Evaporation-induced Self-assembly Method Research Articles

Enhanced Fluorescence Based on Slow Light Effect of ZIF-8 Photonic Crystals for Trace 2,4,6-Trinitrophenol Detection.

In response to growing concerns about public safety and environmental conservation, it is essential to develop a precise identification method for trace explosives. To improve the stability and detection sensitivity of perovskite quantum dots (PQDs) and address the issue of low porosity in traditional polymer-based photonic crystals (PhCs), this study proposed a PQD photoluminescence (PL) enhancement strategy based on the slow light effect of ZIF-8 PhCs for highly sensitive, selective, and convenient detection of 2,4,6-trinitrophenol (TNP). The slow light effect at the photonic band gap edge is the basis of amplifying the PL signal. PhCs were fabricated by the evaporation-induced self-assembly method. The diffraction wavelength overlapping the whole visible region was designed to match the emission wavelength of PQDs. Results showed that PhCs matching the PBG edge with PQDs' emission peak amplified the PL signal 11.3 times, significantly improving sensitivity for trace TNP detection with a limit as low as 2.52 nM. Moreover, there was a 13.3-fold enhancement of PQDs' fluorescence lifetime when the emission wavelength fell in the PBG range. The hydrophobic surface of ZIF-8 PhCs enhanced the PQDs' stability and moisture resistance. Furthermore, the selective quenching mechanism of TNP by the sensor was photoinduced electron transfer (PET) verified by DFT calculations and time-resolved PL decay dynamics measurements. This study demonstrated great potential for manipulating light emission enhancement by PhCs in developing efficient fluorescent sensors for trace environmental pollutant detection.

Self-Assembled Hydrogel Membranes with Structurally Tunable Mechanical and Biological Properties.

Using supramolecular self-assembled nanocomposite materials made from protein and polysaccharide components is becoming more popular because of their unique properties, such as biodegradability, hierarchical structures, and tunable multifunctionality. However, the fabrication of these materials in a reproducible way remains a challenge. This study presents a new evaporation-induced self-assembly method producing layered hydrogel membranes (LHMs) using tropocollagen grafted by partially deacetylated chitin nanocrystals (CO-g-ChNCs). ChNCs help stabilize tropocollagen's helical conformation and fibrillar structure by forming a hierarchical microstructure through chemical and physical interactions. The LHMs show improved mechanical properties, cytocompatibility, and the ability to control drug release using octenidine dihydrochloride (OCT) as a drug model. Because of the high synergetic performance between CO and ChNCs, the modulus, strength, and toughness increased significantly compared to native CO. The biocompatibility of LHM was tested using the normal human dermal fibroblast (NHDF) and the human osteosarcoma cell line (Saos-2). Cytocompatibility and cell adhesion improved with the introduction of ChNCs. The extracted ChNCs are used as a reinforcing nanofiller to enhance the performance properties of tropocollagen hydrogel membranes and provide new insights into the design of novel LHMs that could be used for various medical applications, such as control of drug release in the skin and bone tissue regeneration.

Enhancement of carbon dioxide adsorption performance on mesoporous alumina modified with alkaline earth metals

The mesoporous alumina-supported alkaline earth metal 5 M/MA (MA= mesoporous alumina, M=Mg, Ca, Sr, and Ba) and xMg/MA (x=1, 3, 5, and 7 wt%) adsorbents were synthesized via evaporation-induced self-assembly (EISA) and impregnation method. The adsorption properties of CO2 were evaluated by thermal gravimetric analyzer to focus on exploring the dynamic adsorption process of the prepared adsorbents. Loading alkaline earth metals mainly enhanced the basic sites of these adsorbents, and the alkaline sites played an extremely critical role in determining the amount of CO2 adsorbed. Of all the adsorbents prepared, 5Mg/MA exhibited the highest adsorption uptake (1.08 mmol/g), a 2.16-fold enhancement compared to MA (0.50 mmol/g). In-situ DRIFTS indicated that CO2 primarily existed in the form of carbonate species, and the analysis of adsorption kinetics elucidated that the adsorption process was predominantly chemisorbed, with external diffusion being the main process of adsorption. Simultaneously, based on DFT calculations, it has been found that Mg-loaded MA has a higher affinity for CO2 compared to MA, which providing a good explanation for the experimental results. Furthermore, the 5 Mg/MA adsorbent not only exhibited excellent adsorption capacity, but also maintained excellent cyclic stability after 10 adsorption and desorption cycle runs, making it a highly favorable option for capturing CO2.

