Ultrathin Layered Double Hydroxide Research Articles

Ultrathin high-entropy layered double hydroxide electrocatalysts for enhancing oxygen evolution reaction

At the heart of the oxygen evolution reaction (OER), the properties of electrocatalysts play a crucial role in determining reaction efficiency. This underscores the need to design and develop highly effective OER electrocatalysts. The unique layer structure and electronic properties make layer double hydroxide (LDH) a promising candidate for driving OER electrocatalysis. Furthermore, high-entropy materials (HEMs) exhibit core effects such as high entropy, lattice distortion, sluggish diffusion, and cocktail effect, which can enhance active sites and optimize binding energy with intermediates. Combining the advantages of these two material categories, we propose the synthesis of high-entropy layered double hydroxides (HE-LDHs) through a straightforward MOF-mediated synthesis method to showcase exceptional electrocatalytic OER performance. Detailed mechanistic studies have shown that its outstanding performance stems from its ultrathin structure and the inherent activity of a high-entropy material that promotes charge transfer, mass transport, and the evolution of reaction intermediates.

Confined Space Dual-Type Quantum Dots for High-Rate Electrochemical Energy Storage.

Owing to the quantum size effect and high redox activity, quantum dots (QDs) play very essential roles toward electrochemical energy storage. However, it is very difficult to obtain different types and uniformly dispersed high-active QDs in a stable conductive microenvironment, because QDs prepared by traditional methods are mostly dissolved in solution or loaded on the surface of other semiconductors. Herein, dual-type semiconductor QDs (Co9S8 and CdS) are skillfully constructed within the interlayer of ultrathin-layered double hydroxides. Inparticular, the expandable interlayer provides a very suitable confined space for the growth and uniform dispersion of QDs, where Co9S8 originates from in situ transformation of cobalt atoms in laminate and CdS is generated from interlayer pre-embedding Cd2+. Meanwhile, XAFS and GGA+U calculations are employed to explore and prove the mechanism of QDs formation and energy storage characteristics as compared to surface loading QDs. Significantly, the hybrid supercapacitors achieve a high energy density of 329.2µWhcm-2, capacitance retention of 99.1%, and coulomb efficiency of 96.9% after 22000 cycles, which is superior to the reported QDs-based supercapacitors. These findings provide unique insights for designing and developing stable, ordered, and highly active QDs.

Ultra-thin FeCoNi-LDH hollow nanoflower as solid-phase microextraction coating for targeted capture of six pesticides by electrostatic adsorption

Pesticides are common pollutants that cause detriment to the ecological environmental safety and health of human due to their toxicity, volatility and bioaccumulation. In this work, an ultra-thin polymetallic layered double hydroxide (FeCoNi-LDH) with hollow nanoflower structure composite was synthesized using ZIF-67 as a self-sacrificial template, which was used as solid-phase microextraction (SPME) coating for the targeted capture pesticides, which could be combined with high-performance liquid chromatography (HPLC) to sensitive inspection pesticides in real water samples. Orthogonal experimental design (OAD) was applied to ensure the best SPME condition. Additionally, the adsorption properties were evaluated by chemical thermodynamics and kinetics. Under the optimized conditions, high adsorption capacity was obtained (117.0–21.5 mg g−1). A wide linear range (0.020–1000.0 μg L−1), low detection limit (0.008–0.172 μg L−1) and excellent reproducibility were obtained under the established method. This research provided a new strategy for designing hollow materials with multiple cations for the adsorption of anion or organic pollutants.

Intracellular Delivery of Therapeutic Protein via Ultrathin Layered Double Hydroxide Nanosheets.

The therapeutic application of biofunctional proteins relies on their intracellular delivery, which is hindered by poor cellular uptake and transport from endosomes to cytoplasm. Herein, we constructed a two-dimensional (2D) ultrathin layered double hydroxide (LDH) nanosheet for the intracellular delivery of a cell-impermeable protein, gelonin, towards efficient and specific cancer treatment. The LDH nanosheet was synthesized via a facile method without using exfoliation agents and showed a high loading capacity of proteins (up to 182%). Using 2D and 3D 4T1 breast cancer cell models, LDH-gelonin demonstrated significantly higher cellular uptake efficiency, favorable endosome escape ability, and deep tumor penetration performance, leading to a higher anticancer efficiency, in comparison to free gelonin. This work provides a promising strategy and a generalized nanoplatform to efficiently deliver biofunctional proteins to unlock their therapeutic potential for cancer treatment.

