Layered Double Hydroxide Composites Research Articles

Hydroxyapatite film prepared by hydrothermal method on layered double hydroxides coated Mg Alloy and its corrosion resistance

Hydroxyapatite (HA) bioactive film is a standard surface modification method for biodegradable Mg alloys. However, the corrosion resistance of HA film prepared before was mediocre, and the preparation process was complicated. In this study, hydroxyapatite film was prepared for the first time on layered double hydroxides (LDHs) coated Mg alloy by hydrothermal method. The structure and composition of LDHs and HA films were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The corrosion resistance and immersion behavior of the films in simulated body fluid (SBF) were investigated by using potentiodynamic polarization curve, electrochemical impedance spectroscopy (EIS) techniques. The effects of different pH and calcium to phosphorus molar ratios (Ca/P ratios) of HA hydrothermal solution were investigated. The experimental results show that HA films appear in petal-like, filamentous and flower-like. The corrosion resistance of the film first increases and then decreases with the pH from weak acid to alkaline. With the increase of the Ca/P ratio, the film is gradually denser, and the protective effect is enhanced. The immersion test results show that after 7 days of immersion, the impedance modulus of the composite film is about 5 × 103 Ω·cm2, which is ten times higher than the single LDHs film. The effects of the pH and Ca/P ratio of the HA hydrothermal solution on the preparation of HA film are simply explained by thermodynamic theory. The Mg-LDHs-HA composite film provide a corrosion protection barrier for Mg substrate and HA film is biologically active. The barrier effect and the mineralization behavior provide a better corrosion protection for Mg substrate.

Composite of Layered Double Hydroxide with Casein and Carboxymethylcellulose as a White Pigment for Food Application.

Titanium dioxide (TiO2) is commonly used in food, cosmetic, and pharmaceutical industries as a white pigment due to its extraordinary light scattering properties and high refractive index. However, as evidenced from recent reports, there are overriding concerns about the safety of nanoparticles of TiO2. As an alternative to TiO2, Mg-Al layered double hydroxide (LDH) and their composite containing casein and carboxymethyl cellulose (CMC) were synthesized using wet chemistry and compared with currently used materials (food grade TiO2 (E171), rice starch, and silicon dioxide (E551)) for its potential application as a white pigment. These particles were characterized for their size and shape (Transmission Electron Microscopy), crystallographic structure (X-Ray Diffraction), agglomeration behavior and surface charge (Dynamic Light Scattering), surface chemistry (Fourier Transform Infrared Spectroscopy), transmittance (UV–VIS spectroscopy), masking power, and cytotoxicity. Our results showed the formation of typical layered double hydroxide with flower-like morphology which was restructured into pseudo-spheres after casein intercalation. Transmittance measurement showed that LDH composites had better performance than pristine LDH, and the aqueous suspension was heat and pH resistant. While its masking power was not on a par with E171, the composite of LDH was superior to current alternatives such as rice starch and E551. Sustainability score obtained by MATLAB® based comparison for price, safety, and performance showed that LDH composite was better than any of the compared materials, highlighting its potential as a white pigment for applications in food.

Two‐step electrodeposition of Hausmannite sulphur reduced graphene oxide and cobalt‐nickel layered double hydroxide heterostructure for high‐performance supercapacitor

Hausmannite/sulphur reduced graphene oxide (MO/RGO-S) and cobalt-nickel layered double hydroxide (CN) composite was synthesized through a two-step electrodeposition approach. This process began with galvanostatic electrodeposition of MO/RGO-Son a nickel foam, followed by cyclic voltammetry electrodeposition of CN. The inclusion of RGO-S increases the electrical conductivity of the active material (AM) and its wettability while Mn3O4 (MO) enhances the pseudocapacitive active sites which help to increase the specific capacity of CN. The materials' electrochemical evaluations were carried out via three- and two-electrode configurations using 2 M KOH electrolyte. An enhanced composite material (MO/RGO-S-50@CN) produced a phenomenal specific capacity of 582.1 mA h g−1 in a three-electrode configuration at 0.5 A g−1. The device (MO/RGO-S-50@CN//CCBW) consisting of MO/RGO-S-50@CN and activated carbon from cooked chicken bone waste (CCBW) as positive and negative electrodes, respectively delivered specific energy of 56.0 Wh kg−1 with a specific power of 515.0 W kg−1 at a specific current of 0.5 A g−1. The device produced capacity retention of 85.1% and coulombic efficiency of 99.7% at 10 000 galvanostatic charge-discharges cycles at 6 A g−1. Because of these excellent results, the fabricated materials demonstrated great potential for application as a high specific energy supercapacitor.

