Nanocontainers encapsulating corrosion inhibitors are commonly incorporated into organic coatings to enable self-healing effects, thereby ensuring long-term anticorrosion performance. In this study, ...a novel dual corrosion inhibitor-loaded self-healing nanocontainer with core-shell structure was proposed for fabricating composite waterborne epoxy coatings with both active and passive corrosion prevention properties.
The nanocontainer, named BTA-ZIF-8@LDH-Mo, was synthesized through the in-situ growth of molybdate-intercalated ZnAl layered double hydroxide (LDH-Mo) on the surface of 1H-benzotriazole-inbuilt zeolitic imidazolate framework (BTA-ZIF-8). Potentiodynamic polarization results showed that the Icorr of bare Q235 carbon steel immersed in a 3.5 wt% NaCl solution decreased from 4.658 × 10−6 A/cm2 to 1.274 × 10−6 A/cm2 after introducing BTA-ZIF-8@LDH-Mo nanocontainers, resulting in a superior corrosion inhibition efficiency of 72.65 %. Electrochemical impedance spectroscopy further demonstrated that the |Z|f=0.01Hz of epoxy coating doped with BTA-ZIF-8@LDH-Mo reached 4.24 × 109 Ω·cm2 after 42 d of immersion in 3.5 wt% NaCl solution, approximately 30 times higher than that of pure EP coating. Moreover, investigations on artificially scratched coatings indicated that the incorporation of BTA-ZIF-8@LDH-Mo nanocontainers effectively mitigated the corrosion process by forming an inhibiting layer on the metal substrate that impeded the corrosion process. The dual corrosion inhibitor strategy relies on the synergistic action of BTA pre-loaded in ZIF-8 nanoparticles and molybdate (MoO42-) intercalated in LDH interlayers for active corrosion protection. Additionally, the nanocontainers enhance passive protection by elongating the diffusion paths of corrosive media and trapping chloride ions. This nanocontainer design offers a facile strategy for fabricating a smart coating with the excellent anticorrosion properties.
•BTA-ZIF-8@LDH-Mo core-shell structured nanocontainers were prepared.•Resulted nanocontainers exhibited effective dual inhibitor release.•The nanocontainers provide both active and passive corrosion protection for waterborne epoxy coating.
As a promising bifunctional electrocatalyst for water splitting, NiFe-layered double hydroxide (NiFe LDH) demonstrates an excellent activity toward oxygen evolution reaction (OER) in alkaline ...solution. However, its hydrogen evolution reaction (HER) activity is challenged owing to the poor electronic conductivity and insufficient electrochemical active sites. Therefore, a three-dimensional self-supporting metal hydroxide/oxide electrode with abundant oxygen vacancies is prepared by electrodepositing CeO x nanoparticles on NiFe LDH nanosheets. According to the density functional theory calculations and experimental studies, the oxygen vacancies at the NiFe LDH/CeO x interface can be introduced successfully because of the positive charges accumulation resulting from the local electron potential difference between NiFe LDH and CeO x . The oxygen vacancies accelerate the electron/ion migration rates, facilitate the charge transfer, and increase the electrochemical active sites, which give rise to an efficient activity toward HER in alkaline solution. Furthermore, NF@NiFe LDH/CeO x needs a lower potential of 1.51 V to drive a current density of 10 mA cm–2 in overall water splitting and demonstrates a superior performance compared with the benchmark Pt/C and RuO2, which is indicated to be a promising bifunctional electrode catalyst.
•A novel layered Ta doped NiFe LDH for electrochemical water splitting catalysis.•Intrinsic electron transfer from Fe to Ta was observed in Ta-NiFe LDH.•The increased activity of OER is due to the ...low coordination state at the Ta-doping site.
Structural manipulation of electrocatalyst via doping strategy has always held great interests for developing advanced and stable non-noble metal electrocatalyst for oxygen evolution reaction (OER). Herein, a high-valence state tantalum (Ta) was incorporated into the pristine NiFe layered double hydroxide (LDH) by hydrothermal method. Interestingly, as revealed by structural characterizations, Ta doping causes the lattice expansion of LDH and electronic structure modification through electron transfer from Fe to Ta. DFT calculations further verified that the modulated electronic structure among Ni, Fe and Ta and the modified eg orbital of Ta induced by charge transfer are beneficial for the adsorption of OH species on Ta site in Ta-doped NiFe LDH and increasing the intrinsic metallic property of NiFe LDH. Consequently, the Ta site has lower overpotential compared with other sites on NiFe LDH including the pristine oxygen vacancies, which can improve the electrocatalytic activity for OER. Furthermore, the optimized Ta-NiFe LDH (0.5:6:1.5) exhibited a superior OER activity in contrast to bimetallic LDH, with a low overpotential of 260 mV to drive the current density of 50 mA·cm−2 and a small Tafel slope of 58.95 mV·dec-1. This work provides the theoretical basis for the enhancement of electrochemical OER activity by doping LDH with high-valence state foreign metal.
