Gold and platinum bimetallic nanoparticles, Au@PtNPs, have gained attention due to their plasmonic properties. The controlled synthesis of Au@PtNPs involves complex parameters, and the resulting synergy between Au and Pt introduces possibilities for tailoring their properties. This study explores the effects of key-parameters of synthesis (gold core diameters, reaction time, and Pt concentration) on the final properties of Au@PtNPs. Gold nanoparticles of varying diameters were synthesized and used as cores for the reduction of hexachloroplatinic acid, forming a surrounding shell of Pt nanoparticles. The parameters were systematically tuned to understand their impact on morphology, dimension, stability, and plasmonic properties of Au@PtNPs. Increasing Pt precursor concentration resulted in thicker and denser Pt shells, broadening the localized surface plasmon resonance (LSPR) band and improving Au@PtNPs stability. These properties are essential for applications such as photothermal treatment. The synthesis achieved satisfactory products within just 1 h of Pt4+ reduction at mild temperature without using surfactants. Only limited changes in plasmonic properties were observed after 4 h of synthesis, suggesting an optimal reaction period. Manipulating Au core diameter provided LSPR band control, with smaller cores exhibiting greater broadening towards the infrared region. This systematic exploration provided valuable insights for understanding key-parameters governing the synthesis and properties of Au@PtNPs. AuPtNPs PtNPs keyparameters key gold time acid morphology dimension stability shells (LSPR treatment Pt4 surfactants period control region

Abstract In this paper, we present a spectral analysis of a Surface Plasmon Resonance (SPR) sensor based on multilayer graphene (MLG) operating as a terahertz refractometer. This device's structure is based on Kretschmann configuration, and the graphene layers are modeled as surface impedances with conductivity described by the Kubo model. The structure's electromagnetic response is obtained from the Generalized Coefficients Model, considering TM excitation performed in a frequency range from 1 to 4Thz. In this approach, we evaluate the sensor response for two, three, four and five layers of graphene, equally doped. To verify the effects of MLG doping, we varied the chemical potential by 0.35eV and 0.70eV. As a result, we present the plasmonic response of the device, verifying the operating frequency range for each case of multilayer graphene. In addition, the sensitivity, FWHM and Figure of Merit (FOM) are calculated to describe the sensor performance in each demonstrated case. From the results presented, we verified that the increase in doping reduces the sensitivity of the sensor, however, it improves its FOM. The validation of the proposed model was carried out from simulations in a software based on the Finite Element Method. paper SPR (SPR (MLG refractometer devices device s configuration structures Model 4Thz Thz approach two three doped 035eV eV 0 35eV 070eV 70eV 0.70eV result addition FOM (FOM presented however Method

<p>A photocatalytic microreactor is defined as a microfluidic device, which is integrated with a photocatalytic coating of TiO₂ deposited on the inner surface of microchannels. This device is capable of degradation of organic dye solution in water in a continuous flow under the action of ultraviolet light. The objectives of this work were to present a rapid and economically viable approach for the prototyping photocatalytic microfluidic devices and to evaluate their photodegradation capability for organic dyes by ultraviolet-visible spectrophotometry. Prototyping of polydimethylsiloxane PDMS/TiO₂/glass microreactors includes several procedures such as mold preparation, microchannel confection on PDMS surface, deposition of TiO₂ on these microchannels, O₂ plasma treatment of PDMS/TiO₂ and glass surface for sealing these two parts. The efficiency of the photocatalytic microreactors was evaluated by fluxing two organic dye solutions, rhodamine B and methylene blue, with different flow rates of between 2 and 4 mL h^-1. When the flow rate at 2 mL h^-1was applied, discoloration of ~ 65% was achieved for both dye solutions, while PDMS/glass microchannels, without TiO₂ film, demonstrated much lower discoloration of between 24 and 42% for rhodamine B and methylene blue, respectively. This confirmed that TiO₂ was successfully deposited onto PDMS microchannels.</p>