Enhanced Electrochemical Performances of Heterostructures Based on the Colloidal Association of Graphene Oxide and Titanium Disulfide Nanosheets.

Due to the large proliferation of electrical devices combined with the ecological transition for carbon neutrality in various modern countries, the demand for compact and efficient portable energy sources is continuously increasing. In this research work, we have developed electrochemical energy storage heterostructures based on graphene oxides (GOs) and titanium disulfide (TiS2) nanosheets of different lateral sizes through a facile colloidal association thanks to the opposite electric charges of the two types of nanosheets. Large GO (LGO) served as a template system to organize TiS2 nanosheets at different loadings, of which incorporation prevented any restacking of the layered graphitic structure. While large nanosheets led to the decoration of TiS2 aggregates including Li+ cations on LGO, the association of the nanosheets of different compositions but equivalent sizes drove the formation of an interstratified organization of the nanosheets. The singular organization within GO and TiS2 nanosheets remained after a hydrothermal reduction process, leading to heterostructure materials with a large specific surface area and capacitance of 113 F/g obtained in 6 M KOH aqueous solution. These outstanding electrochemical performances, drastically enhanced by about 41% from those of the individual reduced GO (capacitance of 80 F/g) used as a collector for the electric carriers, suggest that the developed heterostructures present a possible application as electrochemical energy storage technology materials for supercapacitor applications.

Porous and Partially Dehydrogenated Fe2+ -Containing Iron Oxyhydroxide Nanosheets for Efficient Electrochemical Nitrogen Reduction Reaction (ENRR).

The design and development of efficient catalysts for electrochemical nitrogen reduction reaction (ENRR) under ambient conditions are critical for the alternative ammonia (NH3 ) synthesis from N2 and H2 O, wherein iron-based electrocatalysts exhibit outstanding NH3 formation rate and Faradaic efficiency (FE). Here, the synthesis of porous and positively charged iron oxyhydroxide nanosheets by using layered ferrous hydroxide as a starting precursor, which undergoes topochemical oxidation, partial dehydrogenated reaction, and final delamination, is reported. As the electrocatalyst of ENRR, the obtained nanosheets with a monolayer thickness and 10-nm mesopores display exceptional NH3 yield rate (28.5 µg h-1 mgcat. -1 ) and FE (13.2%) at a potential of -0.4 V versus RHE in a phosphate buffered saline (PBS) electrolyte. The values are much higher than those of the undelaminated bulk iron oxyhydroxide. The larger specific surface area and positive charge of the nanosheets are beneficial for providing more exposed reactive sites as well as retarding hydrogen evolution reaction. This study highlights the rational control on the electronic structure and morphology of porous iron oxyhydroxide nanosheets, expanding the scope of developing non-precious iron-based highly efficient ENRR electrocatalysts.

Synthesis of a Hybrid Composed of Anisotropic Niobate Layers Modified with MoC Nanoparticles.

The hybrid composed of anisotropic niobate layers modified with MoC nanoparticles is synthesized by multistep reactions. The stepwise interlayer reactions for layered hexaniobate induce selective surface modification at the alternate interlayers, and the following ultrasonication leads to the formation of double-layered nanosheets. The further liquid phase MoC deposition with the double-layered nanosheets leads to the decoration of MoC nanoparticles on the surfaces of the double-layered nanosheets. The new hybrid can be regarded as a stacking of the two layers with anisotropically modified nanoparticles. The relatively high temperature in the MoC synthesis causes partial leaching of the grafted phosphonate groups. The exposed surface of the niobate nanosheets due to the partial leaching may interact with MoC to succeed in the hybridization. The hybrid after heating exhibits photocatalytic activity, indicating that this hybridization method can be useful for hybrid synthesis of semiconductor nanosheets and co-catalyst nanoparticles toward photocatalytic application.

Phase Transfer of Inorganic Nanosheets in a Water/2-Butanone Biphasic System and Lateral Size Fractionation via Stepwise Extractions.

