Layered Double Hydroxides Surface Research Articles

Effect of different organic layered double hydroxides on the anti-aging property of bitumen

Two organic layered double hydroxides (LDHs) were synthesized and utilized to enhance the anti-aging property of bitumen. Fourier infrared spectroscopy and X-ray diffraction showed that sodium dodecyl sulfate was intercalated into the interlayers of LDHs (I-LDHs), and γ-(2,3-Epoxypropoxy)propyltrimethoxy silane was chemically grafted onto the surface of LDHs (S-LDHs). Compared with LDHs, organic LDHs possessed better compatibility and organic LDHs modified bitumen exhibited better performance in high-temperature regions, especially S-LDHs. After aging, the rheological properties dramatically deteriorated. The content of aromatic in bitumen evidently decreased, and the asphaltene noteworthy increased, the colloid structure verged on the gel system. The incorporation of LDHs could relieve the damage of aging on the rheological properties and colloid structure, and strengthen the anti-aging property of bitumen. Moreover, the consequence of LDHs had been further enhanced obviously after organic modification, and S-LDHs exhibited more excellent performance compared with I-LDHs.

Synergetic Removal of Pb(II)- and Sulfonamide-Mixed Pollutants using Ni/Co Layered Double Hydroxide Nanocages Coupled with Peroxymonosulfate

Organic pollutants are often present in wastewater coupled with toxic metallic ions, which are harmful to both human beings and the ecological environment, and their simultaneous removal is of great significance. In this work, hollow Ni/Co layered double hydroxide (LDH) nanocages were synthesized through the hydrothermal method by using zeolitic imidazolate framework-67 as a self-sacrificial template, and it was further used as a catalyst to activate peroxymonosulfate (PMS) for sulfonamide (SA) degradation and an adsorbent for Pb(II) removal simultaneously. The materials were characterized using various techniques, and the effect of parameters including the dosage of the catalyst and PMS, initial temperature, and pH on the performances of the LDH nanocage was investigated. Nearly 80% of SA (15 mg/L) could be degraded via PMS activation, whereas ∼93% of Pb(II) (20 mg/L) could be removed simultaneously within 60 min. During the reaction, there were redox cycles for both Co and Ni over the surface of LDH, but Pb did not participate in the process, and it had a slightly negative effect on SA degradation. The quenching experiments and the electron paramagnetic resonance results showed that the radicals (•OH, •SO4–, O2•–, and 1O2) generated from PMS activation participated in the process. Finally, the possible mechanism and degradation pathways were proposed, based on the intermediate products identified, and the toxicity of the intermediate products was evaluated.

New findings on the contribution of Mg-Al-NO3 layered double hydroxides to the hydration and chloride binding capacity of cement pastes

The impact of the addition of layered double hydroxides (LDHs) on binding of chloride ions was studied by pore expression experiments. A Mg-Al-NO3 type of LDHs was added to paste samples blended with 3 % NaCl in different proportions (4 % and 10 % by mass of the binder). In addition, the influence of LDHs on the hydration process, morphology and porosity of samples containing Portland cement, calcium sulphoaluminate cement and silica fume was investigated. The potential physical and chemical contributions of LDHs to the system (e.g. AFm formation) were discussed comprehensively. According to the results, addition of LDHs by 10 % could reduce the chloride content in the pore solution by over 25 % and increase the carbonate AFm phases. Moreover, formation of reaction products on the LDH grains was observed. Finally, it was clear that a part of the Cl− ions is bound to the surface of LDHs and can be washed out.

