α-Fe2O3 Nanoparticles Research Articles

Vitalizing Perovskite Oxide-Based Acetone Sensors with Metal-Organic Framework-Derived Heterogeneous Oxide Catalysts.

Perovskite oxides are promising candidates for chemiresistive-type gas sensors owing to their exceptional thermal and chemical stability during solid-gas reactions. However, perovskites suffer from critical issues such as low surface area and poor surface activity, which negatively influence the sensing characteristics. While metal nanoparticles can be incorporated in perovskites to improve their reactivity, the fundamental incompatibility between catalytic metals and perovskite oxides often leads to substantial structural degradation as well as phase instability. Herein, we overcome this challenge through the introduction of an intermediary phase that forms coherent interfaces with both the perovskite phase and catalyst metals. Specifically, we present the case study of p-type La0.8Ca0.2Fe0.98Pt0.02O3 perovskite, whose hole accumulation layer was modulated by the incorporation of metal-organic framework (MOF)-derived n-type α-Fe2O3 nanoparticles decorated with highly dispersed Pt catalysts. The resulting composite exhibited significantly improved surface activity over the nonmodified La0.8Ca0.2FeO3 perovskite, leading to exceptional chemiresistive sensing performance toward acetone gas (Rg/Ra = 39.8 toward 10 ppm of acetone at 250 °C) with high cross-sensitivity against interfering gases. Importantly, our findings reaffirm the critical influence of interfacial engineering in facilitating surface chemical reactions on perovskite oxides and, by doing so, effectively provide a general synthetic guideline to the design of perovskite-based chemiresistors.

High Sensing Performance of n-Butanol Gas Sensor Based on Mesoporous Cu-Doped α-Fe₂O₃ Nanoparticle Materials

High Sensing Performance of n-Butanol Gas Sensor Based on Mesoporous Cu-Doped α-Fe₂O₃ Nanoparticle Materials

Z-scheme driven charge transfer in g-C3N4/α-Fe2O3 nanocomposites enabling photocatalytic degradation of crystal violet and chromium reduction

In this study, we demonstrated the design and fabrication of iron oxide-embedded protonated graphitic carbon nitride (α-Fe2O3/p-g-C3N4) nanocomposites for photocatalytic dye degradation and heavy metal reduction applications under sunlight irradiation. The developed nanocomposites, with varying weight percentages of α-Fe2O3, were characterized for their structural (XRD, FTIR, XPS), optical (absorption and photoluminescence), morphological (FE-SEM, TEM), and electrochemical (EIS) properties to elucidate their structure-property relationships. The synthesis method ensures the uniform dispersion of α-Fe2O3 nanoparticles, with a particle size range of 50–60 nm, onto p-g-C3N4. XPS analysis suggests the formation of an electrical layer at the interface of α-Fe2O3/p-g-C3N4, facilitating the formation of a Z-scheme heterojunction. The photoluminescence and EIS spectra of the nanocomposite indicated effective separation and transfer of photo-induced charge carriers, aided by a reduced bandgap energy of ∼2.63 eV. Notably, the optimized 10 wt% α-Fe2O3/p-g-C3N4 nanocomposite exhibited superior photocatalytic activity, degrading nearly 100 % of crystal violate dye and reducing 98 % of Cr(VI) ions, compared to bare p-g-C3N4, which degraded around 43 % of the dye and reduced 39 % of Cr(VI) ions under sunlight irradiation. Scavenger studies indicated that α-Fe2O3/p-g-C3N4 nanocomposites produce adequate superoxide anions and hydroxyl radicals for dye degradation and heavy metal ion reduction. The composite also demonstrated consistent recyclability up to 5 cycles with around 100 % cyclical efficiency. The pH-dependent photoreduction and cyclic dye degradation by the 10 wt% α-Fe2O3/p-g-C3N4 photocatalyst indicated excellent stability, making it suitable for the treatment of multi-pollutant wastewater.

