Pyroelectric synthesis of Au/Pt bimetallic nanoparticles–BaTiO3 hybrid nanomaterials

This paper introduces an approach to synthesize bimetallic nanoparticles under an alternating temperature field in aqueous solution. During the synthesis, pyro-catalytic barium titanate is used as the substrate to reduce the metallic ions dispersed in the solution due to the generated charges at the surface of pyro-materials under temperature oscillation. Chloroauric acid and potassium tetrachloroplatinate are used as precursors to produce gold/platinum bimetallic nanoparticles through a pyro-catalytic process. Transmission electron microscopy characterization, in combination with energy dispersive X-ray spectroscopy mapping, demonstrates that the bimetallic nanoparticle is composed of an Au core and Au/Pt alloy shell structure. Compared to the conventional approaches, the pyroelectric synthesis approach demonstrated in this work requires no toxic reducing agents and waste heat can be used as a thermal energy source in the synthesis. Hence, it offers a potential “green” synthetic method for bimetallic nanoparticles.

A “green” synthetic approach to Au/Pt bimetallic nanoparticles under an alternating temperature field.     

Exploring a lead-free organic–inorganic semiconducting hybrid with above-room-temperature dielectric phase transition

Recently, organic–inorganic hybrid lead halide perovskites have attracted great attention for optoelectronic applications, such as light-emitting diodes, photovoltaics and optoelectronics. Meanwhile, the flexible organic components of these compounds give rise to a large variety of important functions, such as dielectric phase transitions. However, those containing Pb are harmful to the environment in vast quantities. Herein, a lead-free organic–inorganic hybrid, (C₆H₁₄N)₂BiCl₅ (CHA; C₆H₁₄N⁺ is cyclohexylaminium), has been successfully developed. As expected, CHA exhibits an above-room-temperature solid phase transition at 325 K (T_c), which was confirmed by the differential scanning calorimetry measurement and variable temperature single crystal X-ray diffraction analyses. Further analyses indicate the phase transition is mainly governed by the order–disorder transformation of organic cyclohexylaminium cations. Interestingly, during the process of phase transition, the dielectric constant (ε′) of CHA shows an obvious step-like anomaly, which displays a low dielectric constant state below T_c and a high dielectric constant state above T_c. Furthermore, variable temperature conductivity combined with theoretical calculations demonstrate the notable semiconducting feature of CHA. It is believed that our work will provide useful strategies for exploring lead-free organic–inorganic semiconducting hybrid materials with above room temperature dielectric phase transitions.

Recently, organic–inorganic hybrid lead halide perovskites have attracted great attention for optoelectronic applications, such as light-emitting diodes, photovoltaics and optoelectronics.     

Stable carbamate pathway towards organic–inorganic hybrid perovskites and aromatic imines

Methyl ammonium methyl carbamate (MAC), formulated as CH₃NH₃⁺CH₃NHCO₂⁻, was synthesized by reacting liquid methylamine with supercritical CO₂, and its structure was refined by single-crystal X-ray diffraction. MAC is a white crystalline salt and is as reactive as methylamine, and is a very efficient alternative to toxic methylamine. We were able to produce hybrid perovskite MAPbI₃ (MA = methyl ammonium) by grinding MAC with PbI₂ and I₂ at room temperature, followed by storing the mixed powder. Moreover, this one-pot method is easily scalable for the large-scale synthesis of MAPbI₃ in a small vessel. We have also investigated the reactivity of MAC towards aromatic aldehydes in the absence of solvent. The solventless reactions afforded imines as exclusive products with over 97% yield, which show higher selectivity than the methylamine-based synthesis. Complete conversions were typically accomplished within 3 h at 25 °C. The results of this study emphasize the importance of solid carbamates such as MAC to develop an environmentally friendly process for the synthesis of various amine-based materials on the industrial scale.

A stable solid carbamate (MAC) composed of CH₃NH₃⁺ and CH₃NHCO₂⁻ units exhibits high reactivity toward inorganic iodide and aromatic aldehyde.     