Effect of C-Cl functional groups on adsorption and desorption of elemental mercury over an ordered mesoporous carbon modified with C-Cl functional groups

Wet desorption presents an environmentally sustainable approach for the disposal of deactivated elemental mercury (Hg0) removal adsorbents. However, the prevalence of insoluble Hg compounds in the adsorption products poses a significant impediment to the wet desorption process. In this work, an ordered mesoporous carbon modified with C-Cl functional groups (OMC-Cl) was synthesized via the evaporation-induced self-assembly (EISA) method. It has a high specific surface area (∼630 m2/g), large pore volume (∼0.64 cm3/g), and uniform pore size (∼22.0 nm). The presence of C-Cl functional groups provides a remarkable adsorption capacity to the adsorbent, exhibiting high adsorption efficiency in various adsorption atmospheres (96.8 % in pure N2; 91.7 % in N2 + H2S) and promoting the prevalence of soluble HgCl2 in the adsorption product. Density functional theory analysis has elucidated that the C-Cl functional groups exerted inhibitory effects on the formation of HgO and HgS mainly by weakening the adsorption process of Hg0 on C = O and C-S. The desorption efficiencies of adsorption products in the above atmospheres in HCl solution (0.5 mol/L) achieved 95.4 % and 81.3 %, respectively. The high concentration of H+ ions serves to prevent the re-adsorption of Hg2+ by the -SH generated during the adsorption process. Furthermore, the adsorbent desorbed in HCl solution manifests substantial potential for recyclability. This study introduces a novel approach for efficient wet desorption in terms of designing active sites to modulate the adsorption products and pore structures to facilitate mass transfer.

Surface control of Ni-Al2O3 dry reforming of methane catalyst by composition segregation

Catalyst surface control is of great importance considering that a catalytic reaction initially starts with surface atoms’ interaction with reactant molecules. In the present study, we synthesized the Ni-Al2O3 dry reforming of methane (DRM) catalyst via the spray-pyrolysis-assisted evaporation-induced self-assembly (EISA) method in order to systematically investigate catalyst surface change as controlled by composition segregation. The present results showed that segregation in the Ni-Al2O3 catalyst had successfully occurred by the post-annealing process and that the segregated Ni nanoparticles were located on the catalyst surface with simultaneous reduction to metal. The size of the surface Ni nanoparticles was highly dependent on the post-annealing temperature, whereas the electronic properties did not consistently align with the trend of particle-size growth, indicating that the particle-growth mechanism underwent alterations from segregation to sintering as the temperature was increased. In other words, when the reduction temperature for metal segregation is excessively high, particle-growth on the external catalyst surface, as induced by post-annealing, is primarily attributable to particle sintering rather than to metal segregation. This phenomenon directly results in decreased Ni surface density. The catalytic DRM reaction revealed that due to sintering, the catalytic performance did not align with the trend of Ni particle-size growth, and the conversion of CH4/CO2 was closely associated with Ni surface density. This information will offer valuable insight to future research focused on development of Ni-based catalysts for DRM reactions.

Comparative study on Al-SBA-15 prepared by spray drying and traditional methods for bulky hydrocarbon cracking: Properties, performance and influencing factors