Lateral size fractionation of niobate nanosheets derived from K4Nb6O17·3H2O was achieved via phase transfer from the aqueous phase to the 2-butanone phase in a water/2-butanone biphasic system, in which tetra-n-dodecylammonium (TDDA+) bromide was used as a phase transfer reagent. Phase transfer of the nanosheets was observed when the TDDA+/[Nb6O17]4- molar ratios were 0.6 and 1.0, and the phase transfer ratios were 41 and 97%, respectively. FT-IR and thermogravimetry results showed that the extracted nanosheets contained TDDA+ ions. These results indicate that adsorption of TDDA+ likely induced an increase in the hydrophobicity of the nanosheet surface, leading to phase transfer. In the AFM image of the original nanosheets in the aqueous phase, their lateral sizes were in the range from several hundreds of nm to several tens of µm, while those of the nanosheets after phase transfer at a molar ratio of 0.6 were in the range from several hundreds of nm up to 2 µm, indicating that nanosheets with smaller lateral sizes were preferentially extracted into the 2-butanone phase. In addition, the phase transfer ratio of the fragmentated nanosheets with a much smaller lateral size distribution compared with the original nanosheets was 79% when the TDDA+/[Nb6O17]4- molar ratio was 0.6, indicating that phase transfer for the nanosheets with smaller lateral sizes proceeded efficiently. Following this extraction cycle, the nanosheets with a TDDA+/[Nb6O17]4- molar ratio of 0.6 remaining in the aqueous phase after extraction were extracted stepwise again through dilution of the aqueous phase with water and the addition of a fresh 2-butanone solution of tetra-n-dodecylammonium bromide to form a new biphasic system. The lateral sizes of the nanosheets increased as the extraction cycles were repeated. Completion of the three extraction cycles allowed formation of the three classes of the nanosheets with different lateral size ranges of 0.68 ± 0.5, 2.8 ± 1.9, and 6.6 ± 3.1 µm.

Graphene Oxide Sheets Decorated with Octahedral Molybdenum Cluster Complexes for Enhanced Photoinactivation of Staphylococcus aureus.

The emergence of multidrug-resistant microbial pathogens poses a significant threat, severely limiting the options for effective antibiotic therapy. This challenge can be overcome through the photoinactivation of pathogenic bacteria using materials generating reactive oxygen species upon exposure to visible light. These species target vital components of living cells, significantly reducing the likelihood of resistance development by the targeted pathogens. In our research, we have developed a nanocomposite material consisting of an aqueous colloidal suspension of graphene oxide sheets adorned with nanoaggregates of octahedral molybdenum cluster complexes. The negative charge of the graphene oxide and the positive charge of the nanoaggregates promoted their electrostatic interaction in aqueous medium and close cohesion between the colloids. Upon illumination with blue light, the colloidal system exerted a potent antibacterial effect against planktonic cultures of Staphylococcus aureus largely surpassing the individual contributions of the components. The underlying mechanism behind this phenomenon lies in the photoinduced electron transfer from the nanoaggregates of the cluster complexes to the graphene oxide sheets, which triggers the generation of reactive oxygen species. Thus, leveraging the unique properties of graphene oxide and light-harvesting octahedral molybdenum cluster complexes can open more effective and resilient antibacterial strategies.

Two-Dimensional Metal-Organic Framework Superstructures from Ice-Templated Self-Assembly.

Here, we report the synthesis of two-dimensional (2D) layered metal-organic framework (MOF) nanoparticle (NP) superstructures via an ice-templating strategy. MOF NP monolayers and bilayers can be obtained by regulating the concentration of colloidal MOF NPs without any external fields during self-assembly. Adjacent polyhedral MOF NPs are packed and aligned through crystalline facets, resulting in the formation of a quasi-ordered array superstructure. The morphology of the MOF layers is well preserved when subjected to pyrolysis, and the obtained carbon NPs have hollow interiors driven by the outward contraction of MOF precursors during pyrolysis. With the advantages of large surface areas, hierarchical porosity, high exposure of active sites, and fast electron transport of the 2D layered structure, the mono- and bilayered carbon NP superstructures show better oxygen reduction activity than isolated carbon particles in alkaline media. Our work demonstrates that ice-templating is a powerful strategy to fabricate superstructures of various MOFs and their derivatives.

Soft Template-Based Synthesis of Mesoporous Phosphorus- and Boron-Codoped NiFe-Based Alloys for Efficient Oxygen Evolution Reaction.

