Preparation of α-Fe2O3/rGO composites toward supercapacitor applications

Reduced graphene oxide (rGO) integrated with iron oxide nanoparticles (α-Fe₂O₃/rGO) composites with different morphologies were successfully obtained through the in situ synthesis and mechanical agitation methods. It was found that the α-Fe₂O₃ was densely and freely dispersed on the rGO layer. By comparing electrochemical properties, the sheet-like α-Fe₂O₃/rGO composites demonstrate excellent electrochemical performance: the highest specific capacitance, and excellent cycling stability and rate capacity. The specific capacitance is 970 F g⁻¹ at a current density of 1 A g⁻¹ and the capacitance retention is 75% after 2000 cycles with the current density reaching 5 A g⁻¹. It is mainly due to the synergistic effect between the α-Fe₂O₃ and rGO, and the high conductivity of the rGO offers a fast channel for the movement of electrons.

Preparation of α-Fe₂O₃/rGO composites for supercapacitor application using in situ synthesis and a mechanical agitation method.     

Heterostructures of ε-Fe2O3 and α-Fe2O3: insights from density functional theory

Many materials used in energy devices or applications suffer from the problem of electron–hole pair recombination. One promising way to overcome this problem is the use of heterostructures in place of a single material. If an electric dipole forms at the interface, such a structure can lead to a more efficient electron–hole pair separation and thus prevent recombination. Here we model and study a heterostructure comprised of two polymorphs of Fe₂O₃. Each one of the two polymorphs, α-Fe₂O₃ and ε-Fe₂O₃, individually shows promise for applications in photoelectrochemical cells. The heterostructure of these two materials is modeled by means of density functional theory. We consider both ferromagnetic as well as anti-ferromagnetic couplings at the interface between the two systems. Both individual oxides are insulating in nature and have an anti-ferromagnetic spin arrangement in their ground state. The same properties are found also in their heterostructure. The highest occupied electronic orbitals of the combined system are localized at the interface between the two iron-oxides. The localization of charges at the interface is characterized by electrons residing close to the oxygen atoms of ε-Fe₂O₃ and electron–holes localized on the iron atoms of α-Fe₂O₃, just around the interface. The band alignment at the interface of the two oxides shows a type-III broken band-gap heterostructure. The band edges of α-Fe₂O₃ are higher in energy than those of ε-Fe₂O₃. This band alignment favours a spontaneous transfer of excited photo-electrons from the conduction band of α- to the conduction band of ε-Fe₂O₃. Similarly, photo-generated holes are transferred from the valence band of ε- to the valence band of α-Fe₂O₃. Thus, the interface favours a spontaneous separation of electrons and holes in space. The conduction band of ε-Fe₂O₃, lying close to the valence band of α-Fe₂O₃, can result in band-to-band tunneling of electrons which is a characteristic property of such type-III broken band-gap heterostructures and has potential applications in tunnel field-effect transistors.

Electron–hole pair recombination is reduced in heterostructures if used in devices in place of single material.     

Magnetic hyperthermia with ε-Fe2O3 nanoparticles

Biocompatibility restrictions have limited the use of magnetic nanoparticles for magnetic hyperthermia therapy to iron oxides, namely magnetite (Fe₃O₄) and maghemite (γ-Fe₂O₃). However, there is yet another magnetic iron oxide phase that has not been considered so far, in spite of its unique magnetic properties: ε-Fe₂O₃. Indeed, whereas Fe₃O₄ and γ-Fe₂O₃ have a relatively low magnetic coercivity, ε-Fe₂O₃ exhibits a giant coercivity. In this report, the heating power of ε-Fe₂O₃ nanoparticles in comparison with γ-Fe₂O₃ nanoparticles of similar size (∼20 nm) was measured in a wide range of field frequencies and amplitudes, in uncoated and polymer-coated samples. It was found that ε-Fe₂O₃ nanoparticles primarily heat in the low-frequency regime (20–100 kHz) in media whose viscosity is similar to that of cell cytoplasm. In contrast, γ-Fe₂O₃ nanoparticles heat more effectively in the high frequency range (400–900 kHz). Cell culture experiments exhibited no toxicity in a wide range of nanoparticle concentrations and a high internalization rate. In conclusion, the performance of ε-Fe₂O₃ nanoparticles is slightly inferior to that of γ-Fe₂O₃ nanoparticles in human magnetic hyperthermia applications. However, these ε-Fe₂O₃ nanoparticles open the way for switchable magnetic heating owing to their distinct response to frequency.