Mesoporous aluminosilicates Al-SBA-15 with large pore sizes and suitable acid properties are promising substitutes to zeolites for catalytic cracking of bulky hydrocarbons without molecular diffusion limitation. The conventional processes to synthesize Al-SBA-15 are time-consuming and often suffer from low “framework” Al contents. Herein, Al-SBA-15 microspheres are synthesized using the rapid and scalable microfluidic jet spray drying technique. They possess uniform particle sizes (45–60 μm), variable surface morphologies, high surface areas (264–340 m2/g), uniform mesopores (3.8–4.9 nm) and rich acid sites (126–812 μmol/g) and high acid strength. Their physicochemical properties are compared with the counterparts synthesized using traditional hydrothermal and evaporation-induced self-assembly methods. The spray drying technique results in a higher incorporation of aluminum (Al) atoms into the silica “framework” compared to the other two methods. The catalytic cracking efficiencies of 1,3,5-triisopropylbenzene (TIPB) on the Al-SBA-15 materials synthesized using the three different methods and nanosized ZSM-5 are compared. The optimal spray-dried Al-SBA-15 exhibits the best performance with 100 % TIPB conversion, excellent selectivity (about 75 %) towards the formation of deeply cracked products (benzene and propylene) and high stability. The catalytic performances of the spray-dried Al-SBA-15 with varying Si/Al ratios are also compared. The reasons for the different performances of the different materials are discussed, where the mesopores, high acid density and strength are observed to play the most critical role. This work might provide a basis for the synthesis of mesoporous rich metal-substituted silica materials for different catalytic applications.

Tailoring pore size of mesoporous silica and organosilica using biodegradable pentablock copolymer templates via EISA process

In this work, we have designed unique poly(lactic acid-co-glycolic acid)-b-poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(lactic acid-co-glycolic acid) pentablock copolymers using Pluronic F68 and F108 triblock copolymers as macroinitiators. The poly(lactic acid-co-glycolic acid) (PLGA) blocks were attached as glycolide and lactide monomers at the both ends of each F68 and F108 triblock copolymer. The molecular weights and the block fractions were confirmed by gel permeation chromatography (GPC) and proton nuclear magnetic resonance (1H NMR) for the four kinds of pentablock copolymers. Using these pentablock copolymers as templates, we synthesized mesoporous ethane-silicas as well as silicas by the evaporation-induced self-assembly (EISA) method. 1,2-bis(triethoxysily)ethane (BTEE) were used as an organosilica precursor. The mesoporous ethane-silica samples were characterized using synchrotron small angle X-ray scattering (SAXS), nitrogen sorption experiments, transmission electron microscopy (TEM), and solid-state 29Si CP-MAS NMR. Based on the experimental results, it was confirmed that the porosity and pore diameter can be varied with the PLGA weight fraction of the pentablock copolymer. It is due to the PLGA block in polymer forming the hydrophobic domain in micelles, which leads to the formation of increased pore size over 20 nm without any additive pore expander. In addition, it seems that as the organosilica precursor increases, the association number of block copolymers forming one micelle decreases, resulting in a decrease in pore size. In summary, the polymer template plays a vital part in tuning the structure of the mesoporous ethane-silica samples. Thus, the development of synthetic method of mesoporous organosilica materials using polymer templates with different topology is still challenging and can endow the unique structure and property for mesoporous organosilica for future applications.

Photocatalytic Hydrogen Evolution Using Mesoporous Honeycomb Iron Titanate.

Mesoporous honeycomb iron titanate using a sol-gel, evaporation-induced self-assembly method is synthesized. A triblock copolymer, F127, serves as a structure-directing agents, with iron chloride and titanium (IV) isopropoxide as inorganic precursors. The strong intermolecular force of attraction among urea, metal precursors, and polymer led to the formation of the mesoporous honeycomb structure. The study of physicochemical properties using different techniques reveals the formation of microstructures with a remarkable degree of porosity. The amorphous iron titanate outperforms the photochemical generation of H2 due to its disorderly structural arrangement and incomplete crystal formation. The randomness on the structure provides more area for catalytic reaction by providing more contact with the reactant and superior light absorption capability. The high amount of hydrogen gas, 40.66mmolg-1 h-1 , is observed in the investigation over 3h of activity for the iron titanate honeycomb sample. This yield is a more significant amount compared to the obtained for the commercially available TiO2 (23.78mmolg-1 h-1 ). The iron titanate materials synthesized with low-cost materials and methods are very effective and have the potential for hydrogen generation.