Efficient and chromaticity stable green and white organic light-emitting devices with organic–inorganic hybrid materials

Efficient inverted bottom emissive organic light emitting diodes (IBOLEDs) with tin dioxide and/or Cd-doped SnO₂ nanoparticles as an electron injection layer at the indium tin oxide cathode:electron transport layer interface have been fabricated. The SnO₂ NPs promote electron injection efficiently because their conduction band (−3.6 eV) lies between the work function (W_f) of ITO (4.8 eV) and the LUMO of the electron-transporting molecule (−3.32 eV), leading to enhanced efficiency at low voltage. The 2.0% SnO₂ NPs (25 nm) with Ir(ddsi)₂(acac) emissive material (SnO₂ NPs/ITO) have an enhanced current efficiency (η_c, cd A⁻¹) of 52.3/24.3, power efficiency (η_p, lm W⁻¹) of 10.9/3.4, external quantum efficiency (η_ex, %) of 16.4/7.5 and luminance (L, cd m⁻²) of 28 182/1982. A device with a 2.0% Cd-doped SnO₂ layer shows higher η_c (60.6 cd A⁻¹), η_p (15.4 lm W⁻¹), η_ex (18.3%) and L (26 858 cd m⁻²) than SnO₂ devices or control devices. White light emission was harvested from a mixture of Cd–SnO₂ NPs and homoleptic blue phosphor Ir(tsi)₃; the combination of blue emission (λ_EL = 428 nm) from Ir(tsi)₃ and defect emission from Cd–SnO₂ NPs (λ_EL = 568 nm) gives an intense white light with CIE of (0.31, 0.30) and CCT of 6961 K. The white light emission [CIE of (0.34, 0.35) and CCT of 5188 K] from colloid hybrid electrolyte BMIMBF₄–SnO₂ is also discussed.

Efficient inverted bottom emissive organic light emitting diodes (IBOLEDs) with tin dioxide and/or Cd-doped SnO₂ nanoparticles as an electron injection layer at the indium tin oxide cathode:electron transport layer interface have been fabricated.     

The structural transition of bimetallic Ag–Au from core/shell to alloy and SERS application

It is well-known that Ag–Au bimetallic nanoplates have attracted significant research interest due to their unique plasmonic properties and surface-enhanced Raman scattering (SERS). In recent years, there have been many studies on the fabrication of bimetallic nanostructures. However, controlling the shape, size, and structure of bimetallic nanostructures still has many challenges. In this work, we present the results of the synthesis of silver nanoplates (Ag NPls), and Ag–Au bimetallic core/shell and alloy nanostructures, using seed-mediated growth under green LED excitation and a gold salt (HAuCl₄) as a precursor of gold. The results show that the optical properties and crystal structure strongly depend on the amount of added gold salt. Interestingly, when the amount of gold(x) in the sample was less than 0.6 μmol (x < 0.6 μmol), the structural nature of Ag–Au was core/shell, in contrast x > 0.6 μmol gave the alloy structure. The morphology of the obtained nanostructures was investigated using the field emission scanning electron microscopy (FESEM) technique. The UV–Vis extinction spectra of Ag–Au nanostructures showed localized surface plasmon resonance (LSPR) bands in the spectral range of 402–627 nm which changed from two peaks to one peak as the amount of gold increased. Ag–Au core/shell and alloy nanostructures were utilized as surface enhanced Raman scattering (SERS) substrates to detect methylene blue (MB) (10⁻⁷ M concentration). Our experimental observations indicated that the highest enhancement factor (EF) of about 1.2 × 10⁷ was obtained with Ag–Au alloy. Our detailed investigations revealed that the Ag–Au alloy exhibited significant EF compared to pure metal Ag and Ag–Au core/shell nanostructures. Moreover, the analysis of the data revealed a linear dependence between the logarithm of concentration (log C) and the logarithm of SERS signal intensity (log I) in the range of 10⁻⁷–10⁻⁴ M with a correlation coefficient (R²) of 0.994. This research helps us understand better the SERS mechanism and the application of Raman spectroscopy on a bimetallic surface.

It is well-known that Ag–Au bimetallic nanoplates have attracted significant research interest due to their unique plasmonic properties and surface-enhanced Raman scattering (SERS).     

Electronic and optical absorption properties of organic–inorganic perovskites as influenced by different long-chain diamine molecules: first-principles calculations

