Pierre G. Ramos

CoFe2O4/SiO2/TiO2 materials were prepared through a sequential sol–gel route using nominal titanium isopropoxide (TIP) volumes between 0.54 and 2.27 mL. The effect of TIP loading was evaluated through surface charge behavior, magnetic response, and light-assisted RhB removal. Electron microscopy of the component and binary reference samples provided qualitative information on the separate SiO2 formation and TiO2 deposition stages, while XRD analysis of the representative U2 material confirmed anatase TiO2 and spinel CoFe2O4. EDS analysis of the final U1–U4 was implemented. Zeta potential measurements revealed differences in surface charge behavior among the samples prepared with different nominal TIP volumes, while vibrating sample magnetometry confirmed that the ferrimagnetic character of the CoFe2O4 component was retained. The magnetic response decreased at higher TIP volumes. Overall, nominal TIP loading was associated with changes in surface charge behavior, light-assisted RhB removal, and magnetic response under the evaluated conditions.

In the present work, a TiO₂/zeolite photocatalyst was synthesized by dispersing TiO₂ nanoparticles obtained through the sol-gel method onto the surface of natural zeolite derived from ignimbrite residue. The zeolite was obtained from an ignimbrite rubble treatment collected from a quarry in Arequipa City, Peru. The research focused on the effect of zeolite on the TiO₂ nanoparticles. The synthesized photocatalysts were characterized using various techniques, including field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDS), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), and Brunauer–Emmett–Teller surface area analysis (BET). The results revealed that the TiO₂/zeolite samples displayed high crystallinity, with TiO₂ being present in three phases and zeolite being present in the analcime phase. Furthermore, these samples exhibited a band gap of 3.14 eV and a high surface area compared to that of bare TiO₂. Finally, the photocatalytic activity of the TiO₂/zeolite composite obtained was evaluated toward the decomposition of 10 ppm and 20 ppm of methyl orange (MO) dye. The TiO₂/zeolite samples demonstrated improved photocatalytic activity compared to that of pristine TiO₂ under the same experimental conditions. This enhancement is primarily attributed to the increased specific surface area of the TiO₂/zeolite samples, making them promising materials for future efficient and sustainable photocatalytic applications.

Heterostructured photoactive nanomaterials represent innovative construction to absorb UV and UV-vis light. This feature makes heterostructures exciting candidates for environmental photocatalytic applications such as organic pollutants degradation and removal of heavy metals, among others. Therefore, the efficient design of heterostructures based on thin films of oxide semiconductors will allow obtaining a novel material with outstanding properties. This work presents a review of the current heterostructures based on α-Fe2O3 and CuO thin films, which were deposited onto different substrates using physics and chemistry routes. Moreover, we will discuss the key factors to promote structural and morphology control and the drawbacks such as low absorption of the solar spectra, low active surface area, and charge carrier recombination. Finally, the relevance of the results and future directions of the heterostructures as materials for the purification of aqueous systems were discussed.

Capacitive deionization (CDI) is a promising and cost-effective technology that is currently being widely explored for removing dissolved ions from saline water. This research developed materials based on activated carbon (AC) materials modified with zinc oxide (ZnO) nanorods and used them as high-performance CDI electrodes for water desalination. The as-prepared electrodes were characterized by cyclic voltammetry, and their physical properties were studied through SEM and XRD. ZnO-coated AC electrodes revealed a better specific absorption capacity (SAC) and an average salt adsorption rate (ASAR) compared to pristine AC, specifically with values of 123.66 mg/g and 5.06 mg/g/min, respectively. The desalination process was conducted using a 0.4 M sodium chloride (NaCl) solution with flow rates from 45 mL/min to 105 mL/min under an applied potential of 1.2 V. Furthermore, the energy efficiency of the desalination process, the specific energy consumption (SEC), and the maximum and minimum of the effluent solution concentration were quantified using thermodynamic energy efficiency (TEE). Finally, this work suggested that AC/ZnO material has the potential to be utilized as a CDI electrode for the desalination of saline water.