NiFe LDH Research Articles

Engineering heterogeneous nickel-iron oxide/iron phosphate on P, N co-doped carbon fibers for efficient oxygen evolution reaction in neutral and alkaline solutions

The rational design of heterogeneous catalyst can be favored by synergistic interface for promising water electrolysis performance. Herein, the heterogeneous catalyst of NiFe2O4/Fe3(PO4)2-PNC is prepared from NiFe LDH deposited phytic acid incorporated polyaniline nanofibers (PA-PANI) in situ grown on carbon cloth. The hybrid NiFe2O4/Fe3(PO4)2 nanoparticles acquire modulated OER mechanism due to the promoted proton transfer of phosphate group. The nanoparticles decorated tightly on PNC nanofibers assure high exposure of active sites and fast charge exchange. With the aid of above benefits, the NiFe2O4/Fe3(PO4)2-PNC@CC exhibits good OER activities in neutral and alkaline medias, with low overpotentials of 325 mV and 275 mV at current density of 10 mA cm−2, respectively, showing great potential as pH-tolerant OER catalyst for water splitting.

Preparation of magnetite-nanoparticle-decorated NiFe layered double hydroxide and its adsorption performance for congo red dye removal

Magnetite-nanoparticle-decorated NiFe LDH (MNPs@NiFe LDH) has been synthesized by the coprecipitation method followed by subsequent hydrothermal treatment. Material characterization was conducted using XRD, FTIR, SEM, BET surface area, and TG-DTA. MNPs@NiFe LDH exhibited high crystallinity, where the MNPs are uniformly distributed on its surface. MNPs@NiFe LDH showed higher adsorption capacity for congo red dye removal from an aqueous solution (79.6 mg/g). A further adsorption study, kinetics, isotherm, and thermodynamic indicated that the adsorption mechanism is governed by ionic interaction between the positively charged surface of the LDH and negatively charged dye molecules.

Fabrication of nickel-iron layered double hydroxides using nickel plating wastewater via electrocoagulation, and its use for efficient dye removal

Dye wastewater is one of the most challenging pollutants for environmental protection and safe human health. Therefore, development of high-efficiency, non-toxic, renewable, and low-cost adsorbents for dyestuff wastewater is imperative. Considering the recycling of sludge into a high value-added product and utilizing waste to treat pollution, for the first time, we present a novel electrocoagulation method for fabricating a two-dimensional layered material, Ni-Fe LDH, using nickel plating wastewater as a raw material. The obtained Ni-Fe-10 LDH exhibited excellent removal efficiency for Congo red wastewater, and the theoretical maximum adsorption capacity was 476.19 mg/g, which is a remarkable adsorption ability compared to that of previously reported LDH materials. The analysis based on the structural and morphological characteristics of the sample revealed that the excellent absorption capacity of Ni-Fe-10 could be attributed to the mesoporous structure and morphology of the nanosheet, which provided a high surface area, large pore volumes, and numerous adsorption sites. The adsorbed Congo red dye was desorbed using NaOH solution and methanol, and the regenerated Ni-Fe LDH could be reused in multiple regeneration cycles, achieving 78% removal efficiency even after five cycles. The adsorption process of the dye using the Ni-Fe-10 LDH adsorbent coincided with the Langmuir isotherm and pseudo-second-order kinetic models. XRD and infrared analyses indicated that the adsorption mechanism of Ni-Fe-10 mainly depended on the electrostatic attraction accompanied by simultaneous ion exchange and H-bonding.

In situ hierarchical encapsulation of bimetallic selenides into honeycomb-like nitrogen doped porous carbon nanosheets for highly sensitive and selective guanosine detection

