The g-C₃N₄/ZnO nanocomposite materials were applied to degrade methylene blue (MB). The samples were characterized and evaluated to study the adsorption and photocatalytic degradation under visible light. The g-C₃N₄ was incorporated at percentages of 5%, 10%, 20%, and 40% relative to the ZnO weight. These composite materials were prepared using a solvothermal microwave technique. The structural, textural, morphological, and optical properties were investigated using XRD, FTIR, SEM, EDS, STEM, BET, UV-Vis, and XPS techniques. The XRD patterns of the samples showed the coexistence of crystalline phases of g-C₃N₄ and ZnO, while images and elemental composition analysis confirmed the formation of nanocomposite samples. The UV-Vis spectrum revealed a redshift in the absorption edge of the nanocomposites, indicating improved light-harvesting capability. The synthesized material g-C₃N₄/ZnO (20/80), with a surface area of 25 m²/g, exhibited higher photocatalytic performance, achieving 85% degradation of MB after 100 min under visible light, which corresponds to nearly three times the degradation efficiency of commercial P25-TiO₂ (31%) under the same conditions. The reusability and stability tests were conducted up to the fifth cycle, and this material showed 77% degradation, indicating good stability. This nanocomposite material has good potential as a photocatalyst for solar-driven MB.

In the present work, zinc titanates (ZTO) as photocatalysts were synthesized, characterized, and evaluated aiming to study their photocatalytic properties for hydrogen production under visible-light irradiation and employing MeOH (methanol) and TEOA (Triethanolamine) as sacrificial agents. ZTO were synthesized by modified Pechini method. Characterization of materials consisted in TGA, XRD, TEM, EELS, BET, and UV–Vis. Surface interaction studies consisted of FT-IR spectroscopy and determination of MeOH and TEOA adsorption–desorption capacities on the ZTO by TGA. Zinc titanates were evaluated as photocatalyst for H₂ production using an artificial visible light and monitored by GC. TGA results led to establish calcination temperatures of 550 °C (Zn₂Ti₃O₈) and 700 °C (ZnTiO₃) to reach their crystalline phases. XRD analysis of sample cds-ZTO found cubic Zn₂Ti₃O₈ and traces of the ZnO crystalline phase, while p-ZTO exhibited a mixture of cubic and hexagonal ZnTiO₃ crystalline phases. Surface area for cds-ZTO was 88 m²/g, while ZnTiO₃ had 13 m²/g. Photocatalytic H₂ production for cds-ZTO and p-ZTO using TEOA as sacrificial agent showed the highest photocatalytic activities generating 548 and 441 µmolH₂/h.g_cat. TEOA adsorption–desorption capacity was found superior on cds-ZTO and p-ZTO than that for MeOH on both samples.

Chemical looping steam reforming (CL-SMR) thermodynamic analysis and process simulation using Fe₂MnO₄ as an oxygen carrier.

In the present work, manganese cobaltite (MnCo₂O₄) spinel (MCO) was synthetized by Pechini and hydrothermal method, characterized and photocatalytically evaluated toward H₂ production through water splitting under visible-light irradiation. Characterization consisted in Thermogravimetry analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy, scattering transmission electronic microscopy, BET surface area, UV-Vis spectroscopy, cyclic voltammetry, Hall effect, and photoluminescence. The MCO were evaluated as photocatalyst using an artificial visible light lamp and monitored by gas chromatography. XRD analysis found a pure spinel phase MCO. The surface area was ∼5 m²·g⁻¹ for the MCO synthetized by Pechini and increased to 155 m²·g⁻¹ with the hydrothermal method with acetates as precursors. The Pechini MCO showed higher carrier mobility but the fastest recombination. Photocatalytic evaluation of the MCOs showed that the highest photocatalytic activity generated was 12 μmol H₂/g_cat at 8 h with the MCO obtained by hydrothermal method with the acetates.