Capacity augmentation strategy in α-Fe2O3 nanoparticles through multifaceted structural and electrochemical analyses

Hematite (α-Fe₂O₃) has garnered significant research interest for supercapacitor applications, but capacity fading and limited cyclic life remain serious challenges. In this context, the present research provides a comprehensive study of the factors that significantly impact charge kinetics within the electrode and at the solid/electrolyte interface. By integrating structural and electrochemical analyses, this study offers an effective strategy to enhance the capacity of α-Fe₂O₃ nanoparticles through rigorous scientific analysis and identification of various qualitative and quantitative factors that influence charge storage capacity. A simple one-step co-precipitation method was adopted to synthesize porous α-Fe₂O₃ nanoparticles. The quantitative analysis of charge kinetics demonstrated the domination of diffusion-controlled charge storage as the main contributor to the total charge storage. The α-Fe₂O₃ nanoparticles-based electrode delivered a high energy density of 24.6 Wh kg⁻1 at an impressive power density of 478.7 W kg⁻1. Additionally, it displayed a capacity retention of 79 % over 10,000 cycle operations. The choice of electrode material and the superior porous nanoarchitecture have proven to be advantageous for high-performance supercapacitor applications, offering fast electron/ion transport.

Mechanochemical preparation and performance regulation mechanism of highly durable and multifunctional iron red nanocomposite pigments derived from natural mixed-dimensional palygorskite clay

Iron oxide red pigments are one of the most widely used inorganic red pigments around the world. It is always pursed to improve their physicochemical properties. Herein, a continuous mechanochemical method was employed to fabricate high-performance iron red nanocomposite pigments via anchoring α-Fe2O3 nanoparticles on the surface of natural mixed-dimensional palygorskite clay (MDPal). The mechanical force of twin-screw extrusion promoted the Si-OH groups of MDPal to coordinate with Fe3+ to form the precursor, while MDPal was activated with the residual H+ of the involved nitrate to accelerate the thermal diffusion of Al3+ into α-Fe2O3 crystal lattice, thus the nanocomposite pigments presented a bright yellowish-red color (L∗ ​= ​35.61, a∗ ​= ​33.10, b∗ ​= ​35.86, C∗ ​= ​48.80). Furthermore, the mixed-dimensional nanostructure of MDPal served as a good substrate for chemical bonding of α-Fe2O3 nanoparticles to improve the dispersion and environmental stability of iron red pigments. Due to the synergistic effect of each component and the excellent thermal and chemical stability, the obtained nanocomposite pigments exhibited excellent application prospect as functional inorganic pigments for anti-corrosion coating, overglaze ceramic and coloring and reinforcing of polypropylene, respectively. It provided a facile strategy for preparation of high-performance multifunctional iron red pigments based on MDPal.

Cr3+doped α-Fe2O3 nanoparticles for photodegradation of organic pollutants with their disinfection efficacy

Pristine and Cr-doped α-Fe2O3 nanoparticles were synthesized using a low-cost and simple one-step hydrothermal method without any precipitating agent. Cr-doped α-Fe2O3 was found to be a promising candidate for recyclable photocatalytic application for Tetracycline (TC) and Congo-red (CR) degradation under normal sunlight irradiation along with excellent antibacterial properties. Addition of Cr shows a significantly improved degradation efficiency from 20% to 91% in just 25 min for CR, while the degradation rate reached to 81% for TC, which was also monitored in real-time using internet of things (IoT). Also, a high degree of mineralization was achieved (∼87.9%), which was confirmed using total organic carbon (TOC) content. In parallel, the biochemical oxygen demand/chemical oxygen demand (BOD5/COD) ratio confirmed the fast degradation efficiency using a small amount of catalytic dosage (∼ 0.40 g/L). Also, degradation of multiple dyes provides a promising avenue for addressing complex waste water treatment challenges. Moreover, Cr-doped α-Fe2O3 displays excellent antibacterial activity towards E.coli and E.Faecium. Major factors involved in sunlight driven photocatalytic activity for example absorbance range, porosity, separation between e--h+, and charge transfer property were surprisingly improved by Cr doping and henceforth increased photocatalytic activity and antibacterial properties. This work highlights the potential utilization of Cr-doped α-Fe2O3 for the purification and disinfection of industrial waste water.