Insights into formation and properties of amorphous mesostructured alumina

Here, using liquid crystals as template, an EISA (evaporation-induced self-assembly) method has been used to synthesize amorphous mesostructured alumina. The effect of the synthesis parameters such as the presence of a chelating agent, the amounts of both porogen agent and alumina precursor on the materials properties have been investigated in details. Under the optimum conditions, after Soxhlet extraction, the obtained Al2O3 presents an HMS (Hexagonal Molecular Sieves) structure and a high specific surface area (≈400 m2/g) with a mesopore size distribution centered around 8.3 nm.Investigation of the thermal stability shows that the crystallization into γ-Al2O3 of the amorphous alumina walls delimiting mesopores begins after heating at 800 °C. We have also demonstrated that half of the carbon present in the as-synthesized material can be removed by washing with water or ethanol at room temperature instead of Soxhlet extraction.On the basis of SAXS, XRD and N2 adsorption-desorption analyses, we have shown that when treated into boiling water or exposed to water vapor the alteration of the mesostructure occurs quickly. Its collapse has been attributed to the crystallization of the amorphous alumina walls into aluminum hydroxides, mainly boehmite, upon the hydration of the alumina.Dual mesoporous alumina have been also obtained from micelles through a cooperative templating mechanism at low P123 amount and in the presence of citric acid. In that case both mesopores networks adopt a wormhole-like mesostructure.

Ytterbium–nitrogen co-doped ordered mesoporous TiO2: an innovative hetero-phase photocatalyst for harnessing solar energy in green hydrogen production

Ytterbium–nitrogen doubly doped ordered mesoporous titania boosts solar hydrogen generation, a potential breakthrough in renewable energy.

Bio-response of copper-magnesium co-substituted mesoporous bioactive glass for bone tissue regeneration.

Mesoporous bioactive glass (MBG) is widely acknowledged in bone tissue engineering due to its mesoporous structure, large surface area, and bioactivity. Recent research indicates that introduction of metallic ions has beneficial impacts on bone metabolism and angiogenesis. Thus, the features of MBG can be modified by incorporating combinations of ions, such as magnesium (Mg) and copper (Cu), which can play a considerable role in bone formation, influencing angiogenesis, osteogenesis, as well as antibacterial properties. In this study, Mg and Cu were co-doped for the first time (in a ratio of 1 : 1) in 80SiO2-5P2O5-(15 - 2x)CaO-xMgO-xCuO glass composition with x = 0, 0.5, 1, and 2 mol%, synthesized using the sol-gel and evaporation-induced self-assembly method. X-ray diffraction analysis confirmed the amorphous nature of the powders, while inductively coupled plasma-optical emission spectrometry verified the existence of dopant ions in the respective amounts. The nitrogen sorption method indicated the formation of uniform cylindrical mesopores which are open at both ends and a high surface area of the powders. TEM images show fringes, indicating an ordered mesoporous structure in all MgCu co-doped systems. In vitro bioactivity was observed in all MBG powders, confirmed by the formation of an apatite phase when placed in simulated body fluid (SBF). Flake-like microstructure characteristics of HAp crystals found on the surface of MBG powders were visualized using FESEM. Cytotoxicity tests at lower concentrations (0.1 and 1 wt/vol%) of co-doped 2MC MBG (co-doping up to 2 mol%) showed cell proliferation and viability of osteoblast-like MG-63 cells and normal human dermal fibroblast (NHDF) cells similar to the basic glass 80S. Antibacterial study of MBG pellets showed an increment in the zone of inhibition with the sequential addition of doping ions. The turbidity measurement of bacterial cultures revealed that the optimal concentration for effectively inhibiting bacterial growth was 1 wt/vol% (i.e., 10 mg mL-1) concentration of MBG extracts. The result suggested that the incorporation of Mg and Cu ions in MBG in lower concentrations of up to 2 mol% can be useful in bone regeneration owing to bioactivity, cell proliferation, and antibacterial characteristics.