NiAl-layered double hydroxides stabilized Pt clusters with enhanced metal-support interaction: Boosting hydrogen isotope separation

Metal-support interaction plays a key role and remains a challenge in exploring highly efficient heterogeneous catalysts, especially for hydrophobic catalysts in Liquid Phase Catalytic Exchange (LPCE) process for water detritiation. In this work, supported Pt catalysts using layered double hydroxides (LDHs) as supports are featured by highly dispersed Pt nanoparticles, water resisting property, and strong interaction of Pt with LDHs, exhibiting excellent anti-aggregation of Pt nanoparticles and catalytic performance over traditional Pt/C at high temperature and humidity conditions. Density Functional Theory calculations show that there is strong interaction between Pt nanoclusters and hydrogen defective LDHs surface, together with significant interfacial charge transfer and metal electronic structure modification, which can restrain the aggregation of Pt on LDHs and enhance catalytic activity. These findings are helpful to deepen understandings of the effects of metal-support interactions in LPCE process, which shed valuable insights for the design and preparation of highly-efficient hydrophobic catalysts on LDHs with prospective applications in water detritiation.

Molecular orientation rules the efficiency of immobilized antioxidants

Tannic acid (TA) and glutathione (GSH) are important molecular antioxidants against reactive oxygen species. Their efficiency is limited by low solubility and high sensitivity, which may be solved by confinement in composite materials. Here, effect of immobilization of these antioxidants on their radical scavenging activity was investigated using layered double hydroxide (LDH) nanoparticles as hosts. Different preparation methods were applied to build composite systems leading to variations in the molecular orientation of both TA and GSH on the surface or among the layers of LDHs. Systematic combination of spectroscopy (FT-IR, Raman, UV–VIS-NIR-DRS), diffraction (XRD) and microscopy (SEM) methods revealed perpendicular or parallel orientation of TA on the surface of LDH depending on the preparation approach applied. Immobilization of GSH protected the antioxidant molecules from degradation. Radical scavenging tests evidenced that the activity of the antioxidants strongly depends on the molecular orientation. The LDH supported GSH and TA proved as durable and reusable antioxidant agents to be applied as radical scavengers in medical therapies or in industrial processes.

Simultaneous Electrochemical Determination of Catechol and Hydroquinone Using a Flower-Like Ni-Al Layered Double Hydroxide/Carbon Black Nanocomposite-Modified Electrode

We have developed a Ni-Al layered double hydroxide (LDH) and carbon black (CB) composite for the selective electrochemical detection of hydroquinone (HQ) and catechol (CT). LDH exhibits multiple active sites and high adsorption capacity for phenolic substances. CB demonstrates high conductivity and electrocatalytic capacity. The crystal structure was characterized by X-ray diffraction, establishing the successful synthesis of flower-like LDH, and the successful combination of LDH and CB. Fourier-transform infrared spectroscopy confirmed that the LDH surface contained sufficient hydroxyl groups to adsorb CT and HQ. The morphology of LDH/CB was characterized by scanning electron microscopy, and the composition and valence confirmed by X-ray photoelectron spectroscopy. The LDH/CB sensor delivered excellent performance in terms of sensing HQ and CT, with a wide detection range (0.1–150 μM) and detection limits of 0.011 and 0.0091 μM (DL = 3.3σ/S), respectively. The excellent performance of this sensor makes it a reliable choice for detecting HQ and CT in water.

Effect of plasmonic metal (Cu, Ag, and Au) loading over the physicochemical and photocatalytic properties of Mg-Al LDH towards degradation of tetracycline under LED light

This work focused on the enhancement of the photocatalytic activity of solvothermal synthesized Mg0.667 Al0.333 (OH)2 (CO3)0.167 (H2O)0.5 layered double hydroxide (LDH) by plasmonic metal (Cu, Ag, and Au) photodeposition (1-3 wt%). HRTEM analysis confirmed the successful loading of plasmonic nanoparticles with varying sizes (Au (∼4–25 nm) > Ag (∼3–12 nm) > Cu (∼2–7 nm)) on the surface of LDH. The effect of different plasmonic metals and their size on the surface structural, optical, electrokinetic, and photocatalytic properties of LDH was investigated. The prepared catalysts were evaluated for the degradation of tetracycline under LED irradiation for 140 min and the photoactivity trend followed the order: pristine LDH < Cu@LDH < Ag@LDH < Au@LDH. The LC-MS studies revealed that the degradation occurred by the attack of various reactive species (O2.-, h+, OḢ) via four paths mainly including hydroxylation, functional group cleavage, and ring-opening reaction. A possible mechanism was proposed for the appreciable enhancement in performance caused by the formation of Schottky barriers and surface plasmon resonance of plasmonic nanoparticles. The results of total organic carbon (TOC) indicated the acceptable mineralization of about 84 %. Less than a 10 % fall in degradation efficiency was observed within four recycle runs.