Water purification and biological efficacy of green synthesized Co/Zn-Doped α-Fe2O3 nanoparticles

In the present study, Co/Zn doped α-Fe2O3 (Hematite) nanoparticles (NPs) were synthesized using polyvinylpyrrolidone (PVP) and Azadirachta indica (AI) leaves aqueous extract. The analytical techniques including XRD, UV, SEM, EDX, VSM, Raman, and FTIR, we were able to identify and characterize the structural, morphological and magnetic attributes of the synthesized NPs. The findings demonstrated that the synthesized NPs exhibit homogeneous spherical shapes with particle sizes ranging from 8.64 to 15.32 nm. The NPs have rhombohedral crystal lattices, with crystallite sizes of 23.25 nm for chemically synthesized doped α-Fe2O3 NPs and 12.52 nm for those synthesized using green methods. The magnetic study has shown that the saturation magnetization (Ms) value of NPs, which ranges from 36 to 45 emu/g at ambient temperature, exhibits superparamagnetic properties (300 K). The treatment of industrial wastewater and its reuse for agricultural purposes are the subjects of the current study. Different concentrations of doped α-Fe2O3 NPs were used as photocatalysts to degrade dyes in a bioreactor under UV light in a heterogeneous mixture. The degradation rates achieved were 96.42 % for Congo Red (CR) and 98.36 % for Eosin Yellow (EY). DPPH assays were conducted to evaluate the antioxidant activity of the synthesized doped α-Fe2O3 NPs. The percentage inhibition of DPPH radicals ranged from 71.13 % to 90.35 %. Our findings indicate that AI leaf extract holds promise as a valuable resource for the development of bioactive compounds and environmentally friendly approaches to synthesizing green NPs. This is primarily attributed to the increased accessibility of bioactive components with potent antioxidant properties. The combination of these benefits provides opportunities for novel uses in environmental cleanup, biological applications, and energy conversion.

Bio-derived mesoporous carbon confinement synthesis of ultra-small α-Fe2O3 nanoparticles as electrocatalysts for overall water splitting

The use of high-surface-area materials in loading α-Fe2O3 nanoparticles presents an intriguing approach to improve the electrocatalytic efficiency of overall water splitting. Nevertheless, the effective management of α-Fe2O3 nanoparticle size to prevent their agglomeration continues to pose a significant challenge. This study used bio-based porous carbon with a specific surface area of 2876 m2/g and a mesoporous ratio of 95 % as a carrier to effectively disperse and inhibit the growth of α-Fe2O3 nanoparticles. The Fe2O3/NSC-30 was synthesized using urea as a precipitant through an ethylene glycol-assisted hydrothermal method accompanied by high-temperature calcination, with the α-Fe2O3 nanoparticle size being approximately 5.5 nm. The synergistic effect between the ultra-small nanoparticles and the mesoporous structure facilitates the effective diffusion of electrolyte and exposes more catalytic active sites. The Fe2O3/NSC-30 exhibited remarkable catalytic performance in the OER and HER, as evidenced by the respective low overpotentials of 270 mV and 250 mV at 20 mA cm−2. Furthermore, when Fe2O3/NSC-30 was utilized in the overall water-splitting reaction, a low cell voltage of 1.70 V was sufficient to achieve a current density of 20 mA cm−2. In this study, a new method was proposed for loading ultra-small nanoparticles onto bio-derived mesoporous carbon for promoting overall water splitting with remarkable efficiency.

Thermally synthesized hematite (α-Fe2O3) nanoparticles as efficient photocatalyst for visible light dye degradation.