An innovative electrochemical nanocomposite for the detection of guanosine (Gua) was proposed by in situ encapsulation of nickel–iron bimetallic selenides confined into honeycomb-like nitrogen doped porous carbon nanosheets, denoted as (Ni,Fe)Se2/N-PCNs. The porous carbon nanosheets were prepared by utilizing nickel–iron layered double hydroxide (Ni-Fe LDH) as the substrate and zeolitic imidazolate frameworks (ZIF-67) nanocrystals as the sacrificial templates via hydrothermal synthesis, followed by a process of acid etching and pyrolysis selenylation. Interestingly, the nickel-ferric bimetallic selenides material (Ni,Fe)Se2, is rarely fabricated successfully using selenylation treatment, which is a highly conductive and robust support to promote the electron transport. Meanwhile, the obtained (Ni,Fe)Se2/N-PCNs have the favorable architectural features of both unique three-dimensional (3D) porous structural and hierarchical connectivity, which are expected to provide more active sites for electrochemical reactions and ease of electron, ion, and biomolecule penetration. Benefiting from the inherent virtues of its composition, together with unique structural advantages, the (Ni,Fe)Se2/N-PCNs possess ideal sensing properties for guanosine detection with a low detection limit of 1.20 × 10-8 M, a wide linear range of 5.30 × 10-8 ~ 2.27 × 10-4 M and a good stability. Superb selectivity for potential interfering species and superb recoveries in serum suggests its feasibility for practical applications.

Anchoring Active Sites by Pt2FeNi Alloy Nanoparticles on NiFe Layered Double Hydroxides for Efficient Electrocatalytic Oxygen Evolution Reaction

Strategy of anchoring alloy nanoparticles made up of the efficient catalytic element (e.g., Ni, Fe) on dodecyl sulfate (DS‐)‐intercalated NiFe layered double hydroxides (DS‐‐NiFe LDH) obtained by a convenient one‐step hydrothermal coprecipitation method for essentially enhancing oxygen evolution reaction (OER) performance was proposed. The results of structural characterization indicate Pt2FeNi alloy nanoparticles evenly distribute on the surface of DS‐‐NiFe LDH. The sizes of the Pt2FeNi nanoparticles, closely related to their OER performance, could be well‐controlled by adjusting the amount of H2PtCl6 addition. The composite structure of as‐prepared product was stable during processes of synthesis, exfoliation, self‐assembly, and subsequent electrocatalytic OER. Rigorous electrochemical test proving the contributing catalytic active sites was located at the interface between Pt2FeNi and DS‐‐NiFe LDH, and the Ni and Fe were the major active elements while O atoms are adsorption sites. The formation of Pt2FeNi nanoparticles could greatly prompt the reduction of Tafel slope. The best‐performing Pt2FeNi/DS‐‐NiFe LDH with a Pt content of 0.98 wt% achieved low overpotential of 204 mV at 10 mA cm−2 and 262 mV at 50 mA cm−2. This work provides a convenient and effective strategy to create additional active sites for enhancing OER performance of NiFe LDH and make contribution to its wide application.

Electric field polarized sulfonated carbon dots/NiFe layerd double hydroxide as highly efficient electrocatalyst for oxygen evolution reaction

The SO 3 -CDs/NiFe LDH was synthesized through electrochemical and hydrothermal methods. The P-SO 3 -CDs/NiFe LDH catalyst work electrode was obtained via polarized by an electric field of 10,000 V/cm for 30 mins. After that, sulfonate functional groups selectively enrich at the surface of catalysts. Such sulfonate functional groups have a strong ability to capture proton, exhibit excellent OER performances as confirmed by DFT calculation and experimental results. • NiFe LDH/CDs composite was employed as OER catalysts. • Electric field polarization is used to regulate the exposed functional groups. • H + captured from *OH or *OOH species by the sulfonated groups on CDs. • The overpotential is 200 mV@10 mA cm −2 and Tafel slope is 55.2 mV dec −1 . • Polarized catalysts reach a high current density than the unpolarized one. Interfacial design and regulation for electrocatalysts can effectively enhance the performance of oxygen evolution reaction (OER). It is still a challenge to search for a simple and easy way to controllably adjust the interface of catalysts. Here we report a new strategy, electric field polarization to regulate the charged functional groups of nickel–iron layered double hydroxide (NiFe LDH)/carbon dots (CDs) composite catalysts. The selectively exposed sulfonate functional groups on CDs under the electric field have regulated the interfacial environment of the composite catalyst. The density function theory (DFT) calculation also reveals that the high electrocatalytic activity can be attributed to H + capture from *OH or *OOH species by the sulfonated groups on the surface of CDs. Thus, the synergistic effect between the catalytic activity of NiFe LDH and the functional group-modified CDs enhances the OER performance of the composite catalyst, showing low overpotential of 200 mV at 10 mA cm −2 and outstanding kinetics with Tafel slope of 55.2 mV dec −1 . Moreover, the polarized composite catalysts can reach a high current density of 51.7 mA cm −2 at 1.46 V vs. reversible hydrogen electrode (RHE), which is 9.2 times higher than the unpolarized one (5.6 mA cm −2 ).

