Activated carbon modified titanium dioxide/bismuth trioxide adsorbent: One-pot synthesis, high removal efficiency of organic pollutants, and good recyclability.

Considerable endeavors have focused on tightly combining adsorption with photocatalysis in designing composite materials for environmental pollution treatment. Recent advances in coupling titanium dioxide/bismuth trioxide (TiO2/Bi2O3) with activated carbon (AC) show significantly enhanced photocatalytic performance but face critical limitations including low adsorption capacity and multi-step synthesis. In this work, we introduce a one-pot synthesis of activated carbon modified TiO2/Bi2O3 composite materials (TiO2/Bi2O3/AC). Thanks to the integrated adsorbent/photocatalyst system, TiO2/Bi2O3/AC shows a drastically enhanced removal efficiency for sulfamethazine (>81%), far beyond the corresponding value of the reported AC/TiO2/Bi2O3 adsorbent (<40%). Notably, the removal rates of other typical pollutants including tetracyclines, methyl orange, and rhodamine B are as high as >98%. Furthermore, TiO2/Bi2O3/AC obtains >80% of its adsorption rate for the fifth cycle after simple photo-regeneration without any other post-treatments. Kinetic analysis and photoelectric characterization are carried out to provide insight into adsorption mechanism. Therefore, this work demonstrates a considerable potential to design and construct other multifunctional adsorbents with advanced performance.

Hierarchically-structured SiO2-Ag@TiO2 hollow spheres with excellent photocatalytic activity and recyclability.

A new protocol for constructing sandwich-like SiO2-Ag@TiO2 hollow spheres (SAT) is introduced, in which SiO2 acts as an efficient support for the Ag nanoparticles (Ag NPs) immobilization, while TiO2 maintains its hierarchical structure and prevents the aggregation of Ag NPs during the photocatalytic reaction. As a photocatalytic agent, the inner and outer surfaces of TiO2 can be fully occupied by pollutants molecules because of its unique structure, which faster boosts the photo-generated electrons to transfer the substrates, leading to an enhanced photocatalytic performance. Compared with Ag NPs deposited on the surface of SiO2@TiO2 (STA), the as-synthesized SAT exhibits a markedly enhanced visible-light and UV light activity than STA for degrading tetracycline and traditional dyes. The excellent photocatalytic performances are ascribed to the enhanced transport paths of photo-generated electrons, reduced recombination probability of e-/h+ pairs, and decreased threat of oxidation and corrosion. Especially, the SAT still maintains its photocatalytic efficiency after five consecutive runs even though the sample is recovered under visible-light irradiation, far beyond the reusability of STA under the same conditions. Therefore, the outstanding photocatalytic activity and excellent recyclability make SAT more potential to purify aquatic contaminants and to meet the demands of future environmental issues.

High photocatalytic activity of hierarchical SiO2@C-doped TiO2 hollow spheres in UV and visible light towards degradation of rhodamine B.

Ongoing research activities are targeted to explore high photocatalytic activity of TiO2-based photocatalysts for the degradation of environmental contaminants under UV and visible light irradiation. In this work, we devise a facile, cost-effective technique to in situ synthesize hierarchical SiO2@C-doped TiO2 (SCT) hollow spheres for the first time. This strategy mainly contains the preparation of monodisperse cationic polystyrene spheres (CPS), sequential deposition of inner SiO2, the preparation of the sandwich-like CPS@SiO2@CPS particles, and formation of outer TiO2. After the one-step removal of CPS templates by calcination at 450°C, hierarchical SiO2@C-doped TiO2 hollow spheres are in situ prepared. The morphology, hierarchical structure, and properties of SCT photocatalyst were characterized by TEM. SEM, STEM Mapping, BET, XRD, UV-vis spectroscopy, and XPS. Results strongly confirm the carbon doping in the outer TiO2 lattice of SCT hollow spheres. When the as-synthesized SCT hollow spheres were employed as a photocatalyst for the degradation of Rhodamine B under visible-light and ultraviolet irradiation, the SCT photocatalyst exhibits a higher photocatalytic activity than commercial P25, effectively overcoming the limitations of poorer UV activity for many previous reported TiO2-based photocatalysts due to doping.

A self-switchable Ag nanoreactor exhibiting outstanding catalytic properties.

A highly efficient nanoreactor that contains silver nanoparticles in hollow silica spheres and an interpolymer network as a gate-keeper has been developed following a facile procedure. The fast "signal-triggered" switch of the smart network results in a high reactivity and a high response rate, yielding improved potential for many practical applications.

Stimuli-responsive controlled release and molecular transport from hierarchical hollow silica/polyelectrolyte multilayer formulations.

The smart designing of polymer hybrid carriers with a selective property will play a pivotal role in improving patient care and simplifying treatment regimes in the clinic. The controlled drug release of biomolecules from thin film coatings provides a simple pathway to offer complex localized in vivo dosing. In this investigation, we showed that it is possible to take advantage of the structure of hierarchically structured hollow silica/polymer hybrid system to control drug release. Drug-loaded polyelectrolyte multilayer films were developed using layer-by-layer assembly, incorporating the surface of the hierarchically structured hollow silica spheres. In comparison to the conventional hollow silica system, the synthesized formulation exhibited an enhanced stability, higher drug loading and better residual capacity of biomolecules. This rationally integrated architecture was demonstrated to be a very effective and controllable carrier for the drug release by changing the pH value. In addition, the developed system presented a highly selective molecular transport of doxorubicin hydrochloride (DOX), a model anti-cancer agent, at different pH values; moreover, it could be further applied to tailor cell viability, making it more promising for advanced drug therapy.