Heterogeneous Fenton reactions have gained widespread attention in removing recalcitrant organic contaminants as the reaction between solid Fenton catalysts and H2O2 can generate highly reactive hydroxyl radicals (HO[rad]). However, several drawbacks, such as the low-speed generation of Fe(II), high consumption of H2O2, and acidic reaction conditions (generally at ˜ pH 3), are always the core issues that hamper the large-scale application of heterogeneous Fenton reactions in environmental remediation. Thus, a large number of studies have been devoted to tackling these drawbacks, and this paper intends to comprehensively review the developed strategies for enhancing heterogeneous Fenton reactivity, mainly over the last decade. Based on a comprehensive survey of previous studies, we categorize these strategies according to their reaction mechanisms. For example, introducing additional electrons (e.g., from external electric fields, electron-rich materials, semiconductors, plasmonic materials, or doped metals) to heterogeneous Fenton catalysts can accelerate the generation of Fe(II); the in situ generation of H2O2 can be achieved by combining ultrasound, electricity, semiconductors, and iron-based catalysts in the system; and controlling the specific morphologies and exposed facets of heterogeneous Fenton catalysts can greatly promote the decomposition of H2O2. In addition, we briefly introduce some recent novel heterogeneous Fenton-like reactions that are of particular interest, including constructing dual reaction centers (i.e., the electron-poor center and the electron-rich center) and synthesizing single-atom catalysis-based heterogeneous Fenton-like catalysts. Moreover, this review article analyzes and compares the merits of each strategy for enhancing heterogeneous Fenton/Fenton-like reactions. We believe this review can motivate the construction of novel and efficient heterogeneous Fenton/Fenton-like systems and help readers choose proper Fenton/Fenton-like reaction systems for industrial applications.

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Strategies for Enhancing the Heterogeneous Fenton Catalytic Reactivity: A review

Multiferroic bismuth ferrite-based materials for multifunctional applications: Ceramic bulks, thin films and nanostructures

An efficient binary Bi2Fe4O9/Bi2WO6 Z-scheme heterojunction was fabricated through a facile hydrothermal route. The obtained Bi2Fe4O9/Bi2WO6 displays high catalytic activity for rhodamine B (RhB) photodegradation, and 100% of RhB was photodegraded by Bi2Fe4O9 (7%)/Bi2WO6 within 90 min, which is much better than that by pure Bi2Fe4O9 and Bi2WO6. The effective photoinduced carrier separation, the broadened photoabsorption range, high oxidation capacity of hole, and the high reduction power of electron are in charge of the elevated catalytic activity because of the formed Z-scheme system. In addition, the effects such as pollutant concentration, pH, inorganic anions, and water sources exerted on photocatalytic performance were also investigated, and the results suggest that Bi2Fe4O9/Bi2WO6 still possesses a high photocatalytic performance. The free-radical trapping experiments and electron spin resonance spin-trapping technology disclose that hole (h+), hydroxy radical (•OH), and superoxide radical (•O2-) are cardinal active radicals in the catalytic system. In terms of the above experimental analysis, a possible photodegradation mechanism of the as-fabricated photocatalyst is thoroughly elucidated. In addition, the possible RhB photodegradation pathway is also raised in the light of the analysis of liquid chromatography-mass/mass spectrometry. In addition, Bi2Fe4O9/Bi2WO6 composite does not display dramatic reduction of the catalytic performance after five recycles. Thus, this study reveals that the as-obtained Bi2Fe4O9/Bi2WO6 catalyst has a great prospect for the environmental purification.

Facile Hydrothermal Synthesis of Z-Scheme Bi2Fe4O9/Bi2WO6 Heterojunction Photocatalyst with Enhanced Visible Light Photocatalytic Activity.

In this critical review we consider the large literature that has accumulated in the past 5-10 years concerning solution-mediated crystallisation of complex oxide materials using hydrothermal, or more generally solvothermal, reaction conditions The aim is to show how the synthesis of dense, mixed-metal oxide materials, usually prepared using the high temperatures associated with solid-chemistry, is perfectly feasible from solution in one step reactions, typically at temperatures as low as 200 °C, and that important families of oxide materials have now been reported to crystallise using such synthetic approaches We will focus on two common structures seen in oxide chemistry, ABO(3) perovskites and A(2)B(2)O(6)O' pyrochlores, and include a systematic survey of the variety of chemical elements now included in these two prototypical structure types, from transition metals, in families of materials that include titanates, niobates, manganites and ferrites, to main-group elements in stannates, plumbates and bismuthates The significant advantages of solution-mediated crystallisation are well illustrated by the recent literature: examples are provided of elegant control of crystal form from the nanometre to the micron length scale to give thin films, anisotropic crystal morphologies, or hierarchical structures of materials with properties desirable for many important contemporary applications In addition, new metastable materials have been reported, not stable once high temperatures and pressures are applied and hence not amenable using conventional synthesis We critically discuss the possible control offered by solvothermal synthesis from crystal chemistry to crystal form and how the discovery of new materials may be achieved Computer simulation, combinatorial synthesis approaches and in situ methods to follow crystallisation will be vital in providing the predictability in synthesis that is needed for rational design of new materials (232 references)