NiFe LDH/MXene Derivatives Interconnected with Carbon Fabric for Flexible Electromagnetic Wave Absorption.

Cross-linking network structures are critical to construct flexible and lightweight electromagnetic (EM) wave absorbers, for which effective regulation of the EM parameters is essential. Herein, a versatile strategy has been developed by interconnecting carbon fibers with NiFe-layered double hydroxide (NiFe LDH)/MXene derivatives. The large-sized flaky morphology and conductive nature of the interconnectors induce the percolation effect in the fabric networks with ultralow addition. As such, efficient adjustment of the EM parameters can be achieved by tuning the content of the interconnectors around the percolation threshold, giving rise to an optimal reflection loss (RL) of -58.0 dB and a wide effective absorption band (EAB) of 7.0 GHz at a thickness of 2.5 mm under the incorporation of 7.0 wt % NiFe LDH/MXene. This work provides insights on constructing percolation networks and effective manipulation of electronic and magnetic properties, which can be extended to various areas such as sensing, catalysis, and energy storage.

Hydrangea-like sulfide NiFe layered double hydroxides grown on an undulate nickel framework as bifunctional electrocatalysts for overall water splitting

Developing efficient and low-priced catalysts with predominant durableness for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is an extraordinary challenge in the preparation of green hydrogen energy by electrochemical water splitting. Thence, we report a ponderable and accomplished method to fabricate active bifunctional electrocatalysts, in which hydrangea-like NiFe LDH sulfide nanosheets are supported on a hill-like nickel framework (NiFe LDH-Ni-S/NF). This optimal NiFe LDH-Ni-S/NF electrode exhibits excellent electrochemical properties in an alkaline medium, which requires 256 mV to fulfill a current density of 100 mA/cm2 for the OER and 94 mV to reach 10 mA/cm2 for the HER. An electrochemical water splitting appliance uses this bifunctional electrocatalyst as both anode and cathode, exhibiting a small cell potential (1.56 V@10 mA/cm2). Besides, the water electrolyzer can suffer a long time of 20 h at 10 mA/cm2, showing the feasibility in a practical unbiased alkaline water splitting system.

Dendrimer-Ni-Based Material: Toward an Efficient Ni-Fe Layered Double Hydroxide for Oxygen-Evolution Reaction.

Ni/Fe oxides are among the most widely used catalysts for water splitting. This paper outlines a new approach to synthesize Ni-Fe layered double hydroxides (Ni-Fe LDHs) for oxygen-evolution reaction (OER). Herein, we show that a dendrimer with carboxylate surface groups (generation 3.5) could react with Ni(II) ions to form a precatalyst for OER. During electrochemical OER, this precatalyst converted to Ni-Fe LDH, which is an efficient catalyst toward OER in the presence of Fe(III) ions. The catalyst was characterized by a number of methods and applied for OER using fluorine-doped tin oxide (FTO), Au, Pt, Ni foam, and glassy carbon electrodes. The catalyst shows a current density of 100 mA/cm2 on the surface of the Ni foam, using only 297 mV overpotential and with the Tafel slope of 60.8 mV/decade. A current density of 50 mA/cm2 on the surface of Au or Pt requires 333 and 317 mV overpotentials, respectively. The slopes of the Tafel plots for the catalyst on Au, GC, and Pt are 52.5, 47.1, and 37.4 mV/decade, respectively. The dendrimer resulted in a large dispersibility and an increase in active sites of Ni-Fe LDH, as well as the formation of Ni-Fe LDH.

Electrostatic adsorbing graphene quantum dot into nickel–based layered double hydroxides: Electron absorption/donor effects enhanced oxygen electrocatalytic activity

Exploring electrocatalysts with optimal electronic structure and understanding the relationship between electronic structure and activity are highly required for designing advanced OER catalysts. Recently, introducing nanocarbon materials into LDHs has been demonstrated as an effective way to improve the OER activity; however, deeply understanding the regulating effect of nanocarbon on the electronic structure of LDHs is still a critical challenge. Herein, it is reported that the regulating of the surface electronic structure of nickel-based layered double hydroxides (NiM-LDHs (M = Fe, Co, Mn)) by adsorbing graphene quantum dot (GQDs). The Ni-based LDHs/GQDs delivers enhanced OER activity, and particularly NiFe LDH/GQDs achieves an ultralow overpotential of 189 mV (10 mA cm−2) and superior performance in rechargeable Zn–air battery tests. Combining with theoretical calculations and X-ray photoelectron spectroscopy, we ascribe the excellent OER activity of Ni-based LDHs/GQDs to the strong interaction between NiFe LDH and GQDs, which changes the charge distribution around metal ions and triggers the charge accumulation of the active Ni species. The above results demonstrate the significance of controlling the surface electronic structure for designing advanced 3d metal electrocatalysts.