One-Step Synthesis of Ultrathin High-Entropy Layered Double Hydroxides for Ampere-Level Water Oxidation

The development of high-entropy anodes, known for their excellent catalytic activity for water oxidation, can depress the energy consumption of hydrogen production by water electrolysis. However, the complex preparation methods and poor stability hindered their practical application. In this work, a one-step co-precipitation method has been modified to rapidly synthesize ultrathin high-entropy layered double hydroxide containing Ni, Co, Fe, Cr, Zn. Through the rational selection of metal elements, the stability of the optimized anode under Ampere-level current density has been significantly improved. Compared to NiFe-LDH, the active site leaching of high-entropy LDH is reduced by 42.7%, and as a result, it achieves a performance decay that is approximately eight times lower than that of NiFe-LDH. Experiment results show that the active sites in the high-entropy LDH can maintain a relatively low oxidation state both before and after activation, thus preventing material deactivation caused by excessive oxidation.

Sonochemical‐Assisted Synthesis of Ultrathin NiCu layered Double Hydroxide for Enhanced CN Coupling toward Electrocatalytic Urea Synthesis

The electrocatalytic carbon–nitrogen (CN) coupling, facilitating one‐step urea synthesis under ambient conditions, holds great promise as a viable alternative to conventional protocols. However, developing efficient and low‐cost electrocatalysts for CN coupling remains a great challenge. Herein, a “bottom‐up” strategy is proposed to synthesize multidimensional hybrid materials of ultrathin NiCu layered double hydroxide (LDH) nanosheets on carbon nanofiber (u‐NiCu‐LDH/CNF) through an ultrasonic‐assisted solvothermal method. The NiCu‐LDH nanosheets in the u‐NiCu‐LDH/CNF composite exhibit a significantly thinner morphology compared to NiCu‐LDH/CNF prepared by conventional solvothermal without ultrasonic assistance. Leveraging its large specific surface area and well‐exposed active sites, the u‐NiCu‐LDH/CNF demonstrates dramatically improved electrocatalytic activity in CN coupling for urea production, leading to a satisfactory urea yield rate (19.43 mmol g−1 h−1) and a high Faradaic efficiency (13.95%). Density functional theory calculations reveal that the CN coupling step on the NiCu‐LDH model starts through the reaction between *NO2 and *CO2 intermediates. This spontaneous CN coupling process is beneficial in promoting high levels of urea yield. This work presents a facile approach for preparing 2D ultrathin LDH, showcasing tremendous prospects in electrocatalytic urea synthesis.

An ultrathin Zn-based layered double hydroxides augment degradation of mutant p53 to improve tumor therapy

Tumor protein 53 (Tp53), a key regulator of suppressor genes, is commonly mutated in numerous malignant diseases. Consequently, elimination mutant protein 53 (mutp53) represents an appealing strategy for treating mutp53-related tumors. However, the treatment of these mutations remained challenging due to its formidable limitations. In this study, by loading glucose oxidase (GOX) into Zn-based layered double hydroxides (Zn-LDH) interlayer, a pH-responsive ultrathin nanotherapeutic platform (Zn-LDH@GOX) was created to suppress tumors growth by degrading mutp53. Upon exposure to the acidic environment of lysosomes, the lattice structure of Zn-LDH@GOX was partially disrupted, leading to the release of Zn2+ ions and GOX into the cytoplasm. The increased intracellular concentration of Zn2+ facilitated the restoration of wild-type protein 53 (wtp53) conformation, which in turn degraded mutp53 through activated autophagic pathways. Meanwhile, GOX-induced Heat Shock Protein 90 (HSP90) disruption resulted in the liberation of mutp53 from the HSP90/mutp53 complex and reactivated its degradation via the ubiquitination-mediated proteasomal pathway. In vitro and in vivo experiments confirmed the significant suppression of mutp53 expression and inhibition of tumor growth by Zn-LDH@GOX. Our work offers a novel pH-responsive nanotherapeutic platform with immense potential for mutp53 tumor-specific therapy.