Synthesis of Mg-Al LDH and its calcined form with natural materials for efficient Cr(VI) removal

Layered double hydroxide (LDH) has been extensively studied due to its excellent capacity of heavy metal adsorption. However, the synthesis of LDH is always complex and requiring pure chemical reagents. In this study, two solid minerals, MgO and metakaolin (MK), derived from abundant natural resources, were used as raw materials to synthesize Mg-Al LDH via a facile one-pot method. The compositions and morphologies of synthetic products and its calcined form(C-LDH) were characterized by X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Cr(VI) adsorption by the LDH and C-LDH was systematically studied including the effect of contact time, initial pH value, temperature, liquid/solid ratio, and initial Cr(VI) concentration. The adsorption kinetics and isotherms were modelled, and thermodynamic parameters were determined. Results showed that the LDH and C-LDH exhibited high adsorption capacities (23.5–33.2 mg/g and 33.2–38.9 mg/g, respectively) within a wide pH range of 1.75–6.0, and maintained a higher adsorption capacity in all cases afterwards. The pseudo-second-order kinetic model fitted the kinetic data well in which the Langmuir model described the adsorption isotherms the best. The adsorption process was endothermic and spontaneous. The adsorption mechanisms may include anion exchange, redox reaction, and electrostatic adsorption. Moreover, the effect of the synthesis conditions (i.e., alkali concentration, temperature and liquid/solid ratio) on the adsorption characteristics were discussed. And XPS, UV-Vis Spectrophotometer (UV-Vis) and FTIR analysis confirmed Cr(VI) adsorption on the LDH and C-LDH surface, followed by its subsequent reduction to Cr(III). It has been revealed that the LDH/C-LDH synthesized in this work exhibited higher Cr(VI) removal capacities compared to the ones reported in the literature, demonstrating the significant potential of synthesizing high performance absorbents by low-cost natural materials.

Facile synthesis of hydrophilic layered double hydroxide film on aluminum plate

A facile synthesis method of a hydrophilic layered double hydroxide (LDH) film is required when the LDH film is used as an adsorbent, catalyst, and catalyst support in an aqueous solution. We successfully synthesized a hydrophilic film of a layered double hydroxide (LDH) on an aluminum (Al) plate at room temperature (20 °C) in a short time (120 min) by simply immersing it in a 25 mmol/L MgCl2 solution containing the optimal amount of NH3 water. The contact angle of the water was less than 5o on the obtained LDH surface of the Al plate. The surface morphology of the flower-like porous structure of the LDH film produced the hydrophilicity, because the water dropped on the porous LDH surface penetrated inside the void by capillary action. The obtained hydrophilic film on aluminum is expected to be used for various practical applications in an aqueous solution.

Co and Ni Double Substituted Zn-Fe Layered Double Hydroxide as 2D Nano-Adsorbent for Wastewater Treatment

Recently, several types of nanomaterials gained attention as promising nanoadsorbents to remove dyes from wastewater such as layered double hydroxides (LDHs). In this work, Fe-Zn-Co-Ni LDH was developed by the basic co-precipitation method. In order to emphasize and characterize the developing of this quaternary LDH, six techniques (x-ray diffraction (XRD), scan electron microscope (SEM), Fourier transforms infrared (FTIR), transmission electron microscope (TEM), zeta potential measurements) have been investigated. The LDH was studied for the uptake of anionic dye, methyl orange (MO), under numerous adsorption factors such as solution pH, contact time, dye initial concentration and adsorbent dosage, and. The XRD data states that the crystallite size of MO@LDH (93.1 nm) is increased compared with that of LDH (12.7 nm) owning to the adsorption of MO onto LDH surface. Two new peaks have appeared for the MO@LDH owning to the bending vibrations of the MO functional groups C-N and C-H. The highest adsorption capacity for the prepared MO@LDH was 418 mg/g and it reached the equilibrium state at 60 min. The adsorption kinetic was obeyed to the pseudo-first order model. Additionally, the LDH showed a positive antibacterial effect towards both Gram-negative and Gram-positive bacteria.