Spherical mesoporous silica-supported Ru nanoparticles for ammonia decomposition

To synthesize highly dispersed Ru nanoparticles (NPs) with desired particle size for NH3 decomposition, an appropriate support is crucial. Herein, spherical mesoporous silica (SMS) NPs with ∼3 nm pores are synthesized by a microwave-assisted evaporation-induced self-assembly method and used as support of Ru NPs for NH3 decomposition. Characterization shows that compared to Ru NPs supported on SBA-15 and fumed SiO2, Ru NPs supported on SMS (Ru@SMS) exhibit superior NH3 decomposition performance, achieving a hydrogen generation rate of 31.4 mmol·g-1 cat·min−1 at 500 °C, which is one of the highest reported values for supported Ru catalysts in NH3 decomposition. The excellent NH3 decomposition performance observed on Ru@SMS should be attributed to effective dispersion and appropriate particle size (2.22 ± 0.29 nm) of Ru NPs. This work highlights the potential of SMS as support of Ru catalyst in NH3 decomposition.

Engineering bifunctional Pd/CeNbTiOx catalyst for the simultaneous removal of NO and CO under oxygen-rich conditions at low temperature

The simultaneous elimination of CO and NO has practical significance for the control of air pollutants in the flue gas operating temperature range of 240–320 °C. CeNbTiOx catalyst was prepared by evaporation-induced self-assembly method (EISA), and the 0.3 % Pd/CeNbTiOx catalyst was obtained by appropriate Pd anchoring at the defects of CeNbTiOx. CO and NO removal efficiency were above 90 % from 240 to 320 °C, which exhibited satisfactory N2 selectivity. The CO and NO removal efficiency of the 0.3 % Pd/CeNbTiOx catalyst exceeded 92 % during stability and water resistance. Oα and Oβ were involved in the oxidation of NO and CO, respectively, promoting the fast SCR and CO oxidation reaction within the ordered mesoporous of the 0.3 % Pd/CeNbTiOx catalyst. In addition, the efficiency of CO and NO elimination had been further improved due to the enhancement of defects after resistance of H2O. Therefore, this work provided a new and efficient way to control CO and NO by the efficient using of oxygen species.

Pyrolysis of model plastic component polypropylene to hydrogen over mesoporous alumina catalysts: Effect of pluronic structure directing agents

Catalytic pyrolysis of the large and complex polymeric structure of plastic to gaseous fuel has been investigated in this work. A two-stage pyrolytic system is reported for cracking model waste plastic, polypropylene, over mesoporous alumina catalyst to produce H2 and CH4. The experiments have been conducted in the temperature range of 750–900 °C and various catalyst-to-plastic ratios under atmospheric pressure. The alumina-based catalysts were synthesized via the one-pot evaporation-induced self-assembly (EISA) method using four different structure-directing agents (SDA) namely PEG-1000, PEG-4000, P123, and F127 to understand the effect on catalytic properties and performance evaluation. Results revealed that the structured directing agents improve the catalyst's surface properties and affect the product yield. All synthesized catalysts were characterized for crystallinity, topography, and surface properties using X-ray diffraction analysis (XRD), Scanning Electron Microscope (SEM), Brunauer–Emmett–Teller (BET), Pyridine-Transmission Fourier transform infrared (Py-FTIR) spectroscopy, and atomic force microscopy (AFM) analysis. A significant effect of SDA was observed on the surface area of the synthesized mesoporous alumina (SMA) catalyst. The decreasing order in terms of the surface area of the SMA is SMAF127 >SMAP40 >SMAP123 >SMAP10> Alumina (without SDA). Approximately, a tenfold increase in surface area was observed with SMAF127 (mesoporous alumina) compared to non-mesoporous alumina. A maximum yield of hydrogen∼40.79 mmol/gram polypropylene was obtained with a catalyst-plastic (C/P) ratio of 1:2.5 at a temperature of 900 °C using SMAF127 owing to its high surface area, and other physiochemical properties.