Engineering Lattice Planes of NiCo-LDH Ultrathin Sheets for Boosting Methanol/Ethanol Oxidation Performance.

Alcohol oxidation reactions are known to be significant in the advancement of sustainable, renewable energy sources. Searching for catalytic materials with powerful, reliable, and economic performance is of great importance. Due to their excellent intrinsic performance, outstanding stability, and inexpensiveness, ultrathin layered double hydroxides (LDHs) are considered to be competitive electrocatalysts. However, the electrocatalytic property of ultrathin LDHs is still confined by the predominant exposure of the (003) basal plane. Hence, we have engineered active edge facets in ultrathin NiCo-LDHs, which possess abundant oxygen vacancies (VO), by a facile one-step strategy. Experimental results show that NiCo-LDH-E synthesized in ethanol demonstrates an ultrathin structure, rich oxygen vacancies, and more active facets, exhibiting a higher electrochemical active area of 3.25 cm2, which is 1.18 times that of NiCo-LDH-W (2.75 cm2). In addition, the current density of NiCo-LDH-E in methanol and ethanol oxidation reactions could reach 159.5 and 136.3 mA cm-2, which are 2.8 and 1.7 times that of NiCo-LDH-W, respectively.

Self-supported ultrathin NiCo layered double hydroxides nanosheets electrode for efficient electrosynthesis of formate

Electrochemical CO2 reduction into energy-carrying compounds, such as formate, is of great importance for carbon neutrality, which however suffers from high electrical energy input and liquid products crossover. Herein, we fabricated self-supported ultrathin NiCo layered double hydroxides (LDHs) electrodes as anode for methanol electrooxidation to achieve a high formate production rate (5.89 mmol h−1 cm−2) coupled with CO2 electro-reduction at the cathode. A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO2 reduction can reach up to 188% driven by a low cell potential of only 2.06 V at 100 mA cm−2 in membrane-electrode assembly (MEA). Physical characterizations demonstrated that Ni3+ species, formed on the electrochemical oxidation of Ni-containing hydroxide, acted as catalytically active species for the oxidation of methanol to formate. Furthermore, DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni3+ in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation. This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.

Bridging Au nanoclusters with ultrathin LDH nanosheets via ligands for enhanced charge transfer in photocatalytic CO2 reduction

Au nanoclusters (NCs) bring new opportunities for constructing visible-light photocatalysts for solar-driven CO2 conversion, whereas the agglomeration under illumination and lack of catalytic sites severely hinder their application. One promising approach to address the limitations is the confinement of Au NCs on a heterogeneous substrate with efficient catalytic sites, in which a concomitant bottleneck originates from the electron transfer between Au NCs and catalytic sites determining the charge transfer dynamics. Herein, we develop an effective strategy for grafting Au NCs onto ultrathin layered double hydroxide (LDH) nanosheets via engineering bridging ligands. The bridging ligands function as both surface anchors and electron mediators, which confine and stabilize Au NCs on LDH, as well as facilitate electron transfer from Au NCs to catalytic sites. As a result, the durability and efficiency for photocatalytic CO2 reduction is significantly enhanced. This work provides a fresh hint for stabilizing ultrasmall nanoclusters and facilitating the electron transfer between light-harvesting nanoclusters and catalytic sites through bridging ligands.

Monodispersed Pt Sites Supported on NiFe-LDH from Synchronous Anchoring and Reduction for High Efficiency Overall Water Splitting.