Enhanced ethylene glycol (EG)-blocking property of cation exchange membrane by layered double hydroxides modification for electrodialysis-based reclamation of EG waste fluid

Recycling toxic ethylene glycol (EG) solutions, which act as an inhibitor in the process of deep water gas fields exploitation activities, is an indispensable procedure for saving economic costs and avoid potential environmental hazards. In the recovery process, electrodialysis (ED) is an alternative technology for removing salts from high-saline EG wastewater caused by seawater infiltration. To further reduce the leakage transport of EG during ED desalination, a cation exchange membrane (CEM) layer facing the dilute cell was fabricated by electrodepositing layered double hydroxides (LDHs). Introduction of a LDH-modified layer enabled CEMs to have better EG-blocking properties without affecting cation transport, which was due to dense and hydrophilic transport channels formed by the two-dimensional (2D) lamellar structure of LDHs. This further led to differences in migration rates between hydrated cations and EG molecules. The results of ED desalination tests showed that these modified CEMs reduced the EG leakage content by 81 and 46%, compared with commercial CEMs in high-saline EG solution, with EG content of 20 and 60 wt%, respectively. Therefore, this study provided new insight for the application of CEMs based on LDHs surface modification in the special ED field of EG solution desalination.

Dual Modification of Layered Double Hydroxide by Phosphonitrilic Chloride Trimer and Aniline for Enhancing the Flame Retardancy of Polypropylene

Owing to the poor dispersion of layered double hydroxide (LDH) in a polypropylene (PP) matrix and its own flame-retardant efficiency being finite, the development of high-performance PP/LDH-based composites is still a tremendous challenge. To improve the dispersion of LDH and its inherent flame retardancy, phosphonitrilic chloride trimer (HCCP) was grafted onto the surface of LDH through the bridging effect of (3-aminopropyl)triethoxysilane and then further modified with aniline to replace the chlorine element in HCCP, so a flame-retardant (LDH@HA) was successfully synthesized. The flame retardancy and smoke suppression of LDH@HA with PP composites (PP/LDH@HA) were tested with the limit oxygen index (LOI), UL-94, and cone calorimetry tests. With a loading of 20 wt % LDH@HA, the peak heat release rate, total heat release, and total smoke rate of PP/LDH@HA composites were 300.1 kW·m–2, 57.7 MJ·m–2, and 697.5 m2·m–2, respectively, which were decreased by 64.4, 46.4, and 49.1% in comparison to those of PP, and the LOI value of PP/LDH@HA reached 30.6% and achieved the UL-94 V-0 rating. The improvements in flame retardancy and smoke suppression were due mainly to the physical barrier effect of LDH and the catalytic carbonization effect of HCCP together with the nonflammable gases formed by the decomposition of aniline, which diluted the combustible gas concentration. Compared with PP/LDH, the optimization of the mechanical properties of composites was due mainly to the introduction of HCCP and aniline, which significantly enhanced the compatibility between LDH and PP and promoted the uniform distribution of LDH in the PP matrix. In conclusion, LDH@HA has low cost, easy fabrication, and an excellent smoke suppression effect, and the strategy provides a specific idea for the preparation of fire-resistant PP composites.

