Ionic Porous Aromatic Framework as a Self-Degraded Template for the Synthesis of a Magnetic γ-Fe2O3/WO3·0.5H2O Hybrid Nanostructure with Enhanced Photocatalytic Property

An ionic porous aromatic framework is developed as a self-degraded template to synthesize the magnetic heterostructure of γ-Fe2O3/WO3·0.5H2O. The Fe3O4 polyhedron was obtained with the two-phase method first and then reacted with sodium tungstate to form the γ-Fe2O3/WO3·0.5H2O hybrid nanostructure. Under the induction effect of the ionic porous network, the Fe3O4 phase transformed to the γ-Fe2O3 state and complexed with WO3·0.5H2O to form the n-n heterostructure with the n-type WO3·0.5H2O on the surface of n-type γ-Fe2O3. Based on a UV-Visible analysis, the magnetic photocatalyst was shown to have a suitable band gap for the catalytic degradation of organic pollutants. Under irradiation, the resulting γ-Fe2O3/WO3·0.5H2O sample exhibited a removal efficiency of 95% for RhB in 100 min. The charge transfer mechanism was also studied. After the degradation process, the dispersed powder can be easily separated from the suspension by applying an external magnetic field. The catalytic activity displayed no significant decrease after five recycles. The results present new insights for preparing a hybrid nanostructure photocatalyst and its potential application in harmful pollutant degradation.

Application of Spinel and Hexagonal Ferrites in Heterogeneous Photocatalysis

Semiconducting materials display unique features that enable their use in a variety of applications, including self-cleaning surfaces, water purification systems, hydrogen generation, solar energy conversion, etc. However, one of the major issues is separation of the used materials from the process suspension. Therefore, chemical compounds with magnetic properties have been proposed as crucial components of photocatalytic composites, facilitating separation and recovery of photocatalysts under magnetic field conditions. This review paper presents the current state of knowledge on the application of spinel and hexagonal ferrites in heterogeneous photocatalysis. The first part focuses on the characterization of magnetic (nano)particles. The next section presents the literature findings on the single-phase magnetic photocatalyst. Finally, the current state of scientific knowledge on the wide variety of magnetic-photocatalytic composites is presented. A key aim of this review is to indicate that spinel and hexagonal ferrites are considered as an important element of heterogeneous photocatalytic systems and are responsible for the effective recycling of the photocatalytic materials.

Characteristic and photocatalytic performance of magnetic photocatalyst β-Bi2O3/MnxZn1−xFe2O4 synthesized by hydrothermal and calcination method

A magnetic photocatalyst [Formula: see text]-Bi2O3/Mn[Formula: see text]Zn[Formula: see text]Fe2O4 (Bi2O3/MZF) was fabricated by hydrothermal and calcination method, and characterized by XRD, FTIR, XPS and SEM, BET and VSM. The photocatalytic efficiency was measured by the degradation experiment of Rhodamine B (RhB). The degradation rate of the optimum sample Bi2O3/MZF (10 wt.%) could reach 96.8% after 3 h under visible light, and was improved significantly compared with pure [Formula: see text]-Bi2O3 due to the larger pore size (11.76 nm) and specific surface area (17.87 m2 ⋅ g[Formula: see text]. Meanwhile, the Bi2O3/MZF (10 wt.%) could be recovered under the external magnetic field due to its high magnetization saturation (9.22 emu ⋅ g[Formula: see text]. After reusing three times, the Bi2O3/MZF could still maintain the excellent photocatalytic activity and structural stability.