Growth of anatase nanoparticles inside the mesopores of SBA-15 for photocatalytic applications

Simple Quaternary Templating Systems for Direct Synthesis of Unique SBA-15 Mesopore Frameworks Embedded with High-Content TiO2 Nanoparticles as High-Performance Photocatalysts

This work presents a simple P123-based quaternary templating system using titanyl sulfate (TS) as the TiO₂ precursor and self-contained sulfuric acid as the catalyst (TS/TEOS/P123/H₂O). A unique structural configuration of SBA-15-type mesopore frameworks embedded with high-content TiO₂ nanoparticles can be directly obtained. Even with a high TiO₂ content (29.1 wt %), well-defined mesostructures free of pore blocking can be secured. A new structural formation mechanism is unveiled: a self-assembly process between inorganic species and P123 micelles yields ordered mesostructures catalyzed by self-contained TS in the low-temperature step, while sol-gel reaction and crystallization of TS coincide with processes of mesostructural re-organization and partial evacuation of P123 from mesopores. The incorporation of high-content TiO₂ nanoparticles into mesopore frameworks mainly happens during the hydrothermal treatment step. Not surprisingly, thanks to well-defined mesostructures containing high-content accessible TiO₂ nanoparticles, such TiO₂/SBA-15 composites show high activity and good reusability in photodegrading Rhodamine B and humic acids and photoreducing highly toxic Cr⁶⁺ in water under UV irradiation.

Mesoporous materials for clean energy technologies

Alternative energy technologies are greatly hindered by significant limitations in materials science. From low activity to poor stability, and from mineral scarcity to high cost, the current materials are not able to cope with the significant challenges of clean energy technologies. However, recent advances in the preparation of nanomaterials, porous solids, and nanostructured solids are providing hope in the race for a better, cleaner energy production. The present contribution critically reviews the development and role of mesoporosity in a wide range of technologies, as this provides for critical improvements in accessibility, the dispersion of the active phase and a higher surface area. Relevant examples of the development of mesoporosity by a wide range of techniques are provided, including the preparation of hierarchical structures with pore systems in different scale ranges. Mesoporosity plays a significant role in catalysis, especially in the most challenging processes where bulky molecules, like those obtained from biomass or highly unreactive species, such as CO2 should be transformed into most valuable products. Furthermore, mesoporous materials also play a significant role as electrodes in fuel and solar cells and in thermoelectric devices, technologies which are benefiting from improved accessibility and a better dispersion of materials with controlled porosity.