Anti-inflammatory drug diclofenac removal by a synthesized MgAl layered double hydroxide

Layered double hydroxides (LDHs) containing Mg:Al (molar ratio 3:1) were synthesized by co-precipitation from nitrate salts under alkaline conditions. Their further characterisation by different techniques allowed the determination of their structural, nanotextural and chemical properties. XRD measurements confirmed the high crystallisation with the presence of two metal cations (Mg2+ and Al3+). The use of these materials as eco-friendly adsorbents was analysed to remove diclofenac from wastewater. Under optimal conditions (0.4 g L−1, 30 ppm initial pollutant concentration, pH ∼ 8.5), around 65% diclofenac removal was achieved after 60 min of treatment. The pseudo-second kinetic order model and Freundlich isotherm accurately described the experimental data, suggesting chemisorption process on the heterogeneous LDH surface. After diclofenac adsorption, XRD analysis revealed an increase in interlayer spacing followed by contraction of adjacent layers, so that anion exchange between layer was considered to be the main mechanism for diclofenac adsorption. Thermodynamic studies indicate diclofenac adsorption occurs spontaneously, endothermically, and also, with increasing randomness at the solid/solution surface. Batch test revealed limitations in terms of long-term stability of the material. Therefore, a post-synthesis strategy, calcination, was required to increase the degree of resistance. For this purpose, the effect of calcination temperature was examined in the range 200–300 °C. Although, the kinetic rate constant decreased slightly after calcination, the improvement of its structural properties allowed to operate under continuous system.

Flame retardancy of carboxylated polyhedral oligosilsesquioxane modified layered double hydroxide in the process of leather fatliquoring

AbstractCarboxyl polyhedral oligomeric silsesquioxane(P[POSS‐MAA]) modified layered double hydroxides (LDHs) (P[POSS‐MAA]‐LDHs) was prepared by exfoliating and recombination method, which used P(POSS‐MAA) and LDHs attracted each other through electrostatic force and hydrogen bond. The structure and morphology of P(POSS‐MAA)‐LDHs were characterized by X‐ray diffraction and transmission electron microscope, which showed that LDHs was exfoliated and P(POSS‐MAA) was on the surface of LDHs. Then it was introduced into the modified zanthoxylum bungeanum seed oil(MZBMSO) to obtain MZBMSO/P(POSS‐MAA)‐LDHs and applied it in leather fatliquoring process. The effect of the introduction of P(POSS‐MAA)‐LDHs on the flame retardancy, thermal stability, thermal insulation and smoke suppression of leather was investigated. Compared to the MZBMSO treated leather, the after flame time of MZBMSO/P(POSS‐MAA)‐LDHs treated leather decreased from 84 s to 32 s, and the limiting oxygen index increased from 23.1% to 27.5%, which exhibited improvement on flame retardancy of the leather. The temperature at 50% mass loss of MZBMSO/P(POSS‐MAA)‐LDHs treated leather increased from 375.1 to 408.3°C, which showed improvement on thermal stability of the leather. And the leather treated by MZBMSO/P(POSS‐MAA)‐LDHs had reduction of the total heat release and the total smoke production around 26.8% and 65.7%, respectively, which showed that MZBMSO/P(POSS‐MAA)‐LDHs treated leather had heat insulation and smoke suppression. Flame retardant mechanism of MZBMSO/(P(POSS‐MAA)‐LDHs) treated leather involved a combination of the gaseous phase and condensed phase flame retardancy. This work provided a new material for the flame retardant field and expanded the application range of polyhedral oligomeric silsesquioxane(POSS).

Smart Interfacing between Co‐Fe Layered Double Hydroxide and Graphitic Carbon Nitride for High‐efficiency Electrocatalytic Nitrogen Reduction

Bimetallic compounds such as hydrotalcite‐type layered double hydroxides (LDHs) are promising electrocatalysts owing to their unique electronic structures. However, their abilities toward nitrogen adsorption and reduction are undermined since the surface‐mantled, electronegative –OH groups hinder the charge transfer between transition metal atoms and nitrogen molecules. Herein, a smart interfacing strategy is proposed to construct a coupled heterointerface between LDH and 2D g‐C3N4, which is proven by density functional theory (DFT) investigations to be favorable for nitrogen adsorption and ammonia desorption compared with neat LDH surface. The interfaced LDH and g‐C3N4 is further hybridized with a self‐standing TiO2 nanofibrous membrane (NM) to maximize the interfacial effect owing to its high porosity and large surface area. Profited from the synergistic superiorities of the three components, the LDH@C3N4@TiO2 NM delivers superior ammonia yield (2.07 × 10−9 mol s−1 cm−2) and Faradaic efficiency (25.3%), making it a high‐efficiency, noble‐metal‐free catalyst system toward electrocatalytic nitrogen reduction.