Organic–inorganic perovskites have demonstrated significant promise as photovoltaic materials due to their excellent photoelectric properties. However, monoamino three-dimensional (3D) perovskites, such as CH₃NH₃PbI₃ (MAPbI₃) and NH₂CHNH₂PbI₃ (FAPbI₃) exhibit low thermal and chemical stability, leading to low device durability. As such, we sought to address this problem by evaluating the performance of five diamino-3D perovskites with different molecule chain lengths, including NH₃(CH₂)₂NH₃PbI₄ (EDAPbI₄), NH₃(CH₂)₃NH₃PbI₄ (DPAPbI₄), NH₃(CH₂)₄NH₃PbI₄ (BDAPbI₄), NH₃(CH₂)₅NH₃PbI₄ (PDAPbI₄), and NH₃(CH₂)₆NH₃PbI₄ (HDAPbI₄), as well as one monoamino-2D perovskite, (CH₃(CH₂)₃NH₃)₂PbI₄ (BA₂PbI₄) using first-principles calculations. We analyzed the geometries, formation energies, electronic structures, and optical absorption properties of each of these materials. We determined the composition of the conduction and valence bands and analyzed the charge transfer between the inorganic layer and organic molecules. The transport characteristics of the electrons in the different directions were analyzed by calculating the effective mass in different directions. Based on these results, BDAPbI₄ was predicted to exhibit the best photovoltaic performance, as well as demonstrating a light effective mass of the electrons and holes, a reduced bandgap, and a large optical absorption, compared to the other perovskites assessed in this study.

Organic–inorganic perovskites have demonstrated significant promise as photovoltaic materials due to their excellent photoelectric properties.     

Thermal property and structural molecular dynamics of organic–inorganic hybrid perovskite 1,4-butanediammonium tetrachlorocuprate

We investigate the thermal behaviour and physical properties of the crystals of the organic inorganic hybrid perovskite [(NH₃)(CH₂)₄(NH₃)]CuCl₄. The compound''s thermal stability curve as per thermogravimetric analysis exhibits a stable state up to ∼495 K, while the weight loss observed near 538 K corresponds to partial thermal decomposition. The ¹H nuclear magnetic resonance (NMR) chemical shifts for NH₃ change more significantly with temperature than those for CH₂, because the organic cation motion is enhanced at both ends of the organic chain. The ¹³C NMR chemical shifts for the ‘CH₂-1’ units of the chain show an anomalous change, and those for ‘CH₂-2’ (units closer to NH₃) are shifted sharply. Additionally, the ¹⁴N NMR spectra reflect the changes of local symmetry near T_C (=323 K). Moreover, the ¹³C T_1ρ values for CH₂-2 are smaller than those for CH₂-1, and the ¹³C T_1ρ data curve for CH₂-1 exhibits an anomalous behaviour between 260 and 310 K. These smaller T_1ρ values at lower temperatures indicate that ¹H and ¹³C in the organic chains are more flexible at these temperatures. The NH₃ group is attached to both ends of the organic chain, and NH₃ forms a N–H⋯Cl hydrogen bond with the Cl ion of inorganic CuCl₄. When H and C are located close to the paramagnetic Cu²⁺ ion, the T_1ρ value is smaller than when these are located far from the paramagnetic ion.

We investigate the thermal behaviour and physical properties of the crystals of the organic inorganic hybrid perovskite [(NH₃)(CH₂)₄(NH₃)]CuCl₄.     

Green synthesis of biocompatible core–shell (Au–Ag) and hybrid (Au–ZnO and Ag–ZnO) bimetallic nanoparticles and evaluation of their potential antibacterial,antidiabetic, antiglycation and anticancer activities

The fabrication of bimetallic nanoparticles (BNPs) using plant extracts is applauded since it is an environmentally and biologically safe method. In this research, Manilkara zapota leaf extract was utilized to bioreduce metal ions for the production of therapeutically important core–shell Au–Ag and hybrid (Au–ZnO and Ag–ZnO) BNPs. The phytochemical profiling of the leaf extract in terms of total phenolic and flavonoid content is attributed to its high free radical scavenging activity. FTIR data also supported the involvement of these phytochemicals (polyphenols, flavonoids, aromatic compounds and alkynes) in the synthesis of BNPs. Whereas, TEM and XRD showed the formation of small sized (16.57 nm) spherical shaped core–shell Au–Ag BNPs and ZnO nano-needles with spherical AuNPs (48.32 nm) and ZnO nano-rods with spherical AgNP (19.64 nm) hybrid BNPs. The biological activities of BNPs reinforced the fact that they show enhanced therapeutic efficacy as compared to their monometallic components. All BNPs showed comparable antibacterial activities as compared to standard tetracycline discs. While small sized Au–Ag BNPs were most effective in killing human hepato-cellular carcinoma cells (HepG2) in terms of lowest cell viability, highest intracellular ROS/RNS production, loss of mitochondrial membrane potential, induction of caspase-3 gene expression and enhanced caspase-3/7 activity. BNPs also effectively inhibited advanced glycation end products and carbohydrate digesting enzymes which can be used as a nano-medicine for aging and diabetes. The most important finding was the permissible biocompatibility of these BNPs towards brine shrimp larvae and human RBCs, which suggests their environmental and biological safety. This research study gives us insight into the promise of using a green route to synthesize commercially important BNPs with enhanced therapeutic efficacy as compared to conventional treatment options.

