Dinuclear vanadium and tetranuclear iron complexes obtained with the open Wells–Dawson [Si2W18O66] tungstosilicate

Reaction of two transition metal cations M (M = V^V, Fe^III) on the open Wells–Dawson anion α-[{K(H₂O)₂}Si₂W₁₈O₆₆]^15– leads to dinuclear and tetranuclear complexes, respectively. The molecular anions [{KV₂O₃(H₂O)₂}(Si₂W₁₈O₆₆)]^11– and [{Fe₄(OH)₆}(Si₂W₁₈O₆₆)]^10– have been structurally characterized by single crystal X-ray diffraction. The oxo/hydroxometallic clusters [KV₂O₃(H₂O)₂]⁵⁺ and [Fe₄(OH)₆]⁶⁺ are included in the pocket between the two subunits of [Si₂W₁₈O₆₆]^16–. The Fe^III atoms of the iron complex can be reduced to Fe^II by a single four-electron step. To cite this article: N. Leclerc-Laronze et al., C. R. Chimie 9 (2006).     

Mössbauer study of the FeV2O4---Fe3O4 system

Mössbauer spectra of the Fe_1+xV_2−xO₄ spinel solid solutions are taken to investigate the cation distribution. Room temperature spectra can be interpreted by assuming that the cation distribution is represented approximately as Fe²⁺[Fe³⁺_xV³⁺_2−x]O₄ for 0 x 0.35 and Fe³⁺[Fe²⁺Fe³⁺_x−1V³⁺_2−x]O₄ for 1 x 2 and the ionic valence arrangement changes from the 2-3-3 type (Fe²⁺[Fe³⁺_xV³⁺_2−x]O₄) to the 3-2-3 one (Fe³⁺[Fe²⁺V³⁺]O₄) in the range 0.35 x 1. Fe₂VO₄ is found to be 3-2-3 spinel, Fe³⁺[Fe²⁺V³⁺]O₄. Its paramagnetic spectrum at 473°K is, however, composed of a broad single line with isomer shift value of 0.61 mm/sec relative to stainless steel, in which the line splitting due to the ferric and ferrous ions is rendered indistinguishable.     

Reaction of (±)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate {(±)-phosH} with copper(II), cobalt(II) and iron(II) compounds; Identification by x-ray diffraction of [Co(CH3OH)4(H2O)2][(+)-phos][(−)-phos]. 2CH3OH·H2O

[Cu₂(μO₂CCH₃)₄(H₂O)₂], [CuCO₃·Cu(OH)₂], [CoSO₄·7H₂O], [Co((+)-tartrate)], and [FeSO₄·7H₂O] react with excess racemic (±)- 1,1′-binaphthyl-2,2′-diyl hydrogen phosphate {(±)-PhosH} to give mononuclear Cu^II, Co^II and Fe^II products. The cobalt product, [Co(CH₃OH)₄(H₂O)₂]((+)-Phos)((−)-Phos) ·2CH₃OH·H₂O (7), has been identified by X-ray diffraction. The high-spin, octahedral Co^II atom is ligated by four equatorial methanol molecules and two axial water molecules. A (+)- and a (−)-Phos⁻ ion are associated with each molecule of the complex but are not coordinated to the metal centre. For the other Co^II, Cu^II and Fe^II samples of similar formulation to (7) it is also thought that the Phos⁻ ions are not bonded directly to the metal. When some of the Cu^II and Co^II samples are heated under high vacuum there is evidence that the Phos⁻ ions are coordinated directly to the metals in the products.     

Pillaring of Layered Perovskites, K1−xLaxCa2−xNb3O10, with Nanosized Fe2O3 Particles