Precise design of low-cost, efficient and definite electrocatalysts is the key to sustainable renewable energy. Herein, this work develops a targeted-anchored and subsequent spontaneous-redox strategy to synthesize nickel-iron layered double hydroxide (LDH) nanosheets anchored with monodispersed platinum (Pt) sites (Pt@LDH). Intermediate metal-organic frameworks (MOF)/LDH heterostructure not only provides numerous confine points to guarantee the stability of Pt sites, but also excites the spontaneous reduction for PtII . Electronic structure, charge transfer ability and reaction kinetics of Pt@LDH can be effectively facilitated by the monodispersed Pt moieties. As a result, the optimized Pt@LDH that with the 5% ultra-low content Pt exhibits the significant increment in electrochemical water splitting performance in alkaline media, which only afford low overpotentials of 58mV at 10 mAcm-2 for hydrogen evolution reaction (HER) and 239mV at 10 mAcm-2 for oxygen evolution reaction (OER), respectively. In a real device, Pt@LDH can drive an overall water-splitting at low cell voltage of 1.49V at 10 mAcm-2 , which can be superior to most reported similar LDH-based catalysts. Moreover, the versatility of the method is extended to other MOF precursors and noble metals for the design of ultrathin LDH supported monodispersed noble metal electrocatalysts promoting research interest in material design.

Ultrathin NiFe-LDH nanosheets strongly coupled with MOFs-derived hybrid carbon nanoflake arrays as a self-supporting bifunctional electrocatalyst for flexible solid Zn-air batteries

The construction of a hybrid hierarchical architecture is a promising strategy for optimizing the electrocatalytic activity and the performance of flexible Zn-air battery. However, it still remains a challenging task. This study reports on the use of a simple approach in the preparation of a flexible 3D self-supporting bifunctional catalyst. Ultrathin NiFe-based layered double hydroxide nanosheets (NiFe-LDH) have in this approach been strongly coupled to a metal-organic framework (MOF)-derived carbon nanoflake array, to be used in flexible Zn-air batteries. Importantly, the introduction of Co nanoparticles that were anchored onto the nitrogen-doped porous carbon (Co-NC) nanoflakes provided an abundance of active sites for the oxygen reduction reaction (ORR). Moreover, the catalytic oxygen evolution reaction (OER) process was improved by altering the local electronic structure of the Ni and Fe species in NiFe-LDH. The 3D interconnected conductive network structure, in addition to the strong coupling between NiFe-LDH and Co-NC, was found to give a catalyst with superior electrocatalytic OER performances. The overpotential was only 284 mV at 50 mA cm−2 in an alkaline medium, which is a result that outperforms the commercial RuO2 catalyst. This bifunctional catalyst did also exhibit a good catalytic performance that is comparable to that of commercial Pt/C towards ORR. Interestingly, when this catalyst was used as binder-free air cathode, the assembled flexible solid-state Zn-air battery demonstrated a favorable power density, cycling stability, and mechanical flexibility. The present work offers a facile and efficient strategy for the development and construction of self-supporting bifunctional OER/ORR electrocatalysts, to be used in wearable and flexible electronic devices.

Controllable Synthesis of Ultrathin Defect-Rich LDH Nanoarrays Coupled with MOF-Derived Co-NC Microarrays for Efficient Overall Water Splitting.

Water electrolysis has attracted immense research interest, nevertheless the lack of low-cost but efficient bifunctional electrocatalysts for both hydrogen and oxygen evolution reactionsgreatly hinders its commercial applications. Herein, the controllable synthesis of ultrathin defect-rich layered double hydroxide (LDH) nanoarrays assembled on metal-organic framework (MOF)-derived Co-NC microarrays for boosting overall water splitting is reported. The Co-NC microarrays can not only provide abundant nucleation sites to produce a large number of LDH nuclei for favoring the growth of ultrathin LDHs, but also help to inhibit their tendency to aggregate. Impressively, five types of ultrathin bimetallic LDH nanoarrays can be electrodeposited on the Co-NC microarrays, forming desirable nanoarray-on-macroarray architectures, which show high uniformity with thicknesses from 1.5 to 1.9nm. As expected, the electrocatalytic performance is significantly enhanced by exploiting the respective advantages of Co-NC microarrays and ultrathin LDH nanoarrays as well as the potential synergies between them. Especially, the optimal Co-NC@Ni2 Fe-LDH as both cathode and anode can afford the lowest cell voltage of 1.55V at 10mA cm-2 , making it one of the best earth-abundant bifunctional electrocatalysts for water electrolysis. This study provides new insights into the rational design of highly-active and low-cost electrocatalysts and facilitates their promising applications in the fields of energy storage and conversion.