In recent years, water pollution has become a pressing global issue because of the continuous release of organic dyes from various industries. Therefore, finding an easy way to remove these harmful dyes from water has drawn the attention of researchers. This study investigates the removal of toxic Rose Bengal (RB) dye using hematite nanoparticles as a visible light photocatalyst without any additive. It is observed that by controlling particle size, quantity of the nanoparticles and reaction temperature, the dye degradation can be improved up to 95.33% with a half-life of 26 min. To understand photodegradation kinetic behavior, the Langmuir-Hinshelwood kinetic equation can be employed. The scavenger test indicated that the OH* radicals majorly led to the photodegradation process. The reaction rate values strongly depended on the size, quantity of the nanoparticles and reaction temperature. Controlling the optimizing condition, faster reaction rate (k = 0.027 min-1) can be achieved as compared to earlier reports. It is also noted that the change in the degradation efficiency of the reused catalyst is negligible when compared to the fresh one. Here, the dye degradation mechanism is discussed. Overall, this study reveals that hematite nanoparticles can be used as efficient photocatalyst for dye degradation applications by optimizing the controlling factors. These observations provide novel perspectives on the development of effective and sustainable photocatalytic technologies for pollution control and water treatment applications.

In vitro cytotoxic study of synthesized Ag and Ce dual-doped α-Fe2O3 nanoparticles on NIH/3T3 and U87 cell lines

The significant potential of iron oxide nanoparticles in biomedical fields, particularly in the delivery of anticancer drugs and in sono-chemodynamic therapy, can be attributed to their remarkable physicochemical properties. Consequently, this study aimed to organize artificially produced hematite nanospheres (α-Fe2O3 NS) that were doped with silver (Ag) and cerium (Ce) using an environmentally sustainable method utilizing taranjabin. Following this, an assessment of their cytotoxicity was conducted. The structure and morphology characteristics of nanoparticles were analyzed using powder X-ray diffraction (PXRD), Field Emission Scanning Electron Microscope (FESEM), energy dispersive X-ray(EDX), and Raman techniques. The FESEM images revealed that the α-Fe2O3 NS exhibited a spherical shape; however, the morphology of the α-Fe2O3 NS doped with Ag and Ce transitioned to a conical form. The doping of Ag and Ce within the α-Fe2O3 structure was thoroughly validated through EDX and Raman analysis. Based on the cytotoxic outcomes, the impacts of Ag and Ce-doped α-Fe2O3 against human glioblastoma(U87) and mouse embryonic fibroblast (NIH/3T3) cells were studied using MTT assay. The results indicated that doped nanoparticles exhibited greater cytotoxic than α-Fe2O3 in both NIH/3T3 and U87 cells. The IC50 values were determined to be 188.33 μg ml−1 for Ag-doped α-Fe2O3 and 308.58 μg ml−1 for Ce-doped α-Fe2O3 against U87 and NIH/3T3 cells, respectively, both of which were lower than the IC50 of α-Fe2O3. Consequently, the doping process significantly enhanced the cytotoxic effect of α-Fe2O3 NS. This study represents the first documentation of the synthesis and anticancer activity of Ag and Ce-doped α-Fe2O3 on NIH/3T3 and U87 cells. However, further investigation into the antitumor efficacy of Ag and Ce-doped α-Fe2O3 in appropriate in vivo models is recommended.

Synergistic photocatalytic breakdown of azo dyes coupled with H2 generation via Cr-doped α-Fe2O3 nanoparticles

This research addresses the scalable and inexpensive synthesis of α-Fe2O3via hydrothermal method without any precipitating agent as well as the enhancement of solar driven photocatalytic and H2 production through doping different chromium proportions. Competency of α-Fe2O3, both pure and doped with chromium, to function as photocatalyst was evaluated by its interaction with multiple dyes, which was real-time monitored utilizing (Internet of Things) IoT technique. By adding chromium, the rate of deterioration increased substantially from 15 to 94% for TB under sunlight in a remarkably brief 20 min by employing a very small amount of Cr0.8Fe1.2O3 (0.3 g/L), as evidenced by high degree of mineralization i.e. 85% and LC-HRMS. Also, the rapid breakdown of Trypan Blue (TB) was indicated by BOD5/COD ratio. Moreover, Cr-doped α-Fe2O3 displays excellent H2 production (~ 132 μmol h−1 g−1) as compared to α-Fe2O3. This work highlights the potential utilization of Cr-doped α-Fe2O3 for the purification of industrial waste water and green energy harvesting.

