NiFe Layered Double Hydroxide Research Articles

Integrating Sulfur Doping with a Multi-Heterointerface Fe7S8/NiS@C Composite for Wideband Microwave Absorption.

Heterointerface engineering is presently considered a valuable strategy for enhancing the microwave absorption (MA) properties of materials via compositional modification and structural design. In this study, a sulfur-doped multi-interfacial composite (Fe7S8/NiS@C) coated with NiFe-layered double hydroxides (LDHs) is successfully prepared using a hydrothermal method and post-high-temperature vulcanization. When assembled into twisted surfaces, the NiFe-LDH nanosheets exhibit porous morphologies, improving impedance matching, and microwave scattering. Sulfur doping in composites generates heterointerfaces, numerous sulfur vacancies, and lattice defects, which facilitate the polarization process to enhance MA. Owing to the controllable heterointerface design, the unique porous structure induced multiple heterointerfaces, numerous vacancies, and defects, endowing the Fe7S8/NiS@C composite with an enhanced MA capability. In particular, the minimum reflection loss (RLmin) value reached -58.1dB at 15.8GHz at a thickness of 2.1mm, and a broad effective absorption bandwidth (EAB) value of 7.3GHz is achieved at 2.5mm. Therefore, the Fe7S8/NiS@C composite exhibits remarkable potential as a high-efficiency MA material owing to the synergistic effects of the polarization processes, multiple scatterings, porous structures, and impedance matching.

Electrodeposition Fabrication of La-Doped NiFe Layered Double Hydroxide to Improve Conductivity for Efficient Overall Water Splitting

Electrodeposition Fabrication of La-Doped NiFe Layered Double Hydroxide to Improve Conductivity for Efficient Overall Water Splitting

Effect of Interlayer Anions on NiFe Layered Double Hydroxides for Catalytic Ozone Decomposition.

NiFe layered double hydroxides (NiFe-LDH) exhibited an outstanding performance and promising application potential for removing ozone. However, the effect of interlayer anions on ozone removal remains ambiguous. Here, a series of NiFe-LDH with different interlayer anions (F-, Cl-, Br-, NO3-, CO32-, and SO42-) were prepared to investigate the effect of the interlayer anion on ozone removal for the first time. It was found that the interlayer anions are a key factor affecting the water resistance of the NiFe-LDH catalyst under moist conditions. NiFe-LDH-CO32- exhibited the best water resistance, which was much better than that of NiFe-LDH containing other interlayer anions. The in situ DIRFTS demonstrates that the carbonates in the interlayer of NiFe-LDH-CO32- will undergo coordination changes through the interaction with water molecules under moist conditions, exposing new metal sites. As a result, the newly exposed metal sites could activate water molecules into hydroxyl groups that act as active sites for catalyzing ozone decomposition. This work provides a new insight into the interlayer anions of LDH, which is important for the design and development of LDH catalysts with excellent ozone removal properties.

Two-Dimensional SnS Mediates NiFe-LDH-Layered Electrocatalyst toward Boosting OER Activity for Water Splitting.

NiFe-layered double hydroxides (NiFe-LDHs), as promising electrocatalysts, have received significant research attention for hydrogen and oxygen generation through water splitting. However, the slow oxidation kinetics of NiFe-LDH, due to the limited number of active sites and the low conductivity, hinders the improvement of the water-splitting efficiency. Therefore, to overcome the obstacles, two-dimensional (2D) SnS was first explored to tailor the prepared NiFe-LDH via the hydrothermal method. A NiFe-LDH/SnS heterojunction is built, which is observed from the microstructural investigations. SnS incorporation could greatly improve the conductivity of the NiFe-LDH sheets, which was reflected by the reduced charge transfer resistance. Moreover, SnS layers modulated the electronic environment around the active sites, favoring the adsorption of intermediates during the oxygen evolution reaction (OER) process, which was verified by density functional theory calculations. A synergistic effect induced by the NiFe-LDH/SnS heterostructure promoted the OER activities in electrical, electronic, and energetic aspects. Consequently, the as-prepared NiFe-LDH/SnS electrocatalyst greatly improved the electrocatalytic performance, exhibiting 20% and 27% reductions in the overpotential and Tafel slope compared with those of pristine NiFe-LDH, respectively. The results provide a strategy for regulating NiFe-based electrocatalysts by using emerging 2D materials to enhance water-splitting efficiency.