Display omitted
•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.
Oxygen evolution reaction (OER) is a significant half-reaction in varied energy conversion devices. Ni-based layered double hydroxides (LDHs) have attracted immense attention recently for OER. ...Herein, we have provided a comprehensive overview of the recent development of the Ni-based LDHs for OER. We firstly introduced some fabrication strategies and in situ characterization followed by some typical Ni-based LDHs as electrocatalysts for OER. Then the structure modifications such as exfoliation, layer composition tuning, interlayer space adjustment and integrating Ni-based LDHs with complementing functional materials were overviewed. Some obstacles that hinder the practical applications of Ni-based LDHs were also discussed and it was pointed out that more efforts should be given to structure rational design and the catalyst application in the real water electrolysis technique. This review can help readers understand the recent development of the Ni-based LDHs and get some insights into the rational design of Ni-based LDHs catalyst and catalytic performance improvement strategy.
TOC:. Display omitted
•Ni-based LDHs were reviewed for oxygen evolution reaction.•Fabrication strategy and in situ characterization overview for some typical Ni-based LDHs materials.•Structure modification and activity correlation for Ni-based LDHs materials.•Problems and challenges for practical application of Ni-based LDHs.
A high removal rate (>99.7%) of combined arsenite (As(III)) and Cd (Cd(II)) in low concentration (1000 μg/L) from contaminated water was achieved by a calcined MgZnFe-CO3 layered double hydroxide ...(CMZF) adsorbent. Batch control studies and a series of spectroscopy detection technologies were employed to investigate the removal mechanism and interactions between As(III) and Cd(II) on the interface of water/CMZF. Synergistic adsorption and photooxidation occurred based on the systematical kinetic and isotherm studies. The enhanced removal of As(III) was achieved by the photooxidation, formation of ternary As(III)Cd(II) surface complexes and enhanced hydrogen bond. Meanwhile, oxidative formed negative charged As(V) could reduce the electrostatic repulsion force between Cd(II) cations and play a role as anion bridging, consequently resulted in a stronger attraction between CMZF and Cd(II). Combined with the verdicts of relevant characterizations such as XRD, XPS and EPR, it was assumed that the deep co-removal mechanism could be attributed to the coupling of various processes including intercalation, complexation, photooxidation of As(III) and precipitation of CdCO3. Moreover, the successful removal of As(III) and Cd(II) from real water matrix qualified the CMZF a potentially attractive adsorbent for both As(III) and Cd(II) deep treatment in practical engineering.
Display omitted
•Multiple functions of photooxidation, precipitation and adsorption were integrated into CMZF nanoparticle.•CMZF exhibits excellent synchronous removal ability towards trace concentration As(III) and Cd(II).•The synergistic interaction among As(III) molecule, As (V) anion and Cd(II) cation in removal process was proposed.•As(III) and Cd(II) in actual water were removed simultaneously and efficiently to satisfy drinking water provision.
Layered double hydroxides (LDHs) have been considered as promising electrodes for supercapacitors due to their adjustable composition, designable function and superior high theoretic capacity. ...However, their experimental specific capacity is significantly lower than the theoretical value due to their small interlayer spacing. Therefore, obtaining large interlayer spacing through the intercalation of large‐sized anions is an important means to improve capacity performance. Herein, a metal organic framework derived cobalt‐nickel layered double hydroxide hollowcage intercalated with different concentrations of 1,4‐benzenedicarboxylic acid (H2BDC) through in‐situ cationic etching and organic ligand intercalation method is designed and fabricated. The superior specific capacity and excellent rate performance are benefit from the large specific surface area of the hollow structure and increasing interlayer spacing of LDH after H2BDC intercalation. The sample with the largest layer spacing displays a maximum specific capacity of 229 mA h g−1 at 1 A g−1. In addition, the hybrid supercapacitor assembled from the sample with the largest layer spacing and active carbon electrode has a maximum specific capacity of 158 mA h g−1 at 1 A g−1; the energy density is as high as 126.4 W h kg−1 at 800 W kg−1 and good cycle stability.