Showcasing advanced electrocatalytic behavior of layered double hydroxide wrapped on carbon nanotubes: Real-time monitoring of L-cysteine in biological matrices

L-cysteine is an imperative amino acid which exists in natural proteins and plays crucial roles in biological systems, thereby its sensitive and selective monitoring is extremely necessary. In this work, novel hybrid nanoarchitectures have been fabricated by wrapping positively charged NiAl layered double hydroxide (LDH) nanosheets on negatively charged carbon nanotubes (CNTs). The electrochemical behavior of CNTs@NiAl LDH hybrids having different concentrations of NiAl LDH precursor salts with fixed amount of CNTs have been explored in detection of L-cysteine using cyclic voltammetry and amperometry techniques. High conductivity of CNTs together with enhanced electrocatalytic properties of NiAl LDH and plentiful surface active sites are accountable to facilitate the direct detection of L-cysteine. Therefore, the fabricated electrode exhibits excellent sensing performance with 0.05 µM to 780 µM wide linear range, sensitivity of 351 μA mM−1 cm−2, low limit of detection upto 3 nM (S/N = 3), superb reproducibility and stability as well as brilliant selectivity against common interferents. Arising from remarkable efficiency, the CNTs@NiAl LDH based sensing system has been practically used in real-time detecting L-cysteine effluxes from different living cells upon stimulation as-well-as in-vitro monitoring of L-cysteine concentrations in human samples (urine and serum).

Simultaneous removal of cesium and iodate using prussian blue functionalized CoCr layered double hydroxide (PB-LDH)

Radioactive cesium and iodine have become an emerging issue because these radionuclides have high radiotoxicity and solubility, and they can easily transport to the surrounding environment. Prussian blue, known as metal hexacyanoferrate compound, has a cubic face-centered structure and similar ionic size to Cs+, known to be used for Cs+ removal. In addition, layered double hydroxides (LDHs) have anion exchange properties and become the promising sorbents of iodine. In this study, based on the advantages of both Prussian blue (PB) and layered double hydroxide (LDH), Prussian blue functionalized layered double hydroxide (PB-LDH) was synthesized to concurrently remove both Cs+ and IO3− from radioactive solutions. During the synthesis of PB-LDH, Fe(CN)64− does not intercalate into the LDH structure, but aggregates on the LDH surface according to electrostatic force and ion-specific effects and forms the PB on the surface of LDH. The synthesized PB-LDH simultaneously removed 32 mg/g of Cs+ and 91 mg/g of IO3− from the mixed waste solutions. The main removal mechanism of Cs+ was redox coupled alkali metal ion transport to form Cs4Co4FeⅡ3(CN)18 species at the surface of PB-LDH. However, IO3− was mainly removed by ion exchange with intercalated Cl− in addition to the redox effect of Co ions.

Metal (hydr)oxide surface precipitates and their effects on potassium sorption.