Silica-based silver nanocomposite 80S/Ag as Aggregatibacter actinomycetemcomitans inhibitor and its in vitro bioactivity

Background/purposeAs a commonly-found pathogen in periodontal disease, Aggregatibacter actinomycetemcomitans has been reported with several antibiotic resistance. Thus, to develop an alternative and protective therapy for A. actinomycetemcomitans infections is urgently needed in dentistry. In this study, we sought to synthesize a silica-based material to deliver silver nanoparticles for antibacterial purposes. Also, the bioactivities were examined via analyzing the formation of hydroxyapatite. Materials and methodsThe 80S/Ag powders were prepared by the evaporation-induced self-assembly method, with Si, Ca, P, and Ag composition ratios of 80, 15, 5, and 1/5/10 (mole percentage), respectively. The nitrogen adsorption-desorption isotherms, transmission electron microscope, selected area electron diffraction, and Fourier transform infrared spectroscopy were conducted for textural analyses. The disk diffusion test was carried out against A. actinomycetemcomitans strain ATCC 29523. In vitro bioactivity assessment involved soaking 80S/Ag membrane powders in acellular simulated body fluid. ResultsWe successfully developed a material consisting of Si, Ca, P, and Ag, namely the 80S/Ag. In the antibacterial testing, the 80S/Ag demonstrated antibacterial activity against the commonly-found oral pathogen, A. actinomycetemcomitans, with a long-lasting effect for 168h. The formation of hydroxyapatite in simulated body fluid highlighted the characteristic of dentine remineralization for the 80S/Ag. The increased pH values after immersion in simulated body fluid would help neutralize the acidic oral environment. ConclusionOur results indicate that 80S/Ag possesses remarkable antibacterial properties, hydroxyapatite formation, and increased pH values after immersion in simulated body fluid, supporting the potential therapeutic application of 80S/Ag for treating periodontal disease.

Enhanced photoelectrochemical performance of mesoporous TiO2 photoanode prepared by multi-step evaporation-induced self-assembly method

Mesoporous TiO2 films are promising in photocatalysis and photoelectrochemistry for energy and environment applications, because of its high specific surface area and regular mesopore structure. However, the performances of mesoporous TiO2 films are still limited by low catalyst loading due to the damage during the preparation process. In this study, a multi-step evaporation-induced self-assembly method is proposed to develop a mesoporous TiO2 photoanode with high catalyst loading. The prepared mesoporous TiO2 photoanodes possess not only high catalyst loading without damage but also large specific surface area, which provides more active sites. Moreover, regular mesopore structure is remained to benefit mass transport. Because of these merits, the mesoporous TiO2 photoanode prepared by the multi-step evaporation-induced self-assembly method exhibits superior performance than does conventional nanoparticles-packed TiO2 photoanode. The superiority of the mesoporous TiO2 photoanode prepared by this multi-step evaporation-induced self-assembly method is also demonstrated by incorporating it into a photocatalytic fuel cell. The short circuit current density and maximum power density increase by 90.9% and 25.0%, respectively. The present work provides a new way to prepare high-performance mesoporous TiO2 films for various photocatalytic and photoelectrochemical applications.

(Digital Presentation) Large-Scale Synthesis of Nanoporous Tungsten Oxide for Supercapacitor Application

The development of materials delivering high specific capacitance and energy density is a major challenge for supercapacitors. Due to high redox activity, several metal oxides like RuO2, MnO2, MoO3, Fe3O4, WO3 and CoOx have been broadly utilized as the active material for pseudo-capacitors. Among these, tungsten oxide (WO3), being less toxic, chemically stable, and abundantly available, has become a potential candidate and is widely investigated for pseudo-capacitors. However, some modifications are required to bring its performance to a commercial scale. Various approaches like composites with carbon and other oxides, doping, confinement, and porosity improvement are followed to improve their performances. But there is a need to find the potential of solely WO3 for supercapacitors. Looking forward to it, we have synthesized highly porous pure WO3 using the solution-based nanoprecipitation method. Our approach offers the possibility of large-scale production of porous materials with tunable pore sizes and structures compared to the traditionally used solvent evaporation-induced self-assembly (EISA) method. Herein, we used PS-b-PAA block copolymer as pore creating agent, which was removed after giving thermal treatment. The prepared material was analyzed using Brunauer-Emmett-Teller (BET) and exhibited a high specific surface area of 55.5 m2 g-1 with an average pore diameter of 3.7 nm. A detailed crystallographic and morphological analysis of these materials was carried out to check the feasibility of our material for energy storage applications. Furthermore, electrochemical investigations were carried out in 3E and 2E device configurations. The electrochemical studies demonstrate that porous WO3 has achieved a specific capacitance of 555 F g-1 at 10 mV s-1 scan rate. Figure 1

