Enhanced photocatalytic properties of defect-rich α-MoO3 nanoflakes by cavitation and pitting effect

Synergistic adsorption and photocatalytic degradation of tetracycline using a Z-scheme kaolin/g-C3N4/MoO3 nanocomposite: A sustainable approach for water treatment

This research focuses on the synthesis and application of a novel kaolin-supported g-C3N4/MoO3 nanocomposite for the degradation of tetracycline, an important antibiotic contaminant in water systems. The nanocomposite was prepared through a facile and environmentally friendly approach, leveraging the adsorption and photocatalytic properties of kaolin, g-C3N4 and MoO3 nanoparticles, respectively. Comprehensive characterization of the nanocomposite was conducted using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and optical spectra. The surface parameters were studied using N2 adsorption-desorption isotherm. The elemental composition was studied using X-ray photoelectron spectroscopy. The efficiency of the developed nanocomposite in tetracycline degradation was evaluated and the results revealed an efficient tetracycline degradation exhibiting the synergistic effects of adsorption and photocatalytic degradation in the removal process. The tetracycline degradation was achieved in 60 min. Kinetic studies and thermodynamic analyses provided insights into the degradation mechanism, suggesting potential applications for the nanocomposite in wastewater treatment. Additionally, the recyclability and stability of the nanocomposite were investigated, demonstrating its potential for sustainable and long-term application in water treatment.

Enhanced chirality induced in a composite structure consisting of α-MoO3 film and a silver metasurface

Chiral structures have been widely used in many fields, such as biosensing and analytical chemistry. In this paper, the chiral response of a composite structure consisting of α-M o O 3 film and a silver (Ag) metasurface is studied. First, the effect of the thickness of α-M o O 3 film on the circular dichroism (CD) is discussed, and it is found that CD can reach 0.93 at a wavelength of 9.6 µm when the thickness of α-M o O 3 film is 6.075 µm. To better understand the physical mechanism, we analyze the transverse electric and transverse magnetic wave components in the transmitted wave for the whole structure and each layer. One can see that the strong chirality of the structure is attributed to the polarization conversion of α-M o O 3 film and the selective transmissivity of Ag ribbons. In addition, the influence of the filling factor of the Ag ribbons on chirality is also studied. This work combines hyperbolic material α-M o O 3 with Ag ribbons to enhance CD. Also, it provides greater freedom in the tuning of chirality. We believe that this work not only deepens the understanding of the chiral response of anisotropic materials, but also gives promise for its applications in the fields of polarization optics and biosensing.

A single-step plasma method for rapid production of 2D, ferromagnetic, surface vacancy-engineered MoO3-xnanomaterials, for photothermal ablation of cancer

A rapid, clean plasma-chemical technique is demonstrated here, for cost-effective, synthesis of surface vacancy engineered, 2D, molybdenum-oxide nanomaterials, during a one-step, integrated synthesis-hydrogenation process for biomedical applications. A laminar plasma beam populated with O and H radicals impinges on a molybdenum target, out of which molybdenum-oxide nanomaterials are very rapidly generated with controlled surface O vacancies. 2D, dark-blue coloured, nano-flake/ribbon like MoO_3-xis produced maximum up to 194 g h^-1, the core of which still remains as stoichiometric molybdenum-oxide. These nanomaterials can get heated-up by absorbing energy from a near-infrared (NIR) laser, which enable them as photothermal therapy (PTT) candidate material for the invasive precision therapy of cancer. The surface defects endows the products with robust ferromagnetism at room temperature conditions (maximum saturation-magnetization: 6.58 emu g^-1), which is order of magnitude stronger than most other vacancy engineered nanomaterials. These nanometric metal-oxides are observed to be perfectly compatible in animal physiological environment and easily dispersed in an aqueous solution even without any pre-treatment. The MoO_3-xnanomaterials are stable against further oxidation even under prolonged atmospheric exposure.In vitroexperiments confirm that they have ideal efficacy for photothermal ablation of human and murine melanoma cancer at relatively lower dose. Duringin vivoPTT treatments, they may be manipulated with a simple external magnetic field for targeted delivery at the malignant tumours. It is demonstrated that commensurate to the neutralization of the malignant cells, the nanomaterials themselves get self-degraded, which should get easily excreted out of the body.