Nanosized Fe₂O₃ clusters are pillared in the interlayer spaces of layered perovskites, H_1−xLa_xCa_2−xNb₃O₁₀ (0≤x≤0.75) by a guest-exchange reaction using the trinuclear acetato-hydroxo iron cation, [Fe₃(OCOCH₃)₇ OH·2H₂O]⁺. The interlayer spaces of niobate layers are pre-expanded with n-butylammonium cations (n-C₄H₉NH⁺₃), which are subsequently replaced by bulky iron pillaring species to form Fe(III) complex intercalated layer niobates. Upon heating at 380°C, the interlayered acetato-hydroxo iron complexes are converted into Fe₂O₃ nanoclusters with a thickness of ca. 3.5 Å irrespective of the interlayer charge density (x). The band-gap energy of the Fe₂O₃ pillars (E_g2.25 eV) is slightly larger than that of bulk Fe₂O₃ (E_g2.20 eV) but is smaller than that expected for such a small-sized semiconductor, which can be assigned to the pancake-shaped Fe₂O₃ pillars of 3.5 Å in height with comparatively large lateral dimension. X-ray absorption spectroscopic measurements at the Fe K-edge are carried out in order to obtain structural information on the Fe₂O₃ pillars stabilized between the niobate layers. XANES analysis reveals that the interlayer FeO₆ octahedra have coordination environments similar to that of bulk α-Fe₂O₃, but noncentrosymmetric distortion of interlayered FeO₆ is enhanced due to the asymmetric electric potential exerted by the negatively charged niobate layers. Scanning electron microscopic observation and nitrogen adsorption–desorption isotherm measurement suggest that the pillared derivatives are nanoporous materials with the highest BET specific surface area of ca. 116 m²/g.     

Elucidation of methyl tert-butyl ether degradation with Fe/H2O2 by purge-and-trap gas chromatography-mass spectrometry

Degradation of methyl tert-butyl ether (MTBE) with Fe²⁺/H₂O₂ was studied by purge-and-trap gas chromatography-mass spectrometry. MTBE was degraded 99% within 120 min under optimum conditions. MTBE was firstly degraded rapidly based on a Fe²⁺/H₂O₂ reaction and then relatively slower based on a Fe³⁺/H₂O₂ reaction. The dissolved oxygen decreased rapidly in the Fe²⁺/H₂O₂ reaction stage, but showed a slow increase in the Fe³⁺/H₂O₂ reaction stage. tert-Butyl formate, tert-butyl alcohol, methyl acetate and acetone were identified as primary degradation products by mass spectrometry. A preliminary reaction mechanism involving two different pathways for the degradation of MTBE with Fe²⁺/H₂O₂ was proposed. This study suggests that degradation of MTBE can be achieved using the Fe²⁺/H₂O₂ process.     

Magnetic {Mo72Fe30}-embedded hybrid nanocapsules

Magnetic nanocapsules were constructed by fabricating nanometer scaled C₆₀-like “Keplerate” type {Mo₇₂Fe₃₀} with molecular formula [Mo₇₂^VIFe₃₀^IIIO₂₅₂(CH₃COO)₁₂{Mo₂O₇(H₂O)}₂{H₂Mo₂O₈(H₂O)}(H₂O)₉₁]ca.150H₂O into nanocapsule shells using the LbL technique. The morphology of the obtained hybrid nanocapsules was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Shell thickness of the {Mo₇₂Fe₃₀}-embedded nanocapsules can be tailored at the nanometer level more precisely than other nanoparticle-embedded capsules due to the homogeneous diameter and surface charges of {Mo₇₂Fe₃₀}. Interestingly, the {Mo₇₂Fe₃₀}-embedded nanocapsules could be separated and aligned under a circumstance of magnetic field, though {Mo₇₂Fe₃₀} is a paramagnetic molecule. This is the first time to fabricate hybrid magnetic materials containing {Mo₇₂Fe₃₀} using LbL technique. The obtained nanocapsules can be a good candidate for bioseparation as well as targeted delivery.     

Effect of Physiological Concentrations of Vitamin C on the Inhibitation of Hydroxyl Radical Induced Light Emission from Fe2+-EGTA-H2O2 and Fe3+-EGTA-H2O2 Systems In Vitro

