Verifying the relationships of defect site and enhanced photocatalytic properties of modified ZrO2 nanoparticles evaluated by in-situ spectroscopy and STEM-EELS.

Base treatment and metal doping were evaluated as means of enhancing the photocatalytic activity of ZrO2 nanoparticles (NPs) via the generation of oxygen vacancies (OvS), and the sites responsible for this enhancement were identified and characterized by spectroscopic and microscopic techniques. We confirmed that OvS produced by base treatment engaged in photocatalytic activity for organic pollutant degradation, whereas surface defects introduced by Cr-ion doping engaged in oxidative catalysis of molecules. Moreover, we verified that base-treated ZrO2 NPs outperformed their Cr-ion doped counterparts as photocatalysts using in situ X-ray photoelectron spectroscopy and scanning transmission electron microscopy coupled with electron energy loss spectroscopy (STEM-EELS). Thus, our study provides valuable information on the origin of the enhanced photocatalytic activity of modified ZrO2 NPs and demonstrates the practicality of in situ spectroscopy and STEM-EELS for the evaluation of highly efficient metal oxide photocatalysts.

Strategy for Encapsulation of CdS Quantum Dots into Zeolitic Imidazole Frameworks for Photocatalytic Activity.

Encapsulating CdS quantum dots (QDs) into zeolitic imidazole framework-8 (ZIF-8) can offer several advantages for photocatalysis. Various types of capping agents have been used to encapsulate QDs into ZIF-8 nanopores. An effective method for encapsulating CdS QDs into ZIF-8 is to use 2-mercaptoimidazole as the capping agent. This is because 2-mercaptoimidazole is similar to the imidazolate ligands of ZIFs and can used for capping active species with simultaneous encapsulation during the crystal growth of ZIF-8. Compared to other widely used capping agents such as polyvinylpyrrolidone (PVP), using 2-mercaptoimidazole for encapsulating CdS QDs into ZIF-8 revealed photocatalytic effects along with the molecular sieving effect when using differently sized molecular redox mediators such as methyl viologen (MV2+) and diquat (DQ2+).

Comparison of Enhanced Photocatalytic Degradation Efficiency and Toxicity Evaluations of CeO2 Nanoparticles Synthesized Through Double-Modulation.

We demonstrated that Fe/Cr doped and pH-modified CeO2 nanoparticles (NPs) exhibit enhanced photocatalytic performance as compared to bare CeO2 NPs, using photocatalytic degradation. To assess the toxicity level of these double-modified CeO2 NPs on the human skin, they were introduced into HaCaT cells. The results of our conventional cellular toxicity assays (neutral red uptake and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide for assays) indicated that Cr@CeOx NPs prompt severe negative effects on the viability of human cells. Moreover, the results obtained by scanning transmission X-ray microscopy and bio-transmission electron microscope analysis showed that most of the NPs were localized outside the nucleus of the cells. Thus, serious genetic toxicity was unlikely. Overall, this study highlights the need to prevent the development of Cr@CeOx NP toxicity. Moreover, further research should aim to improve the photocatalytic properties and activity of these NPs while accounting for their stability issues.

Chitosan-Derived Porous Activated Carbon for the Removal of the Chemical Warfare Agent Simulant Dimethyl Methylphosphonate.

Methods for the rapid removal of chemical warfare agents are of critical importance. In this work, a porous activated carbon material (C-PAC) was prepared from chitosan flakes via single-step potassium carbonate (K2CO3) activation for the prompt adsorption of dimethyl methylphosphonate (DMMP). C-PAC samples were prepared using different carbonization temperatures (350, 550, and 750 °C) at a constant K2CO3/chitosan ratio (1:2) and using different activator ratios (K2CO3/chitosan ratios of 1:0.5, 1:1, 1:2, and 1:3) at 750 °C. Furthermore, we evaluated the effect of preparation conditions on the adsorption capacities of the various C-PAC materials for DMMP under ambient conditions (25 °C). Notably, for the C-PAC material prepared at 750 °C using a K2CO3/chitosan ratio of 1:2, the DMMP adsorption was saturated at approximately 412 mg·g-1 carbon after 48 h. The good performance of this material makes it a potential candidate for use in remedial applications or protective gear.

Rapid Capture and Hydrolysis of a Sulfur Mustard Gas in Silver-Ion-Exchanged Zeolite Y.

Sulfur mustard gas, also called HD, is one of the main chemical warfare agents and has claimed thousands of lives and left many more contaminated. The development of functional materials to promptly capture and detoxify sulfur mustard within a few minutes is extremely important to save the lives of the affected people. This has motivated us to explore excellent detoxification systems that can be deployed in the field to rapidly capture and hydrolyze mustard gas in a short time. To that end, we present a silver-ion-exchanged zeolite Y [(Ag+) n@Y, n = 5, 13, 21, 32, 43, and 55] that can rapidly capture mustard gas and its simulant (2-chloroethyl ethyl sulfide, CEES) in ambient conditions to enable the prompt hydrolysis of the CEES captured in its nanopores. The capture and hydrolysis ability of Ag+@Y positively correlated with its number of Ag+ ions. In addition, 70% of CEES (2.5 µL in 1 mL) was captured by (Ag+)55@Y within 20 min at 25 °C in ambient conditions. Moreover, 100% CEES (2.5 µL in 1 mL aqueous ethanol cosolvent) was hydrolyzed in 1 min at 25 °C. The efficiency of Ag+@Y in capturing and hydrolyzing CEES as well as mustard gas is thus a system with high detoxification efficiency for this dangerous chemical warfare agent.