Bifunctional vanadium doped mesoporous Co3O4 on nickel foam towards highly efficient overall urea and water splitting in the alkaline electrolyte

Developing more active and stable electrode materials for oxygen evolution reaction (OER) and urea oxidation reaction (UOR) is necessary for electrocatalytic water and urea oxidation which can be used to generate hydrogen. Here, a low-cost vanadium-doped mesoporous cobalt oxide on Ni foam (V/meso-Co/NF) electrodes are obtained via the grouping of an in-situ citric acid (CA)-assisted evaporation-induced self-assembly (EISA) method and electrophoretic deposition process, and work as highly efficient and long-lasting electrocatalytic materials for OER/UOR. In particular, V/meso-Co/NF electrodes require 329 mV overpotential to maintain a 50 mA/cm2, with exceptional long-term durability of 30 h. Interestingly, V/meso-Co/NF also exhibits excellent electrocatalytic UOR performance, reaching 50 and 100 mA/cm2 versus RHE at low potentials of 1.34 and 1.35 V, respectively. By employing the V/meso-Co/NF materials as both the anode and cathode, this urea electrolysis assembly V/meso-Co/NF-5 (+,−) reaches current densities of 100 mA cm−2 at 1.62 V in KOH/urea, which is nearly 340 mV lesser than classical water electrolysis. The V/meso-Co/NF-5 electrocatalysts also exhibit remarkable durability for electrocatalytic OERs and UORs. The obtained findings revealed that the synthesized V/meso-Co/NF might be a promising electrode materials for overall urea-rich wastewater management and H2 generation from wastewater.

Phyllosilicate-derived Ni catalysts with small nanoparticle size and strong metal-support interaction for efficient and robust decomposition of ammonia

Ammonia decomposition is a structure-sensitive reaction, so the difference in structure of similar catalysts may have a great impact on the catalytic performance of ammonia decomposition reaction. However, it is not clear which structural properties can play a role in ammonia decomposition reaction and the degree of influence on catalytic performance. To explore this question, ammonia evaporation-hydrothermal (AEH), impregnation (IM), and evaporation-induced self-assembly (EISA) methods were used to synthesize Ni/SiO2 catalysts to obtain carbon-free hydrogen from catalyzing NH3 decomposition reaction. Among the three, the Ni/SiO2 catalyst synthesized via ammonia evaporation-hydrothermal method is the smallest in terms of Ni nanoparticles (∼3.0 nm) and the strongest Ni-SiO2 interaction. For ammonia decomposition, it is the highest in activity and thermal stability. The NH3 conversion at 650 °C and 30 000 mL gcat−1h−1 (GHSV) over Ni/SiO2-AEH was close to 90 % and remained stable in an evaluation period of 60 h.

Thickness control of dispersion in opal photonic crystals

Opals are naturally occurring photonic crystals which can be formed easily using low-cost self-assembly methods. While the optical behaviour of opals has received significant attention over the last number of decades, there is limited information on the effect of crystal thickness on the optical properties they display. Here, the relationship between volume fraction and crystal thickness is established with an evaporation-induced self-assembly (EISA) method of formation. The extent to which thickness can be used to manipulate the optical properties of the crystals is explored, focusing on the change in the photonic band gap (PBG). Microscopical structural characterization and angle-resolved transmission spectroscopy are used to examine the quality of the photonic crystals formed using different volume fractions of polystyrene spheres, with thicknesses up to 37 layers grown from volume fractions of 0.125%. This work provides a direct correlation between sphere solution volume fraction and crystal thickness, and the associated optical fingerprint of opal photonic crystals. Maximum thickness is examined, which is shown to converge to a narrow range over several evaporation rates. We identify the criteria required to achieve thickness control in relatively fast evaporation induced self-assembly while maintaining structural quality, and the change to the spectroscopic signature to the (111) stopband and higher order (220) reflections, under conditions where a less ordered photonic crystals are formed.