Cold sintering yields first layered double hydroxides (LDH) monolithic materials

Layered double hydroxides (LDHs) are key inorganic compounds relevant to a wealth of applicative purposes, by exploiting their layered structure allowing for ion/molecular sequestration or release. However, a technological barrier exists in the fabrication of cohesive LDH monoliths in link with their metastability. In this work, a series of cohesive monoliths of different LDH ionic compositions and structures (namely hydrotalcite, pyroaurite and hydrocalumite) were successfully obtained for the first time, using cold sintering via spark plasma sintering (SPS) at 130 °C. Thanks to the low temperature involved in this non-conventional consolidation approach, the structure and chemical stability of the LDHs are preserved and allow preparing densified LDH scaffolds with internal cohesion, as evidenced by densification rates often above 80 %, SEM microstructural observations and mechanical testing assessments, mainly due to a better alignment of adjacent layered particles. By way of water vapor sorption measurements, we demonstrate that the interfacial/interlayer spaces of the LDH structure remain accessible after cold sintering. Also, the porous network of the monoliths and related access to interfacial surface are shown to be tunable by adding a leachable pore-forming agent such as SiO2 beads. Possible sintering mechanisms are discussed by complementary experiments-simulations coupling, unveiling the role of LDH composition as in the case of Cl-bearing LDH. By overcoming the challenge of monolith fabrication out of LDH compounds, applications are expected to benefit from these findings, as in electronics, energy storage, catalysis, biomaterials and depollution.

Sensitive, selective and rapid detection of 4,4′-methylenedianiline by surface-enhanced Raman spectroscopy using flower-like gold-silver nanoalloy embedded nickel-cobalt layered double hydroxide composites

In this paper, an ultra-sensitive and selective surface-enhanced Raman spectroscopy (SERS) substrate was designed and fabricated for rapid determination of 4,4′-methylenedianiline (4,4′-MDA) based on flower-like gold-silver nanoalloys embedded nickel-cobalt layered double hydroxide composites (NiCo/Au2Ag1). Flower-like NiCo-LDH with thin nanosheets were prepared via the hydrothermal method and the gold-silver nanoalloys were in-situ embedded on the surface of NiCo-LDH. The ultrahigh SERS activity of NiCo/Au2Ag1 was originated from the synergistic effect of electromagnetic and chemical mechanism induced by AuAg nanoalloys and NiCo-LDH, respectively. In addition, the flower-like of NiCo-LDH can provide more sites for AuAg and target molecules loading, further making highly sensitive SERS activity. The minimum detectable concentration for 4-mercaptobenzoic acid (4-MBA), crystal violet (CV) and Rhodamine 6 G (R6G) are 1.0 pg L−1 and 1.0 ng L−1 with enhancement factor (EF) of 1.2 × 1010, 1.7 × 108 and 1.1 × 108, respectively. The theoretical simulations and experiment results can further confirm the high SERS performance of NiCo/Au2Ag1 and superiority of NiCo-LDH compared to Ni(OH)2 and Co(OH)2. Good selectivity and anti-interference for 4,4′-MDA indicates great potentials in contaminants screening and detection. Subsequently, the NiCo/Au2Ag1 composites were used to determine group 2B carcinogen of 4,4′-MDA in water samples and indoor dust. The fabricated NiCo/Au2Ag1 substrate show good satisfied linearity (5.0–750.0 μg L−1) with low limits of detection (LOD) of 1.5 μg L−1, and the practical applications in environmental samples were obtained with good rapidity and accuracy. The developed NiCo/Au2Ag1 offers a novel strategy for fabricating SERS substrates with high sensitivity and selectivity in rapid monitoring of environmental pollutants.

A Comprehensive Review of Layered Double Hydroxide-Based Carbon Composites as an Environmental Multifunctional Material for Wastewater Treatment

As is well known, hydrotalcite-like compounds, such as layered-double-hydroxide (LDH) materials, have shown great potential applications in many fields owing to their unique characteristics, including a higher anion exchange capacity, a structure memory effect, low costs, and remarkable recyclability. While the lower surface area and leaching of metal ions from LDH composites reduce the process efficiency of the catalyst, combining LDH materials with other materials can improve the surface properties of the composites and enhance the catalytic performance. Among organic compounds, carbon materials can be used as synergistic materials to overcome the defects of LDHs and provide better performance for environmental functional materials, including adsorption materials, electrode materials, photocatalytic materials, and separation materials. Therefore, this article comprehensively reviews recent works on the preparation and application of layered double-hydroxide-based carbon (LDH–C) composites as synergistic materials in the field of environmental remediation. In addition, their corresponding mechanisms are discussed in depth. Finally, some perspectives are proposed for further research directions on exploring efficient and low-cost clay composite materials.