Tribological Behavior of GTL Base Oil Improved by Ni-Fe Layered Double Hydroxide Nanosheets

The layered double hydroxide (LDH) has been practically applied in the field of tribology and materials science due to its unique physicochemical properties, weak bonding, flexible structural composition, and adjustable interlayer space. In this work, a series of ultrathin and flexible composition of Ni-Fe LDH samples were prepared via a cost-effective room-temperature co-precipitation process. Then, they were mechanically dispersed into GTL base oil and their lubricating performance were tested by a four-ball tribometer. It is found that the variation of Ni-Fe ratio of Ni-Fe LDH has a great influence on the improvement of lubricating performance of GTL base oil. At the same concentration (0.3 mg/mL), the Ni-Fe LDH with Ni/Fe ratio of 6 was demonstrated to exhibit the best lubricating performance and the AFC, WSD, the wear volume, surface roughness and average wear scar depth decreased 51.3%, 30.8%, 78.4%, 6.7% and 50.0%, respectively. SEM-EDS and X-ray photoelectron spectra illustrated that the tribo-chemical film consisting of iron oxides and NiO with better mechanical properties formed and slowly replaced the physical film, which resists scuffing and protect solid surface from severe collisions.

Unravelling the Photoelectrochemical Water Splitting of Nanometer-Thick Carbon Nitride Layer.

Matching the thickness of the graphitic carbon nitride (CN) nanolayer with the charge diffusion length is expected to compensate for the poor intrinsic conductivity and charge recombination in CN for photoelectrochemical cells (PEC). Herein, the compact CN nanolayer with tunable thickness is in situ coated on carbon fibers. The compact packing along with good contact with the substrate improves the electron transport and alleviates the charge recombination. The PEC investigation shows CN nanolayer of 93nm-thick yields an optimum photocurrent of 116µAcm-2 at 1.23V versus RHE, comparable to most micrometer-thick CN layers, with a low onset potential of 0.2V in 1m KOH under 1 sun illumination. This optimum performance suggests the electron diffusion length matches with the thickness of the CN nanolayer. Further deposition of NiFe-layered double hydroxide enhanced the surface water oxidation kinetics, delivering an improved photocurrent of 210µAcm-2 with IPCE of 12.8% at 400nm. The CN nanolayer also shows extended potential in PEC organic synthesis. This work experimentally reveals the PEC behavior of the nanometer-thick CN layer, providing new insights into CN in the application of energy and environment-related fields.

Highly Stable Mo-NiO@NiFe-Layered Double Hydroxide Heterojunction Anode Catalyst for Alkaline Electrolyzers with Porous Membrane.

Heterostructure catalysts are considered as promising candidates for promoting the oxygen evolution reaction (OER) process due to their strong electron coupling. However, the inevitable dissolution and detachment of the heterostructure catalysts are caused by the severe reconstruction, dramatically limiting their industrial application. Herein, the NiFe-layered double hydroxide (LDH) nanosheets attached on Mo-NiO microrods (Mo-NiO@NiFe LDH) by the preoxidation strategy of the core NiMoN layer are synthesized for ensuring the high catalytic performance and stability. Owing to the enhanced electron coupling and preoxidation process, the obtained Mo-NiO@NiFe LDH exhibits a superlow overpotential of 253 mV to achieve a practically relevant current density of 1000 mA cm-2 for OER with exceptional stability over 1200 h. Notably, the overall water splitting system based on Mo-NiO@NiFe LDH reveals remarkable stability, maintaining the catalytic activity at a current density of 1000 mA cm-2 for 140 h under industrial harsh conditions. Furthermore, the Mo-NiO@NiFe LDH demonstrates outstanding activity and long-term durability in a practical alkaline electrolyzer assembly with a porous membrane, even surpassing the performance of IrO2. This work provides a new sight for designing and synthesizing highly stable heterojunction electrocatalysts, further promoting and realizing the industrial electrocatalytic OER.