Controlling the morphology, composition, and crystalline phase of mesoporous nonnoble metal catalysts is essential for improving their performance. Herein, well-defined P- and B-codoped NiFe alloy mesoporous nanospheres (NiFeB-P MNs) with an adjustable Ni/Fe ratio and large mesopores (11 nm) are synthesized via soft-template-based chemical reduction and a subsequent phosphine-vapor-based phosphidation process. Earth-abundant NiFe-based materials are considered promising electrocatalysts for the oxygen evolution reaction (OER) because of their low cost and high intrinsic catalytic activity. The resulting NiFeB-P MNs exhibit a low OER overpotential of 252 mV at 10 mA cm-2 , which is significantly smaller than that of B-doped NiFe MNs (274 mV) and commercial RuO2 (269 mV) in alkaline electrolytes. Thus, this work highlights the practicality of designing mesoporous nonnoble metal structures and the importance of incorporating P in metallic-B-based alloys to modify their electronic structure for enhancing their intrinsic activity.

Highly Efficient Surface Modification of Layered Perovskite Nanosheets with a Phosphorus Coupling Reagent Making Use of Microchannels.

Surface modification of niobate nanosheets in a double-Y-type microchannel was achieved for the first time using parallel flows of an aqueous dispersion of nanosheets derived from ion-exchangeable layered perovskite via delamination with a tetrabutylammonium hydroxide aqueous solution and a cyclohexane solution of oleyl phosphate. The surface modification was essentially completed within 4.6 s, and spectroscopic characterization (IR, solid-state 13C and 31P NMR) demonstrated the successful surface modification. The surface modification using a biphasic system in a vial using the same liquids required more than 4 h, indicating the extremely high efficiency of surface modification in the microchannel.

Chemical Design of Palladium-Based Nanoarchitectures for Catalytic Applications.

Palladium (Pd) plays an important role in numerous catalytic reactions, such as methanol and ethanol oxidation, oxygen reduction, hydrogenation, coupling reactions, and carbon monoxide oxidation. Creating Pd-based nanoarchitectures with increased active surface sites, higher density of low-coordinated atoms, and maximized surface coverage for the reactants is important. To address the limitations of pure Pd, various Pd-based nanoarchitectures, including alloys, intermetallics, and supported Pd nanomaterials, have been fabricated by combining Pd with other elements with similar or higher catalytic activity for many catalytic reactions. Herein, recent advances in the preparation of Pd-based nanoarchitectures through solution-phase chemical reduction and electrochemical deposition methods are summarized. Finally, the trend and future outlook in the development of Pd nanocatalysts toward practical catalytic applications are discussed.

Biomolecule-Assisted Synthesis of Hierarchical Multilayered Boehmite and Alumina Nanosheets for Enhanced Molybdenum Adsorption.

The effective utilization of various biomolecules for creating a series of mesoporous boehmite (γ-AlOOH) and gamma-alumina (γ-Al2 O3 ) nanosheets with unique hierarchical multilayered structures is demonstrated. The nature and concentration of the biomolecules strongly influence the degree of the crystallinity, the morphology, and the textural properties of the resulting γ-AlOOH and γ-Al2 O3 nanosheets, allowing for easy tuning. The hierarchical γ-AlOOH and γ-Al2 O3 multilayered nanosheets synthesized by using biomolecules exhibit enhanced crystallinity, improved particle separation, and well-defined multilayered structures compared to those obtained without biomolecules. More impressively, these γ-AlOOH and γ-Al2 O3 nanosheets possess high surface areas up to 425 and 371 m2 g-1 , respectively, due to their mesoporous nature and hierarchical multilayered structure. When employed for molybdenum adsorption toward medical radioisotope production, the hierarchical γ-Al2 O3 multilayered nanosheets exhibit Mo adsorption capacities of 33.1-40.8 mg g-1 . The Mo adsorption performance of these materials is influenced by the synergistic combination of the crystallinity, the surface area, and the pore volume. It is expected that the proposed biomolecule-assisted strategy may be expanded for the creation of other 3D mesoporous oxides in the future.

Preparation and Comparative Stability of a Kaolinite-Tetrabutylphosphonium Bromide Intercalation Compound for Heat and Solvent Treatments.