ε-Fe₂O₃ is a magnetic iron(iii) oxide with a giant coercivity. Its potential in hyperthermia applications has been evaluated in comparison with γ-Fe₂O₃ over a wide range of field frequencies and amplitudes.     

Morphology control of α-Fe2O3 towards super electrochemistry performance

α-Fe₂O₃ with various morphologies including spindle, rod, tube, disk, and ring were synthesized through controlling the H₂PO₄⁻ etching process. The concentrations of H₂PO₄⁻ plays an important role in controlling the morphology change of the samples. Selected adsorption of H₂PO₄⁻ ions resulted in anisotropic growth. In addition, the etching of H₂PO₄⁻ occurred in the center of rods which resulted in tubal α-Fe₂O₃. Nanodiscs were created once the etching process occurred on the wall of the tube. The electrochemical test shows that disklike samples revealed excellent specific capacitance, rate capacity and cycling stability because of relative higher surface area and pore structure. For the CO catalytic oxidation properties, spindle samples exhibited super catalytic activity.

α-Fe₂O₃ with various morphologies including spindle, rod, tube, disk, and ring were synthesized through controlling the H₂PO₄⁻ etching process.     

Synthesis,structure, magnetism and photocatalysis of α-Fe2O3 nanosnowflakes

In this work, a simple one-step hydrothermal method was developed to synthesize high-quality α-Fe₂O₃ nanoparticles with a snowflake-like microstructure. First, a series of binary supramolecular aggregates were prepared by a non-covalent combination between a polymer such as polyvinylpyrrolidone (PVP) and a complex such as potassium ferrocyanide (PF). Then, the aggregates were used as the precursors of the one-step hydrothermal reactions. The snowflake-like nanostructure has six-fold symmetry as a whole, and each petal is symmetric. This synthesis method has the characteristics of simplicity, rapidity, reliance, and high yield, and can be used for creating high-quality α-Fe₂O₃ nanoparticles. Moreover, our results show that the molar ratio of PVP to PF, reaction time and temperature play important roles in the generation of a complete snowflake structure from different angles. Also, the snowflake-like α-Fe₂O₃ nanostructure exhibits a much higher coercivity (2997 Oe) compared to those reported by others, suggesting a strong hysteresis behaviour, which promises potential applications in memory devices, and other fields. Further, the α-Fe₂O₃ nanosnowflakes show a much higher photocatalytic degradation activity for cationic organic dyes such as crystal violet, rhodamine 6G than for anionic dyes such as methyl orange. A possible photocatalytic mechanism was proposed for explaining the selectivity of the photocatalytic oxidation reaction of organic dyes. We believe that this study provides a direct link among coordination compounds of transition metals, their supramolecular aggregates with polymers, and controlled hydrothermal synthesis of high-quality inorganic metal oxide nanomaterials.

α-Fe₂O₃ nanosnowflakes exhibit enhanced coercivity and improved photocatalytic performance for organic dyes.     