Electrodeposited NiFe‐LDH on the Surface of Ni‐BDC for Electrocatalytic Water Oxidation

Substrate surface modification with a functional material can effectively enhance the electrocatalytic performance of an electrode on oxygen evolution reaction (OER). In this work, a functional Ni‐BDC MOF nanosheet layer was in‐situ grown on the surface of nickel foam (NF). Consequently, the NiFe layered double hydroxides (NiFe‐LDH) electrodeposited on the modified layer exhibited an excellent activity and an amazing long‐term stability on electrocatalytic OER. In alkaline electrolyte, the well‐designed NiFe‐LDH/Ni‐BDC/NF drives a current density of 100 mA cm‐2 at a small overpotential of 223 mV, with a low Tafel slope of 33.1 mV dec‐1 and an outstanding catalytic stability of more than 10 days under continuous electrocatalysis. Such distinguished performances are attributed to the particular hydrophily and electrical conductivity of the Ni‐BDC layer. This work is an important attempt to bring a simple and effective guideline on fabricating a highly efficient catalytic electrode for OER.

Stably Improving the Catalytic Activity of Oxygen Evolution Reactions via Two-Dimensional Graphene Oxide-Incorporated NiFe-Layered Double Hydroxides

Stably Improving the Catalytic Activity of Oxygen Evolution Reactions via Two-Dimensional Graphene Oxide-Incorporated NiFe-Layered Double Hydroxides

Guided Design of Efficient Oxygen Evolution Catalysts Using Patent Analysis.

The facile and rapid design of efficient oxygen evolution reaction (OER) catalysts holds paramount significance for energy conversion devices, such as water electrolyzers and fuel cells. Despite substantial progress in catalyst synthesis and performance exploration, the design and selection processes remain inefficient. In this context, we integrate patent analysis with catalyst design, leveraging the scholarly research functionalities within patent analyses to aid in the design and synthesis of a NiFeRu-carbon catalyst as a high-performance OER catalyst. The results demonstrate that the NiFeRu-Carbon catalyst with low Ru loading (0.3 wt %) exhibits an overpotential of only 219 mV at 10 mA cm-2 under alkaline conditions, and after continuous operation for 200 h, the overpotential only attenuates by 15 mV. The incorporation of high-valence Ru dopants elevated the intrinsic activity of individual catalytic sites within NiFe-layered double hydroxides (LDHs). During the catalytic process, the partial dissolution of Ru might lead to the generation of numerous oxygen vacancies within NiFe- LDH, thereby enhancing the catalyst's activity and stability.

Metallic nonstoichiometric WO3–x-decorated NiFe-layered double hydroxide for boosted urea electro-oxidation reaction: the facilitated dynamics and increasing active sites

Metallic nonstoichiometric WO3–x-decorated NiFe-layered double hydroxide for boosted urea electro-oxidation reaction: the facilitated dynamics and increasing active sites

Graphene Materials from Coke-like Wastes as Proactive Support of Nickel-Iron Electro-Catalysts for Water Splitting.

Graphene materials, used as electrocatalyst support in green hydrogen production, contribute to increasing the efficiency and robustness of various systems. However, the preparation of a hybrid catalyst containing graphene materials from industrial wastes is still a challenge due to the heterogeneity of the waste. We report the synthesis of 3D electrodes using graphene oxides (GOs) from industrial waste (IW) prepared by immersion onto Toray carbon paper as a 3D support onto GO suspensions and electrodepositing NiFe layered double hydroxides (LDHs). Standard graphite was also used as the reference. The morphology of the two hybrid electrodes was determined by SEM, HRTEM, XPS. Although very similar in both, the sample containing graphene from IW (higher Csp3 hybridization in the graphene layer) has a NiFe phase with less crystallinity and larger presence of Fe2+ ions. These electrodes exhibited similar activity and stability as electrocatalysts of the oxygen evolution reaction (OER), demonstrating the proactive effect of the graphene into the 3D electrode even when this is prepared from heterogeneous industrial waste. Moreover, the defective graphenic structure of the waste GO enhances the reaction kinetics and improves the electron transfer rate, possibly due to the small differences in the electrodeposited NiFe LDH structure.