A kaolinite-tetrabutylphosphonium bromide (TBPBr) intercalation compound (Kaol-TBPBr) was prepared from kaolinite providing inorganic aluminosilicate layers and TBPBr as intercalated salts between the layers through the use of an intermediate, a kaolinite-dimethylsulfoxide (DMSO) intercalation compound (Kaol-DMSO). The experimental data through complementary techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, solid-state 13C and 29Si nuclear magnetic resonance (NMR) spectroscopy with cross polarization and magic angle spinning, inductively coupled plasma emission spectrometry, and ion chromatography, indicate complete removal of DMSO and intercalation of TBPBr with an increase in the basal spacing from 1.12 nm (Kaol-DMSO) to 1.53 nm (Kaol-TBPBr). In contrast to a similar intercalation compound, a kaolinite-tetrabutylammonium bromide (TBABr) intercalation compound (Kaol-TBABr) with a basal spacing of 1.51 nm, Kaol-TBPBr displayed interesting features such as enhanced thermal stabilities as well as bold resistance against several solvents. Kaol-TBPBr withstood thermal decomposition of the organic species over 100 °C much better than Kaol-TBABr. When Kaol-TBPBr and Kaol-TBABr were refluxed in methanol, ethanol, acetone, or toluene for 1 day, Kaol-TBPBr preserved the expanded kaolinite layers, while the Kaol-TBABr structure completely collapsed due to the release of TBABr. Thus, with these particular and unique features of Kaol-TBPBr, organophosphonium salts appear to be promising guest species for intercalation chemistry of kaolinite.

Surface Modification of Layered Perovskite Nanosheets with a Phosphorus Coupling Reagent in a Biphasic System.

Oleyl phosphate-modified HLaNb2O7· xH2O nanosheets (OP_HLaNb nanosheets) were prepared via phase transfer from an aqueous phase, comprising a dispersion of HLaNb2O7· xH2O (HLaNb) nanosheets, formed through the intercalation of tetrabutylammonium ion (TBA+) in the interlayer space of HLaNb and subsequent delamination, to a cyclohexane phase containing oleyl phosphate (OP, a mixture of monoester and diester). The modification of HLaNb nanosheets with OP was essentially completed within 3 days at a pH value of 2 or 4. Both infrared and solid-state 13C cross-polarization and magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of the OP_HLaNb nanosheets showed the presence of OP and/or related species and TBA+ on the HLaNb nanosheet surface. The solid-state 31P MAS NMR spectra of OP_HLaNb nanosheets exhibited new signals at -2 and 0 ppm, the former of which indicates the formation of Nb-O-P bonds. These whole data set obtained by complementary techniques clearly point out the modification of the HLaNb nanosheet surface by OP moieties causing a phase transfer. OP_HLaNb nanosheets showed higher dispersibility in cyclohexane than the OP_HLaNb_interlayer nanosheets, which were prepared via stepwise substitution reactions in the interlayers of HLaNb to achieve surface modification with OP and subsequent exfoliation in cyclohexane. The presence of TBA+ on the HLaNb nanosheets and the use of a liquid-liquid biphasic system were likely to improve the dispersibility. These results show that the preparation of OP-modified HLaNb nanosheets which could be well-dispersed in the cyclohexane phase was successful because of the use of a liquid-liquid biphasic system.

Hollow Porous Heterometallic Phosphide Nanocubes for Enhanced Electrochemical Water Splitting.

Highly efficient earth-abundant electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are of great importance for renewable energy conversion systems. Herein, hollow porous heterometallic phosphide nanocubes are developed as a highly active and robust catalyst for electrochemical water splitting via one-step phosphidation of a NiCoFe Prussian blue analogue. Through modulation of the composition of metals in the precursors, the optimal NiCoFeP exhibiting increased electrical conductivity and abundant electrochemically active sites, leading to high electrocatalytic activities and outstanding kinetics for both HER and OER, is successfully obtained. NiCoFeP shows low overpotentials of 273 mV for OER and 131 mV for HER at a current density of 10 mA cm-2 and quite low Tafel slopes of 35 mV dec-1 for OER and 56 mV dec-1 for HER.

Solid-State 31P Nuclear Magnetic Resonance Study of Interlayer Hydroxide Surfaces of Kaolinite Probed with an Interlayer Triethylphosphine Oxide Monolayer.

