nanoparticles in 0%, 0.5% and 1% by weight, commercial TiO2 (P25) was used for comparison purposes. The photocatalytic activity of nanocomposites impregnated with methylene blue was assessed by means of UV–visible spectroscopy. Changes in contact angle were analyzed before and after UV degradation tests. The effect of ultraviolet radiation on the chemical structure of the PDMS matrix was evaluated by Fourier transform infrared spectroscopy (FTIR). The results indicated that the addition of TiO2 nanoparticles in PDMS provides good photocatalytic properties in the decomposition of methylene blue, which is an important characteristic for the development of coatings for self-cleaning. For comparison purposes, commercial P25 was also used to investigate the photocatalytic activity

Fast microwave synthesis and white luminescent emission from Pb1–2xCaxSrxMoO4 (x=0; 0.3; and 0.5) particles

Scheelite with ABO4 structure has been increasingly highlighted in the optoelectronic field. In this study, PbMoO4, Pb0.4Ca0.3Sr0.3MoO4, and Ca0.5Sr0.5MoO4 particles were fast synthesized via microwave-assisted hydrothermal method for 1, 2, 4, and 8 min. The particles were characterized by X-ray diffraction (XRD) and Rietveld refinement, ultraviolet-visible (UV–vis) absorption spectroscopy, photoluminescence (PL), and field emission scanning electron microscopy (FE-SEM). The diffractogram showed a scheelite-type tetragonal structure and a unit cell with space group I41/a, as well as the presence of defects with an increase in the synthesis time in PbMoO4 and Pb0.4Ca0.3Sr0.3MoO4 samples. Rietveld refinement data possibilities the evaluation of distortions in the tetrahedral [MoO4] clusters and FE-SEM images showed octahedral, spherical particles, and flower-like morphology due to the additions of calcium and strontium in the structure. The bandgap of the materials varied between 3.32 and 4.18 eV, which was affected by the increase in the presence of dopants in the materials. The photoluminescence presented by the PL emission spectral showed a typical emission peak in green with the PL signal intensity decreasing with the synthesis time increase for the PCSMO samples, and the longer the synthesis time, the higher the PL signal for CSMO samples. CCT coordinates have been calculated for all samples and its value exhibited that, overall emission is near white light. This parameter infers that Pb0.4Ca0.3Sr0.3MoO4 sample, synthesized in 1 min, may have potential application in commercial LEDs, due to near white emission and fast microwave synthesis

Optimized synthesis of Na2/3Ni1/3Mn2/3O2 as cathode for sodium-ion batteries by rapid microwave calcination

Embargado hasta 15/04/2025Microwave calcination is proposed as an alternative route to conventional heating to prepare layered P2–Na2/3Ni1/3Mn2/3O2 as a positive electrode for sodium-ion batteries. The sample obtained by the fastest conditions, with a heating ramp of 20 °C min−1 for only 2 h, showed well-crystallized rounded particles. Cyclic voltammetry and impedance spectroscopy evidenced a low internal cell resistance, and high diffusion coefficients, which justify its capability to sustain the highest capacity at 1 C and retain the discharge capacity for at least two hundred cycles