Ascorbic acid (AA) has antioxidant properties. However, in the presence of Fe²⁺/Fe³⁺ ions and H₂O₂, it may behave as a pro-oxidant by accelerating and enhancing the formation of hydroxyl radicals (^•OH). Therefore, in this study we evaluated the effect of AA at concentrations of 1 to 200 µmol/L on ^•OH-induced light emission (at a pH of 7.4 and temperature of 37 °C) from 92.6 µmol/L Fe²⁺—185.2 µmol/L EGTA (ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid)—2.6 mmol/L H₂O₂, and 92.6 µmol/L Fe³⁺—185.2 µmol/L EGTA—2.6 mmol/L H₂O₂ systems. Dehydroascorbic acid (DHAA) at the same range of concentrations served as the reference compound. Light emission was measured with multitube luminometer (AutoLumat Plus LB 953) for 120 s after automatic injection of H₂O₂. AA at concentrations of 1 to 50 µmol/L and of 1 to 75 µmol/L completely inhibited light emission from Fe²⁺-EGTA-H₂O₂ and Fe³⁺-EGTA-H₂O₂, respectively. Concentrations of 100 and 200 µmol/L did not affect chemiluminescence of Fe³⁺-EGTA-H₂O₂ but tended to increase light emission from Fe²⁺-EGTA-H₂O₂. DHAA at concentrations of 1 to 100 µmol/L had no effect on chemiluminescence of both systems. These results indicate that AA at physiological concentrations exhibits strong antioxidant activity in the presence of chelated iron and H₂O₂.     

Reinvestigation of the Fe-rich part of the pseudo-binary system SrO–Fe2O3

The phase relations in the Fe-rich part of the pseudo-binary system SrO–Fe₂O₃ (>33 mol% Fe₂O₃) were reinvestigated between 800 and 1500 °C in air. A combination of microscopy, electron probe micro-analysis, powder X-ray diffraction and thermal analysis was used to determine phase relations, crystal structure parameters and phase transition temperatures. M-type hexagonal ferrite SrFe₁₂O₁₉ (85.71 mol% Fe₂O₃) is stable up to 1410 °C. No indication of a significant phase width was found; Sr₄Fe₆O_13±δ appears as a second phase in compositions with <85.71±0.2 mol% Fe₂O₃. Sr₄Fe₆O_13±δ itself is stable between 800 and 1250 °C. Two other hexagonal ferrites were found to exist at high temperatures only: W-type SrFe²⁺₂Fe³⁺₁₆O₂₇ is stable between 1350 and 1440 °C and X-type ferrite Sr₂Fe²⁺₂Fe³⁺₂₈O₄₆ between 1350 and 1420 °C, respectively, which is shown here for the first time. These findings in combination with previously published data were used to derive a corrected phase diagram of the Fe-rich part of the pseudo-binary system SrO–Fe₂O₃.     

BiOBr/g-C3N4 S型异质结无H2O2光-自芬顿高效催化降解RhB

通过焙烧-超声混合法成功地制备了BiOBr/g-C₃N₄ S型异质结复合光催化剂。采用多种表征手段对样品物理属性进行了表征,包括X射线多晶粉末衍射仪(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-VisDRS)。研究了所制备样品有/无Fe³⁺的光-自芬顿催化/光催化降解罗丹明B (RhB)性能。通过捕获实验确定了光催化反应中的主要活性物种,提出了光-自芬顿反应的降解机理。研究结果表明,BiOBr/g-C₃N₄ S型异质结能原位生成H₂O₂,添加Fe³⁺后,H₂O₂被原位活化成活性物种且光生电流和载流子分离效率获得显著提高。该光-自芬顿过程能高效降解RhB,其反应速率常数为0.208 min^-1,约为无Fe³⁺光催化反应速率常数的5.3倍,在光-自芬顿循环使用过程中表现出良好的稳定性。Fe³⁺的加入促进了光生电荷的分离和H₂O₂的活化,超氧阴离子自由基(·O₂^-)、空穴和羟基是光-自芬顿催化过程中的主要活性物种,且·O₂^-作用更大。     

Unusual valences and fast electron exchange in MoFe2O4

The distribution of d electrons over the cations in MoFe₂O₄, which is represented by the formal valence assignment, is shown to be complicated by the equilibrium reactionsFe²⁺_B+Fe³⁺_A+Mo³⁺Fe³⁺_B+Fe²⁺_A+Mo⁴⁺We have used thermal treatment to confirm that the Mo are primarily on octahedral sites; Fe_A[Mo_BFe_B]O₄. K-shell absorption and Mössbauer data at T = 423 K > T_c demonstrate that the iron has an average valence near 2.5+ with fast electron transfer (τ_h < 10⁻⁸ sec) on both octahedral and tetrahedral sites. Paramagnetic susceptibility data give a Curie constant C_M = 7.95 ± 0.2 emu/mole and a Weiss constant θ_p = −445 K; magnetometer measurements confirm a compensation point near 160 K. Transport data give a surprisingly high electronic conductivity, but also give an activated mobility similar to that found in AlFe₂O₄ and CrFe₂O₄ where mixed Fe^3+/2+ valences on both A and B sites have been demonstrated. However, a positive Seebeck coefficient and a preexponential factor one order of magnitude higher in MoFe₂O₄ point to involvement of a fraction of the Mo atoms in electronic transport, which would be consistent with the observation of a τ_h < 10⁻⁸ sec on the A sites of a spinel. An energy diagram consistent with these data and other information about the relative redox potentials of these ions in oxides are proposed for this system.     