How to get to best oxygen evolution behavior from the electrolysis practice of the seawater

Direct seawater electrolysis is the main method of hydrogen energy production in the future. However, due to the competition of anode chlorine evolution and the phenomenon of cathode fouling, direct seawater electrolysis faces great challenges. Alkali treatment of seawater is the treatment method for most work at present, but there is currently no uniform standard for the amount of alkali. Obviously, excessive alkali treatment will increase operating costs. Here, the NiFe LDH material, which is considered to have the best catalytic OER performance, is grown on carbon cloth, and the optimal amount of alkali treatment seawater is explored. By determining the amount of alkali by the amount of precipitation, it can reduce the operating cost of industrial production. It can also prevent the impact of sedimentation on the life of the equipment. We believe that this treatment method will make a great contribution to the future standard seawater pretreatment method.

Highly efficient oxygen evolution and stable water splitting by coupling NiFe LDH with metal phosphides

It is a great challenge to develop highly active oxygen evolution reaction (OER) electrocatalysts with superior durability. In this study, a NiFe layered double hydroxide-decorated phosphide (NiFe LDH@CoP/NiP3) was constructed to display satisfactory OER activity and good stability for water splitting in alkaline media. At an overpotential of 300 mV, NiFe LDH@CoP/NiP3 achieved a current density of 82 mA cm−2 for the OER, which was 9.1 and 2.3 times that of CoP/NiP3 and NiFe LDH, respectively. Moreover, the reconstruction behavior, during which oxyhydroxides formed, was studied by a combination of X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning electron microscopy. A synergistic effect between NiFe LDH and CoP/NiP3 was also observed for the hydrogen evolution reaction. Furthermore, when NiFe LDH@CoP/NiP3 acted as both the cathode and anode for overall water splitting, a high current density of 100 mA cm−2 was maintained for more than 275 h. In addition, under Xe light irradiation, a solar to hydrogen efficiency of 9.89% was achieved for solar-driven water splitting. This work presents the coupling of different active compositions, and can provide a reference for designing bifunctional electrocatalysts.

Electrocatalytic oxygen evolution surpassing benchmark RuO2 using stable, noble metal free vanadium doped hematite co-modified by NiFe Layered Double Hydroxide

Exploring a low-cost, efficient and stable electrocatalyst to replace noble metal-based catalysts for oxygen evolution reaction (OER) is highly demanding for practical applications. Herein, we have proposed vanadium doping and co-modification of α- Fe2O3 utilizing NiFe LDH for noble metal free electrocatalytic oxygen evolution reaction (OER), which exceeds the performance of benchmark RuO2 under similar experimental conditions. Vanadium doping enhances the carrier density, whereas NiFe LDH contributes to the surface active sites for promoting water oxidation kinetics. A five-fold enhancement in electrochemically active surface area (ECSA) for α- Fe2O3:V-NiFe LDH (2.5 mF/cm2) compared to α- Fe2O3 (0.5 mF/cm2) is observed with a turnover frequency (TOF) of 7.6/s (α- Fe2O3:V-NiFe LDH). α- Fe2O3:V-NiFe LDH exhibited an impressive overpotential of 190 mV @ 10 mA/cm2 with corresponding Tafel slopes of 42 mV/dec. The electrocatalyst, α- Fe2O3:V-NiFe LDH also exhibited excellent durability for over 1000 cycles and continuous chronoamperometric responses for over 12 h at 25 mA/cm2, current density with an average Faradaic yield of 93%. Detailed electrochemical studies with long-term stability indicate the potential of as-synthesized composite α- Fe2O3:V-NiFe LDH for utilization as a heterogeneous catalyst for efficient oxygen evolution reaction.

