Traditional Hydrothermal Method Research Articles

Superior performance of hierarchical 3D microflower CuS grown on carbon cloth as binder free electrode for supercapacitor applications

Copper sulfide (CuS) was grown on the carbon cloth (CC) utilizing the traditional hydrothermal method. The role of different reaction time of 5 h, 10 h, and 15 h (C15) were investigated with fixed reaction time of 150 °C. XRD confirmed the growth of pure CuS on CC. Macroscopic changes in morphology were observed with increasing the reaction time and C15 showed ∼3.08 μm diameter of CuS microflowers with ∼ 34.68 nm thickness of nanosheets embedded in the microflowers. C15 showed a lowest bandgap of 1.8 eV with high copper content of 34 % and the copper content increases fast electron movement and maintains structural stability. The supercapacitor behavior was investigated in 1 M Mg(NO3)2 aqueous electrolyte and C15 demonstrated the highest specific capacitance of 83.70 F/g at 5 mV/s. An aqueous symmetric electrode made with C15 displays 149 F/g specific capacitance and 87.2 % retention at 1 A/g for 1000 cycles.

Stoichiometric Study on Ion Composition of a Precursor in Chemical Bottom-Up Synthesis for Peroxo-Titanate.

Layered alkali titanates of the lepidocrocite type are gaining enormous interest in various fields owing to their unique properties. These materials are mainly synthesized through a hydrothermal alkali treatment. However, this method uses a highly concentrated alkali solution, which has high environmental impacts and is therefore unsuitable for mass synthesis. Herein, we propose an efficient method for the large-scale synthesis of layered sodium titanate structures (Na2-x H x Ti2O5) using a recently reported bottom-up chemical process. The effects of the Na:Ti molar ratio in the peroxo-titanium complex ion precursor on the products are investigated through stoichiometric calculations for a molar ratio range of 10:1-1:1. The optimal ratio for the complete ionization of TiH2 (which is the starting material) to form the peroxo-titanium complex ion is found to be 1.1:1. The amount of alkali raw material required is 99.6% lower than that required in the traditional hydrothermal method. The crystal structures and morphologies of the samples are almost identical regardless of the Na:Ti molar ratio. The precursor-derived peroxo bonds narrow the energy band gaps of the layered titanates even when the amount of titanium ions dissolved in the precursor increases. The proposed method is not only an efficient synthetic route for mass production but also has potential applications in the development of photofunctional materials.

Hydrothermal synthesis of Ni, Co hydroxide nanosheet array on vertically suspended carbon cloth for flexible high-performance supercapacitors

The investigation of Ni(OH)2 electrode materials has been a prominent issue in the field of electrochemical energy. The slow ion diffusion kinetics and inherent low electronic conductivity of Ni(OH)2 restrict its electrochemical performance and application in practice. In this work, mixed-phase nickel-cobalt layered double hydroxide (NiCoLDH) array structures are successfully grown directly on vertically suspended carbon cloth (CC). In contrast to the traditional hydrothermal method, the vertically suspended carbon cloth affordes adequate reaction sites to ensure optimum array structure growth. This unique structure realizes a large mass loading of the active material. Meanwhile, the introduction of flexible electrode substrate carbon cloth effectively enhances the mechanical properties of the electrode. Due to the powerful electrochemistry kinetics, NiCoLDH/CC-1.5 exhibites a great capacitive and excellent rate performance of 1516.5 F g−1 at 1 A g−1 and 1073.75 F g−1 even at 20 A g−1. The assembled asymmetric supercapacitor demonstrates a favorable cycling stability (capacitance retention of 90.11 % after 10,000 cycles at 5 A g−1).

Rapid Hydrolysis Precipitation of BiOBr Nanosheets for Boosting Photocatalytic N2 Fixation

AbstractIn this paper, BiOBr nanosheets were synthesized through a novel hydrolysis precipitation method, which significantly reduced energy consumption and time cost compared to traditional hydrothermal synthesis methods. The subjected hydrothermal and high‐temperature calcination process promote the generation of surface oxygen vacancies, which inhibited the recombination of photogenerated electron hole pairs and improve the photocatalytic performance of BiOBr. Additionally, by adjusting the addition amount of KOH in the synthesis process, BiOBr can grow towards more complex crystal structure, which also provides a new path for the fabrication of 2D materials.