Photoactivation-triggered in situ self-supplied H2O2 for boosting chemodynamic therapy via layered double Hydroxide-mediated catalytic cascade reaction

Chemodynamic therapy (CDT) has aroused extensive interest as an advanced anti-cancer approach which is featured with high tumor specificity and selectivity. However, chemodynamic therapeutic efficacy heavily relies on the level of endogenous hydrogen peroxide (H2O2), which is intrinsically heterogenous and insufficient. Herein, a self-supplied H2O2 enhanced chemodynamic therapeutic strategy is developed by constructing a two-dimensional (2D) sheet-like nanocatalyst to mediate catalytic cascade reactions. The cascade nanocatalyst is fabricated by integrating photosensitizer indocyanine green (ICG) and Fenton reaction catalyst Fe2+ ions into a 2D ultrathin layered double hydroxide nanoparticles (NPs). Under near infrared light irradiation, ICG not only produces cytotoxic singlet oxygen (1O2) to damage tumor cells, but also generates superoxide radical (O2·-) that is subsequently converted into H2O2 by reacting with intracellular superoxide dismutase (SOD). A considerable amount of in situ self-supplied H2O2, together with endogenous H2O2, is then catalyzed by Fe2+ released from nanocatalyst to produce abundant, highly cytotoxic hydroxyl radicals (·OH) to trigger apoptosis and death of tumor cells. In vitro and in vivo evaluations manifest the cascade nanocatalyst-mediated remarkable chemodynamic therapeutic performance. Therefore, this work has demonstrated a cascade catalytic therapeutic nanoplatform enabling photoactivation-triggered H2O2 self-supplied synergistic strategy for safe and efficacious tumor treatment.

Universal Strategy for Preparing Highly Stable PBA/Ti3C2Tx MXene toward Lithium-Ion Batteries via Chemical Transformation.

Prussian blue analogues (PBAs) are believed to be intriguing anode materials for Li+ storage because of their tunable composition, designable topologies, and tailorable porous structures, yet they suffer from severe capacity decay and inferior cycling stability due to the volume variation upon lithiation and high electrical resistance. Herein, we develop a universal strategy for synthesizing small PBA nanoparticles hosted on two-dimensional (2D) MXene or rGO (PBA/MX or PBA/rGO) via an in situ transformation from ultrathin layered double hydroxides (LDH) nanosheets. 2D conductive nanosheets allow for fast electron transport and guarantee the full utilization of PBA even at high rates; at the meantime, PBA nanoparticles effectively prevent 2D materials from restacking and facilitate rapid ion diffusion. The optimized Ni0.8Mn0.2-PBA/MX as an anode for lithium-ion batteries (LIBs) delivers a capacity of 442 mAh g-1 at 0.1 A g-1 and an excellent cycling robustness in comparison with bare PBA bulk crystals. We believe that this study offers an alternative choice for rationally designing PBA-based electrode materials for energy storage.

Ultrathin Nanosheet-Supported Ag@Ag2O Core-Shell Nanoparticles with Vastly Enhanced Photothermal Conversion Efficiency for NIR-II-Triggered Photothermal Therapy.

Photothermal therapy (PTT) working in the second near-infrared (NIR-II) region has aroused a huge interest due to its potential application in terms of clinical cancer treatment. However, owing to the lack of photothermal nanoagents with high photothermal conversion efficiency, NIR-II-driven PTT still suffers from poor efficiency and subsequent cancer recurrence. In this work, we show a new and highly efficient preparation approach for NIR-II photothermal nanoagents and tailor ultrathin layered double hydroxide (LDH)-supported Ag@Ag2O core-shell nanoparticles (Ag@Ag2O/LDHs-U), vastly improving NIR-II photothermal performance. A combination study (high-resolution transmission electron microscopy (HRTEM), extended X-ray absorption fine structure spectroscopy (EXAFS), and X-ray photoelectron spectroscopy (XPS)) verifies that ultrafine Ag@Ag2O core-shell nanoparticles (∼3.8 nm) are highly dispersed and firmly immobilized within ultrathin LDH nanosheets, and their Ag2O shell possesses abundant vacancy-type defects. These unique Ag@Ag2O/LDHs-U display an impressive photothermal conversion efficiency as high as 76.9% at 1064 nm. Such an excellent photothermal performance is likely attributed to the enhanced localized surface plasmon resonance (LSPR) coupling effect between Ag and Ag2O and the reduced band gap caused by vacancy-type defects in the Ag2O shell. Meanwhile, Ag@Ag2O/LDHs-U also show prominent photothermal stability, due to the unique supported core-shell nanostructure. Moreover, both in vitro and in vivo studies further confirm that Ag@Ag2O/LDHs-U possess good biocompatible properties and outstanding PTT therapeutic efficacy in the NIR-II region. This research shows a new strategy in the rational design and preparation of an efficient photothermal agent, which is helpful to achieve more accurate and effective cancer theranostics.

