Controlled Synthesis of Hollow α-Fe2O3 Microspheres Assembled With Ionic Liquid for Enhanced Visible-Light Photocatalytic Activity

Investigation of α-Fe2O3 catalyst structure for efficient photocatalytic fenton oxidation removal of antibiotics: preparation, performance, and mechanism

Currently, the surface structure modification of photocatalysts is one of the effective means of enhancing their photocatalytic efficiency. Therefore, it is critically important to gain a deeper understanding of how the surface of α-Fe2O3 photocatalysts influences catalytic activity at the nanoscale. In this work, α-Fe2O3 catalysts were prepared using the solvothermal method, and four distinct morphologies were investigated: hexagonal bipyramid (THB), cube (CB), hexagonal plate (HS), and spherical (RC). The results indicate that the hexagonal bipyramid (THB) exhibits the highest degradation activity towards tetracycline (TC), with a reaction rate constant of k = 0.0969 min-1. The apparent reaction rate constants for the cube (CB), hexagonal plate (HS), and spherical (RC) morphologies are 0.0824, 0.0726, and 0.0585 min-1, respectively. In addition, it has been observed that the enhancement of photocatalytic activity is closely related to the increase in surface area, which provides more opportunities for interactions between Fe2+ and holes. The quenching experiments and electron paramagnetic resonance (EPR) results indicate that the ˙O2, ˙OH and h+ contribute mainly to the degradation of TC in the system. This research contributes to a more comprehensive understanding of catalyst surface alterations and their impact on catalytic performance.

Room-temperature response of MOF-derived Pd@PdO core shell/γ-Fe2O3 microcubes decorated graphitic carbon based ultrasensitive and highly selective H2 gas sensor

With the current upsurge in hydrogen economies all over the world, an increased demand for improved chemiresistive H2 sensors that are highly responsive and fast acting when exposed to gases is expected. Owing to safety concerns about explosive and highly flammable H2 gas, it is important to develop resistive sensors that can detect the leakage of H2 gas swiftly and selectively. Currently, interest in metal-organic frameworks (MOFs) for gas-sensor applications is increasing due to their open-metal sites, large surface area, and unique surface morphologies. In this research, a highly selective and sensitive H2-sensor was established based on graphitic carbon (GC) anchored spherical Pd@PdO core-shells over γ-Fe2O3 microcube (Pd@PdO/γ-Fe2O3@GC which is termed as S3) heterostructure materials. The combined solvothermal followed by controlled calcination-assisted S3 exhibited a specific morphology with the highest surface area of 79.12 m2 g-1, resulting in fast response and recovery times (21 and 29 s, respectively), and excellent sensing performance (ΔR/R0∼ 96.2 ± 1.5), outstanding long-term stability, and a 100 ppb detection limit when detecting H2-gas at room temperature (mainly in very humid surroundings). This result proves that adsorption sites provided by S3 can promote surface reactions (adsorption and desorption) for ultrasensitive and selective H2gas sensors.

α-Fe2O3 nanoparticles and hazardous air pollutants release during cooking using cast iron wok in a commercial Chinese restaurant

Long-term exposure to fine particles (PM_2.5), ultrafine particles (UFPs), and volatile organic compounds (VOCs) emissions from cooking has been linked to adverse human health effects. Here, we measured the real-time number size distribution of particles emitted when cooking two served food in Chinese restaurants and estimated the emission rate of UFPs and PM_2.5. Experiments were conducted under a control hood, and both online measurement and offline analysis of PM_2.5 were carried out. The measured emission rates of PM_2.5 generated from deep-frying and grilling were 0.68 ± 0.11 mg/min and 1.58 ± 0.25 mg/min, respectively. Moreover, the UFPs emission rate of deep-frying (4.3 × 10⁹ #/min) is three times higher than that of grilling (1.4 × 10⁹ #/min). Additionally, the PM_2.5 emission of deep-frying was comprised of a considerable amount of α-Fe₂O₃ (5.7% of PM_2.5 total mass), which is more toxic than other iron oxide species. A total of six carcinogenic HAPs were detected, among which formaldehyde, acrolein, and acetaldehyde were found to exceed the inhalation reference concentration (RfC) for both cooking methods. These findings can contribute to future evaluation of single particle and HAPs emission from cooking to better support toxicity assessment.