Preparation of CeO2 particles via ionothermal synthesis and its application to chemical mechanical polishing

CeO2 is a widely used abrasive for the chemical mechanical polishing of silicon during chip manufacturing. CeO2 can be synthesized via traditional coprecipitation, hydrothermal, and solvothermal methods; however, these methods have some issues, including high vapor pressure, flammability, toxicity, volatile solvents, and narrow heating temperature range. To overcome these issues, we developed a new ionothermal synthesis approach for high-quality CeO2 particles using 1-ethyl-3-methylimidazolium tetrafluoroborate as an imidazole ionic liquid without a template. Based on the scanning electron microscopy and particle size distribution, CeO2 particles synthesized at a reaction temperature of 210 °C for 16 h displayed sizes ranging between 0.1 and 0.3 μm. Additionally, the spherical shapes exhibited good crystallinity, regular morphology, and uniform dispersion. The results of CMP experiments indicated that the abrasives could reduce the surface roughness from 1.63 to 0.29 nm (scanning area is 5 μm × 5 μm). The obtained synthesized CeO2 particles demonstrated promising performance in Si polishing, achieving removal rates of up to 255.5 nm/min. It found that the removal rate of the abrasive prepared by ionic thermal synthesis in Si polishing was twice as much as other abrasives. Further, a possible mechanism was put forward to explain the formation of CeO2 structures with various morphologies. The proposed method presents a new approach for synthesizing CeO2 particles with uniform morphology and excellent polishing properties.

Mesoporous TiO2 and Fe-containing TiO2 prepared by solution combustion synthesis as catalysts for the photodegradation of paracetamol

Water pollution due to emerging contaminants, e.g., pharmaceuticals, is one of the most frequently discussed issues. Among them, paracetamol received great attention due to its physico-chemical properties, persistence, and adverse environmental effects. Different techniques were employed for its degradation and, among them, photodegradation is considered one of the most suitable to pursue the aim. This work aimed to synthesize mesoporous TiO2, even with the presence of iron, through a one-pot method, with an enhanced ability to abate paracetamol. Precisely, pure and iron-containing (3.5 wt%) TiO2 were successfully obtained employing an uncommon procedure for this kind of material, mainly solution combustion synthesis (SCS). Moreover, a traditional hydrothermal method and a commercial Degussa P25 were also investigated for comparison purposes. The samples were characterized through N2-physisorption at − 196 °C, XRD, XPS, EDX, DR UV-Vis, and FESEM analysis. The catalytic activity was investigated for the abatement of 10 ppm of paracetamol, under UV irradiation in acidic conditions (pH = 3) and in the presence of H2O2. As a whole, the best-performing catalysts were those obtained through the SCS procedure, highlighting a complete removal of the organic pollutant after 1 h in the case of Fe/TiO2_SCS, thanks to its highly defective structure and the presence of metal Fe. To better investigate the performance of both pure and Fe-containing SCS samples, further oxidation tests were performed at pH = 7 and in the absence of H2O2. Noteworthy, in these conditions, the two samples exhibited different behaviors, highlighting different mechanisms depending on the presence or absence of iron in the structure. Finally, a kinetic study was conducted, demonstrating that a first order is suitable for its abatement.Graphical abstract

A facile cellulose finishing strategy through in-situ growth of sliver-doped manganese dioxide assisted by amine-quinone for improving indoor living quality

Nowadays, various harmful indoor pollutants especially including bacteria and residual formaldehyde (HCHO) seriously threaten human health and reduce the quality of public life. Herein, a universal substrate-independence finishing approach for efficiently solving these hybrid indoor threats is demonstrated, in which amine-quinone network (AQN) was employed as reduction agent to guide in-situ growth of Ag@MnO2 particles, and also acted as an adhesion interlayer to firmly anchor nanoparticles onto diverse textiles, especially for cotton fabrics. In contrast with traditional hydrothermal or calcine methods, the highly reactive AQN ensures the efficient generation of functional nanoparticles under mild conditions without any additional catalysts. During the AQN-guided reduction, the doping of Ag atoms onto cellulose fiber surface optimized the crystallinity and oxygen vacancy of MnO2, providing cotton efficient antibacterial efficiency over 90 % after 30 min of contact, companying with encouraging UV-shielding and indoor HCHO purification properties. Besides, even after 30 cycles of standard washing, the Ag@MnO2-decorated textiles can effectively degrade HCHO while well-maintaining their inherent properties. In summary, the presented AQN-mediated strategy of efficiently guiding the deposition of functional particles on fibers has broad application prospects in the green and sustainable functionalization of textiles.

