Sun light assisted photocatalytic decontamination of sulfur mustard using ZnO nanoparticles

Bifunctional Europium(III) and Niobium(V)-Containing Saponite Clays for the Simultaneous Optical Detection and Catalytic Oxidative Abatement of Blister Chemical Warfare Agents

For the first time, the co-presence in the saponite structure of luminescent Eu^III and catalytic Nb^V metal sites was exploited for the simultaneous detection and catalytic abatement of sulfur-containing blister chemical warfare agents. Metal centers were introduced in structural positions of the saponite (in the interlayer space or inside the inorganic framework) following two different synthetic methodologies. The functionalized saponites were able to reveal the presence of a sulfur mustard simulant (2-chloroethyl)ethyl sulfide (CEES) after few seconds of contact time and more than 80 % of the substrate was catalytically decomposed after 24 h in the presence of aqueous hydrogen peroxide.

Adsorption of sulfur mustard on clean and water-saturated ZnO(101¯0): Structural diversity from first-principles calculations

We investigate the adsorption of a chemical warfare agent, namely sulfur mustard (SM), on clean and water-saturated ZnO(101¯0) surfaces using density functional theory calculations to understand the first step of its efficient neutralization to less toxic chemical compounds. We determine the relative stability of various SM conformers adsorbed at different sites on both ZnO surfaces. The unique hydrogen bonding patterns obtained for the idealized clean and the more realistic water-saturated ZnO surface are analyzed and their influence on the stability of the SM@ZnO structures is demonstrated. We find that absolute values of the calculated binding and interaction energies are significantly higher for the clean than for the water-saturated ZnO surface due to the formation of Cl⋯Zn and S⋯Zn contacts. The high adsorptive reactivity of the clean ZnO surface is also evident from the strong structural changes of the initial local energy minimum gas-phase conformations of the SM molecules upon adsorption. This phenomenon is not observed for the water-saturated ZnO surface, which has almost no impact on the SM conformation after adsorption, leaving it as it exists in the gas phase. The insights from the results obtained provide a missing piece toward the understanding of the complex mechanism of SM neutralization on ZnO surfaces.

Catalytic reaction system for rapid selective oxidation of alkyl sulphide

Highly efficient catalytic reaction systems are developed to rapidly and selectively oxidize 2-chloroethyl ethyl sulfide (CEES). In the systems, precursors containing bromide(s) and nitrate anions are chosen for the development of cyclic catalytic loop and the effect of acids on the selective oxidation of CEES are investigated by the addition of several homogeneous acid catalysts. The experimental results reveal that addition of acid results in a higher concentration of tribromide, which is reported as a key component for the observed activity in the catalytic solution. As a consequence, a dramatic improvement in catalytic activity is observed, especially when the molar amount of acid is controlled to be more than twice the initial concentration of tribromide. For the efficient design of a catalytic system, heterogeneous acid catalysts possessing different ratios of Brønsted to Lewis acid sites are also considered. Compared to reaction systems catalysed by homogeneous acids, similar reaction behaviour is observed for the reaction with Amerlyst-15, while those with other heterogeneous catalysts, containing Lewis or mixed acid sites in their structure, exhibits an adverse effect of selective sulfoxidation, mainly due to the adsorption of anions onto Lewis sites and consequential deconstruction of the catalytic loop.

A Ternary Magnetic Recyclable ZnO/Fe3O4/g-C3N4 Composite Photocatalyst for Efficient Photodegradation of Monoazo Dye

To develop a highly efficient visible light-induced and conveniently recyclable photocatalyst, in this study, a ternary magnetic ZnO/Fe₃O₄/g-C₃N₄ composite photocatalyst was synthesized for the photodegradation of Monas dye. The structure and optical performance of the composite photocatalyst were characterized using X-ray diffraction (XRD), transmission electron microscopye (TEM), energy dispersive spectroscopy (EDS), photoluminescence (PL) spectra, ultraviolet-visible diffuse reflection, and photo-electrochemistry. The photocatalytic activities of the prepared ZnO/Fe₃O₄/g-C₃N₄ nanocomposites were notably improved, and they were significantly higher than those of pure g-C₃N₄ and ZnO. Given the presence of the heterojunction between the interfaces of g-C₃N₄ and ZnO, the higher response to visible light and separation efficiency of the photo-induced electrons and holes enhanced the photocatalytic activities of the ZnO/Fe₃O₄/g-C₃N₄ nanocomposites. The stability experiment revealed that ZnO/Fe₃O₄/g-C₃N₄-50% demonstrates a relatively higher photocatalytic activity after 5 recycles. The degradation efficiency of MO, AYR, and OG over ZnO/Fe₃O₄/g-C₃N₄-50% were 97.87%, 98.05%, and 83.35%, respectively, which was due to the number of dye molecules adsorbed on the photocatalyst and the structure of the azo dye molecule. Azo dyes could be effectively and rapidly photodegraded by the obtained photocatalyst. Therefore, the environment-friendly photocatalyst could be widely applied to the treatment of dye contaminated wastewater.