Embedding Co in perovskite MoO3 for superior catalytic oxidation of refractory organic pollutants with peroxymonosulfate

A cobalt (Co)-doped perovskite molybdenum trioxide (α-MoO₃) catalyst (Co-MO) was synthesized by a facile pyrolysis strategy and used for degrading various organic contaminants via peroxymonosulfate (PMS) activation. The doped Co was inserted in the inter space between the octahedron [MoO₆], facilitating the growth of the α-MoO₃ crystal on the [010] direction. This unique structure accelerated the activation of PMS as the Co-MO could function as a carrier for electron transfer to facilitate the Co(II)/Co(III) cycle in the Co-MO/PMS system. As a result, the Co-MO/PMS system showed noticeable activity for removing 100% bisphenol A (BPA) under a broad conditions within 30 min. The radical quenching test and electron paramagnetic resonance analysis revealed that singlet oxygen (¹O₂) was the main active species for BPA degradation in the Co-MO/PMS system, while free radicals, such as O₂^•-, SO₄^•- and •OH, were also produced as the intermediate species. Furthermore, the carrier mechanism may enable the Co-MO/PMS system maintain relatively high performance during repeat use, and also excellent adaptability was revealed by the well function in various water matrices and high activity in degrading various refractory organic pollutants. Our findings pave a useful avenue for the rational design of novel cobalt-doped catalysts with high catalytic performance toward wide environmental applications.

Edge-Site-Rich Ordered Macroporous BiOCl Triggers CO Activation for Efficient CO2 Photoreduction

Endowing a semiconductor with tunable edge active sites will effectively enhance catalytic performance. Herein, an edge-site-rich ordered macroporous BiOCl (BiOCl-P) with abundant dangling bonds is constructed via the colloidal crystal template method. The edge-site-rich ordered macroporous structure provides abundant adsorption sites for CO₂ molecules, as well as forms numerous localized electron enrichment areas, accelerating charge transfer. DFT calculations reveal that the dangling bonds-rich configuration can effectively reduce the CO₂ activation energy barrier, boost the CO double bond dissociation, and facilitate the proton electron coupling reaction. As a result, the BiOCl-P achieves a higher CO and CH₄ generation rate of 78.07 and 3.03 µmol g^-1 under 4 h Xe lamp irradiation in a solid-gas system. Finally, the CO₂ molecules' conversion process is further investigated by in situ Fourier-transform infrared spectroscopy. This work realizes a new avenue toward the design of vibrant semiconductors on the nanoscale to boost inert CO₂ photoreduction.

Strong extrinsic chirality in biaxial hyperbolic material α-MoO3 with in-plane anisotropy

Chirality has always been a hot research topic because it possesses potential applications in polarization optics, chemical and biosensing. In the previous works, intrinsic chirality has been extensively explored, but its development is limited due to the complexity in fabrication of chiral metamaterials. Therefore, there is an urgent need to simplify fabrication and design of compact devices with chiral response. Extrinsic chirality has shown great potential because it can be realized in nonchiral anisotropic planar structures with low-cost fabrication techniques. In this paper, the extrinsic chirality of biaxial hyperbolic material $\alpha {\text -}{\rm{Mo}}{{\rm{O}}_3}$ with in-plane anisotropy has been investigated. By analyzing the effect of thickness of $\alpha {\text -}{\rm{Mo}}{{\rm{O}}_3}$ film, the angle of incidence, azimuth angle, and wavelength of incidence on the circular dichroism (CD), the maximum CD can reach 0.77. This strong extrinsic chirality of the $\alpha {\text -}{\rm{Mo}}{{\rm{O}}_3}$ film results from the mutual orientation of the $\alpha {\text -}{\rm{Mo}}{{\rm{O}}_3}$ film and the incident light. In addition, $\alpha {\text -}{\rm{Mo}}{{\rm{O}}_3}$ film can still maintain strong extrinsic chirality when the azimuthal angle ranges from approximately 20°-57° and the angle of incidence is from 55°-80°.

Development of Sustainable Heterogeneous Catalysts for the Photocatalytic Treatment of Effluents

The inadequate discharge of effluents from different sources without prior treatment can impact the characteristics of soil and water, which reflect serious environmental problems. Advanced oxidative processes (AOP) appear as a viable alternative for environmental remediation, including wastewater treatment. Herein, α-MoO3 and α-Fe2O3 semiconductors were synthesized at low temperature by a Pechini-based method and then applied in photocatalysis. The catalytic efficiency was performed under visible light toward the degradation of an organic persistent pollutant (Rhodamine B dye, RhB), commonly present in industries wastewater. The results indicated that the synthesized α-MoO3 or α-Fe2O3 photocatalysts presented a pronounced activity and promoted an efficient RhB degradation after 15 min of reaction. α-MoO3 had a degradation efficiency of 93% and 98%, while α-Fe2O3 showed 67% and 100% RhB degradation without and with the addition of H2O2, respectively. These results suggest that the synthesized oxides have high oxi-reductive capacity, which can be used for a fast and effective photodegradation of RhB and other organic persistent pollutants to minimize environmental impacts.