A review on heavy metal ions adsorption from water by layered double hydroxide and its composites

• We selected to review topics related to the specific application of LDH removal of heavy metals. • Classify and summarize its modification methods, absorption properties, composition, structure, and other aspects. • It is determined that future research needs to reduce environmental impact and economic costs to promote the synthesis and use of LDH. • This system summary will provide helpful guidance for preparing high-efficiency LDHs-based adsorbents and offer critical clues to elucidating the adsorption behavior of heavy metals on LDHs-based materials. Heavy metal pollution is highly toxic and persistent, posing a severe threat to human health, agriculture, and the safe environment. Therefore, there is an urgent need for fast and efficient heavy metal removal technology to deal with emergency response to heavy metal leakage. In recent years, the development of a unique layered double hydroxide material has attracted widespread attention in sewage treatment. Due to these fundamental scientific issues, the general concern about environmental pollution management of LDH-based materials, and the recent significant developments in this field, it is necessary to conduct a thematic review. This article summarizes 474 related articles published since 2005 and outlines functionalized layered double hydroxide (LDH) research status as heavy metal adsorption materials. In addition, there is still a lack of reviews on the adsorption characteristics, interaction mechanism, and application of LDHs-based nanomaterials in heavy metal removal. Here, the primary purpose of this article is to systematically summarize LDHs-based materials and their applications in removing heavy metals from aqueous solutions ( Fig. 1 ). First, we will focus on its preparation and modification methods to understand LDH intuitively. Subsequently, the effects of different environmental conditions on factors such as pH, temperature, and contact time were summarized. Finally, the interaction mechanism between LDHs composites and heavy metals is briefly described, and a quick conclusion is given.

Reconstruction and intercalating anion exchange of ZnAl-layered double hydroxide

Layered double hydroxides (LDHs) have recently attracted considerable attention as a promising multi-functional material due to their controllable properties depending on the type and composition ratio of metal cations and interlayer anions. Despite active research on controlling the composition to improve the properties of LDHs, anion intercalation techniques capable of obtaining the desired morphologies of LDHs have rarely been investigated. Herein, we report the anion exchange of ZnAl-LDHs grown on a silicon substrate using a post-treatment-based reconstruction process. Structural and chemical investigations verified that the calcined ZnAl-LDH was reconstructed by a NaCl solution during the anion exchange process. The anion exchange rate and the reconstructed fraction of the ZnAl-LDH increased as the NaCl concentration increased from 0.15 M to 0.60 M, though they decreased when the NaCl concentration exceeded 0.90 M. Therefore, the anion composition and morphology of the ZnAl-LDHs could be modulated by controlling the NaCl concentration during the reconstruction process. These results provide important information about the probability of controlling the structure and composition of LDHs intercalated with desired anions for a wide variety of device applications, such as memory, sensor, and energy storage.

Fe(III)‐Based Layered Double Hydroxides Carrying Model Naproxenate Anions: Compositional and Structural Aspects

AbstractIn this work, Al cation was gradually replaced by FeIII in the composition of Layered Double Hydroxides (LDH) and systematically investigated for LDH application as drug carriers, ultimate aiming to improve their biointegration. The incorporation of FeIII into LDH layers, as well the intercalation of organic anions in the iron‐based materials, is challenging. Several studies approach the intercalation of non‐steroidal anti‐inflammatory drugs such as anionic naproxen (NAP) into Al‐LDH. Thus, NAP was applied here as a model drug for the study of compositional and structural aspects of novel FeIII‐LDH carriers envisaging to shed light on the intercalation of other carboxylate drugs into these materials. LDH of general [M2FeyAl(1‐y)(OH)6]An− compositions (MII=Mg or Zn; An−=anion of charge n) were investigated using two synthetic methods for NAP intercalation. Full X‐ray diffraction profile refinement and a crystal‐geometrical reasoning were used to strengthen the results interpretation. Unlike coprecipitation, in which probably NAP complexation with FeIII hinders LDH‐NAP self‐assembling, topotactic ion exchange demonstrated to be a potential approach.