Hydrothermal synthesis of highly cross‐linked PtZn@Silicalite‐1 structured catalysts for propane dehydrogenation

AbstractStructured catalysts coatings exhibit excellent performance on non‐adiabatic gas–solid process, deriving from their enhanced heat and mass transfer properties. However, the coating catalysts prepared by traditional hydrothermal method of zeolite encapsulating noble metal are prone to spalling, especially under conditions of large flow rate and high temperature. Herein, we prepared PtZn clusters encapsulated in silicalite‐1 zeolite coating on stainless steel with high bonding strength by an improved in situ growth method. The optimized catalyst exhibited ultra‐thin, uniform, continuous, and high degree of crosslinking, thereby enhancing mass transfer and thermal stability. In propane dehydrogenation reaction, the optimized PtZn@S‐1‐R showed a high specific activity of 14.7 molPt−1 s−1 and a propylene selectivity above 99% at 600°C with a high weight hourly space velocity of 120 h−1. The metal‐encapsulated zeolite coating catalysts broaden the application avenue for heterogeneous catalysis with great application prospects.

Comparative study on Al-SBA-15 prepared by spray drying and traditional methods for bulky hydrocarbon cracking: Properties, performance and influencing factors

Mesoporous aluminosilicates Al-SBA-15 with large pore sizes and suitable acid properties are promising substitutes to zeolites for catalytic cracking of bulky hydrocarbons without molecular diffusion limitation. The conventional processes to synthesize Al-SBA-15 are time-consuming and often suffer from low “framework” Al contents. Herein, Al-SBA-15 microspheres are synthesized using the rapid and scalable microfluidic jet spray drying technique. They possess uniform particle sizes (45–60 μm), variable surface morphologies, high surface areas (264–340 m2/g), uniform mesopores (3.8–4.9 nm) and rich acid sites (126–812 μmol/g) and high acid strength. Their physicochemical properties are compared with the counterparts synthesized using traditional hydrothermal and evaporation-induced self-assembly methods. The spray drying technique results in a higher incorporation of aluminum (Al) atoms into the silica “framework” compared to the other two methods. The catalytic cracking efficiencies of 1,3,5-triisopropylbenzene (TIPB) on the Al-SBA-15 materials synthesized using the three different methods and nanosized ZSM-5 are compared. The optimal spray-dried Al-SBA-15 exhibits the best performance with 100 % TIPB conversion, excellent selectivity (about 75 %) towards the formation of deeply cracked products (benzene and propylene) and high stability. The catalytic performances of the spray-dried Al-SBA-15 with varying Si/Al ratios are also compared. The reasons for the different performances of the different materials are discussed, where the mesopores, high acid density and strength are observed to play the most critical role. This work might provide a basis for the synthesis of mesoporous rich metal-substituted silica materials for different catalytic applications.

Catalytic Acetone Oxidation over MnOx Catalysts: Regulating Their Crystal Structures and Surface Properties

This study investigates the catalytic oxidation of acetone by different crystal phases of MnO2 prepared via different methods. Compared with β-MnO2 and γ-MnO2, α-MnO2 exhibited superior catalytic activity. Moreover, as replacements for traditional hydrothermal methods and air calcination, the use of microwave hydrothermal methods and N2 calcination significantly enhanced the catalytic performance of the MnO2 catalyst. The optimal catalyst, MnO2-WN (α-MnO2 synthesized via microwave hydrothermal method and N2 calcination), converted 100% of 100 ppm acetone below 150 °C, with the CO2 yields reaching 100%. Further, the stability of the catalyst and its potential for other volatile organic compounds (VOCs) were also determined. The experimental data demonstrated that its outstanding activity primarily stemmed from the improved preparation method, enhancing the specific surface area of the catalyst, optimizing the pore structure, improving the redox performance, and generating more acidic sites and active oxygen species, thereby creating a synergistic effect. Finally, the reaction pathway of acetone oxidation on the catalyst surface has been explored. This work provides a new perspective for developing economically efficient MnOx catalysts for removing VOCs.