Enhanced performance of aerobic granular sludge-membrane system through the utilization of different iron-based nano-metal oxides for mitigating membrane fouling

Fe3O4, γ-Fe2O3, and α-Fe2O3 nanoparticles play a crucial role in influencing the adsorption capacity and pretreatment efficacy as iron-based nano-metal oxides due to their distinct structural and physicochemical properties. However, the impact of these adsorbents on membrane filtration efficiency remains unexplored. This study aimed to investigate the influence of these three adsorbents on membrane fouling in an aerobic granular sludge–membrane system (AGSMS) used for municipal wastewater reuse treatment. The results demonstrated that under optimal conditions, γ-Fe2O3 exhibited superior effectiveness in removing low and medium molecular weight contaminants from wastewater, resulting in a higher normalized flux (0.59) and reduced total fouling resistance (2.66 × 1011 m−1). It also showed the highest removal rate for organic matter and suspended solids, making it particularly effective in mitigating AGSMS membrane fouling. However, excessive addition (2 g/L) of Fe3O4, γ-Fe2O3, and α-Fe2O3 could potentially hinder the proper operation of the AGSMS. Pre-adsorption facilitated the formation of a porous cake layer while inhibiting standard blocking behavior. Additionally, the extended Derjaguin–Landau–Verwey–Overbeek theory analysis revealed a substantial energy barrier between membrane-foulant interactions (125.65 kT) as well as foulant-foulant interactions (62.06 kT) within the γ-Fe2O3 system, confirming its exceptional antifouling characteristics. This study offers valuable insights into the selection of iron oxide adsorbents for membrane fouling mitigation and wastewater reuse.

Understanding Reaction Kinetics of Iron Oxide (α- Fe2O3) Reduction with Single Entity Measurements

Emitting minimal amount of CO2 during the production of steel is one of the major challenges that can be overcome by producing iron using electrowinning method. The reaction of interest is at the cathode where the direct reduction of Iron oxide (α-Fe2O3) to iron takes place. In this study, we are investigating the electrochemical conversion of hematite (α-Fe2O3) Nanoparticles to iron in an extremely alkaline medium (50 wt% NaOH) using Single Entity Electrochemistry (SEE).Single Entity Electrochemistry is the study of single atom, molecule or particle colliding with the surface of the electrode usually by diffusion or migration. For these experiments, we are developing alkaline stable carbon-fiber (C)/Nickel (Ni) ultra-microelectrode (UME), prepared using multiple pathways such as plasma-focused ion beam.A spike in current transient during chronoamperometry (CA) experiments is observed when a hematite particle collides stochastically with the UME and gets reduced in the process. Each spike is the reduction event of one hematite nanoparticle to iron. Individual reduction events, that last 0.2-0.3 s and resulting in 0.1-0.2 nC of charge being passed were observed at Ni and C microelectrodes, this shows good agreement with the average particle radius of 100 nm. The shape of the current transient was distinct from previously reported transients for metal deposition at cathode1-3. However, A. Allanore, et.al. model was used to support a mechanism for the direct oxide reduction process at nanoscale particles4.The results presented here illustrate the reaction kinetics and the mode of reduction propagation in a single nano-sized hematite particle in alkaline conditions. The kinetics of hematite reduction in alkaline medium is considerably slow as observed from the slope of current spikes in SEE experiments. Furthermore, considering Allanore’s model, the reduction propagation occurs from the outer surface to the inner core.(1) Luo, L.; White, H. S. Electrogeneration of single nanobubbles at sub-50-nm-radius platinum nanodisk electrodes. Langmuir 2013, 29 (35), 11169-11175.(2) Xiao, X.; Fan, F.-R. F.; Zhou, J.; Bard, A. J. Current transients in single nanoparticle collision events. Journal of the American Chemical Society 2008, 130 (49), 16669-16677.(3) Bard, A. J.; Zhou, H.; Kwon, S. J. Electrochemistry of single nanoparticles via electrocatalytic amplification. Israel Journal of Chemistry 2010, 50 (3), 267-276.(4) Allanore, A.; Lavelaine, H.; Valentin, G.; Birat, J.; Delcroix, P.; Lapicque, F. Observation and modeling of the reduction of hematite particles to metal in alkaline solution by electrolysis. Electrochimica Acta 2010, 55 (12), 4007-4013.