Optimization, equilibrium, adsorption behaviour of Cu/Zn/Fe LDH and LDHBC composites towards atrazine reclamation in an aqueous environment

Cu–Zn–Fe Layered double hydroxides (LDH) and LDH dispersed on bamboo biochar (LDHBC) was used to study the adsorption of Atrazine by characterizing the adsorption kinetics, isotherms and response surface methodology (RSM) to reveal interactive effects of pH, adsorbent dosage and adsorbate initial concentration towards LDH optimum performance. The estimate of parameters determined for Langmuir isotherm quantities were in the range (21.84–37.91 mg/g) for LDH and (63.64–87.04 mg/g) for LDHBC. Regeneration and reusability after five cycles detected that the adsorption efficiencies of the adsorbents were reduced to 36% for LDH and 66% for LDHBC. Box Behnken design analysis could further reveal optimized conditions for higher Atrazine removal by LDH up to 74.8%. The adsorption mechanisms could be determined by π-π interactions occurring at the interfaces by hydrogen bonding and pore filling effects.

Removal of Pb(Ii), Cd(Ii), Cu(Ii), Cr (Vi), Acid Red 1, Phenol and Toluene Using Carbon Sphere and Layered Double Hydroxide Composites

Removal of Pb(Ii), Cd(Ii), Cu(Ii), Cr (Vi), Acid Red 1, Phenol and Toluene Using Carbon Sphere and Layered Double Hydroxide Composites

Chitosan-Ni/Fe Layered Double Hydroxide Composites as an Efficient Sorbent for Gc-Ms Quantitation of Phthalates

Chitosan-Ni/Fe Layered Double Hydroxide Composites as an Efficient Sorbent for Gc-Ms Quantitation of Phthalates

Activated layered double hydroxides: assessing the surface anion basicity and its connection with the catalytic activity in the cyanoethylation of alcohols.

Layered double hydroxides (LDHs) act as catalysts in several reactions like in the cyanoethylation of alcohols with acrylonitrile to produce alkoxypropionitriles. Here we report an experimental and theoretical study in which it is shown that the experimental catalytic activity of LDHs in the cyanoethylation of 2-propanol and methanol correlates with the predicted strength of the basicity of the adsorbed surface species. First, it is shown that using activated LDHs containing Mg2+ and Al3+ (MgAl-LDH), Mg2+ and Ga3+ (MgGa-LDH), and Mg2+, Al3+ and Ga3+ (MgAlGa-LDH) great conversions to alkoxypropionitriles in high yields are obtained. Next, the basicity of these LDHs is estimated by means of the local softness, a local reactivity index calculated using density functional theory and appropriate surface models. For that, the adsorption of hydroxide and methoxide anions at the (001) surface of MgAl and MgGa-LDHs is investigated. We include LDHs containing Zn2+ and Al3+ (ZnAl-LDH) and Zn2+ and Ga3+ (ZnGa-LDH) in this part of the study to account for the effect of changing the divalent and trivalent metal composition on the basicity. It is found that hydroxide anions adsorbed on the MgGa-LDH surface and methoxide anions adsorbed on the MgAl-LDH surface are the most basic ones. This basicity trend correlates with our experimental findings about the catalytic activity of the activated LDHs. Further analyzing the connection between the LDH composition and the anion basicity, it is argued that the key steps dictating the LDH catalytic activity are the alcohol deprotonation in the cyanoethylation of 2-propanol, as it has been previously suggested, and the methoxide anion attack to the acrylonitrile double bond in the methanol cyanoethylation reaction.

CeO2/Ni-Al layered double hydroxide composite electrode for the enhancement of specific capacitance and capacitance retention performance

Layered double hydroxides(LDH) possessed excellent capacitive properties but with poor cycling performance and low specific capacitance at high current density. CeO2/Ni-Al LDH (NAHCe) composite was synthesized by a one-step hydrothermal method to improve the electrochemical performance Ni-Al LDH. The scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) results proved the well distribution of cerium on the surface of the Ni-Al LDH laminate structure. The specific capacitance and capacitance retention after 1000 cycles of the optimal composite NAHCe-2.5 reached 879.63 F·g−1 at 1 A g−1 and 90.36% at 2 A g−1, which was higher than that of NAH (541.82 F·g−1 at 1 A·g−1, 62.9% at 2 A·g−1 after 1000 cycles) under the same conditions. The CeO2 particles loaded on Ni-Al LDH sheets effectively reduce the internal electrochemical resistance of the composite electrode which contributed to the improvement of the specific capacitance and capacitance retention performance of the electrode. The idea of CeO2/LDH composite for the enhancement of electrochemical performance could be of help for the synthesis of other new-type supercapacitors.