Graphical demonstartion of the Manikara zapota-mediated biosynthesis of Bimetallic nanoparticles (BNPs) and evalution of their biological activities.     

Insight into the photoelectrical properties of metal adsorption on a two-dimensional organic–inorganic hybrid perovskite surface: theoretical and experimental research

In order to study the photoelectric properties of the adsorption of different metal atoms on a two-dimensional (2D) perovskite surface, in this article, we built many models of Ag, Au, and Bi atoms adsorbed on 2D perovskite. We studied the rules influencing 2D perovskite adsorbing metal atoms with different n values (the n value is the number of inorganic layers of 2D perovskite; here n = 1, 2, and 3). Based on n = 2 2D perovskite, we successively used Ag, Au, and Bi metal atoms to adsorb on the 2D perovskite surface. Firstly, we calculated their adsorption energies. Based on the lowest energy principle, we found that Bi atom adsorption on the 2D perovskite surface gave the most stable structure among the three metal adsorptions because the energy of the Bi adsorption system was the smallest. Secondly, the electron transport process takes place from the s to the p orbital when Au and Ag atoms adsorb on the 2D perovskite surface, but in the Bi atom adsorption, the electron transport process takes place from the p to the p orbital, because the p–p orbital transport energy is lower than that of the s–p orbital. Therefore, Bi atom adsorption on the 2D perovskite surface can improve charge carrier transfer. Thirdly, we calculated the bond angles and bond energies of different metal adsorptions on 2D perovskite. Bi adsorption has greater interaction with the surface atoms of 2D perovskite than Ag or Au atom adsorption, which effectively enhances the surface polarization effects, and enhances the photoelectric properties of 2D perovskite. The light absorption spectrum further confirms that Bi atom adsorption has a greater impact on the 2D perovskite than the action of Ag or Au adsorption. Finally, in an experiment, we fabricated a 2D perovskite solar cell with an ITO/PEDOT:PSS/2D perovskite/PEI/Ag (Au, Bi) structure. The Bi electrode solar cell achieves the highest photoelectric conversion efficiency (PCE) of 15.16% among the three cells with forward scanning, which is consistent with the theoretical analysis. We believe that the adsorption of metals like Bi on a 2D perovskite surface as an electrode is conducive to improving the charge transport performance.

Bi atom adsorption on a 2D perovskite surface structure has the minimum adsorption energy. When it uses on the solar cell electrode, the 2D perovskite solar cell of ITO/PEDOT:PSS/2D perovskite/PEI/Bi structure exhibits the highest photoelectric conversion efficiency (PCE) of 15.16%.     

Efficient and chromaticity-stable flexible white organic light-emitting devices based on organic–inorganic hybrid color-conversion electrodes

We have developed a novel organic–inorganic hybrid color conversion electrode composed of Ag NWs/poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) via a solution process, which is the first report on a color conversion electrode for applications in flexible optoelectronics. Using the Ag NWs/MEH-PPV composite film as the anode on polyethylene terephthalate substrate and combined with a blue organic light emitting devices (OLEDs) unit employing bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(iii)) (Flrpic) in 1,3-bis(carbazol-9-yl)benzene (mCP) as the emitting layer, a highly efficient and chromaticity-stable color-conversion flexible white OLEDs (WOLEDs) is achieved with a maximum current efficiency of 20.5 cd A⁻¹. To the best of our knowledge, this is the highest efficiency reported for color-conversion based flexible WOLEDs. Our work provides an approach to achieving high-performance flexible WOLEDs devices and demonstrates great potential for lighting and display applications.

We have developed a novel color conversion electrode composed of Ag NWs/MEH-PPV via a solution process, which is the first report on a color conversion electrode for applications in flexible optoelectronics.     