Synthesis of Ni-MOF loaded Pt nanoparticle composites for the electro-oxidation of methanol in acidic media

A series of Pt/Ni-MOF nanocomposites with different atom molar ratio of Pt/Ni were synthesized by the traditional hydrothermal method. Various methods including element mapping, X-ray diffraction (XRD) were employed to characterize the crystal structure and surface morphology of the materials. TEM (Transmission Electron Microscopy) confirms that the Pt nanoparticles are highly dispersed onto the Ni-MOF nanosheet surface, which can provide an abundance of active sites for efficient oxidation of methanol. Electrochemical measurements showed that Catalyst b (the atomic molar ratio of Pt to Ni is 2:1 in the precursor materials) exhibited a higher oxidation current density in MOR and larger electrochemically active surface area (ECSA) than other catalysts with different atomic ratios and commercial Pt/C. Meanwhile, the synthesized catalysts showed long-term activity and good resistance to toxicity.

Engineering of binder-free cobalt carbonate hydroxide hydrate nanostructure for high-performance hybrid supercapacitors

Cobalt-based binder-free electrode materials, such as Co(CO3)0.5(OH)⋅0.11H2O nanowires (Co@Urea) and Co(OH)F microcrystals (Co@NH4F), were synthesized on a nickel foam substrate by a traditional hydrothermal method using urea and ammonium fluoride (NH4F) as the complexing reagents. The nanowire structure of the Co@Urea electrode promoted efficient charge transfer and high electrochemical active centers. The Co@Urea electrode exhibited a large specific capacity (693.0 C g−1 at 1 A g−1), better rate performance (50.8 % after 20 A g−1), and exceptional cyclic durability (84.0 % capacity retention after 10,000 cycles) compared to Co@NH4F electrode in a three-electrode configuration. A hybrid supercapacitor device was fabricated with Co@Urea as the cathode and activated charcoal as the anode, exhibiting high specific energy and specific power of 53.8 Wh kg−1 and 799.9 W kg−1, respectively. Furthermore, this hybrid device shows excellent long-term stability with 88.2 % capacity retention after 10,000 cycles at a current density of 40 A g−1. This study proposes developing binder-free cobalt-based compounds for electrochemical energy storage applications.

Preparation of Coal Gangue Based LSX Zeolite and Its Application for Zn2+ and Ni2+ Adsorption

In this paper, LSX zeolite was synthesized in a sodium-potassium system through the traditional hydrothermal synthesis method with coal gangue in Wuhai area as raw material. The synthesized products were characterized by XRD, SEM, TEM, BET, IR and so on. The synthetic LSX zeolite was utilized to adsorb simulated wastewater containing Zn2+ and Ni2+, and the optimal adsorption conditions were determined. The removal rate and adsorption capacity of Zn2+ and Ni2+ were studied under these conditions, which were 96.36%, 96.83%, 96.36, 72.62 mg/g, respectively. The zeolite after adsorption saturation can be recycled 4 times in the mixed solution of 6% NaOH and 1% NaCl as the regenerant, and the regeneration rate is above 90%.

Synthesis of five polyoxometalate-based compounds by using hydrothermal one pot method: Structures, supercapacitor, electrocatalytic and photocatalytic properties

Five polyoxometalate (POM) based compounds were synthesized by traditional hydrothermal method, namely {Co2(HTPT)2(H2O)2[Mo8O27]} (1), {Co2(TPT)2(H2O)6}(β-Mo8O26)·4H2O (2), {Co2(TPT)2(H2O)2(δ-Mo8O26)}·2H2O (3), {M(TPT)2(H2O)2}(Mo6O19) (M = Co 4, Ni 5) (TPT = 3-(4-terahydro-2H-pyran-4-yl)methyl)-4H-1,2,4-triazol-3-yl)pyridine). Compounds 1−3 were obtained in one pot, realizing efficient utilization of the hydrothermal method. The photocatalytic activities of compounds 1, 2, 4 and 5 were evaluated by the degradation of Methylene blue (MB) and Rhodamine B (RhB) and the reduction of Cr6+. The effects of the amount of catalyst and the pH of the system on the photocatalytic performance were also studied. Experimental studies have shown that compounds 1 and 4 also exhibit good bifunctional electrocatalytic activity for reducing NO2−, Cr6+ and H2O2, but also oxidizing AA (Ascorbic Acid). Compounds 1, 2, 4 and 5 can serve as amperometric sensors for NO2− and Cr6+. Compounds 1 and 4 own properties of capacitor materia.