Advances and Challenges in Industrial-Scale Water Oxidation on Layered Double Hydroxides

A substantial effort is devoted to the development of efficient electrolyzers made of earth-abundant elements for low-temperature industrial-scale water electrolysis. However, a large current density leads to the decline of the reaction kinetics that result from the decrease of local pH, the irreversible redox states of active metal sites, and the structure and composition collapse. Currently, the transition metal layered double hydroxides (LDHs) are proven as efficient alkaline oxygen evolution catalysts and demonstrate promising current density, generally at the scale of 10 mA cm–2 for the potential solar-driven catalysis concerning 10% solar-to-fuels efficiency. However, there is very limited progress in understanding the activity and stability degradation mechanism of LDHs at high current density, for instance above 100 mA cm–2. Here we introduce the current advances in achieving activity enhancement by tuning the composition, structure, and morphology of LDHs and present the degradation mechanism during the electrolysis under oxidative alkaline environments, long-term operation, and voltage fluctuations. Finally, we present the state-of-the-art approaches to stabilize the overall performance of LDHs for water oxidation and provide an outlook in this field.

Comparison of Zn–Al and Mg–Al layered double hydroxides for adsorption of perfluorooctanoic acid

Per-and polyfluoroalkyl substances (PFAS), a large class of synthesized chemicals, are persistent in nature and generally recalcitrant to conventional chemical and biological treatment. Adsorption is considered an economical and practical method for PFAS treatment. Layered double hydroxides (LDHs) represent a promising class of mineral-based adsorbents for PFAS removal because of the highly positive charge of their structural layers. In this research, the performance of two representative LDHs with varied cation compositions, namely Zn–Al and Mg–Al LDHs, were investigated and compared for the removal of perfluorinated carboxylic acids (PFCAs) with an emphasis on perfluorooctanoic acid (PFOA). Zn–Al LDH showed high efficiency for the removal of medium- and long-chain PFCAs (i.e., C ≥ 7), and performed consistently better than Mg–Al LDH. Based on detailed adsorption kinetics and isotherm studies toward PFOA, Zn–Al LDH showed higher adsorption capacity, stronger adsorption affinity, and faster kinetics than Mg–Al LDH. Presence of natural organic matter had minimal impact on PFOA removal by Zn–Al LDH, but sulfate severely inhibited PFOA adsorption. Combined results of aqueous adsorption experiments and sorbent characterization suggested that electrostatic interactions may be the primary mechanism for PFOA adsorption onto LDHs. Our results suggested that cation composition of LDHs can have significant effect on the performance for PFCA removal.

Tunning the defects in lignin-derived-carbon and trimetallic layered double hydroxides composites (LDH@LDC) for efficient removal of U(VI) and Cr(VI) in aquatic environment

Utilizing different absorbents to remove heavy metals from aquatic environment has been extensively investigated because of its simple operation, good reusability, and low cost. The removal efficiency of these adsorbents, nevertheless, need to be further enhanced to meet the practical requirement. In this study, we demonstrate defect engineering as an effective approach to enhance the performance of biochar-based composites for U(VI) and Cr(VI) removal. Lignin derived carbon and Ca/Fe/Al-trimetallic layered double hydroxide composites (LDH@LDC) is prepared by hydrothermal method. Defects are introduced into the LDH layer by H2 plasma treatment. The obtained defective LDH@LDC exhibits outstanding removal efficiency for U(VI) (267.65 mg/g at pH = 5.0, T = 308.15 K, CInitial = 30 mg/L), which is much higher than LDH@LDC as-prep (190.47 mg/g at pH = 5.0, T = 308.15 K, CInitial = 30 mg/L). Similar defect-induced enhancement is observed for the removal of Cr(VI). The thermodynamic and kinetic studies of the removal process, as well as the surface analyze suggest that the removal mechanism of U(VI) and Cr(VI) by the as-prepared and plasma-treated LDH@LDC were both dominated by ion exchange. The plasma treatment introduces defects into the LDH layer, which effectively promote the ion exchange between the LDH layer and the heavy metal in the aquatic environment, leading to strongly enhanced removal performance. This study clarifies the critical role of defects in heavy metal removal process and provides a new pathway of designing high performance absorbents for water remediation.