Biogenic synthesis of Hematite (α-Fe2O3) and Ni doped Hematite (α-Fe2O3) nanoparticles for enhanced In vitro cytotoxic studies on MCF-7 cell lines

Hematite (α-Fe2O3) and Ni doped Hematite (α-Fe2O3) nanoparticles were synthesized with different pH values employ with catharanthus roseus leaf extract as reducing and capping agents. X-ray diffraction analysis reported that the prepared nanoparticles exhibited rhombohedral in structure. FESEM micrographs revealed the prepared nanoparticles are needle in structure to plates like structure when the pH value is increased. FTIR analysis confirmed the bonds and functional groups of the prepared Hematite (α-Fe2O3) and Nickel doped Hematite (α-Fe2O3) nanoparticles. The UV spectra of the prepared nanoparticles revealed the band gap energies ranging from 1.12 eV to 1.54 eV. The hysteresis loop showed the magnetic properties of the prepared nanoparticles exhibited ferromagnetic behavior. The antioxidant DPPH radical scavenging and the antimicrobial activity confirmed the inhibition of nanoparticles against gram positive and gram negative bacteria in concentration dependent manner. Moreover, the cytotoxicity effect against MCF-7 cancer cell lines revealed the inhibitory potential of the prepared nanoparticles. Bio efficacy of the prepared nanoparticles may leads to its potential and practicable applications in environmental and biomedical fields.

Hematite Nanoparticle Mediated Enhancement of Chlorella minutissima Lipid Productivity for Sustainable Biodiesel Production

This study aims to enhance lipid and biofuel productivity from Chlorella minutissima with hematite (α-Fe2O3) nanoparticles (IONPs) as a growth stimulant. The IONPs were synthesized using chemical method and characterized using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) analysis to confirm their structure and composition. The experimental setup involved inoculating various concentrations of IONPs (10, 20, and 30 mg·L−1) into the microalgal BG-11 growth medium to evaluate their impact on microalgal growth and biodiesel production. Results of this study showed that a concentration of 10 mg·L−1 of IONPs significantly increased the biomass concentration to 508.1 mg·L−1 over a 20-day cultivation period, achieving the highest biomass production rate of 31.7 mg·L−1·d−1 at this concentration. The lipid extracted from the microalgal biomass was subsequently transesterified into biodiesel. Key biodiesel properties, such as cetane number, calorific value, density, and viscosity, were measured to assess fuel quality. The findings demonstrate that incorporating hematite nanoparticles into the microalgal growth medium can significantly boost both lipid content and overall growth, thereby improving biodiesel production. This study suggests that the use of α-Fe2O3 nanoparticles presents a promising approach for scalable and sustainable biofuel production from microalgae.

Modification of α-Fe2O3 Nanoparticles with Carbon Layer for Robust Photo-Fenton Catalytic Degradation of Methyl Orange

Modification of α-Fe2O3 Nanoparticles with Carbon Layer for Robust Photo-Fenton Catalytic Degradation of Methyl Orange

Nonenzymatic electrochemical detection of endocrine disruptor (Bisphenol-A) based on biogenic α-Fe2O3 nano enabled interface prepared by Bluemea sinuata leaf extract