Hydrothermal synthesis of Ni,Co hydroxide nanosheet array on vertically suspended Ni foam for high performance supercapacitors

Ni(OH)2 have attracted great attention as pseudocapacitor electrode materials due to its high theoretical capacitance. However, the intrinsic disadvantaged in low electronic conductivity and sluggish ion diffusion kinetics of Ni(OH)2 limit its performance and practical application. Herein, we report a simple hydrothermal method to synthesize Co doped Ni(OH)2 and NiOOH array structure on vertical hanging Ni foam. Compared with traditional hydrothermal methods, vertical hanging Ni foam provide sufficient reaction sites and ensure fully growth of array structure, leading to large mass loading of active materials. The array structure and the wide interlayer spacing due to interlayer embedded CH3COO− together build an effcient ion diffusion path. Morevoer, strong electron exchange between Ni(OH)2 or NiOOH and Ni provide high electrical conductivity at the interface, forming the fast and complete electron transport channel inside the electrode. As a result of robust electrochemical kinetics, NiCoLDH@vNF-12 shows a high capacitive and outstanding rate performance of 952.9 C g−1 at 1 A g−1 and 660.0 C g−1 even at 50 A g−1.

Microfluidic one-step synthesis of a metal-organic framework for osteoarthritis therapeutic microRNAs delivery.

As a class of short non-coding ribonucleic acids (RNAs), microRNAs (miRNA) regulate gene expression in human cells and are expected to be nucleic acid drugs to regulate and treat a variety of biological processes and diseases. However, the issues with potential materials toxicity, quantity production, poor cellular uptake, and endosomal entrapment limit their further applications in clinical practice. Herein, ZIF-8, a metal-organic framework with noncytotoxic zinc (II) as the metal coordination center, was selected as miRNA delivery vector was used to prepare miR-200c-3p@ZIF-8 in one step by Y-shape microfluidic chip to achieve intracellular release with low toxicity, batch size, and efficient cellular uptake. The obtained miR-200c-3p@ZIF-8 was identified by TEM, particle size analysis, XRD, XPS, and zeta potential. Compared with the traditional hydrothermal method, the encapsulation efficiency of miR-200c-3p@ZIF-8 prepared by the microfluidic method is higher, and the particle size is more uniform and controllable. The experimental results in cellular level verified that the ZIF-8 vectors with low cytotoxicity and high miRNAs loading efficiency could significantly improve cellular uptake and endosomal escape of miRNAs, providing a robust and general strategy for nucleic acid drug delivery. As a model, the prepared miR-200c-3p@ZIF-8 is confirmed to be effective in osteoarthritis treatment.

The electromagnetic wave absorption composite of flower-like structure NiCo2O4 and Fe3O4 derived from low-temperature preparation method

The NiCo2O4@Fe3O4 composites with excellent electromagnetic wave absorption performance was prepared by the low-temperature (50 °C) co-precipitation method, avoiding the traditional high-temperature hydrothermal synthesis method. The specific surface area of the composite material was increased due to the combination of NiCo2O4 with 3D hierarchical flower-like structure and Fe3O4 with spherical structure, which is conducive to the full reflection and scattering of electromagnetic waves. The combination of typical magnetic material and excellent dielectric material could adjust the impedance matching value of the material and thus the absorption loss performance of electromagnetic wave was improved. The ε value of the dielectric material was larger than those of magnetic materials and the maximum reflection loss value appeared at the high frequency (the thickness is small), while the μ value of magnetic materials was larger than those of dielectric materials and the maximum reflection loss value generally appeared at low frequency (the thickness is large).The results showed that the maximum RL value reached −53.35 dB at about 13 GHz with the thickness of 2.0 mm and the effective absorption bandwidth was 4.4 GHz when the weight ratio (NiCo2O4:Fe3O4) of composite samples was 6:1. The excellent EMW absorption property was mainly due to the combination of NiCo2O4 and Fe3O4, which could achieve impedance matching to loss EMW by dielectric loss and magnetic loss.