Preparation of Synthetic Clays to Remove Phosphates and Ibuprofen in Water

The main objective of this study consists in the synthesis of a layered double hydroxide (LDH) clay doped with magnesium and aluminum in order to test the removal of phosphates and ibuprofen in water. Two different LDH composites are assessed: oven-dried (LDHD) and calcined (LDHC). Single adsorptions of phosphate and ibuprofen showed up to 70% and 58% removal in water, when LDHC was used. A poorer performance was observed for LDHD, which presented adsorption efficiencies of 52% and 35%, respectively. The simultaneous removal of phosphate and ibuprofen in water showed that LDHC allows a greater reduction in the concentration of both compounds than LDHD. Phosphate adsorption showed a close agreement between the experimental and theoretical capacities predicted by the pseudo-second-order model, whereas ibuprofen fitted to a first-order model. In addition, phosphate adsorption showed a good fit to an intraparticle diffusion model and to Bangham model suggesting that diffusion into pores controls the adsorption process. No other mechanisms may be involved in ibuprofen adsorption, apart from intraparticle diffusion. Finally, phosphate desorption could recover up to 59% of the initial concentration, showing the feasibility of the recuperation of this compound in the LDH.

Process Optimization and Modeling of Phenol Adsorption onto Sludge-Based Activated Carbon Intercalated MgAlFe Ternary Layered Double Hydroxide Composite.

A sewage sludge-based activated carbon (SBAC) intercalated MgAlFe ternary layered double hydroxide (SBAC-MgAlFe-LDH) composite was synthesized via the coprecipitation method. The adsorptive performance of the composite for phenol uptake from the aqueous phase was evaluated via the response surface methodology (RSM) modeling technique. The SBAC-MgAlFe-LDH phenol uptake capacity data were well-fitted to reduced RSM cubic model (R2 = 0.995, R2-adjusted = 0.993, R2-predicted = 0.959 and p-values < 0.05). The optimum phenol adsorption onto the SBAC-MgAlFe-LDH was achieved at 35 °C, 125 mg/L phenol, and pH 6. Under the optimal phenol uptake conditions, pseudo-first-order and Avrami fractional-order models provided a better representation of the phenol uptake kinetic data, while the equilibrium data models’ fitting follows the order; Liu > Langmuir > Redlich–Peterson > Freundlich > Temkin. The phenol uptake mechanism was endothermic in nature and predominantly via a physisorption process (ΔG° = −5.33 to −5.77 kJ/mol) with the involvement of π–π interactions between the phenol molecules and the functionalities on the SBAC-LDH surface. The maximum uptake capacity (216.76 mg/g) of SBAC-MgAlFe-LDH was much higher than many other SBAC-based adsorbents. The improved uptake capacity of SBAC-LDH was attributed to the effective synergetic influence of SBAC-MgAlFe-LDH, which yielded abundant functionalized surface groups that favored higher aqueous phase uptake of phenol molecules. This study showcases the potential of SBAC-MgAlFe-LDH as an effective adsorbent material for remediation of phenolic wastewater

Research on Li0.3Na0.18K0.52NO3 promoted Mg20Al-CO3 LDH/GO composites for CO2 capture

It has been reported that the addition of graphene oxide (GO) can increase the dispersion and heterogeneous nucleation of layered double hydroxide (LDH), thus providing more active sites, which is more conducive to CO2 adsorption. Herein, we reported alkali metal nitrates ((Li0.3Na0.18K0.52)NO3) promoted LDH and GO composites (LDH/GO) as adsorbents for CO2 capture. The influence of mass ratio of LDH to GO, the impregnation ratio of alkali metal nitrates, the calcination and adsorption temperature, as well as the cycling stability were investigated systematically. The results indicated that the CO2 capture capacity of LDH/GO composite with 30 mol% (Li0.3Na0.18K0.52)NO3 could reach 4.51 mmol·g−1, which was 5.86 times higher than LDH/GO1 without loading alkali metal nitrates. Moreover, it had outstanding CO2 adsorption capacity in the range from 200 °C to 320 °C. In addition, the cyclic adsorption and desorption test manifested that the CO2 uptake of the material can reach 3.07 mmol·g−1 after 22 cycles. We believe that this study will give a significant contribution to fabrication of LDH based composites as CO2 adsorbents in future study.