Preparation of core/shell organic–inorganic hybrid polymer nanoparticles and their application to toughening poly(methyl methacrylate)

On account of the utility of poly(methyl methacrylate) (PMMA) as a glass substitute, toughening of PMMA has attracted significant attention. Brittle failure can often be avoided by incorporating a small fraction of filler particles. Core–shell composite particles composed of a rubbery core and a glassy shell have recently attracted interest as a toughening agent for brittle polymers. Here, core/shell organic–inorganic hybrid polymer nanoparticles (Si-ASA HPNs) with a silicone-modified butyl acrylate copolymer (PBA) core and a styrene-acrylonitrile copolymer (SAN) shell were used to toughen PMMA. Silicone plays dual roles as a compatibilizer and a chain extender, and it not only improves interfacial adhesion between the PBA particles and SAN copolymer, but it also increases chain entanglement of poly(acrylonitrile-styrene-acrylate) (ASA). The mechanical properties of the PMMA/ASA alloys strongly depend on the Si content, and the impact strength and elongation at break greatly improve when silicone-modified ASA is added. However, this is accompanied by loss of rigidity. Specifically, the PMMA/ASA-2 composite exhibits a good balance between toughness and rigidity, indicating that ASA-2 with 5 wt% KH570 is the most suitable impact modifier. This research provides a facile and practical method to overcome the shortcomings of ASA and promote its application in a wider range of fields.

Core/shell organic–inorganic hybrid polymer nanoparticles are synthesized by micellar nucleation, core enlarged polymerization and a grafting reaction in the system.     

Earth-abundant and environment friendly organic–inorganic hybrid tetrachloroferrate salt CH3NH3FeCl4: structure,adsorption properties and photoelectric behavior

Organic–inorganic hybrid-based lead perovskites show inherent and unavoidable problems such as structural instability and toxicity. Therefore, developing low-cost and environment-friendly organic–inorganic hybrid materials is extremely urgent. In this study, we prepared earth-abundant and environment-friendly organic–inorganic hybrid tetrachloroferrate salt CH₃NH₃FeCl₄ (MAFeCl₄) for optoelectronic applications. The single crystal diffraction data are assigned to the orthorhombic MAFeCl₄ (Pnma space group), with parameters a = 11.453 (5) Å, b = 7.332 (3) Å, c = 10.107 (5) Å, α = 90.000, β = 90.000, and γ = 90.000. The band gap of MAFeCl₄ is approximately 2.15 eV. Moreover, three-emission luminescence (398, 432 and 664 nm) was observed. To the best of our knowledge, this is the first study involving the investigation of the structure, adsorption properties and photoelectric behavior of MAFeCl₄. A low cost photodetector based on the MAFeCl₄ thin film is efficient under different monochromatic light from 330 nm to 410 nm with different chopping frequencies (1.33 Hz to 40 Hz). The photoelectric conversion efficiency based on FTO/TiO₂/MAFeCl₄/carbon electrode device reaches 0.054% (V_oc = 319 mV, J_sc = 0.375 mA cm⁻², and fill factor = 0.45) under AM1.5, 100 mW cm⁻² simulated illumination. Our findings will attract attention from the magnetic, piezoelectric and photoelectronic research fields.

We prepare earth-abundant and environmentally friendly organic–inorganic hybrid tetrachloroferrate salt CH₃NH₃FeCl₄ (MAFeCl₄) for optoelectronic applications.     

Deposition of Ag and Ag–Au nanocrystalline films with tunable conductivity at the water–toluene interface

Thin films of Au, Ag and Ag–Au alloy nanocrystals extending to areas of several square centimetres are obtained by deposition at the interface of water and toluene. Toluene containing chlorotris(triphenylphosphine)silver(i) and/or chlorotriphenylphosphine gold(i) is reacted with aqueous tetrakishydroxymethylphosphonium chloride to obtain nanocrystalline films adhered to the interfacial region. Alloying was induced by varying the composition of the toluene layer. The composition change results in regular and reproducible variation in the transport characteristics of the films, with the initially metallic deposits turning non-metallic with increased Au content. The films at the interface were transferred to different substrates and characterised using atomic force microscopy, UV-visible spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy.

Thin films of Au, Ag and Ag–Au alloy nanocrystals extending to areas of several square centimetres are obtained by deposition at the interface of water and toluene.     