The solid acidity of the interlayer aluminol surfaces of kaolinite was explored by solid-state 31P nuclear magnetic resonance with magic angle spinning (MAS) using triethylphosphine oxide (TEPO), which formed a monolayer with a uniform orientation between the layers of kaolinite as a probe molecule. Intercalation of TEPO between the layers of kaolinite was achieved using methoxy-modified kaolinite as an intermediate. The presence of TEPO in the reaction products was revealed by the two signals at 21 and 7 ppm, which were assignable to ethyl groups in TEPO, in the solid-state 13C nuclear magnetic resonance with cross polarization and magic angle spinning techniques (13C CP/MAS NMR). The presence of TEPO between the layers of kaolinite was demonstrated by the expansion of basal spacing from 0.86 nm, the interlayer distance of methoxy-modified kaolinite to 1.16 nm, as shown by the X-ray diffraction patterns, suggesting the formation of a TEPO monolayer between the layers of kaolinite. The formation of hydrogen bonds between the P═O groups of TEPO and the aluminol groups on the interlayer surfaces of kaolinite was also revealed by the appearance of an additional OH stretching band at 3598 cm-1 in the Fourier-transform infrared spectrum and narrow solid-state 31P MAS NMR signals observed at 55-53 ppm which were shifted from the position of the physisorbed TEPO (50 ppm). These results clearly indicate that the solid acidity of interlayer aluminol groups of methoxy-modified kaolinite was probed using an interacted TEPO monolayer.

Distribution Control-Oriented Intercalation of a Cationic Metal Complex into Layered Silicates Modified with Organosulfonic-Acid Moieties.

A layered sodium silicate, octosilicate (Na2Si8O17· nH2O), was modified with an organosulfonic-acid moiety (sulfonated propyl (SPr) group, sulfonated phenethyl (SPhE) group, or sulfonated p-trifluoromethylphenyl (STFPh) group) for use as a host material to accommodate a cationic guest, tris(2,2'-bipyridine)ruthenium(II) cation ([Ru(bpy)3]2+). The organosulfonic-acid moiety was bound to the silicate layer via a reaction of an alkylammonium-exchanged octosilicate with a silane coupling agent, and subsequent treatment (oxidation or sulfonation) of the bound organosilyl groups; the surface densities of the organosulfonic-acid moiety were varied by controlling the added amount of silane coupling agents. Adsorption of [Ru(bpy)3]2+ onto surface-modified octosilicates was conducted to find that some surface-modified octosilicates successfully adsorbed [Ru(bpy)3]2+ in the interlayer space (intercalation), while other surface-modified octosiliates did not. In addition, the UV-vis absorption and the luminescence indicate that intercalated [Ru(bpy)3]2+ diffused in the interlayer and that the distribution of the time-averaged location varied depending on the kind and amount of the organosulfonic-acid moieties. Thus, the kind and surface density of the organosulfonic-acid moiety, which correlates to the interactions between the group and the guest species, the volume of free nanospace for adsorption and motion of guests, and the swelling properties, are the key factors not only for the intercalation ability but also for the dynamics of the guest in the interlayer space.

Unprecedentedly enhanced solar photocatalytic activity of a layered titanate simply integrated with TiO2 nanoparticles.

We report a simple, low-cost methodology for unprecedentedly enhancing the photocatalytic activity of layered inorganic semiconductors. A layered titanate with a lepidocrocite-type structure scarcely showed photocatalytic activity for a test reaction, the oxidative decomposition of formic acid in water into CO2, under simulated solar light, but it showed highly enhanced photocatalytic activity upon mixing with a much smaller amount (approximately 10 wt%) of commercially available TiO2 nanoparticles (P25) in water. The photocatalytic activity of the mixture was approximately 5 times that of P25, a benchmark photocatalyst. From various analyses, the enhancement resulted from the transfer of photoexcited electrons from the layered titanate to P25 at their particle interfaces and retardation of charge recombination. When applied to a photocatalyst for H2 production from water containing methanol under simulated solar light, the layered titanate/P25 mixture showed considerably enhanced activity and the apparent quantum yield was 23% (at 320 nm). By replacing P25 with Pt co-catalyst-loaded P25, the apparent quantum yield of the mixture increased from 23 to 73%, although an extremely small amount (below 0.06%) of Pt was used in the system.

Remarkable Charge Separation and Photocatalytic Efficiency Enhancement through Interconnection of TiO2 Nanoparticles by Hydrothermal Treatment.