Effect of Different Activated Carbon as Carrier on the Photocatalytic Activity of Ag-N-ZnO Photocatalyst for Methyl Orange Degradation under Visible Light Irradiation

In order to enhance the photodegradation of methyl orange (MO) by ZnO under visible light irradiation, ZnO nanoparticles co-doped with Ag and N and supported on activated carbon (AC) with different properties were synthesized through the sol-gel method. The prepared photocatalysts were characterized in terms of the structure and properties through X-ray diffraction, N₂ adsorption-desorption, ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence, and electron spin resonance. The photocatalytic activities of these photocatalysts followed the order: Ag-N-ZnO/ACs > Ag-N-ZnO > N, or Ag single-doped ZnO > commercial ZnO. This result was attributed to the small particle size, large surface area, narrow band gap, and high charge separation of Ag-N-ZnO/ACs. The Ag-N-ZnO/coconut husk activated carbon (Ag-N-ZnO/CHAC) exhibited the highest degradation efficiency of 98.82% for MO under visible light irradiation. This outcome was due to the abundant pore structure of Ag-N-ZnO/CHAC, resulting in stronger adsorption than that of other Ag-N-ZnO/ACs. Moreover, the degradation of MO on photocatalysis followed first order kinetics. The reactive species ·OH and ·O₂⁻ played more important roles in the photocatalytic degradation of MO over composite photocatalyst. Ag-N-ZnO/CHAC photocatalyst exhibited higher photocatalytic activity than unsupported Ag-N-ZnO after five recycling runs.

The Application of Graphene and Its Derivatives to Energy Conversion, Storage, and Environmental and Biosensing Devices

Graphene (GR) and its derivatives are promising materials on the horizon of nanotechnology and material science and have attracted a tremendous amount of research interest in recent years. The unique atom-thick 2D structure with sp(2) hybridization and large specific surface area, high thermal conductivity, superior electron mobility, and chemical stability have made GR and its derivatives extremely attractive components for composite materials for solar energy conversion, energy storage, environmental purification, and biosensor applications. This review gives a brief introduction of GR's unique structure, band structure engineering, physical and chemical properties, and recent energy-related progress of GR-based materials in the fields of energy conversion (e.g., photocatalysis, photoelectrochemical water splitting, CO2 reduction, dye-sensitized and organic solar cells, and photosensitizers in photovoltaic devices) and energy storage (batteries, fuel cells, and supercapacitors). The vast coverage of advancements in environmental applications of GR-based materials for photocatalytic degradation of organic pollutants, gas sensing, and removal of heavy-metal ions is presented. Additionally, the use of graphene composites in the biosensing field is discussed. We conclude the review with remarks on the challenges, prospects, and further development of GR-based materials in the exciting fields of energy, environment, and bioscience.

Rapid and complete degradation of sulfur mustard adsorbed on M/zeolite-13X supported (M = 5 wt% Mn, Fe, Co) metal oxide catalysts with ozone

Complete degradation of sulfur mustard adsorbed over M/zeolite-13X (M = 5 wt% Mn, Fe, Co) catalysts using ozone gas under ambient conditions.

Zinc oxide based photocatalysis: tailoring surface-bulk structure and related interfacial charge carrier dynamics for better environmental applications

Surface-bulk modification of zinc oxide for efficient photocatalysis.

N-doped, S-doped TiO2nanocatalysts: synthesis, characterization and photocatalytic activity in the presence of sunlight

N doped and S doped nano TiO₂catalysts were synthesized by a sol–gel process followed by hydrothermal treatment at low temperature and tested for catalytic activity by natural sunlight photocatalytic degradation of a toxic chemical warfare agent.

Photoassisted and photocatalytic degradation of sulfur mustard using TiO2 nanoparticles and polyoxometalates

The decomposition of highly toxic chemical warfare agent, sulfur mustard (bis(2-chloroethyl) sulfide or HD), has been studied by homogeneous photolysis and heterogeneous photocatalytic degradation on titania nanoparticles. Direct photolysis degradation of HD with irradiation system was investigated. The photocatalytic degradation of HD was investigated in the presence of TiO(2) nanoparticles and polyoxometalates embedded in titania nanoparticles in liquid phase at room temperature (33 ± 2 °C). Degradation products during the treatment were identified by gas chromatography-mass spectrometry. Whereas apparent first-order kinetics of ultraviolet (UV) photolysis were slow (0.0091 min(-1)), the highest degradation rate is obtained in the presence of TiO(2) nanoparticles as nanophotocatalyst. Simultaneous photolysis and photocatalysis under the full UV radiation leads to HD complete destruction in 3 h. No degradation products observed in the presence of nanophotocatalyst without irradiation in 3 h. It was found that up to 90 % of agent was decomposed under of UV irradiation without TiO(2), in 6 h. The decontamination mechanisms are often quite complex and multiple mechanisms can be operable such as hydrolysis, oxidation, and elimination. By simultaneously carrying out photolysis and photocatalysis in hexane, we have succeeded in achieving faster HD decontamination after 90 min with low catalyst loading. TiO(2) nanoparticles proved to be a superior photocatalyst under UV irradiation for HD decontamination.