Mesoporous anodic α-Fe2O3 interferometer for organic vapor sensing application

In this work, we reported the utilization of mesoporous α-Fe₂O₃ films as optical sensors for detecting organic vapors. The mesoporous α-Fe₂O₃ thin films, which exhibited obvious Fabry–Perot interference fringes in the reflectance spectrum, were successfully fabricated through electrochemical anodization of Fe foils. Through monitoring the optical thickness of the interference fringes, three typical organic species with different vapor pressures and polarities (hexane, acetone and isopropanol) were applied as probes to evaluate the sensitivity of the α-Fe₂O₃ based interferometric sensor. The experiment results showed that the as-synthesized mesoporous α-Fe₂O₃ interferometer displayed high reversibility and stability for the three organic vapors, and were especially sensitive to isopropanol, with a detection limit of about 65 ppmv. Moreover, the photocatalytic properties of α-Fe₂O₃ under visible light are beneficial for degradation of dodecane vapor residues in the nano-pores and refreshment of the sensor, demonstrating good self-cleaning properties of the α-Fe₂O₃-based interferometric sensor.

Mesoporous α-Fe₂O₃ interferometers with well-resolved optical fringes can display high sensitivity to organic vapors.     

Crystal growth control of rod-shaped ε-Fe2O3 nanocrystals

Herein we report crystal growth control of rod-shaped ε-Fe₂O₃ nanocrystals by developing a synthesis based on the sol–gel technique using β-FeO(OH) as a seed in the presence of a barium cation. ε-Fe₂O₃ nanocrystals are obtained over a wide calcination temperature range between 800 °C and 1000 °C. A low calcination temperature (800 °C) provides an almost cubic rectangular-shaped ε-Fe₂O₃ nanocrystal with an aspect ratio of 1.4, whereas a high calcination temperature (1000 °C) provides an elongated rod-shaped ε-Fe₂O₃ nanocrystal with an aspect ratio of 3.3. Such systematic anisotropic growth of ε-Fe₂O₃ is achieved due to the wide calcination temperature in the presence of barium cations. The surface energy and the anisotropic adsorption of barium on the surface of ε-Fe₂O₃ can explain the anisotropic crystal growth of rod-shaped ε-Fe₂O₃ along the crystallographic a-axis. The present work may provide important knowledge about how to control the anisotropic crystal shape of nanomaterials.

Crystal growth control of rod-shaped ε-Fe₂O₃ nanocrystals is achieved by a synthesis based on the sol–gel technique.     

Novel magnetic g-C3N4/α-Fe2O3/Fe3O4 composite for the very effective visible-light-Fenton degradation of Orange II

A novel magnetic heterogeneous g-C₃N₄/α-Fe₂O₃/Fe₃O₄ catalyst was successfully synthesized through a simple hydrothermal method. The structure, morphology, and optical properties of the catalyst were characterized. The photocatalytic activity of the heterogeneous g-C₃N₄/α-Fe₂O₃/Fe₃O₄ catalyst for the photo-Fenton degradation of Orange II in the presence of H₂O₂ irradiated with visible light (λ > 420 nm) at neutral pH was evaluated. The g-C₃N₄/α-Fe₂O₃/Fe₃O₄ photocatalyst was found to be an excellent catalyst for the degradation of Orange II and offers great advantages over the traditional Fenton system (Fe(ii/iii)/H₂O₂). The results indicated that successfully combining monodispersed Fe₃O₄ nanoparticles and g-C₃N₄/α-Fe₂O₃ enhanced light harvesting, retarded photogenerated electron–hole recombination, and significantly enhanced the photocatalytic activity of the system. The g-C₃N₄/α-Fe₂O₃/Fe₃O₄ (30%) sample gave the highest degradation rate constant, 0.091 min⁻¹, which was almost 4.01 times higher than the degradation rate constant for α-Fe₂O₃ and 2.65 times higher than the degradation rate constant for g-C₃N₄/α-Fe₂O₃ under the same conditions. A reasonable mechanism for catalysis by the g-C₃N₄/α-Fe₂O₃/Fe₃O₄ composite was developed. The g-C₃N₄/α-Fe₂O₃/Fe₃O₄ composite was found to be stable and recyclable, meaning it has great potential for use as a photo-Fenton catalyst for effectively degrading organic pollutants in wastewater.