Co2 Methanation Over Catalyst Derived from Ultrathin Nizral Layered Double Hydroxide Nanosheets Precursor

Co2 Methanation Over Catalyst Derived from Ultrathin Nizral Layered Double Hydroxide Nanosheets Precursor

Zif-67-Derived Ultrathin Co-Ni Layered Double Hydroxides Wrapped on 3d G-C3n4 with Enhanced Visible-Light Photocatalytic Performance for Greenhouse Gas Co2 Reduction

Zif-67-Derived Ultrathin Co-Ni Layered Double Hydroxides Wrapped on 3d G-C3n4 with Enhanced Visible-Light Photocatalytic Performance for Greenhouse Gas Co2 Reduction

Hierarchical ultrathin NiFe-borate layered double hydroxide nanosheets encapsulated into biomass-derived nitrogen-doped carbon for efficient electrocatalytic oxygen evolution

Exploring highly efficient, cost-effective, and stable electrocatalysts toward oxygen evaluation reaction (OER) is of great significance for hydrogen generation. Herein, in situ growth of NiFe-borate layered double hydroxide (NiFe-BLDH) nanosheets on waste biomass-derived nitrogen-doped carbon (NC) with hierarchical architecture under microwave hydrothermal conditions is reported. The as-synthesized NiFe-borate layered double hydroxide/nitrogen-doped carbon (NiFe-BLDH/NC) exhibits outstanding OER activity, showing an extremely low overpotential of 243 mV at the current density of 10 mA cm−2 and a relatively small Tafel slope of 42.7 mV dec−1, which are superior to the commercial RuO2 and many previously reported NiFe-LDH-based OER electrocatalysts. Additionally, the catalyst also shows remarkable stability with unobvious decrease of current density over a period of 24 h. These excellent catalytic performances could be attributable to the synergistic effects between the conductive NC scaffold and NiFe-BLDH with excellent hydrophilicity caused by the intercalated borate anions, which provide many advantages, such as large surface area, abundant active sites, fast charge and mass transport pathways. This work provides new insights into the design and facile preparation green and efficient electrocatalysts

Precursor-mediated synthesis of interconnected ultrathin NiFe-layered double hydroxides nanosheets for efficient oxygen evolution electrocatalysis

Developing two-dimensional layered double hydroxides (LDHs) electrocatalysts with high efficiency for oxygen evolution reaction (OER) is crucial to the electrocatalytic water splitting. However, the large thickness of the bulk LDHs electrocatalysts greatly limit the OER activity. Hereby, a simple precursor-mediated strategy for synthesis of interconnected ultrathin NiFe-layered double hydroxides (NiFe-LDHs) nanosheets is first proposed, taking the “pre-synthesized” Ni-Fe alkoxides as precursors. The electrochemical studies illustrate that Ni2Fe1-LDHs catalyst with the optimum Ni/Fe ratio shows excellent low overpotential of 245 mV at 10 mA cm−2 and the Tafel slope of 57 mV dec−1, superior to commercial IrO2 and most reported the Ni, Fe based LDH OER electrocatalysts previously, indicating its enormous potential as a low-cost and efficient electrocatalyst for OER. We anticipated that the precursor-mediated synthetic strategy would open a new avenue to offer ultrathin LDHs based electrocatalysts for water splitting.