Ultra-Fine Ruthenium Oxide Quantum Dots/Reduced Graphene Oxide Composite as Electrodes for High-Performance Supercapacitors

This study synthesized ultra-fine nanometer-scaled ruthenium oxide (RuO2) quantum dots (QDs) on reduced graphene oxide (rGO) surface by a facile and rapid microwave-assisted hydrothermal approach. Benefiting from the synergistic effect of RuO2 and rGO, RuO2/rGO nanocomposite electrodes showed ultra-high capacitive performance. The impact of different RuO2 loadings in RuO2/rGO nanocomposite on their electrochemical performance was investigated by various characterizations. The composite RG-2 with 38 wt.% RuO2 loadings exhibited a specific capacitance of 1120 F g-1 at 1 A g-1. In addition, it has an excellent capacity retention rate of 84 % from 1A g-1 to 10 A g-1, and excellent cycling stability of 89% retention after 10,000 cycles, indicating fast ion-involved redox reactions on the nanocomposite surfaces. These results illustrate that RuO2/rGO composites prepared by this facile process can be an ideal candidate electrode for high-performance supercapacitors.

Subcellular proteomics

The eukaryotic cell is compartmentalized into subcellular niches, including membrane-bound and membrane-less organelles. Proteins localize to these niches to fulfil their function, enabling discreet biological processes to occur in synchrony. Dynamic movement of proteins between niches is essential for cellular processes such as signalling, growth, proliferation, motility and programmed cell death, and mutations causing aberrant protein localization are associated with a wide range of diseases. Determining the location of proteins in different cell states and cell types and how proteins relocalize following perturbation is important for understanding their functions, related cellular processes and pathologies associated with their mislocalization. In this Primer, we cover the major spatial proteomics methods for determining the location, distribution and abundance of proteins within subcellular structures. These technologies include fluorescent imaging, protein proximity labelling, organelle purification and cell-wide biochemical fractionation. We describe their workflows, data outputs and applications in exploring different cell biological scenarios, and discuss their main limitations. Finally, we describe emerging technologies and identify areas that require technological innovation to allow better characterization of the spatial proteome.

Synthesis of Magnetic α-Fe2O3/Rutile TiO2 Hollow Spheres for Visible-Light Photocatalytic Activity

The high recombination rate of the electron-hole pair on the surface of rutile TiO2 (RT) reduces its photocatalytic performance, although it has high thermodynamic stability and few internal grain defects. Therefore, it is necessary for RT to develop effective methods to reduce electron-hole pair recombination. In this study, magnetic α-Fe2O3/Rutile TiO2 self-assembled hollow spheres were fabricated via a facile hydrothermal reaction and template-free method. Based on the experimental result, phosphate concentration was found to play a crucial role in controlling the shape of these hollow α-Fe2O3/RT nanospheres, and the optimal concentration is 0.025 mM. Due to a heterojunction between α-Fe2O3 and RT, the electron-hole pair recombination rate was reduced, the as-synthesized hollow α-Fe2O3/RT nanospheres exhibited excellent photocatalysis in rhodamine B (RhB) photodegradation compared to α-Fe2O3 and RT under visible-light irradiation, and the degradation rate was about 16% (RT), 60% (α-Fe2O3), and 93% (α-Fe2O3/RT) after 100 min. Moreover, α-Fe2O3/RT showed paramagnetism and can be recycled to avoid secondary environmental pollution.

Enhancement of photocatalytic potential and recoverability of Fe3O4 nanoparticles by decorating over monoclinic zirconia

BACKGROUND

Photodegradation of organic pollutants is considered to be the most suitable and cheaper technique to counter the decontamination issues. Metal nanoparticles are considered to be the most effective heterogeneous photocatalysts for photodegradation of organic pollutants. Besides, iron oxide nanoparticles are well-known photocatalysts for degrading organic pollutants.

METHODS

We reported the synthesis of neat iron oxide nanoparticles (Fe3O4 NPs) and zirconia supported iron oxide nanoparticles (Fe3O4/ZrO2 NPs) by facile chemical reduction technique for photodegradation ofa toxic azo dye namely methyl red.

