[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Ferromagnetic materials

Activation of persulfate (PS) and peroxymonosulfate (PMS) and application for the degradation of emerging contaminants

Hexagonal ferrites: A review of the synthesis, properties and applications of hexaferrite ceramics

Sulfate radical-based advanced oxidation processes (SR-AOPs) employing heterogeneous catalysts to generate sulfate radical (SO4 −) from peroxymonosulfate (PMS) and persulfate (PS) have been extensively employed for organic contaminant removal in water. This article aims to provide a state–of–the–art review on the recent development in heterogeneous catalysts including single metal, mixed metal, and nonmetal carbon catalysts for organic contaminants removal, with particular focus on PMS activation. The hybrid heterogeneous catalyst/PMS systems integrated with other advanced oxidation technologies is also discussed. Several strategies for the identification of principal reactive radicals in SO4 −–oxidation systems are evaluated, namely (i) use of chemical probe or spin trapping agent coupled with analytical tools, and (ii) competitive kinetic approach using selective radical scavengers. The main challenges and mitigation strategies pertinent to the SR-AOPs are identified, which include (i) possible formation of oxyanions and disinfection byproducts, and (ii) dealing with sulfate produced and residual PMS. Potential future applications and research direction of SR-AOPs are proposed. These include (i) novel reactor design for heterogeneous catalytic system based on batch or continuous flow (e.g. completely mixed or plug flow) reactor configuration with catalyst recovery, and (ii) catalytic ceramic membrane incorporating SR-AOPs.

Generation of sulfate radical through heterogeneous catalysis for organic contaminants removal: Current development, challenges and prospects

A novel heterostructure coupling MOF-derived fluffy porous indium oxide with g-C3N4 for enhanced photocatalytic activity

M-type barium ferrite (BaFe12O19) particles, from a mixture of barium nitrate, ferric nitrate, cetyltrimethylammonium bromide (CTAB), and ammonium carbonate, have been successfully prepared through simple grinding and calcination in the absence of any solvent. The products are characterized by X-ray diffraction, scanning electron microscope, and vibrating sample magnetometer, whose results indicate that they have well crystalline phase of BaFe12O19, typically hexagonal platelet-like structure, large saturation magnetization, even submicrometer particle size under the optimum condition. Meanwhile, the effects of Fe/Ba ratio, CTAB, and ammonium carbonate are also investigated. It has been found that the proper Fe/Ba ratio could suppress the intermediate phase such as α-Fe2O3 and BaFe2O4, CTAB could promote the crystallinity of BaFe12O19 and produce hexagonal crystal structure, and ammonium carbonate was the key for forming BaFe12O19 phase. This facile method may be helpful for the preparation of other multicomponent functional materials.

Solvent-free synthesis of hexagonal barium ferrite (BaFe12O19) particles

Heteroatom-doped carbon materials have been one of the most remarkable families of materials with promising applications in fuel cells, supercapacitors, and batteries. Among them, conjugated polymer (CP)-derived heteroatom-doped carbon materials exhibit remarkable electrochemical performances because the heteroatoms can be preserved at a relatively high content and keep stable under harsh working conditions. In this review, we summarized recent advances in the rational design and various applications of CP-derived heteroatom-doped carbon materials, including polyaniline (PANI), polypyrrole (PPy), and their ramification-derived carbons, as well as transition metal-carbon nanocomposites. The key point of considering CP-derived heteroatom-doped carbon materials as important candidates of electrode materials is that CPs contain only nonmetallic elements and some key heteroatoms in their backbones which provide great chances for the synthesis of metal-free heteroatom-doped carbon nanostructures. The presented examples in this review will provide new insights in designing and optimizing heteroatom-doped carbon materials for the development of anode and cathode materials for electrochemical device applications.

Heteroatom-Doped Carbon Nanostructures Derived from Conjugated Polymers for Energy Applications

Water electrolysis affords a promising approach to large-scale hydrogen yield, but its efficiency is restrained by the sluggish water dissociation kinetics. Here, an efficient bifunctional electrocatalyst of in situ formed crystalline nickel metaphosphate on amorphous NiMoOx nanoarrays supported on nickel foam (c-Ni2 P4 O12 /a-NiMoOx /NF) for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution is reported. The c-Ni2 P4 O12 /a-NiMoOx /NF can deliver a current density of 10 mA cm-2 at a low potential of 78 mV for HER, and a current density of 20 mA cm-2 at an overpotential of 250 mV for OER. Moreover, it only requires a small cell voltage of 1.55 V at 10 mA cm-2 for robust water splitting with outstanding long-term durability over 84 h. Various spectroscopic studies reveal that in situ surface reconstruction is crucial for the enhanced catalytic activity, where c-Ni2 P4 O12 /a-NiMoOx is transformed into c-Ni2 P4 O12 /a-NiMoO4 during the HER process, and into c-Ni2 P4 O12 /a-NiOOH in the OER process. This work may provide a new strategy for uncovering the catalytic mechanism of crystalline-amorphous catalysts.

Crystalline-Amorphous Ni2 P4 O12 /NiMoOx Nanoarrays for Alkaline Water Electrolysis: Enhanced Catalytic Activity via In Situ Surface Reconstruction.

Defective ZnIn2S4 nanosheets/mesoporous black TiO2 heterojunction hollow spheres (H-ZIS/b-TiO2) are prepared through hydrothermal and surface low-temperature hydrogenation strategies, which show broad-spectrum response and excellent charge separation efficiency. This H-ZIS/b-TiO2 flower-like heterojunction hollow spheres with a narrow band gap of ∼1.88 eV expand the light response to visible light and show excellent photocatalytic hydrogen evolution rate (278 μmol h-1 50 mg-1) under visible-light irradiation, which is 1.5 times as high as that of ZnIn2S4/black TiO2 heterojunction hollow spheres (ZIS/b-TiO2) (181 μmol h-1 50 mg-1). The excellent photocatalytic performance is due to the formation of O, S dual vacancies in b-TiO2 and H-ZIS providing more active sites for photocatalytic reaction and improving the charge separation efficiency, heterojunctions promoting transport of photogenerated carriers, and the hollow structure increasing light utilization by reflecting light. The novel heterojunction hollow sphere with high performance has broad application prospects in the field of energy.

O, S-Dual-Vacancy Defects Mediated Efficient Charge Separation in ZnIn 2 S 4/Black TiO 2 Heterojunction Hollow Spheres for Boosting Photocatalytic Hydrogen Production

Yunchen Du

Papers

A novel heterostructure coupling MOF-derived fluffy porous indium oxide with g-C3N4 for enhanced photocatalytic activity

Solvent-free synthesis of hexagonal barium ferrite (BaFe12O19) particles

Heteroatom-Doped Carbon Nanostructures Derived from Conjugated Polymers for Energy Applications

Crystalline-Amorphous Ni2 P4 O12 /NiMoOx Nanoarrays for Alkaline Water Electrolysis: Enhanced Catalytic Activity via In Situ Surface Reconstruction.

O, S-Dual-Vacancy Defects Mediated Efficient Charge Separation in ZnIn 2 S 4/Black TiO 2 Heterojunction Hollow Spheres for Boosting Photocatalytic Hydrogen Production