Combining ceramic materials such as MgO and ZrO₂ can have a wide chemical and technological application. In this context, the sol–gel method is a very noble method for preparing mixed oxides, as it allows the control of their textural and surface properties. This paper aims to evaluate the structural and morphological properties of MgO-ZrO₂ mixed oxides as a function of their composition, for which solids of 10, 25, 50, 75, and 90% mol of ZrO₂ were synthesized by the sol–gel method. The obtained materials were characterized by N₂ physisorption, X-ray diffraction, scanning electron microscopy and diffuse reflectance, Fourier transform infrared, and Raman spectroscopy. The results showed that the textural properties of MgO improved by adding 25% ZrO₂, such that this solid showed the highest surface area (124 m²/g) and pore diameter of 12 nm. FTIR, RD-UV–Vis, and Raman spectra showed the presence of O–H chemical bonds due to the hygroscopic character of the materials. In contrast, XRD results showed MgO in the periclase phase and ZrO₂ mostly in the tetragonal phase. It was also observed that the bandgap energy increases slightly as a function of ZrO₂ content. On the other hand, SEM micrographs showed that the increase of ZrO₂ changes the morphology of the particles, size and shape.

Au nanoparticles were supported on TiO₂ nanotubes by a novel vapor phase impregnation approach (VPI) using gold dimethyl-acetylacetonate as a precursor. This study aimed to evaluate the capacity of these materials in the photodecoloration of malachite green dye, with the vision to correlate the chemical, structural, morphological, and optical properties with its photocatalytic performance. The photocatalysts were characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectronic spectroscopy (XPS), electronic microscopy (HAADF-STEM and HRTEM), and UV–vis spectroscopy. The techniques mentioned above made it possible to detect the presence of small gold nanoparticles (around 3.1 nm), with a high apparent dispersion even at high metal loading for all analyzed systems. According to the XPS results, the Au nanoparticles remain reduced (Au°), and they have a high electronic interaction with TiO₂, which eventually originates an electronic exchange between them and consequently a decrease in the band gap energy. In addition, the surface plasmonic resonance observed through UV–vis spectroscopy of the Au nanoparticles are factors that can be related to the high decoloration observed in these photocatalysts, specifically in the 15 wt% Au material, which achieves maximum photodecoloration of malachite green dye at 93%.

En este trabajo se evaluó la actividad del carbón activado como soporte de catalizadores para la producción de biodiesel. Se sintetizaron carbones activados a partir del bagazo de caña, se activaron con HNO3 y se calcinaron a 550 °C y 650 °C; posteriormente se impregnaron con un contenido de 15 y 3 % p/p de Mo y Ni, respectivamente. Los materiales sintetizados se caracterizaron mediante fisisorción de N2, difracción de rayos X y microscopía electrónica de barrido. Asimismo, la evaluación catalítica se realizó en la transesterificación del aceite de palma en presencia de metanol a 60 °C con diferentes tiempos de reacción. Luego, las muestras de biodiesel obtenido se caracterizaron fisicoquímicamente. Los resultados mostraron una baja dispersión de los metales en el soporte, lo que originó pocos sitios activos catalíticos, debido principalmente a la baja área superficial de los carbones activados, lo cual disminuyó la actividad de los materiales y condujo a un bajo rendimiento, que fue significativamente menor que los reportados en la literatura. Sin embargo, este puede mejorar al aumentar el contenido de catalizador y mediante la optimización de las condiciones de reacción, con lo que también se podría mejorar considerablemente la calidad del biodiesel obtenido.

En este trabajo se sintetizaron nanomateriales de plata (Ag), óxido de zinc (ZnO) y microestructuras de ZnO decoradas con Ag (Ag/ZnO) mediante el método Pechini, para determinar sus propiedades antimicrobianas. Las muestras fueron caracterizadas por Difracción de Rayos X (DRX), Microscopia Electrónica de Barrido (MEB) y fisisorción de nitrógeno. Los resultados de DRX revelaron una sola fase cristalina para la muestra de Ag, la fase zincita en el espécimen de ZnO, así como una combinación de ambas fases en los materiales de Ag/ZnO. Los resultados de MEB indican aglomerados con morfologías granuladas en la muestra de Ag y estructuras semilaminares en el espécimen de ZnO. Además, se evaluó el efecto antimicrobiano de los nanomateriales y se seleccionaron las concentraciones a evaluar mediante pruebas de difusión en disco (prueba de Kirby-Bauer) y Concentración Mínima Inhibitoria (MIC). Los resultados revelaron que los diversos nanomateriales presentan actividad bacteriostática y/o bactericida, destacando los materiales de Ag/ZnO (efecto bactericida) con una eficiencia de ~75 % en Escherichia coli (ATCC 108412) y ~89 % en S. aureus (ATCC 25923).

Background: The development of advanced materials catalyzing solar-driven degradation is essential for sustainable water remediation strategies. This study sheds light on how zeolitic supports influence the microstructural and charge-transfer properties of ternary photocatalysts. Methods: Hybrid Titanium dioxide (TiO2)-cadmium sulfide (CdS) composites supported on natural (clinoptilolite) and synthetic (NaA) zeolites were synthesized via an in situ sol–gel method. The structural and optical properties of these composites were characterized using instrumental techniques, and their photocatalytic performance was evaluated through the degradation of methylene blue (MB) under simulated solar light. Results: X-ray diffraction identified anatase as the dominant phase. Williamson-Hall analysis revealed a reduction in TiO2 crystal size (from 7.2 nm for bare TiO2 to 5.6 nm for the optimal composite) and support-dependent compressive lattice deformation. Specific surface area increased (from 65.88 to 78.91 m2/g) with the emergence of hierarchical porosity. The TiO2-CdS/clinoptilolite composite with a moderate zeolite content (TiO2-CdS/CLI0.5) exhibited the most balanced performance, featuring an optimal crystallite size, a moderate compressive lattice strain, a low recombination rate, and an absolute photocatalytic MB degradation of 53% (as well as 16% dark adsorption), outperforming synthetic NaA counterparts. Conclusions: The zeolitic support strongly influences structure–property relationships in TiO2-CdS/zeolite composites. By acting as rigid nanoreactors, the matrices induce microstrain and facilitate charge separation via a direct Z-scheme mechanism, thereby enhancing visible-light photocatalysis.