Cactus-like NiCo2S4@NiFe LDH hollow spheres as an effective oxygen bifunctional electrocatalyst in alkaline solution

The high-performance non-precious electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial to the practical application of fuel cells and metal-air batteries. Herein, a novel cactus-like NiCo2S4@NiFe LDH hollow sphere assembled by one-dimensional (1D) NiFe LDH nanowires and two-dimensional (2D) NiFe LDH nanosheets on the NiCo2S4 hollow spheres is prepared by a facile hydrothermal method. The outer NiFe LDH nanowires and NiFe LDH nanosheets can effectively suppress the collapse and corrosion of inner NiCo2S4 hollow structure during long-term stability tests. The integration of the effective OER electrocatalyst NiFe LDH into NiCo2S4 to form heterostructures, as well as the strong electronic interaction between NiCo2S4 and NiFe LDH, can greatly boost both ORR and OER activities. Due to the above merits, the NiCo2S4@NiFe LDH achieves remarkably a small potential gap (ΔE = Ej=10-E1/2) of only 0.667 V. This work offers a facile strategy to design efficient catalysts with heterostructures.

Boosting oxygen evolution activity of NiFe-LDH using oxygen vacancies and morphological engineering

Oxygen vacancy-rich hierarchical NiFe LDH microtubes with excellent intrinsic conductivity and stability exhibit fantastic OER activity.

Recent advances in highly active nanostructured NiFe LDH catalyst for electrochemical water splitting

The progress in the design strategies and synthetic mechanisms for each class of NiFe LDH electrocatalysts as well as the key trends in structural characterizations in catalyzing the water splitting process are discussed.

Electrochemical oxidation of boron-doped nickel-iron layered double hydroxide for facile charge transfer in oxygen evolution electrocatalysts.

The oxygen evolution reaction (OER) is the key reaction in water splitting systems, but compared with the hydrogen evolution reaction (HER), the OER exhibits slow reaction kinetics. In this work, boron doping into nickel–iron layered double hydroxide (NiFe LDH) was evaluated for the enhancement of OER electrocatalytic activity. To fabricate boron-doped NiFe LDH (B:NiFe LDH), gaseous boronization, a gas–solid reaction between boron gas and NiFe LDH, was conducted at a relatively low temperature. Subsequently, catalyst activation was performed through electrochemical oxidation for maximization of boron doping and improved OER performance. As a result, it was possible to obtain a remarkably reduced overpotential of 229 mV at 10 mA cm−2 compared to that of pristine NiFe LDH (315 mV) due to the effect of facile charge-transfer resistance by boron doping and improved active sites by electrochemical oxidation.

Revealing the effect of interfacial electron transfer in heterostructured Co9S8@NiFe LDH for enhanced electrocatalytic oxygen evolution

The heterointerface between Co9S8 and NiFe LDH decreases Gibbs free energy for the rate-determining step of the OER, thus promoting catalytic activity.

Layered double hydroxide derived bimetallic nickel–iron selenide as an active electrocatalyst for nitrogen fixation under ambient conditions

NiFe–LDH derived nickel–iron selenide can cause an NRR positive process due to the exposure of N2 adsorption sites resulting from the lattice distortion related to the Jahn–Teller effect after selenization.

Rational construction of 3D MoNi/NiMoOx@NiFe LDH with rapid electron transfer for efficient overall water splitting

It is still a great challenge to develop efficient and stable monolithic electrocatalysts with effective cost and abundant natural resources. Herein, a 3D structured NiFe layered double hydroxide (NiFeLDH) nanosheets rationally decorated on MoNi/NiMoOx nanowires array supported on Ni foam (MoNi/NiMoOx@NiFe LDH) are fabricated by an in-situ growth process is firstly reported. The results show that MoNi alloys can build a fast electron transport channel, thus improving the efficiency of the electrocatalyst. And the ultrathin NiFe LDH nanosheets would provide abundant exposed defects and catalytic active sites. A low overpotential (278 mV at 100 mA cm−2) and Tafel slope (44.7 mV dec−1) for oxygen evolution reaction, and overpotential (134 mV at 100 mA cm−2) and Tafel slope of 81.0 mV dec−1 for hydrogen evolution reaction in 1 M KOH can achieved. The overall water splitting system composed with 3D core–shell catalyst (MoNi/NiMoOx@NiFe LDH) and MoNi/NiMoOx nanowire arrays, which can obtain 100 mA cm−2 at a voltage of 1.64V, even superior to the benchmark of IrO2 (+) // Pt/C (-).