A novel magnetic heterogeneous g-C₃N₄/α-Fe₂O₃/Fe₃O₄ catalyst was firstly synthesized and exhibited very effective visible-light-Fenton degradation of Orange II at neutral pH.     

MOF-derived (MoS2, γ-Fe2O3)/graphene Z-scheme photocatalysts with excellent activity for oxygen evolution under visible light irradiation

Constructing Z-scheme heterojunctions is considered as an effective strategy to obtain catalysts of high efficiency in electron–hole separation in photocatalysis. Unfortunately, suitable heterojunctions are difficult to fabricate because the direct interaction between two semiconductors may lead to unpredictable negative effects such as electron scattering or electron trapping due to the existence of defects which causes the formation of new substances. Furthermore, the van der Waals contact between two semiconductors also results in bad electron diffusion. In this work, a MOF-derived carbon material as a Z-scheme photocatalyst was synthesized via one-step thermal treatment of MoS₂ dots @Fe-MOF (MIL-101). Under visible light irradiation, the well-constructed Z-scheme (MoS₂, γ-Fe₂O₃)/graphene photocatalyst shows 2-fold photocatalytic oxygen evolution activity (4400 μmol g⁻¹ h⁻¹) compared to that of γ-Fe₂O₃/graphene (2053 μmol g⁻¹ h⁻¹). Based on ultraviolet photoelectron spectrometry (UPS), Mott–Schottky plot, photocurrent and photoluminescence spectroscopy (PL) results, the photo-induced electrons from the conduction band of γ-Fe₂O₃ could transport quickly to the valence band of MoS₂via highly conductive graphene as an electron transport channel, which could significantly enhance the electron–hole separation efficiency as well as photocatalytic performance.

The heterojunction between MoS₂ and γ-Fe₂O₃ was constructed via linking by in situ formed graphene, which resulted in a good photocatalyst for the oxygen evolution reaction, showing O₂ evolution activity of 4400 μmol g⁻¹ h⁻¹.     

Highly efficient reduction of 4-nitrophenolate to 4-aminophenolate by Au/γ-Fe2O3@HAP magnetic composites

In this article, the catalyst Au/γ-Fe₂O₃@hydroxyapatite (Au/γ-Fe₂O₃@HAP) consisting of Au nanoparticles supported on the core–shell structure γ-Fe₂O₃@HAP was prepared through a deposition–precipitation method. The catalyst was characterized by transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, N₂ adsorption–desorption and atomic absorption spectrometry. The as-prepared Au/γ-Fe₂O₃@HAP exhibited excellent performance for the reduction of 4-nitrophenolate (4-NP) to 4-aminophenolate (4-AP) in the presence of NaBH₄ at room temperature. Thermodynamic and kinetic data on the reduction of 4-NP to 4-AP catalyzed by the as-prepared catalyst were studied. The as-prepared catalyst could be easily separated by a magnet and recycled 6 times with over 92% conversion of 4-NP to 4-AP. In addition, the as-prepared catalyst showed excellent catalytic performance on other nitrophenolates. The TOF value of this work on the reduction of 4-NP to 4-AP was 241.3 h⁻¹. Au/γ-Fe₂O₃@HAP might have a promising potential application on the production of 4-AP and its derivatives.

In this article, the catalyst Au/γ-Fe₂O₃@hydroxyapatite (Au/γ-Fe₂O₃@HAP) consisting of Au nanoparticles supported on the core–shell structure γ-Fe₂O₃@HAP was prepared through a deposition–precipitation method.     