Modified graphene supported Ag–Cu NPs with enhanced bimetallic synergistic effect in oxidation and Chan–Lam coupling reactions

Herein, well dispersed Ag–Cu NPs supported on modified graphene have been synthesized via a facile and rapid approach using sodium borohydride as a reducing agent under ambient conditions. Dicyandiamide is selected as an effective nitrogen source with TiO₂ as an inorganic material to form two kinds of supports, labelled as TiO₂–NGO and NTiO₂–GO. Initially, the surface area analysis of these two support materials was carried out which indicated that N-doping of GO followed by anchoring with TiO₂ has produced support material of larger surface area. Using both types of supports, ten nano-metal catalysts based on Ag and Cu were synthesized. Benefiting from the bimetallic synergistic effect and larger specific surface area of TiO₂–NGO, Cu@Ag–TiO₂–NGO is found to be a highly active and reusable catalyst out of other synthesized catalysts. It exhibits excellent catalytic activity for oxidation of alcohols and hydrocarbons as well as Chan–Lam coupling reactions. The nanocatalyst is intensively characterized by BET, SEM, HR-TEM, ICP-AES, EDX, CHN, FT-IR, TGA, XRD and XPS.

Cu@Ag–TiO₂–NGO prepared from modified graphene by simple methodology exhibits enhanced catalytic activity towards oxidation and Chan–Lam coupling due to the synergistic effect between Ag and Cu NPs.     

Ultra-small aqueous glutathione-capped Ag–In–Se quantum dots: luminescence and vibrational properties

We introduce a direct aqueous synthesis of luminescent 2–3 nm Ag–In–Se (AISe) quantum dots (QDs) capped by glutathione (GSH) complexes, where sodium selenosulfate Na₂SeSO₃ is used as a stable Se²⁻ precursor. A series of size-selected AISe QDs with distinctly different positions of absorption and PL bands can be separated from the original QD ensembles by using anti-solvent-induced size-selective precipitation. The AISe–GSH QDs emit broadband PL with the band maximum varying from 1.65 eV (750 nm) to 1.90 eV (650 nm) depending on the average QD size and composition. The PL quantum yield varies strongly with basic synthesis parameters (ratios of constituents, Zn addition, duration of thermal treatment, etc.) reaching 4% for “core” AISe and 12% for “core/shell” AISe/ZnS QDs. The shape and position of PL bands is interpreted in terms of the model of radiative recombination of a self-trapped exciton. The AISe–GSH QDs reveal phonon Raman spectra characteristic for small and Ag-deficient tetragonal Ag–In–Se QDs. The ability of ultra-small AISe QDs to support such “bulk-like” vibrations can be used for future deeper insights into structural and optical properties of this relatively new sort of QDs.

A direct aqueous synthesis, composition- and size-dependent absorption, photoluminescence, and vibrational properties of ultra-small glutathione-capped Ag-deficient Ag–In–Se quantum dots are reported.     

A review on organic–inorganic hybrid nanocomposite membranes: a versatile tool to overcome the barriers of forward osmosis

Forward osmosis (FO) processes have recently attracted increasing attention and show great potential as a low-energy separation technology for water regeneration and seawater desalination. However, a number of challenges, such as internal concentration polarization, membrane fouling, and the trade-off effect, limit the scaleup and industrial practicality of FO. Hence, a versatile method is needed to address these problems and fabricate ideal FO membranes. Among the many methods, incorporating polymeric FO membranes with inorganic nanomaterials is widely used and effective and is reviewed in this paper. The properties of FO membranes can be improved and meet the demands of various applications with the incorporation of nanomaterials. This review presents the actualities and advantages of organic–inorganic hybrid nanocomposite FO membranes. Nanomaterials applied in the FO field, such as carbon nanotubes, graphene oxide, halloysite nanotubes, silica and Ag nanoparticles, are classified and compared in this review. The effects of modification methods on the performance of nanocomposite FO membranes, including blending, in situ interfacial polymerization, surface grafting and layer-by-layer assembly, are also reviewed. The outlook section discusses the prospects of organic–inorganic hybrid nanocomposite FO membranes and advanced nanotechnologies available for FO processes. This discussion may provide new opportunities for developing novel FO membranes with high performance.

Nanocomposite forward osmosis (FO) membranes have attracted increasing attentions recently and showed great comprehensive performance. Various modification methods have been employed to incorporate inorganic nanomaterials to FO membranes.     

Thermal and structural properties,and molecular dynamics in organic–inorganic hybrid perovskite (C2H5NH3)2ZnCl4

The thermal and structural properties and molecular dynamics of layered perovskite-type (C₂H₅NH₃)₂ZnCl₄ are investigated by differential scanning calorimetry, thermogravimetric analysis, and magic angle spinning nuclear magnetic resonance spectroscopy. The thermal properties and phase transitions are studied. Additionally, the Bloembergen–Purcell–Pound (BPP) curves for the ¹H spin–lattice relaxation time T_1ρ in the C₂H₅NH₃ cation and for the ¹³C T_1ρ in C₂H₅ are shown to have minima as a function of inverse temperature. This observation implies that these curves represent the rotational motions of ¹H and ¹³C in the C₂H₅NH₃ cation. The activation energies for ¹H and ¹³C in the C₂H₅NH₃ cation are obtained; the molecular motion of ¹H is enhanced at the C-end and N-end of the organic cation, and that at the carbons of the main chain is not as free as that for protons at the C-end and N-end.