CoNi‐BDC hollowcage is obtained by intercalating H2BDC ligand into the CoNi‐LDH nanocage through in‐situ cationic etching and organic ligand intercalation methods for the first time. The structure design and engineering strategies of molecular layer spacing regulation endow larger specific surface areas and increase the interlayer spacing of CoNi‐LDH, thereby evidently boosting their electrochemical performance.
Seawater electrolysis is an extremely attractive approach for harvesting clean hydrogen energy, but detrimental chlorine species (i.e., chloride and hypochlorite) cause severe corrosion at the anode. ...Here, we report our recent finding that benzoate anions-intercalated NiFe-layered double hydroxide nanosheet on carbon cloth (BZ-NiFe-LDH/CC) behaves as a highly efficient and durable monolithic catalyst for alkaline seawater oxidation, affords enlarged interlayer spacing of LDH, inhibits chlorine (electro)chemistry, and alleviates local pH drop of the electrode. It only needs an overpotential of 320 mV to reach a current density of 500 mA·cm–2 in 1 M KOH. In contrast to the fast activity decay of NiFe-LDH/CC counterpart during long-term electrolysis, BZ-NiFe-LDH/CC achieves stable 100-h electrolysis at an industrial-level current density of 500 mA·cm–2 in alkaline seawater. Operando Raman spectroscopy studies further identify structural changes of disordered δ (NiIII-O) during the seawater oxidation process.
Display omitted
•V-doped ZnFe LDH was synthesized by co-precipitation.•V doping to ZnFe LDH increased the sonocatalytic removal of pymetrozine by 32%.•The synergy factor of the sonocatalytic process ...using V-doped ZnFe LDH was 7.17.•O2•−, h+ and •OH took part in the sonocatalytic degradation of pymetrozine.•The V-doped ZnFe LDH presented high activity stability for five repetitive runs.
In ultrasonic (US) processes, the development of environmentally friendly, effective, low-cost, and durable catalysts is needed to degrade pollutants. Here, ZnFe layered double hydroxide (LDH) was doped with vanadium (V) for the sonocatalytic degradation of a pesticide pymetrozine. The resulting catalyst had an average thickness of 25 nm, a specific surface area of 125.38 m2/g, and a bandgap value of 2.20 eV. In 90 min ultrasonic treatment, V-doped ZnFe LDH had 73% pymetrozine removal efficiency, which was 32% more than that of undoped ZnFe LDH. The US/V-doped ZnFe LDH process had a strong synergistic effect (synergy factor 7.17), which resulted in 57% and 68% greater efficiencies than the US alone and V-doped ZnFe LDH alone, respectively. The role of radical oxygen species was confirmed by carrying out radical trapping experiments using different scavengers and electron paramagnetic resonance analyses. Due to its high stability, the catalyst had good reuse potential with only an 8% performance reduction after 5 reuse cycles. Besides, the leaching of heavy metals was insignificant owing to the high integrity of the catalyst as confirmed by SEM and X-ray diffraction analysis. According to the GC–MS analysis, pymetrozine was first transformed into cyclic compounds then into aliphatic compounds such as animated products and carboxylic acids.
Display omitted
•The high adsorption capacity of A-LDH is due to the metal-chelating function.•The reactive sites in ATMP are firstly revealed by Multiwfn calculation.•The non-covalent interactions ...of water/clay interface are firstly presented by IGM.•IGM analysis confirmed that ATMP/LDH is combined together mainly by H-bond.•The reactive sites and non-covalent interactions support experimental results.
Phosphonates are environmental friendly materials, and can be potentially employed to improve the removal efficiency of the clay materials. In the present work, Zn-Al layered double hydroxide (LDH) intercalated with amino trimethylene phosphonic acid (ATMP) by a facile technique and employed as an adsorbent for Cu2+ and Pb2+ from wastewater. The adsorption characteristics and microscopic mechanism of ATMP in the interlayer space were explored by a combination of experimental and density functional theory (DFT). The adsorption capacity for Cu2+ and Pb2+ could reach 42.02 mg.g−1 and 84.06 mg.g−1, respectively. The adsorption kinetics curves were matched well with the pseudo-second-order model, indicating chemical adsorption via electrostatic interaction mechanism. Based on Multiwfn and VMD program calculation, the ways of electrostatic potential and average local ionization energy were firstly applied to predict reactive sites of ATMP molecule and corresponding anion, suggesting that anion state was more easily to provide lone pair electrons for electrophilic reaction. The weak interaction analysis indicated that interactions among ATMP and LDH are mainly dominated by H-bond. These results recommended that modified LDH can be a promising adsorbent for the adsorption of toxic metal ions in practical applications.