The production of an efficient visible light photocatalyst for CO oxidation through the surface plasmonic effect of Ag nanoparticles on SiO2@α-Fe2O3 nanocomposites

A process for the photo deposition of noble Ag nanoparticles on a core–shell structure of SiO₂@α-Fe₂O₃ nanocomposite spheres was performed to produce a CO photo oxidation catalyst. The structural analyses were carried out for samples produced using different Ag metal nanoparticle weight percentages on SiO₂@α-Fe₂O₃ nanocomposite spheres by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), UV-vis spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). A computational study was also performed to confirm the existence of the synergic effect of surface plasmon resonance (SPR) for different weight percentages of Ag on the SiO₂@α-Fe₂O₃ nanocomposites. The mechanism for CO oxidation on the catalyst was explored using diffuse reflectance infrared Fourier transform spectroscopy (DRFIT). The CO oxidation results for the Ag (2 wt%)-SiO₂@α-Fe₂O₃ nanocomposite spheres showed 48% higher photocatalytic activity than α-Fe₂O₃ and SiO₂@α-Fe₂O₃ at stable temperature.

We present a systematic investigation of CO oxidation and surface plasmon resonance on SiO₂@α-Fe₂O₃ nanocomposite spheres with different weight percentages of Ag nanoparticles.     

A type II heterojunction α-Fe2O3/g-C3N4 for the heterogeneous photo-Fenton degradation of phenol

The heterogeneous photo-Fenton reaction is an effective method of chemical oxidation to remove phenol in wastewater with environmental friendliness and sustainability. Herein, the composite α-Fe₂O₃/g-C₃N₄, as a catalyst of the heterogeneous photo-Fenton reaction, has been synthesized by hydrothermal-calcination method using the abundant and low-cost FeCl₃·6H₂O and g-C₃N₄ as raw materials. The influence of the annealing temperature during calcination was also investigated. The UV-Vis diffuse reflectance spectra of samples show that the composite α-Fe₂O₃/g-C₃N₄ possesses the widest light response range. Furthermore, the transient photocurrent response curves demonstrated the strongest intensity of α-Fe₂O₃/g-C₃N₄. The annealed α-Fe₂O₃/g-C₃N₄ is indicative of the highest degradation efficiency in all samples due to the improvement of the charge transfer ability caused by the tight heterojunction structure. The results of the scavenger trapping experiments show that the hydroxyl radical was the main active species in degradation. Based on experimental results, a type II heterojunction should be built in the composite α-Fe₂O₃/g-C₃N₄, driving the photoelectrons transfer and migration by internal electronic field. This work provides a facile and new method to synthesize α-Fe₂O₃/g-C₃N₄ as an effective heterogeneous photo-Fenton catalyst for environmental remediation.

Composite α-Fe₂O₃/g-C₃N₄ with type II heterojunction to degrade phenol by heterogeneous photo-Fenton reaction.     

Enhanced legume root growth with pre-soaking in α-Fe2O3 nanoparticle fertilizer

The rising demand for food and energy crops has triggered interest in the use of nanoparticles for agronomy. Specifically, iron oxide-based engineered nanoparticles are promising candidates for next-generation iron-deficiency fertilizers. We used iron oxide and hybrid Pt-decorated iron oxide nanoparticles, at low and high concentrations, and at varied pHs, to model seed pre-soaking solutions for investigation of their effect on embryonic root growth in legumes. This is an environmentally friendly approach, as it uses less fertilizer, therefore less nanoparticles in contact with the soil. Analysis from varied material characterization techniques combined with a statistical analysis method found that iron oxide nanoparticles could enhance root growth by 88–366% at low concentrations (5.54 × 10⁻³ mg L⁻¹ Fe). Hybrid Pt-decorated iron oxide nanoparticles and a higher concentration of iron oxide nanoparticles (27.7 mg L⁻¹ Fe) showed reduced root growth. The combined materials characterization and statistical analysis used here can be applied to address many environmental factors to finely tune the development of vital nanofertilizers for high efficiency food production.

A new approach to increase root growth in legumes by pre-soaking seeds in iron oxide nanoparticle growth solution.     