Near room temperature synthesis of Cs2InCl5-xBrx·H2O (x = 0–5) perovskites with tunable yellow to red emissions

Lead-free halide perovskites have recently evoked considerable interest in illumination and display, due to their intriguing optical properties. Herein, we present an efficient and facile strategy to prepare Cs2InCl5-xBrx·H2O (x = 0–5) perovskites. The preparation was performed at a low temperature of 80 °C under atmospheric pressure, and required no complex technological process. Comparing with that prepared by the traditional hydrothermal method, the emission intensity of the prepared Cs2InX5·H2O (X = Cl/Br) perovskites were increased by two times. Besides, Sb3+ ions were successfully doped into the matrix of Cs2InX5·H2O (X = Cl/Br) by our method. After doping with Sb3+, the emission intensities of Cs2InX5·H2O were greatly enhanced, with enhanced by a factor of ∼187 and ∼102, respectively. Importantly, the PLQYs were greatly improved, reaching 79.6% and 42.7%, respectively. Additionally, the effects of Br− on luminescent properties of Cs2InCl5-xBrx·H2O:Sb3+ (x = 0–5) were also investigated in this work. Though the control of the Br− content, tunable emissions from 575 nm to 630 nm were achieved. These results indicate the prepared samples could be promising environmentally-friendly materials for lightings. Furthermore, this work presents a reliable and simple method for preparing high-quality perovskites.

Blue light induced red phosphors Sr2CeO4:Eu3+ through co-doping with M2+ (Mg, Ba, Ca) and spectroscopic properties applied in WLEDs

In the present work, A series of Sr2CeO4:xEu3+ (x = 0.15, 1, 2, 5 mol%) (SCO:xEu3+) and co-doped with different divalent metal ions (M2+: Mg, Ca, Ba) phosphors were successfully synthesized through traditional hydrothermal method. All the samples performed pure Sr2CeO4 phase. The absorption spectra show that an overlap between Ce4+–O2- CTS band and Eu3+ ions results in the energy transfer from the matrix to the emitting center. With the concentration of Eu3+ ion increasing, the phosphors exhibit orange red emission, and the highest intensity was achieved when the Eu3+ concentration was 2 mol%. The energy transfer mechanism would be dipole–dipole interaction. Furthermore, when the concentration of Eu3+ ion is at 2 mol%, the samples co-doped with M2+ ion performed intense red emission of Eu3+ ion under 467 nm excitation, which is ascribed to M2+ ions disturbed the anisotropic structure to create defects so that make much more efficient energy transfer from Ce-O band to Eu3+ ions. Moreover, CIE chromaticity showed SCO:2%Eu3+/2%M2+ phosphors performed pure red warm light. The above results suggest that SCO:2%Eu3+/2%M2+ can be of potential as red-emitting phosphor for blue-excitation WLEDs.

Synthesis of Bi25FeO40 Nanoparticles with Oxygen Vacancies via Ball Milling for Fenton Oxidation of Tetracycline Hydrochloride and Reduction of Cr(VI)

Though heterogeneous Fenton-like reactions possess various characteristics such as a wide application range and mild reaction conditions, their reactivity is currently restricted by unsatisfactory H2O2 decomposition efficiency and low pH adaptation. Hence, Bi25FeO40 nanoparticles prepared via the mechanical ball-milling method (Bi25FeO40-B) with extensive oxygen vacancies possess high reactive oxygen species production performance by enhancing the H2O2 decomposition for tetracycline hydrochloride oxidation and Cr(VI) reduction. H2O2 decomposition efficiency can reach 55.3% in the presence of the Bi25FeO40-B catalyst, which is much higher than that of Bi25FeO40 prepared by the traditional hydrothermal method (23.8%). The Bi25FeO40-B/H2O2 heterogeneous Fenton system demonstrates efficient performance for simultaneous oxidation of tetracycline hydrochloride (TCH) and reduction of Cr(VI). It is capable of removing 75.2% of 50 mg/L TCH and 93.0% of 20 mg/L Cr(VI) at pHinitial = 7, respectively. Abundant oxygen vacancies on the surface of Bi25FeO40-B nanoparticles due to the nanometer size effect can accelerate the decomposition of H2O2 to promote the formation of reactive oxygen species for removing the target organic pollutants and reduction of Cr(VI). Consequently, this work provides a strategy for the preparation of oxygen-rich Bi25FeO40 catalysts for efficient degradation of contaminants and depicts the bright future of Fe-based metal oxides with oxygen vacancies on H2O2 activation in Fenton-like reactions.