NiFe-LDH Nanosheets Research Articles

Iron-nickel layered dihydroxide nanosheet-wrapped single-layer ordered mesoporous carbon with novel riveting structure as a superior composite electrocatalyst for oxygen evolution reaction

Iron-nickel layered hydroxide (FeNi LDH) electrocatalysts have low overpotential for the oxygen evolution reaction (OER) in alkaline environments but poor conductivity. The cutting-edge solution is to combine nano-FeNi LDHs with conductive carbon materials. However, the inevitable carbon corrosion during alkaline electrolysis makes it challenging to preserve conductivity between the carbon matrix and nano-FeNi LDHs. This study proposes a novel riveting structural mechanism and a template-replacement synthesis strategy for preparing a high conductivity and stable composite electrocatalyst, i.e., FeNi LDH nanosheet-wrapped single-layer ordered mesoporous carbon (FeNi LDHs@SOMC). The SOMC is produced by carbonizing the resin on the refractory template of MgO/Mg(OH)2 nanosheets, and then the product is immersed in a solution containing Ni2+ and Fe2+ ions for ion exchange under the template induction. Highly active NiFe LDH nanosheets, which are more insoluble than Mg(OH)2, grow from the mesopores of SOMC and wrap the SOMC so that the two are mechanically riveted together. This structure also allows electron transfer from all catalytic sites to SOMC at the nanoscale. The experimental results demonstrated that FeNi LDHs@SOMC is a superior composite electrocatalyst with an OER overpotential of 270 mV at 10 mA.cm−2 and a Tafel slope of 60 mV dec−1. FeNi LDHs@SOMC exhibits extraordinary corrosion resistance and does not degrade after 12 h electrolysis. The study offers an alternative strategy for designing and synthesizing highly hybridized composite electrocatalysts.

Surface Reconstruction of an FeNi Foam Substrate for Efficient Oxygen Evolution.

Designing earth-abundant electrocatalysts that are highly active, low-cost, and stable for the oxygen evolution reaction (OER) is crucial for electrochemical water splitting. However, in conventional electrode fabrication strategies, NiFe layered double hydroxide (NiFe LDH) catalysts are usually coated onto substrates as external components, which suffers from poor conductivity, easily detaches from the substrate, and hinders their long-term utilization. Herein, the surface-reconstruction strategy is used to synthesize in situ autologous NiFe LDH to increase the surficial active sites numbers. The FeNi foam (FNF) serves as both the metal source and substrate, and the obtained NiFe LDH nanosheets (NSs) are firmly anchored in the monolithic FNF. What needs to be emphasized is that the strategy does not involve any high-temperature or high-pressure processes, apart from a cost-effective etching and a specified drying treatment. The nanostructure of NiFe LDH and the synergistic effect between Fe and Ni simultaneously lead to an enhanced catalytic effect for the OER. Remarkably, the sr-FNF46 requires only an ultralow overpotential of 283 mV to achieve a current density of 100 mA cm-2 for the OER in 1 M KOH electrolyte, and exhibits excellent stability. Thus, the obtained electrode holds promise for electrocatalytic applications. Finally, the formation mechanism of NiFe LDH NSs due to surface reconstruction is investigated and discussed in detail.

Microwave-assisted growth of spherical core-shell NiFe LDH@CuxO nanostructures for electrocatalytic water oxidation reaction

The high energy demand for electrochemical water splitting arises from sluggish oxygen evolution reaction (OER) kinetics. In this regard, Layered double hydroxide (LDH) has been introduced as an outstanding catalyst for the OER due to its exceptional physiochemical and 2D infrastructure properties. Herein, we report the design and synthesiss of core-shell nanostructured electrocatalyst by rationally decorating vertically oriented NiFe LDH ultrathin nanosheets on CuxO support (NiFe LDH@CuxO) via microwave-assisted hydrothermal reaction. For OER, the NiFe LDH@CuxO core-shell nanostructured catalyst demonstrated promising electrocatalytic performance, requiring only 1.43 V onset potential and 270 mV overpotential at 10 mA cm−2. The NiFe LDH@CuxO also outperformed pristine NiFe LDH and iridium oxide (IrO2) in terms of electrocatalytic activity, durability, and Faradaic efficiency. The fabricated NiFe-LDH@CuxO electrocatalyst with outer shell NiFe-LDH ultrathin nanosheets provides numerous exposed active sites, benefits electrolyte diffusion and oxygen gas releasing and also reduces the interfacial charge transfer resistance to enhance OER activity. Furthermore, exclusive core-shell 3D infra-structure effectively prevents NiFe-LDH nanosheets agglomeration and restacking, enhancing electrochemical stability.