Facile one-step hydrothermal synthesis of α-Fe2O3/g-C3N4 composites for the synergistic adsorption and photodegradation of dyes

With the expansion of industrialization, dye pollution has become a significant hazard to humans and aquatic ecosystems. In this study, α-Fe₂O₃/g-C₃N₄-R (where R is the relative percentage of α-Fe₂O₃) composites were fabricated by a one-step method. The as-prepared α-Fe₂O₃/g-C₃N₄-0.5 composites showed excellent adsorption capacities for methyl orange (MO, 69.91 mg g⁻¹) and methylene blue (MB, 29.46 mg g⁻¹), surpassing those of g-C₃N₄ and many other materials. Moreover, the ionic strength and initial pH influenced the adsorption process. Relatively, the adsorption isotherms best fitted the Freundlich model, and the pseudo-second-order kinetic model could accurately describe the kinetics for the adsorption of MO and MB by α-Fe₂O₃/g-C₃N₄-0.5. Electrostatic interaction and π–π electron donor–acceptor interaction were the major mechanisms for MO/MB adsorption. In addition, the photocatalytic experiment results showed that more than 79% of the added MO/MB was removed within 150 min. The experimental results of free-radical capture revealed that holes (h⁺) were the major reaction species for the photodegradation of MO, whereas MB was reduced by the synergistic effect of hydroxyl radicals (·OH) and holes (h⁺). This study suggests that the α-Fe₂O₃/g-C₃N₄ composites have an application potential for the removal of dyes from wastewater.

Simple one-step hydrothermal synthesis of α-Fe₂O₃/g-C₃N₄ composites for the synergistic adsorption and photodegradation of dyes     

Efficient electrocatalyst of α-Fe2O3 nanorings for oxygen evolution reaction in acidic conditions

Large-scale application of sustainable energy devices urgently requires cost-effective electrocatalysts to overcome the sluggish kinetics related to the oxygen evolution reaction (OER) under acidic conditions. Here, we first report the highly efficient electrocatalytic characteristics of α-Fe₂O₃ nanorings (NRs), which exhibits prominent OER electrocatalytic activity with lower overpotential of 1.43 V at 10 mA cm⁻² and great stability in 1 M HCl, surpassing the start-of-the art Ir/C electrocatalyst. The significantly optimized OER activity of the α-Fe₂O₃ NRs mainly attributes to the synergistic effect of the excellent electrical conductivity and a large effective active surface because of their unique nanoring structure, disordered surface, and the dynamic stability of α-Fe₂O₃ NRs in acidic conditions.

α-Fe₂O₃ NRs is obtained for OER with lower small overpotential and great stability in 1 M HCl, surpassing Ir/C electrocatalyst.     

Catalyst-free chemoselective α-sulfenylation/β-thiolation for α,β-unsaturated carbonyl compounds

A novel, efficient, catalyst-free and product-controllable strategy has been developed for the chemoselective α-sulfenylation/β-thiolation of α,β-unsaturated carbonyl compounds. An aromatic sulfur group could be chemoselectively introduced at α- or β-position of carbonyls with different sulfur reagents under slightly changed reaction conditions. A series of desired products were obtained in moderate to excellent yields. Mechanistic studies revealed that B₂pin₂ played the key role in activating the transformation towards the β-thiolation of α,β-unsaturated carbonyl compounds. This transition-metal-catalyst-free method provides a convenient and efficient tool for the highly chemoselective preparation of α-thiolation or β-sulfenylation products of α,β-unsaturated carbonyl compounds.

This catalyst-free method provides a useful and efficient tool for the highly chemoselective preparation of α-thiolation or β-sulfenylation products of α,β-unsaturated carbonyl compounds.     

Optical and dielectric properties of NaCoPO4 in the three phases α, β and γ

In this work, we are interested in the synthesis of monophosphate α-NaCoPO₄, β-NaCoPO₄ and γ-NaCoPO₄ compounds by mechanochemical method and their characterization by X-ray powder diffraction patterns. These compounds are crystallized in the orthorhombic, hexagonal and monoclinic system, in Pnma, P6₅ and P2₁/n space groups, respectively. The optical properties were measured by means of the UV-vis absorption spectrometry in order to deduce the absorption coefficient α and optical band gap E_g. The calculated values of the indirect band gaps (E_gi) for three samples were estimated at 4.71 eV, 4.63 eV and 3.8 for compounds α, β and γ, respectively. The Tauc model was used to determine the optical gap energy of the synthesized compounds. Then, the results of the dielectric proprieties measured by varying the frequency are described.

