This work studies the variation in the photocatalytic properties of CdS derived from the insertion of In, Ga, Ag-In and Ag-Ga in the CdS lattice through solvothermal methodology. Solvothermal synthesis of CdS-M photocatalysts has been succesful for the insertion of Ga3þ, In3þ, Ga3þ/Agþ and In3þ/Agþ into the hexagonal crystal lattice of one-dimensional CdS. The insertion of In, Ga, Ag-In and Ag-Ga modifies the band gap and the relative position of EVB. CdS modified with In3þ or Ga3þ shows an increase in the band gap and upshift in the relative position of the valence band energy which leads to a low efficiency hydrogen production. The co-addition of Agþ-In3þ or Agþ-Ga3þ favours the insertion of Agþ ions into the CdS lattice with narrower band gap. Of all the co-substituted photocatalysts, the CdS-AgGa was the only one that showed a higher photoactivity with respect to the CdS. The increase in the photoactivity of the CdS-AgGa photocatalyst is related to the band gap narrowing and downshift in the relative position of the valence band energy which enhance their visible light absorption and potential for oxidation. The CdS-AgGa photocatalyst shows small segregation of metallic Ag nanoparticles at the surface which also assist in the photoactivity of the sample.

This work reports the use of cerium - titania - alumina - based systems modified with Ag and Fe by the wetness impregnation method for the discoloration of blue 5G dye. The techniques employed to characterize the photocatalysts were: temperature - programmed reduction (TPR), X - ray diffraction (XRD), specific surface area, average pore volume, and average pore diameter. The characterization results indicated that the photocatalysts had different crystalline structures and textural properties. Discoloration with the mixed oxide photocatalyst CeO2 - TiO2 - Al2O3 gave a result similar to that of TiO2. On the other hand, the addition of Ag and Fe to the mixed oxide increased the discoloration and reaction rates of reactive blue 5G dyes.

The search for sustainable energy sources has been a global demand in recent decades. In this context, thermoelectric materials (TE) have been an interesting alternative for this purpose and constitute a relevant research topic for increasing the efficiency of sustainable energy production. In this sense, computational simulation of the functionalization of SrTiO3 is proposed via Ag-doping on the (0 0 1) surface. The results show the emergence of a midgap trap state, leading to a band gap energy decrease, an increase in dielectric constants and the effective mass electron. The Ag-doping generates a decrease in electrical conductivity and an increase in the figure of merit, which are associated with a significant reduction in thermal conductivity (∼5 times), indicating that the material can be used with TE at high temperatures. The Ag-SrTiO3 (0 0 1) surface is promising for developing new thermoelectric devices.

ZrO2 nanoparticles (ZrO2 NPs) and Ag@ZrO2 nanocomposite (Ag@ZrO2 NCs) were prepared from zirconium (IV) butoxide in the absence of base or acid mineraliser by the advanced oxidation processes (AOP) and subsequent hydrothermal treatment. Samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), Raman, Photoluminescence (PL), Fourier transform infrared (FTIR), and diffuse reflectance spectroscopy (DRS). XRD and Raman analyses confirmed ZrO2 NPs and Ag@ZrO2 NCs tetragonal crystalline phase synthesized at 200 °C for 1 h. HRTEM images of ZrO2 NPs and Ag@ZrO2 NCs after treatment at 200 °C indicated small nanoparticles with characteristic size of 5–8 nm (ZrO2) and 40–50 nm (Ag NPs). It was found that Ag@ZrO2 NCs showed outstanding photocatalytic activity in photodegradation Rhodamine B dye compared with pure ZrO2 NPs. Antibacterial activity tests of ZrO2 NPs and Ag@ZrO2 NCs were carried out using E. coli and S. aureus as model strains of Gram-negative and Gram-positive bacteria, respectively. Ag@ZrO2 NCs were capable of efficiently growth inhibition of bacteria cultures in more than 75% E. Coli compared to ZrO2 NPs that exhibited <10% instead. However, at the same concentration (for example 0.25 mg/mL) we found that both ZrO2 NPs and Ag@ZrO2 NCs were significantly more effective against S. aureus in comparison with E. coli showing bacterial growth inhibition higher than 90% for S. aureus. Morphological observation of bacterial cells by scanning electron microscopy (SEM) revealed that nanoparticles and nanocomposite caused irreversible damage to the cell membrane. [Figure not available: see fulltext.].

Graphene [1] is a material that has been extensively explored in recent years as a material with optical properties that enable its application as active material in sensing devices. In this work we will study plasmonic effects and optical properties of graphene and metal nanoparticles (AuNPs), comparing its results, whenever possible, with results obtained in previous studies. Analysis will be supported by simulation results obtained with Matlab (“Mie analysis”).