The thermal and structural properties and molecular dynamics of layered perovskite-type (C₂H₅NH₃)₂ZnCl₄ are investigated by DSC, TGA, and MAS NMR spectroscopy.     

Novel organic–inorganic hybrid powder SrGa12O19:Mn2+–ethyl cellulose for efficient latent fingerprint recognition via time-gated fluorescence

Latent fingerprints (LFPs) are important evidence in crime scenes and forensic investigations, but they are invisible to the naked eye. In this work, a novel fluorescent probe was developed by integrating a narrow-band-emitting green afterglow phosphor, SrGa₁₂O₁₉:Mn²⁺ (SGO:Mn), and ethyl cellulose (EC) for the efficient visualization of LFPs. The hydrophobic interactions between the powder and lipid-rich LFPs made the ridge structures more defined and easily identifiable. The background fluorescence of the substrates was completely avoided because of the time-gated fluorescence of the afterglow phosphor. All the three levels of LFP degrees were clearly imaged due to the high sensitivity. Moreover, the SGO:Mn–EC powder was highly stable in neutral, acidic, and alkaline environments. In addition, 60 day-aged LFPs were successfully visualized by the powder. All performances showed that this strategy for LFP recognition has merits such as low cost, non-destructive nature, reliability, superior universality, and legible details. Together, these results show the great application prospects of this powder in forensic identification and criminal investigation.

A easy and efficient strategy for latent fingerprints recognition was developed by this work.     

Novel crystalline organic–inorganic hybrid silicate material composed of the alternate stacking of semi-layered zeolite and microporous organic layers

A novel type of crystalline organic–inorganic hybrid microporous silicate material, KCS-5, was synthesized supposedly from a lamellar precursor composed of amphiphilic organosilicic acids. This well-ordered material has a crystalline structure, is thermally stable up to 500 °C and has lipophilic 1-dimensional micropores.

A novel crystalline organic–inorganic hybrid microporous silicate material was successfully synthesized from a lamellar precursor composed of amphiphilic organosilicic acids.