RESULTS

The XRD and FTIR analysis has demonstrated a crystalline phase Fe3O4 NPs. The morphological features via scanning electronic microscopy (FESEM) suggested agglomerated morphology of neat Fe3O4 NPs with 803.54 ± 5.11 nm average particle size and revealed the uniform morphology and homogenous dispersion of Fe3O4 NPs over ZrO2 surface in Fe3O4/ZrO2 nanocomposite. A polydispersity index (PDI) of 0.47 showed sufficient variations in the particle size of neat Fe3O4 NPs, which is also supported by the results obtained from atomic force microscopy (AFM), FESEM and Transmission Electron Microscopy (TEM). Fe3O4/ZrO2 NPs demonstrated efficient methyl red degradation over a short period of time under simulated light and degraded about ~ 91.0 ± 1.0% and 87.0 ± 1.0% dye in 40 min, under UV and visible light, respectively.

CONCLUSION

The excellent photodegradation efficacy and sustainability of Fe3O4/ZrO2 NPs can be attributed to the homogenous distribution of Fe3O4 NPs over ZrO2, which facilitates the generation of photoexcitons (electrons and holes), enhanced charge transfer and minimize the charge recombination.

Facile Controlled Synthesis of Spinel LiMn2O4 Porous Microspheres as Cathode Material for Lithium Ion Batteries

Although the electrochemical properties of porous LiMn₂O₄ microspheres are usually improved compared to those of irregular LiMn₂O₄ particles, the effects of the different synthesis conditions on the preparation of the porous LiMn₂O₄ microspheres are rarely discussed in detail. In the present work, porous LiMn₂O₄ microspheres were successfully synthesized by using molten LiOH and porous Mn₂O₃ spheres as a template. Multiple factors were considered in the preparation process, including reagent concentration, pH, adding mode, heating time, etc. The morphology of the MnCO₃ template was crucial for the preparation of porous LiMn₂O₄ microspheres and it was mainly affected by the concentration of reactants and the pH value of the solution during the precipitation process. During the lithiation of Mn₂O₃ microspheres, the heating temperature and the ratio between Mn₂O₃ and lithium salt were the most significant variables in terms of control over the morphology and purity of the LiMn₂O₄ microspheres. Furthermore, we demonstrated that the porous LiMn₂O₄ microspheres presented better rate capability and cyclability compared to commercial LiMn₂O₄ powder as cathode materials for lithium-ion batteries (LIBs). This study not only highlights the shape-controllable synthesis of LiMn₂O₄ microspheres as promising cathode materials, but also provides some useful guidance for the synthesis of porous LiMn₂O₄ microspheres and other LIB' electrode materials.

Sustainable preparation of sunlight active α-Fe2O3 nanoparticles using iron containing ionic liquids for photocatalytic applications

Inspired by the nano-segregation of ionic liquids (ILs) into bi-continuous structures constituting of arrays of ionic and non-ionic components, herein, a new and sustainable strategy for preparation of mesh-like nano-sheet α-Fe₂O₃ nanoparticles and their photo-catalytic activity under sunlight, is presented. For the purpose, metal (iron) containing ionic liquids (MILs), 1-alkyl-3-methylimidazolium tetrachloroferrates, [C_nmim][FeCl₄], (n = 4, 8 and 16), which not only act as precursors and solvents but also as structure directing agents have been used. Thus prepared NPs show MIL dependent structural, photophysical and magnetic properties. The catalytic efficiency of NPs has been tested for the photo-degradation of organic dyes (Rhodamine B) in aqueous solution under sunlight. The NPs are found to exhibit comparable catalytic efficiency under sunlight as compared to that observed under high intensity visible lamplight, without showing a decline in their catalytic efficiency even after 4 catalytic cycles. It is anticipated that the present work will provide a new platform for preparation of sunlight active nanomaterials for photo-catalytic applications with control over the structural and physical properties via varying the molecular structure of MILs.

Inspired by nanosegregation of ionic liquids into bicontinuous structures of arrays of ionic and non-ionic components, we present a new sustainable strategy for preparation of mesh-like nano-sheets of α-Fe₂O₃ nanoparticles and their photocatalytic activity under sunlight.