Uncompensated magnetization in the layered molecular antiferromagnet {N(n-C5H11)4[MnFe(ox)3]}∞

Studies on the magnetic properties of the molecular antiferromagnetic material {N(n-C₅H₁₁)₄[Mn^IIFe^III(ox)₃]}_∞, carried out by various physical techniques (AC/DC magnetic susceptibility, magnetization, heat capacity measurements and Mössbauer spectroscopy) at low temperatures, have been presented. Different experimental observations complement each other and provide a clue for the observation of an uncompensated magnetization below the Néel temperature and short-range correlations persisting high above T_N. It is understood that the honeycomb layered structure of the compound contains non-equivalent magnetic sub-lattices, (Mn^II–ox–Fe^III_A–...) and (Mn^II–ox–Fe^III_B–...), where different responses of the Fe^III_A and Fe^III_B spin sites towards an external magnetic field might be responsible for the observation of the uncompensated magnetization in this compound at T < T_N. The present magnetic system is an S = 5/2 2-D Heisenberg antiferromagnet system with the intralayer exchange parameter J/k_B = −3.29 K. A very weak interlayer exchange interaction was anticipated from the spin wave modeling of the magnetic heat capacity for T < 0.5T_N. The positive sign of the coupling between the layers has been concluded from the Mössbauer spectrum in the applied magnetic field. Frustration in the magnetic interactions gives rise to the uncompensated magnetic moment in this compound at low temperatures.     

Energetics of copper diphosphates – Cu2P2O7 and Cu3(P2O6OH)2

Differential scanning calorimetry and high temperature oxide melt solution calorimetry are used to study enthalpy of phase transition and enthalpies of formation of Cu₂P₂O₇ and Cu₃(P₂O₆OH)₂. α-Cu₂P₂O₇ is reversibly transformed to β-Cu₂P₂O₇ at 338–363 K with an enthalpy of phase transition of 0.15 ± 0.03 kJ mol⁻¹. Enthalpies of formation from oxides of α-Cu₂P₂O₇ and Cu₃(P₂O₆OH)₂ are −279.0 ± 1.4 kJ mol⁻¹ and −538.8 ± 2.7 kJ mol⁻¹, and their standard enthalpies of formation (enthalpy of formation from elements) are −2096.1 ± 4.3 kJ mol⁻¹ and −4302.7 ± 6.7 kJ mol⁻¹, respectively. The presence of hydrogen in diphosphate groups changes the geometry of Cu(II) and decreases acid–base interaction between oxide components in Cu₃(P₂O₆OH)₂, thus decreasing its thermodynamic stability.     

Properties of the perovskites, SrMn1−xFexO3−δ (x=1/3, 1/2, 2/3)

The SrMn_1−xFe_xO_3−δ (x=1/3, 1/2, 2/3) phases have been prepared and are shown by powder X-ray and neutron (for x=1/2) diffraction to adopt an ideal cubic perovskite structure with a disordered distribution of transition-metal cations over the six-coordinate B-site. Due to synthesis in air, the phases are oxygen deficient and formally contain both Fe³⁺ and Fe⁴⁺. Magnetic susceptibility data show an antiferromagnetic transition at 180 and 140 K for x=1/3 and 1/2, respectively and a spin-glass transition at 5, 25, 45 K for x=1/3, 1/2 and 2/3, respectively. The magnetic properties are explained in terms of super-exchange interactions between Mn⁴⁺, Fe^(4+δ)+ and Fe⁽³⁺⁾⁺. The XAS results for the Mn-sites in these compounds indicate small Mn-valence changes, however, the Mn-pre-edge spectra indicate increased localization of the Mn-e_g orbitals with Fe substitution. The Mössbauer results show the distinct two-site Fe⁽³⁺⁾+/Fe^(4+δ)+ disproportionation in the Mn- substituted materials with strong covalency effects at both sites. This disproportionation is a very concrete reflection of a localization of the Fe-d states due to the Mn-substitution.     