Solvothermal synthesis of perovskites and pyrochlores: crystallisation of functional oxides under mild conditions

Since the first connection between Fenton chemistry and biomedicine, numerous studies have been presented in this field. Comprehensive presentation of the guidance from Fenton chemistry and a summary of its representative applications in cancer therapy would help us understand and promote the further development of this field. This comprehensive review first supplies basic information regarding Fenton chemistry, including Fenton reactions and Fenton-like reactions. Subsequently, the current progress of Fenton chemistry is discussed, with some corresponding representative examples presented. Furthermore, the current strategies for further optimizing the performance of chemodynamic therapy guided by Fenton chemistry are highlighted. Most importantly, future perspectives on the combination of biomedicine with Fenton chemistry or a wider range of catalytic chemistry approaches are presented. We hope that this review will attract positive attention in the chemistry, materials science, and biomedicine fields and further tighten their connections.

Biomedicine Meets Fenton Chemistry.

Enhanced thermal stability of lead-free high temperature 0.75BiFeO3–0.25BaTiO3 ceramics with excess Bi content

Temperature dependence of dielectric, piezoelectric and elastic properties of BiScO3–PbTiO3 high temperature ceramics with morphotropic phase boundary (MPB) composition

Colossal low-frequency resonant magnetomechanical (MM) and magnetoelectric (ME) coupling effects have been found in a three-phase composite made of Pb(Zr,Ti)O3 ceramic fibers/phosphor copper-sheet unimorph and NdFeB magnets. The experimental results revealed that the ferromagnetic/elastic/piezoelectric three-phase composite with a cantilever beam structure could show huge bending MM coefficient of ∼145.9 × 10−3/Oe (unit in bending radian per Oe) and ME voltage coefficient of ∼16 000 V/cm·Oe at the first-order bending resonance frequency of ∼5 Hz. The achieved results related to ME effect are at least one order of magnitude higher over those of other ME materials and devices reported ever. The extremely strong MM and ME couplings in the three-phase composite are due to strong magnetic force moment effect induced by the interaction between NdFeB magnets and the applied magnetic field, and further resonant enhancement via the strain-mediated phosphor copper-sheet with a relatively high mechanical quality factor.

Colossal low-frequency resonant magnetomechanical and magnetoelectric effects in a three-phase ferromagnetic/elastic/piezoelectric composite

In recent years, industries in the fields of petrochemical, automotive, and aerospace have expressed their interest in utilizing piezoelectric actuators for high-temperature (HT) operations at the temperature above 150°C. HT piezoelectric ceramics (1-x) BiScO3–xPbTiO3 (BS–PT) are considered as one of the most competitive piezoelectric actuation materials used in the harsh environment because of its high Curie temperature (TC = 450°C) as well as high piezoelectric coefficient (d33 = 460 pC/N ) in the MPB composition. This paper summarized the recent progress in HT piezoelectric ceramics and actuators based on BS–PT solid solutions. The properties of BS–PT piezoelectric ceramics and actuators, including driving mechanisms, actuation performances and their applications in HT environment were also discussed.

https://www.worldscientific.com/doi/pdf/10.1142/S2010135X14300023

Review on high temperature piezoelectric ceramics and actuators based on BiScO3–PbTiO3 solid solutions

Bi 1− x La x FeO 3 (BLFO, x  = 0.0–0.2) crystallites were synthesized by the hydrothermal route. X-ray diffraction results indicate that pure BLFO crystallites could be obtained for x  ≤ 0.1, and the phase purity was sensitive to the PH value of precursor solutions. Transmission electron microscope observation reveals that needle like BLFO crystallites were formed for x  = 0.1. The coexistence of ferroelectric and magnetic transition is detected by using differential thermal analysis, indicating the multiferroic characteristics of BLFO crystallites. The Neel temperature of BLFO crystallites for x  = 0.1 shifts upwards, whereas the Curie temperature shifts downwards, compared with those of BFO crystallites without La substitution. Weak ferromagnetic property of BLFO crystallites was induced and enhanced with increasing the La content.

Jianguo Chen

Papers

Enhanced thermal stability of lead-free high temperature 0.75BiFeO3–0.25BaTiO3 ceramics with excess Bi content

Temperature dependence of dielectric, piezoelectric and elastic properties of BiScO3–PbTiO3 high temperature ceramics with morphotropic phase boundary (MPB) composition

Colossal low-frequency resonant magnetomechanical and magnetoelectric effects in a three-phase ferromagnetic/elastic/piezoelectric composite

Review on high temperature piezoelectric ceramics and actuators based on BiScO3–PbTiO3 solid solutions

Hydrothermal synthesis and characterization of multiferroic Bi1−xLaxFeO3 crystallites