Organic–inorganic hybridization of silicate materials has been diligently studied because it can control surface properties to improve their adsorption capacities and catalytic activities. In these studies, bridged organosilanes, where an organic group connects two trialkoxysilyl species, are frequently employed as a silicon source. For example, Shea et al. prepared microporous amorphous materials named bridged polysilsesquioxanes¹ by sol–gel synthesis from various organosilanes with bulky bridging organic groups, such as bis(triethoxysilyl)benzene (BTEB), and Inagaki et al. obtained surfactant-templated hexagonally-ordered mesoporous silicates from organosilanes bridged with aliphatic or aromatic organic groups.² Tatsumi et al. discovered an improvement in catalytic activities and surface hydrophobicity through the syntheses of a mesoporous titanosilicate³ and zeolites⁴ from bridged organosilanes. In particular, Bellussi et al. crystallized microporous aluminosilicates called ECS,⁵ composed of layered aluminosilicate and bridging organic groups. Such bridged organosilanes were used as a single silicon source, presumably because they can theoretically build a three-dimensional silicate framework without introducing structural defects.In contrast to bridged organosilanes, terminal organosilanes, where a terminal organic group like a methyl or phenyl group functionalizes trialkoxysilyl species, were not employed as a single silicon source but were subsidiarily added as part of a silicon source because terminal organic groups inevitably cause structural defects which cause a deterioration in the 3-dimensional structure of tectosilicates. However, we conceived an idea to obtain well-ordered materials only from terminal organosilanes inspired by our material KCS-2.⁶ KCS-2, also synthesized using a bridged organosilane BTEB, is a crystalline organic–inorganic hybrid material with a large 12-ring micropore and unique amphiphilic inner surface properties. Considering that the finely-designed layered structure of KCS-2 is similar to that of a Langmuir–Blodgett membrane, it is deduced that KCS-2 is crystallized via a well-ordered lamellar precursor composed of hydrolysed bridged organosilane (Fig. 1 middle). Because a lamellar structure is formed from amphiphilic surfactant molecules (Fig. 1 top), a well-ordered lamellar precursor should also be formed from amphiphilic organosilicic acid molecules made from terminal organosilanes (Fig. 1 bottom). For example, phenyltriethoxysilane (PTES) was hydrolysed into an amphiphilic molecule with a hydrophilic trihydroxysilyl head group and a hydrophobic phenyl group, which would be self-organized into a lamellar phase. Therefore, through the condensation of silicic acid (with aluminum, if necessary), it would be possible to synthesize a crystalline layered (alumino)silicate.Open in a separate windowFig. 1The induced formation scheme of lamellar precursors from bridged and terminal organosilanes.Actually, we have succeeded in synthesizing a novel crystalline silicate material, KCS-5, from PTES as a single silicon source. In a typical synthesis (please refer to ESI^†), a mixture with the molar composition of 1.0 PTES : 1.0 NaOH : 5.0H₂O was stirred at r.t. for 2–4 days to promote the hydrolysis of PTES to amphiphilic organosilicic acid, which could be arranged into a lamellar-structured precursor. After the addition of fumed alumina powder (Al₂O₃/Si = 0.2), this mixture was hydrothermally treated at 100 °C for 7 days under static conditions. Generally, KCS-5 was obtained preferentially from mixtures with low H₂O/PTES ratios, where the concentration of amphiphilic organosilicic acid was high. In addition, no crystalline products were obtained from this organosilane without the addition of an aluminum source. Fig. 2 exhibits the powder X-ray diffraction (PXRD) pattern of KCS-5. A low and wide background ranging from 15° to 40° would be derived from a concomitant amorphous by-product and a borosilicate glass capillary tube. By an indexing analysis, the lattice constant belonging to an orthorhombic system was uniquely found. A crystal structure model of KCS-5 was tentatively built from local structural units, such as SiO₄, AlO₄ and C₆H₅–SiO₃, elucidated from the solid-state NMR. (The ²⁹Si, ²⁷Al, and ¹³C solid-state MAS NMR spectra are shown in ESI.^†) The packing structure of these units was solved by the direct-space method with the parallel tempering algorithm using the program FOX.⁷8 using the program RIETAN-FP.⁹ Reliability factors obtained in this analysis were small enough. The calculated and difference plots obtained by the Rietveld analyses are also exhibited in Fig. 2.Open in a separate windowFig. 2Observed (red) and calculated (light blue), background (black), and difference (blue) intensity curves of KCS-5 obtained by Rietveld refinement. The green tick marks denote the peak positions of possible Bragg reflections.Conditions for the PXRD experiments and crystallographic information obtained therein for KCS-5

Supported Pt–Cu bimetallic catalysts: preparation and synergic effects in their catalytic oxidative degradation of aniline

Catalytic Fenton oxidation is an effective way to remove organic pollutants in water, and the performance of the catalyst is a key issue for the competiveness of this method. In this work, various supported bimetallic Pt–Cu catalysts were prepared by different impregnation methods and their performances for catalytic Fenton oxidation of aniline in water were investigated. In the different impregnation methods employed, factors including the reduction method of the metal precursor, type of catalytic support, and loading of metal were investigated. The effect of different reduction methods on actual loadings of the active components on the supported Pt–Cu catalysts showed the order of (i) H₂ reduction > (ii) liquid phase methanal reduction. Meanwhile, compared with the monometallic catalysts, the Pt–Cu alloy phase (mainly in the form of PtCu₃) was generated and the specific surface area was significantly reduced for the bimetallic catalysts. In the process of Fenton catalytic oxidation of aniline, it was found that most of the prepared catalysts had a certain catalytic activity for H₂O₂ accompanied with aniline degradation. It was found that Pt_0.5Cu_1.5/AC (where AC denotes activated carbon) exhibited superb catalytic activity compared with all other prepared catalysts. In particular, aniline was almost completely mineralized in a neutral solution (500 mg L⁻¹ aniline, 0.098 mol L⁻¹ H₂O₂) after 60 min at 50 °C using Pt–Cu/AC (Pt: 0.5%, Cu: 1.5%). The characterization results showed that the Pt and Cu components were rather evenly distributed on the AC support for this catalyst. More importantly, there was an obvious synergic effect on the supported bimetallic catalyst between the Pt and Cu components for the catalytic oxidation of aniline.

An AC supported Pt–Cu catalyst prepared with a new methanal reduction method was found to be quite effective for catalytic Fenton oxidation of aniline in water. The Pt and Cu components showed a synergic effect for the catalytic process.