Elimination of 4‐chlorophenol in aqueous solution by the Novel Pd/MIL‐101(Cr)‐Hydrogen‐Accelerated catalytic fenton system

Excessive consumption of Fe (II) and massive generation of sludge containing Fe (III) from classic Fenton process remains a major obstacle for its poor recycling of Fe (III) to Fe (II). Therefore, the MHACF‐MIL‐101(Cr) system, by introducing H₂, Pd⁰ and MIL‐101(Cr) into Fenton reaction system, was developed at normal temperature and pressure. In this system, the reduction of Fe^III back to Fe^II by solid catalyst Pd/MIL‐101(Cr) for the storage and activation of H₂, was accelerated significantly by above 10‐fold and 5‐fold controlled with the H₂‐MIL‐101(Cr) system and H₂‐Pd⁰ system, respectively. However, the concentration of Fe (II) generated by the reduction of Fe (III) could not be detected with the only input of H₂ and without the addition of MOFs material. In addition, the apparent consumption of Fe (II) in MHACF‐MIL‐101(Cr) system was half of that in classical Fenton system, while more Fe (II) might be reused infinitely in fact. Accordingly, only trace amount of Fe (II) vs H₂O₂ concentration was needed and hydroxyl radicals through the detection of para‐hydroxybenzoic acid (p‐HBA) as the oxidative product of benzoic acid (BA) by·OH could be continuously generated for the effective degradation of 4‐chlorophenol(4‐CP). The effects of initial pH, concentration of 4‐CP, dosage of Fe²⁺, H₂O₂ and Pd/MIL‐101(Cr) catalyst, Pd content and H₂ flow were investigated, combined with systematic controlled experiments. Moreover, the robustness and morphology change of Pd/MIL‐101(Cr) were thoroughly analyzed. This study enables better understanding of the H₂‐mediated Fenton reaction enhanced by Pd/MIL‐101(Cr) and thus, will shed new light on how to accelerate Fe (III)/Fe (II) redox cycle and develop more efficient Fenton system.     

Structural Characterization of Divalent Magnesium-Dopedα-Fe2O3

The defect structure of divalent magnesium-dopedα-Fe₂O₃has been examined by Rietveld structure refinement of the X-ray powder diffraction data. The results show that the Mg²⁺ions occupy the vacant interstitial octahedral sites as well as substituting on the two adjacent octahedral Fe³⁺sites in the corundum-relatedα-Fe₂O₃structure. The structure therefore involves a linear cluster of three Mg²⁺ions replacing two Fe³⁺ions. Interatomic potential calculations indicate that this is the most energetically favorable defect cluster for the system.     

Redox Equilibria in the System Fe(OH)3(H2SO4)-Na2SO3-H2O Involving Precipitation of Iron(II) Sulfite as a Fe2O3 Precursor

Experimental data on the equilibria Fe²⁺/Fe³⁺ and SO₃ ²⁻/SO₄ ²⁻ in the system Fe(OH)₃(H₂SO₄)-Na₂SO₃-H₂O are presented. The quantitative relations between the reduction of Fe(III) and the precipitation of FeSO₃·2.5H₂O as a Fe₂O₃ precursor have considered graphically.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1, 2005, pp. 41–44.Original Russian Text Copyright © 2005 by Vasekha, Motov.     

Magnetic and EPR Studies of α-, β-, and γ-Fe2WO6 Phases at Low Temperatures

The polymorphic modifications α-, β-, and γ-Fe₂WO₆ of the iron tungstate system were studied by means of magnetic susceptibility and EPR measurements at low temperatures. Both methods revealed a significant paramagnetic contribution, probably resulting from local distortions of the antiferromagnetic bulk structure induced by a disturbed cation ordering or the presence of Fe²⁺ ions. The magnetic susceptibility revealed a peak at 260 K for all samples which can be related with an AF phase transition. The EPR spectra comprised the contribution of various isolated paramagnetic iron centers, one arising from high-spin Fe³⁺ ions in rhombic crystal field symmetry with E/D ≈ 1/3 and D ≈ 0.22 cm^-1, an anisotropic EPR signal consistent with an S= 3/2 ground state with large zero-field splitting, and a dominant component in the g ≈ 2 region presumably arising from an S = 1/2; spin state. The latter spectra were tentatively attributed to the formation of multi-iron clusters, one of them invoking the presence of Fe²⁺ ions as well. For the βFe₂WO₆ phase an additional EPR spectrum was observed, which probably results from high-spin Fe³⁺ ions in a weak crystal field.     