Although tremendous effort has been directed to synthesizing advanced TiO2 , it remains difficult to obtain TiO2 exhibiting a photocatalytic efficiency higher than that of P25, a benchmark photocatalyst. P25 is composed of anatase, rutile, and amorphous TiO2 particles, and photoexcited electron transfer and subsequent charge separation at the anatase-rutile particle interfaces explain its high photocatalytic efficiency. Herein, we report on a facile and rational hydrothermal treatment of P25 to selectively convert the amorphous component into crystalline TiO2 , which is deposited between the original anatase and rutile particles to increase the particle interfaces and thus enhance charge separation. This process produces a new TiO2 exhibiting a considerably enhanced photocatalytic efficiency. This method of synthesizing this TiO2 , inspired by a recently burgeoning zeolite design, promises to make TiO2 applications more feasible and effective.

Single- and double-layered organically modified nanosheets by selective interlayer grafting and exfoliation of layered potassium hexaniobate.

Organically modified niobate nanosheets are promising building blocks for the design of advanced hybrid materials. Nanosheets with controlled thickness and surface composition are important for precise structural design of the nanosheet-based materials. In this work, single-layered and double-layered niobate nanosheets functionalized by phenylphosphonate moieties were selectively prepared by interlayer grafting of A-type and B-type intercalation derivatives of potassium hexaniobate (K4Nb6O17·3H2O) with phenylphosphonic acid (PPA), followed by exfoliation by ultrasonication in acetonitrile. The interlayer grafting of PPA was monitored using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and solid-state NMR spectroscopy, and the thicknesses of the exfoliated nanosheets were measured by atomic force microscopy (AFM). Transparent hybrid films were obtained by incorporating the single- and double-layered nanosheets into an epoxy matrix.

Au-Loaded Superparamagnetic Mesoporous Bimetallic CoFeB Nanovehicles for Sensitive Autoantibody Detection.

Construction of a well-defined mesoporous nanostructure is crucial for applying nonnoble metals in catalysis and biomedicine owing to their highly exposed active sites and accessible surfaces. However, it remains a great challenge to controllably synthesize superparamagnetic CoFe-based mesoporous nanospheres with tunable compositions and exposed large pores, which are sought for immobilization or adsorption of guest molecules for magnetic capture, isolation, preconcentration, and purification. Herein, a facile assembly strategy of a block copolymer was developed to fabricate a mesoporous CoFeB amorphous alloy with abundant metallic Co/Fe atoms, which served as an ideal scaffold for well-dispersed loading of Au nanoparticles (∼3.1 nm) via the galvanic replacement reaction. The prepared Au-CoFeB possessed high saturation magnetization as well as uniform and large open mesopores (∼12.5 nm), which provided ample accessibility to biomolecules, such as nucleic acids, enzymes, proteins, and antibodies. Through this distinctive combination of superparamagnetism (CoFeB) and biofavorability (Au), the resulting Au-CoFeB was employed as a dispersible nanovehicle for the direct capture and isolation of p53 autoantibody from serum samples. Highly sensitive detection of the autoantibody was achieved with a limit of detection of 0.006 U/mL, which was 50 times lower than that of the conventional p53-ELISA kit-based detection system. Our assay is capable of quantifying differential expression patterns for detecting p53 autoantibodies in ovarian cancer patients. This assay provides a rapid, inexpensive, and portable platform with the potential to detect a wide range of clinically relevant protein biomarkers.

UV-visible Faraday rotators based on rare-earth fluoride single crystals: LiREF4 (RE = Tb, Dy, Ho, Er and Yb), PrF3 and CeF3.

High optical quality LiREF(4) (RE = Tb(3+), Dy(3+), Ho(3+), Er(3+) and Yb(3+)), PrF(3) and CeF(3) single crystals have been grown by the Czochralski technique. Their magneto-optical properties have been measured and analyzed in detail in the ultraviolet-visible wavelength region, and their figures of merit as Faraday rotators have been determined. CeF(3) presents superior properties above 300 nm, showing a figure of merit higher than that of the reference material, terbium-gallium-garnet, which is nowadays used in the visible-near infrared. PrF(3) is the best rotator for the 220-300 nm range. Towards shorter wavelength and in the vacuum ultraviolet, it is shown that the LiREF(4) crystals are unique rotators. Overall, the rare-earth fluoride single crystals studied here exhibit better properties than other materials considered so far, and therefore they have potential to cover the increasing demand for new and improved Faraday rotators in the ultraviolet-visible wavelength region.