Magnetic MgFe2O4-CaFe2O4 S-scheme photocatalyst prepared from recycling of electric arc furnace dust

Development of high performance microwave absorption modified epoxy coatings based on nano-ferrites

With the rapid spread of wireless technologies and increasing electromagnetic energy, electromagnetic waves (EMW) have become a severe threat to human health. Therefore, minimizing the harmful effects of electromagnetic wave radiation is possible through the development of high-efficiency EMW absorption coatings. The aim of this work was to generate microwave absorbance coatings containing synthesized nano-CuFe2O4 and nano-CaFe2O4. Firstly, nano-CuFe2O4 and nano-CaFe2O4 were synthesized using the sol-gel method. Then, their structure, electrical, dielectric, and magnetic properties were investigated to find out the possibility of using these materials in high-frequency applications (e.g., microwave absorbance coatings). After that, two dosages (2.5 wt% and 5 wt%) of nano-CuFe2O4 and nano-CaFe2O4 were incorporated into epoxy resin to prepare modified epoxy resin as microwave coatings. The dielectric studies show that the AC conductivity of the prepared samples is high at high frequencies. Additionally, the magnetic properties reveal a low coercivity value, making these samples suitable for high-frequency devices. The microwave results illustrate that adding nano-ferrites with high content enhances the absorption characteristics of the tested films. The results showed that the two films have two absorption bands with RL < -10 dB ranging from 10.61 to 10.97 GHz and from 10.25 to 11.2 GHz. The minimum return loss achieved for the two cases is -13 and -16 dB, respectively. Indicating that the film coated with CuFe has a better absorption value than the one coated with CaFe.

Impact of alternate Mn doping in ternary nanocomposites on their structural, optical and antimicrobial properties: Comparative analysis of photocatalytic degradation and antibacterial activity

The present study was done to investigate and compare the photocatalytic and antibacterial activity of two in situ Manganese doped ternary nanocomposites. The dual ternary hybrid systems comprised Mn-doped Ag₂WO₄ coupled with MoS₂-GO and Mn-doped MoS₂ coupled with Ag₂WO₄-GO. Both hierarchical alternate Mn-doped ternary heterojunctions formed efficient plasmonic catalysts for wastewater treatment. The novel nanocomposites were well-characterized using XRD, FTIR, SEM-EDS, HR-TEM, XPS, UV-VIS DRS, and PL techniques confirming the successful insertion of Mn⁺² ions in respective host substrates. The bandgap of the ternary nanocomposites evaluated by the tauc plot showed them visible light-active nanocomposites. The photocatalytic ability of both Mn-doped coupled nanocomposites was investigated against the dye methylene blue. Both ternary nanocomposites showed excellent sunlight harvesting ability for dye degradation in 60 min. The maximum catalytic efficiency of both photocatalysts was obtained at a solution pH value of 8, photocatalyst dose and oxidant dose of 30 mg/100 mL and 1 mM for Mn-Ag₂WO₄/MoS₂-GO, 50 mg/100 mL, 3 mM for Mn-MoS₂/Ag₂WO₄-GO keeping IDC of 10 ppm for all photocatalysts. The nanocomposites showed excellent photocatalytic stability after five successive cycles. The response surface methodology was used as a statistical tool for the evaluation of the photocatalytic response of several interacting parameters for dye degradation by ternary composites. The antibacterial activity was determined by the inactivation of gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria by support-based doped ternary hybrids.

Photocatalytic removal of 2-chlorophenol from water by using waste eggshell-derived calcium ferrite

A new approach to recycling low-value eggshell food waste was to produce a CaFe₂O₄ semiconductor with a narrow band gap (E_g = 2.81 eV) via hydrothermal treatments of powdered eggshell suspended in aqueous ferric salt (Fe³⁺) solutions at varying Fe loadings. It was possible to obtain a single phase of CaFe₂O₄ without any Ca(OH)₂ and CaO impurities using an optimal Fe loading (30 wt% of Fe³⁺ by eggshell weight). The CaFe₂O₄ material was used as a photocatalyst for the breakdown of 2-chlorophenol (2-CP, a herbicide model chemical) as a pollutant in water. The CaFe₂O₄ with a Fe loading of 7.1 wt% exhibited a high 2-CP removal efficiency of 86.1% after 180 min of UV-visible light irradiation. Additionally, the eggshell-derived CaFe₂O₄ photocatalyst can be effectively reused, giving a high removal efficiency of 70.5% after the third cycle, without the requirement of regeneration processes (washing or re-calcination). Although radical trapping experiments confirmed that hydroxyl radicals were generated in the photocatalytic reactions, photogenerated holes play a significant role in the high 2-CP degradation efficiencies. The performance of the bioderived CaFe₂O₄ photocatalysts in the removal of pesticides from water demonstrated the benefits of resource recycling in the area of materials science and in environmental remediation and protection.

Emerging S-Scheme Photocatalyst

Photocatalysis is a green technology to use ubiquitous and intermittent sunlight. The emerging S-scheme heterojunction has demonstrated its superiority in photocatalysis. This article covers the state-of-the-art progress and provides new insights into its general designing criteria. It starts with the challenges confronted by single photocatalyst from the perspective of energy dissipation by borrowing the common behaviors in the dye molecule. Subsequently, other problems faced by single photocatalyst are summarized. Then a viable solution for these problems is the construction of heterojunctions. To overcome the problems and mistakes of type-II and Z-scheme heterojunctions, S-scheme heterojunction is proposed and the underlying reaction mechanism is summarized. Afterward, the design principles for S-scheme heterojunction are proposed and four types of S-scheme heterojunctions are suggested. Following this, direct characterization techniques for testifying the charge transfer in S-scheme heterojunction are presented. Finally, different photocatalytic applications of S-scheme heterojunctions are summarized. Specifically, this work endeavors to clarify the critical understanding on curved Fermi level in S-scheme heterojunction interface, which can help strengthen and advance the fundamental theories of photocatalysis. Moreover, the current challenges and prospects of the S-scheme heterojunction photocatalyst are critically discussed.