About the OH yield in the radiolysis of an aqueous/H2O2 system. Its optimisation for water treatment

Unless the radiolytic reducing species are neutralised or converted into oxidising species, an EB remediation system cannot be considered a true Advanced Oxidation Processes (AOP). A water/H₂O₂ system irradiated by UVC mercury lamps constitutes a widely used OH production method. Employing H₂O₂ in radiolysis as well, an enhancement of the oxidative efficiency of an EB treatment can be obtained. Pulse radiolysis measurements of an aerated aqueous/H₂O₂/KSCN system have been systematically undertaken to assess the optimal H₂O₂ concentration. By linearly fitting a competition kinetics relationship, it is found that the scavengeable extra-yield of OH is ΔG(OH)=0.24 μmol J^?1 (R=0,9958), while the maximum experimental yield is measured G(OH)_max=(0.52±0.02) μmol J^?1 when [H₂O₂]=5–10 mM. Exceeding these concentrations the OH yield drops off.     

Reactions of small negative ions with O2(a Δg) and O2(X Σg)

The rate constants and product ion branching ratios were measured for the reactions of various small negative ions with O₂(X ³Σ_g⁻) and O₂(a ¹Δ_g) in a selected ion flow tube (SIFT). Only NH₂⁻ and CH₃O⁻ were found to react with O₂(X) and both reactions were slow. CH₃O⁻ reacted by hydride transfer, both with and without electron detachment. NH₂⁻ formed both OH⁻, as observed previously, and O₂⁻, the latter via endothermic charge transfer. A temperature study revealed a negative temperature dependence for the former channel and Arrhenius behavior for the endothermic channel, resulting in an overall rate constant with a minimum at 500 K. SF₆⁻, SF₄⁻, SO₃⁻ and CO₃⁻ were found to react with O₂(a ¹Δ_g) with rate constants less than 10⁻¹¹ cm³ s⁻¹. NH₂⁻ reacted rapidly with O₂(a ¹Δ_g) by charge transfer. The reactions of HO₂⁻ and SO₂⁻ proceeded moderately with competition between Penning detachment and charge transfer. SO₂⁻ produced a SO₄⁻ cluster product in 2% of reactions and HO₂⁻ produced O₃⁻ in 13% of the reactions. CH₃O⁻ proceeded essentially at the collision rate by hydride transfer, again both with and without electron detachment. These results show that charge transfer to O₂(a ¹Δ_g) occurs readily if the there are no restrictions on the ion beyond the reaction thermodynamics. The SO₂⁻ and HO₂⁻ reactions with O₂(a) are the only known reactions involving Penning detachment besides the reaction with O₂⁻ studied previously [R.S. Berry, Phys. Chem. Chem. Phys., 7 (2005) 289–290].     

BiOBr/g-C3N4 S型异质结无H2O2光-自芬顿高效催化降解RhB

通过焙烧-超声混合法成功地制备了BiOBr/g-C₃N₄S型异质结复合光催化剂。采用多种表征手段对样品物理属性进行了表征,包括X射线多晶粉末衍射仪(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-Vis DRS)。研究了所制备样品有/无Fe³⁺的光-自芬顿催化/光催化降解罗丹明B(RhB)性能。通过捕获实验确定了光催化反应中的主要活性物种,提出了光-自芬顿反应的降解机理。研究结果表明,BiOBr/g-C₃N₄S型异质结能原位生成H₂O₂,添加Fe³⁺后,H₂O₂被原位活化成活性物种且光生电流和载流子分离效率获得显著提高。该光-自芬顿过程能高效降解RhB,其反应速率常数为0.208 min^-1,约为无Fe³⁺光催化反应速率常数的5.3倍,在光-自芬顿循环使用过程中表现出良好的稳定性。Fe...