In this work, we are interested in the synthesis of monophosphate α-NaCoPO₄, β-NaCoPO₄ and γ-NaCoPO₄ compounds by mechanochemical method and their characterization by X-ray powder diffraction patterns.     

Enhanced photocatalytic water splitting of a SILAR deposited α-Fe2O3 film on TiO2 nanoparticles

We have investigated the effect of deposition of a α-Fe₂O₃ thin layer on a substrate of TiO₂ nanoparticles for photoelectrochemical (PEC) water splitting. The TiO₂ layer was coated on an FTO substrate using the paste of TiO₂ nanoparticles. The α-Fe₂O₃ layer was deposited on the TiO₂ thin film, using the method of Successive Ionic Layer Adsorption and Reaction (SILAR) with different cycles. Various characterizations including XRD, EDX and FE-SEM confirm the formation of α-Fe₂O₃ and TiO₂ nanoparticles on the electrode. The UV-visible absorption spectrum confirms a remarkable enhancement of the absorption of the α-Fe₂O₃/TiO₂/FTO composite relative to the bare TiO₂/FTO. In addition, the photocurrents of the composite samples are remarkably higher than the bare TiO₂/FTO. This is mainly due to the low band gap of α-Fe₂O₃, which extends the absorption spectrum of the α-Fe₂O₃/TiO₂ composite toward the visible region. In addition, the impedance spectroscopy analysis shows that the recombination rate of the charge carriers in the α-Fe₂O₃/TiO₂ is lower than that for the bare TiO₂. The best PEC performance of the α-Fe₂O₃/TiO₂ sample was achieved by the sample of 70 cycles of α-Fe₂O₃ deposition with about 7.5 times higher photocurrent relative to the bare TiO₂.

Optimization of photoelectrochemical water splitting by a composite of SILAR-deposited α-Fe₂O₃ thin film on a substrate of TiO₂ nanoparticles.     

Thermal stability and oxidation characteristics of α-pinene, β-pinene and α-pinene/β-pinene mixture

Turpentine is a renewable resource, has good combustion performance, and is considered to be a fuel or promising additive to diesel fuel. This is very important for the investigation of thermal stability and energy oxidation characteristics, because evaluation of energy or fuel quality assurance and use safety are necessary. The main components of turpentine are α-pinene and β-pinene, which have unsaturated double bonds and high chemical activity. By investigating their thermal stability and oxidation reaction characteristics, we know the chemical thermal properties and thermal explosion hazard of turpentine. In this present study, the thermal stability and oxidation characteristics of α-pinene, β-pinene and α-pinene/β-pinene mixture were investigated using a high sensitivity accelerating rate calorimeter (ARC) and C80 calorimeter. The important parameters of oxidation reaction and thermal stability were obtained from the temperature, pressure and exothermic behavior in chemical reaction. The results show that α-pinene and β-pinene are thermally stable without chemical reaction under a nitrogen atmosphere even when the temperature reaches 473 K. The initial exothermic temperature of the two pinenes and their mixture is 333–338 K, and the heat release (−ΔH) of their oxidation is 2745–2973 J g⁻¹. The oxidation activation energy (E_a) of α-pinene, β-pinene and α-pinene/β-pinene mixture is 116.25 kJ mol⁻¹, 121.85 kJ mol⁻¹, and 115.95 kJ mol⁻¹, respectively. There are three steps in the oxidation of pinenes: the first is the induction period of the oxidation reaction; the second is the main oxidation stage, and the pressure is reduced; the third is thermal decomposition to produce gas.

Turpentine is a renewable resource, has good combustion performance, and is considered to be a fuel or promising additive to diesel fuel.