Surface precipitation has been shown to occur on rapid time scales in clay and metal oxide mineral systems. The formation of surface precipitates is hypothesized to present new potential sorption sites for potassium (K), where K can become incorporated into newly formed interlayer spaces (e.g., between tetrahedral-octahedral-tetrahedral stacked sheets). The objective of this study is to determine the effects of newly formed mineral surface precipitates on K sorption. Potassium adsorption experiments were conducted by utilizing Al2O3 and SiO2 sorbents in the presence of various cations (magnesium, zinc, and nickel) that helped to catalyze the formation of surface precipitates. Dissolved concentrations of elements were monitored via inductively coupled plasma optical emission spectrometry (ICP-OES). Solids were characterized via X-ray diffraction (XRD), and K surface complexation was analyzed via X-ray absorption near edge structure (XANES) spectroscopy. X-ray diffraction analysis indicated bayerite, layered double hydroxides (LDH), and silicated LDH were formed as reaction products, thus creating new surface sites for potential K adsorption. The presence of Si increased K adsorption perhaps due to its role in the formation of LDH surface precipitates. When the differences between observed and theoretical surface area normalized K sorption densities were averaged, a 31% increase in K adsorption was observed in the presence of Si. XANES analysis indicated that the binding mechanism of K to Si is different than that of K to Al, perhaps due to the presence of inner-sphere complexation of K to Al-oxide. Samples reacted for one month versus one week yielded more intense XANES post-edge peaks which indicated that the K sorption complex changes over time. Overall, our findings provide novel insights into the mechanisms of K fixation in soil and has high implication in providing improved K fertilizer recommendation to growers.

Atomic Metal–Support Interaction Enables Reconstruction-Free Dual-Site Electrocatalyst

Real bifunctional electrocatalysts for hydrogen evolution reaction and oxygen evolution reaction have to be the ones that exhibit a steady configuration during/after reaction without irreversible structural transformation or surface reconstruction. Otherwise, they can be termed as "precatalysts" rather than real catalysts. Herein, through a strongly atomic metal-support interaction, single-atom dispersed catalysts decorating atomically dispersed Ru onto a nickel-vanadium layered double hydroxide (LDH) scaffold can exhibit excellent HER and OER activities. Both in situ X-ray absorption spectroscopy and operando Raman spectroscopic investigation clarify that the presence of atomic Ru on the surface of nickel-vanadium LDH is playing an imperative role in stabilizing the dangling bond-rich surface and further leads to a reconstruction-free surface. Through strong metal-support interaction provided by nickel-vanadium LDH, the significant interplay can stabilize the reactive atomic Ru site to reach a small fluctuation in oxidation state toward cathodic HER without reconstruction, while the atomic Ru site can stabilize the Ni site to have a greater structural tolerance toward both the bond constriction and structural distortion caused by oxidizing the Ni site during anodic OER and boost the oxidation state increase in the Ni site that contributes to its superior OER performance. Unlike numerous bifunctional catalysts that have suffered from the structural reconstruction/transformation for adapting the HER/OER cycles, the proposed Ru/Ni3V-LDH is characteristic of steady dual reactive sites with the presence of a strong metal-support interaction (i.e., Ru and Ni sites) for individual catalysis in water splitting and is revealed to be termed as a real bifunctional electrocatalyst.

Synthesis of Organic-Inorganic Hybrid Material with a Synergistic Interface as a Release Agent for Free Acid β-Hydroxy-β-Methyl Butyrate

We report the preparation and characterization of a new organic-inorganic hybrid system composed of type-I collagen and ZnAl layered double hydroxide (LDH) particles loaded with β-hydroxy-β-methyl butyrate (HMB) by coprecipitation reaction. X-ray diffraction (peaks well agree with those reported in the literature), infrared spectroscopy (stretching bonds for both organic-inorganic compounds), and X-ray photoelectron spectroscopy confirmed the hybrid system retained HMB in the carboxylate form, and a small fraction turned to the acid form. In both cases, the HMB molecules are assembled to the LDH surface. The hybrid compound results in improved thermal stability for HMB and collagen, as shown by thermal analysis. Scanning electron microscopy data reflects different arrangements from LDH sheets with interesting physicochemical properties since LDH and collagen protect free HMB and make it more bioavailable and functional. In vitro studies as part of high-throughput screening strategies indicated that LDH hybrids reduced cell viability around 75-90%, which is an acceptable viability value because of the L6 cell line susceptibility. However, all new nanomaterials must be carefully analyzed by different toxicity tests because a single test does not evaluate complete physiological compartments.