Ag engineered NiFe-LDH/NiFe2O4 Mott-Schottky heterojunction electrocatalyst for highly efficient oxygen evolution and urea oxidation reactions

Efficient and durable electrocatalysts with sufficient active sites and high intrinsic activity are essential for advancing energy-saving hydrogen production technology. In this study, a Mott-Schottky heterojunction electrocatalyst with Ag nanoparticles in-situ grown on NiFe layered double hydroxides (NiFe-LDH)/NiFe2O4 nanosheets (Ag@NiFe-LDH/NiFe2O4) were designed and successfully synthesized through a hydrothermal process and subsequent spontaneous redox reaction. The in-situ growth of metallic Ag on semiconducting NiFe-LDH/NiFe2O4 triggers a strong electron interaction across the Mott-Schottky interface, leading to a significant increase in both the intrinsic catalytic activity and the electrochemical active surface area of the heterojunction electrocatalyst. As a result, the Ag@NiFe-LDH/NiFe2O4 demonstrates impressive oxygen evolution reaction (OER) performance in alkaline KOH solution, achieving a low overpotential of 249 mV at 100 mA cm−2 and a Tafel slope of 42.79 mV dec−1. When the self-supported Ag@NiFe-LDH/NiFe2O4 is coupled with the Pt/C electrocatalyst, the alkaline electrolyzer reaches a current density of 10 mA cm−2 at a cell voltage of only 1.460 V. Furthermore, X-ray photoelectron spectroscopy and in-situ Raman analysis reveal that the Ni(Fe)OOH is the possible active phase for OER in the catalyst. In addition, when employed for UOR catalysis, the Ag@NiFe-LDH/NiFe2O4 also displays intriguing activity with an ultralow potential of 1.389 V at 50 mA cm−2. This work may shed light on the rational design of multiple-phase heterogeneous electrocatalysts and demonstrate the significance of interface engineering in enhancing catalytic performance.

Surface-derived phosphate layer on NiFe-layered double hydroxide realizes stable seawater oxidation at the current density of 1 A°cm−2

Surface-derived phosphate layer on NiFe-layered double hydroxide realizes stable seawater oxidation at the current density of 1 A°cm−2

LDH/MXene Synergistic Carrier Separation Effects to Improve the Photoelectric Catalytic Activities of Bi2WO6 Nanosheet Arrays.

Photoelectric catalysis is a green and efficient way to degrade pollutants, which has been paid more and more attention by researchers. Among them, Bi2WO3 has been proved to have excellent photocatalytic oxidation activity on its {001} facets. In this study, {001}-oriented facets with high exposure were successfully integrated into Bi2WO6 nanoplate arrays (Bi2WO6 NAs) to create a photoelectrode. This structure was grown in situ on an indium tin oxide (ITO) substrate. To promote photogenerated carrier separation efficiency and reduce agglomeration of Bi2WO6 photocatalysts, the electrochemical deposition of NiFe-layered double hydroxide (NiFe-LDH) and Ti3C2 (MXene) were introduced in this research to synergistically catalyze pollutant degradation. Morphology, spectral characterization, and electrochemical analysis jointly confirmed that the outstanding performance of hole capture behavior with LDH and electron conduction properties with MXene were the main reasons for the improvement in catalytic activity of the photoelectrode. Taking bisphenol A (BPA) as the model pollutant, the rate constant k of the NiFe-LDH/Ti3C2/Bi2WO6 NAs photoelectrode reaches 0.00196 min-1 under photoelectrocatalytic (PEC) conditions, which is 4.5 times that of the pure Bi2WO6 NAs photoelectrode. This work provides a new way to improve the reaction kinetics of the PEC degradation of pollutants.

An efficient solution based on the synergistic effects of nickel foam in NiFe-LDH nanosheets for oil/water separation

Efficient oil-water separation has always been a research hotspot in the field of environmental studies. Employing a one-step hydrothermal approach, NiFe-layered double hydroxides (LDH) nanosheets were synthesized on nickel foam substrates. The resulting NiFe-LDH/NF membrane exhibited rejection rates exceeding 99% across six diverse oil-water mixtures, concurrently demonstrating a remarkable ultra-high flux of 1.4 × 106 L·m−2·h−1. This flux value significantly surpasses those documented in existing literature, maintaining stable performance over 1000 manual filtration cycles. These breakthroughs stem from the synergistic interplay among the three-dimensional channels of the nickel foam, the nanosheets, and the hydration layer. By leveraging the pore size of the foam to enhance the functionality of the hydration layer, the conventional trade-off between permeability and selectivity was transformed into a balanced force relationship between the hydration layer and the oil phase. The operational and failure mechanisms of the hydration layer were examined using the prepared NiFe-LDH/NF membrane, validating the correlation between oil phase viscosity and density with hydration layer rupture. Additionally, an extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory was employed to investigate changes in interaction energy, further reinforcing the study's findings. This research contributes novel insights and assistance to the comprehension and application of hydration layers in other membrane studies dedicated to oil-water separation.