One of the most important organic monomers in the manufacturing of plastic is bisphenol-A (BPA), which is widely used in food packaging, containers, and water pipelines, among other industries. However, because of how easily it contaminates food and water and causes illnesses, including cancer, heart disease, and developmental abnormalities, its extensive usage carries serious dangers to human health and the environment. BPA is nevertheless widely used in numerous products despite its negative effects. A new technique using α-Fe2O3 nanoparticles synthesized from Bluemea sinuate leaf extract is offered to address the requirement for effective BPA detection. The production and composition of α-Fe2O3 nanoparticles were confirmed via rigorous characterization techniques, such as XRD, IR, Raman spectroscopy, XPS, TEM, and UV–Vis spectrophotometry. The nanoparticles showed promising morphology and structure. Then, via electrophoretic deposition, an α-Fe2O3/ITO electrode was created, which showed superior electrochemical qualities for BPA detection. The electrode demonstrated excellent durability and reusability along with great sensitivity (14.4 µA µM−1 cm−2) and a low detection limit (0.03256 µM). The created electrode offers a viable way to quickly and precisely identify BPA in a variety of samples, supporting initiatives related to health, safety, and the environment.

Trimetallic doped hematite (α-Fe2O3) nanoparticles using biomolecules of Azadirachta indica leaf extract for photocatalytic dye removal: insights into catalyst stability and reusability

Trimetallic doped hematite (α-Fe2O3) nanoparticles using biomolecules of Azadirachta indica leaf extract for photocatalytic dye removal: insights into catalyst stability and reusability

Oxygen vacancies enhanced photo-fenton-like catalytic degradation of rhodamine B by electrochemical synthesized α-Fe2O3 nanoparticles

Hematite is widely used as a catalyst in a photo-Fenton-like process for the oxidation of dyes. We report on the electrochemical synthesis of α-Fe2O3 nanoparticles. The structure, morphology, chemical composition, and surface chemical state of the catalyst, as well as its optical and magnetic properties, were thoroughly characterized by scanning electron microscopy, X-ray diffraction spectroscopy (XRD), shift combination scattering spectroscopy, X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). It was found that the crystal size was 63.9 nm. It was shown that the presence of Fe2+ on the surface was due to oxygen vacancies rather than impurity phases. The optical bandgap was determined to be 1.87 eV. Nanoparticles exhibit weak ferromagnetic behavior with a magnetization of 1.09 emu/g at maximum applied magnetic field 1 kOe. The catalytic activity in the photo-Fenton-like process for the degradation of Rhodamine B (RhB) dye was investigated, and the effect of working parameters, including H2O2 concentration, catalyst concentration, and RhB concentration, on the degradation efficiency was studied. The maximum degradation rate was 99.15 % in 12 min under optimal conditions. The catalyst showed long-term stability over 5 repeated cycles.

Oxygen vacancy-mediated metal-organic gel-derived α-Fe2O3 for anomalous acetone sensing behavior

The development of acetone gas sensors with high sensitivity, low detection limits and scalability holds significant importance for industrial production safety and disease diagnosis. Herein, oxygen vacancies-enriched α-Fe2O3 nanoparticles (M-Fe2O3 NPs) were synthesized through a novel metal-organic gel template strategy. Gas sensing experiments revealed that the prepared M-Fe2O3 sensor displayed unique p-type semiconductor behavior, distinct from the n-type commercial α-Fe2O3 (C-Fe2O3) sensor. Moreover, the sensor demonstrated excellent acetone sensing performance, including high response (2.6 @ 20 ppm), low detection limit (0.5 ppm), remarkable repeatability and selectivity, even under 80% relative humidity (RH), displaying impressive response and recovery properties. The enhanced p-type sensing properties of the M-Fe2O3 sensor were attributed to oxygen vacancies facilitating inversion (hole) layer formation and accelerating chemical reactions on the sensing materials surface, as evidenced by gas sensing performance data and O2-TPD characterization. Finally, the feasibility of preliminary diabetes diagnosis was demonstrated by detecting acetone levels in human exhaled breath. This work not only presents a straightforward approach for designing oxygen vacancies-enriched metal oxides but also has potential applications in constructing high-performance acetone sensing systems for diabetes diagnosis.