Defect Engineering of Oxygen Vacancies in Ultrathin NiFe-Layered Double Hydroxides: Insights from Density Functional Theory

Defect Engineering of Oxygen Vacancies in Ultrathin NiFe-Layered Double Hydroxides: Insights from Density Functional Theory

Synthesis of 3D CC/NCNF/NiFe LDH composites as highly active oxygen evolution reaction electrocatalysts

Nitrogen doped carbon nanofibers (NCNFs), which are grown on carbon cloth (CC) and loaded with NiFe layered double hydroxide (LDH) nanosheets, are synthesized by chemical vapor deposition, ammonia annealing and electrodeposition. The obtained three dimensional CC/NCNF/NiFe LDH composites demonstrate an overpotential of 220 mV at current density of 10 mA cm−2 and a small Tafel slope of 30 mV dec−1 for oxygen evolution reaction (OER), both of which are superior to those of the state-of-the-art iridium oxide catalysts. The excellent OER performances of the CC/NCNF/NiFe LDH composites may be attributed to collective contributions of large surface areas of CNFs, nitrogen doping and synergy between NCNFs and NiFe LDHs.

Dual efficiency enhancement in overall water splitting with defect-rich and Ru atom-doped NiFe LDH nanosheets on NiCo2O4 nanowires

The development of layered double hydroxides (LDHs) as bifunctional catalysts for efficient overall water splitting by controlling the composition and structure of the material remains challenging. In this study, defect-rich and Ru-doped NiFe LDH nanosheet shells on NiCo2O4 (NCO) nanowires were successfully synthesized using a hydrothermal method, followed by alkaline etching. The resulting def-Ru-NiFe LDH/NCO (def = defects) catalyst exhibited remarkable catalytic activity with overpotentials of 122 and 225 mV for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, at a current density of 10 mA cm−2. Density functional theory calculations demonstrated that atomic vacancy defects and the rational incorporation of Ru single atoms in def-Ru-NiFe LDH/NCO induced the regulation of the electronic structure and optimized the adsorption energies, thus enhancing the OER and HER performances. Particularly, an electrolyzer utilizing def-Ru-NiFe LDH/NCO exhibited exceptional performance, achieving cell voltages of 1.58 and 1.46 V in 1 M KOH at 25 and 75 °C, respectively. Moreover, the catalyst exhibited outstanding stability during 60 h of operation at a high applied voltage and temperature (75 °C). These results highlight the potential of def-Ru-NiFe LDH/NCO for hydrogen production.

NiFe layered double hydroxide (LDH) anchored, Fe single atom and nanoparticle embedded on nitrogen-doped carbon-CNT (carbon nanotube) framework as a bifunctional catalyst for rechargeable zinc-air batteries

Zinc-air batteries (ZAB) have significant potential for practical energy storage, but their rechargeability has been limited by the lack of a suitable bifunctional catalyst. Here, we developed NiFe LDH-A-Fe/NC-CNT, a remarkable bifunctional catalyst that is built on a hierarchically porous nitrogen-doped carbon and carbon nanotube (NC-CNT) framework enriched with iron single atoms and nanoparticles, with nickel‑iron layered double hydroxides (NiFe LDH) anchored onto it. The NiFe LDH-A-Fe/NC-CNT exhibited remarkable performance in the ORR, with Eonset of 0.94 V, a half-wave potential of 0.84 V, and a limited current of 6.89 mA cm−2. A remarkable Eonset of 1.47 V and a potential of 1.59 V at 10 mA cm−2 (Ej = 10) in the OER were also observed. Significantly, the difference in potential (ΔE) between the ORR and OER was only 0.74 V. The stability tests, tolerance assessments, and poisoning experiments consistently demonstrated the superior performance of this cutting-edge catalyst in comparison to the commercial Pt/C and RuO2. In ZAB tests, it achieves a discharge capacity of 818 mAhg−1 and an impressive power density of 293 mWcm−2, enduring nearly 1000 cycles (320h). Flexible ZABs with this catalyst maintain a 629 mAhg−1 capacity, a power density of 195 mWcm−2, and a lifespan of 95 h (280 cycles), outperforming benchmark catalysts. In conclusion, a remarkable bifunctional catalyst was synthesized, demonstrating its immense capacity for utilization in zinc-air batteries.