Facile construction of well-defined hierarchical NiFe2O4/NiFe layered double hydroxides with a built-in electric field for accelerating water splitting at the high current density

Interfacial charge redistribution induced by a strong built-in electric field can expertly optimize the adsorption energy of hydrogen and hydroxide for improving the catalytic activity. Herein, we develop a well-defined hierarchical NiFe2O4/NiFe layered double hydroxides (NFO/NiFe LDH) catalysts, exhibiting superior performance due to the strong interfacial electric field interaction between NiFe2O4 nanoparticle layers and NiFe LDH nanosheets. In 1 M KOH, NFO/NiFe LDH needs 251 mV and 130 to drive 50 and 10 mA cm−2 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Moreover, only 1.517 V cell voltage is needed to reach 10 mA cm−2 towards overall water splitting. Notably, under simulated industrial electrolysis conditions, NFO/NiFe LDH only needs 289 mV to drive 1000 mA cm−2. This work puts a deep insight into the role of the built-in electric field in transition metal-based catalysts for accelerating water splitting and scalable industrial electrolysis applications.

Modulating interfacial charge distribution of NiSe nanoarrays with NiFe-LDH nanosheets for boosting oxygen evolution reaction

Developing efficient, robust non-noble electrodes for the water oxidation in electrocatalytic water splitting is challenging because the physicochemical properties of the electrocatalysts can extremely affect their OER catalytic activity. The interface engineering of materials is promising for modulating the surface properties of catalysts. Herein, vertically aligned NiSe nanoarrays were prepared in situ using a facile solvothermal selenization technique. NiSe@NiFe-LDH nanointerfaces were produced by electrodeposition. The remarkable OER electrocatalytic performance of NiSe@NiFe-LDH heterojunction was evidenced by the overpotentials for driving 100 and 500 mA cm−2, which are only 232 and 302 mV, respectively. Theoretical arithmetic and experimental tests revealed that the prepared electrode possessed high OER catalytic activity, may be ascribed to charge redistribution between the interfaces of NiSe and NiFe-LDH. The theoretical calculation showed that the generated electron transfer enable the electronic structure to be sufficiently modulated, which perfected the binding energy of the *OOH intermediates, issuing in a reduction of the reaction obstacle of the rate-determining procedure, and improved the OER activity consequently. This work proposes an effective and promising solution to fabricate non-precious metal-based heterostructure materials with excellent catalytic properties for energy storage and transduction.

Electronically Modified Ce3+ Ion Doped 2D NiFe-LDH Nanosheets over a 1D Microfiber: A High-Performance Electrocatalyst for Overall Water Splitting

Electronically Modified Ce³⁺ Ion Doped 2D NiFe-LDH Nanosheets over a 1D Microfiber: A High-Performance Electrocatalyst for Overall Water Splitting

Inducing the SnO2-based electron transport layer into NiFe LDH/NF as efficient catalyst for OER and methanol oxidation reaction

• Introduce the electron transport layer SnO 2 between NiFe LDH and conductive substrate NF was first reported. • SnO 2 nanosheets are interwoven to form a sponge-like 3D structure, which promotes the formation of relatively smaller and thinner NiFe LDH nanosheets, thereby generating more active sites and reducing electron transmission resistance. • It was verified that the electronic structure of Ni and Fe was optimizing via the introduction of SnO 2 . • NiFe LDH@SnO 2 /NF possesses a low overpotential of 234 mV at 10 mA cm −2 for OER and 1.396 V at 10 mA cm −2 for methanol oxidation reaction. In an electrocatalyst with a heterointerface structure, the different interfaces can efficiently adjust the catalyst's conductivity and electron arrangement, thereby enhancing the activity of the electrocatalyst. Ultrathin and smaller NiFe LDH was successfully constructed on the surface of SnO 2 nanosheet supported NF by layer by layer assembly, and exhibits lower overpotential of 234 mV at a current density of 10 mA cm −2 , which only increases by 6.4% even at a high current density of 100 mA cm −2 . The excellent OER activity of catalyst is attributed to the contribution of the semiconductor SnO 2 electron transport layer. Through experiments and characterization, 3d structure SnO 2 nanosheets control the growth of ultra-thin nickel-iron, the hierarchical interface between SnO 2 and NiFe LDH can change the electron arrangement around the iron and nickel active centers at the interface, resulting the valence states of iron slightly increased and Ni 3+ content increased. The result will promote the oxidation of water. Meanwhile, the SnO 2 semiconductor as electron transport layer is conducive to trapping electrons generated in oxidation reaction, promoting electrons transferring from the NiFe LDH active center to the Ni substrate more quickly, and enhance the activity of NiFe LDH. It also shows excellent activity in an electrolyte solution containing 0.5 M methanol and 1 M KOH, and only 1.396 V (vs. RHE) is required to drive a current density of 10 mA cm −2 .

Flower-like Co3O4@NiFe-LDH nanosheets enable high-performance bifunctionality towards both electrocatalytic HER and OER in alkaline solution

Exploring highly active and cost-effective metal-based overall water splitting catalysts are crucial for the large-scale conversion of sustainable electrical energy to fuels, feedstocks and green economy. Here, a nickel foam-supported electrocatalyst consisting of a one-dimensional Co3O4 nanowire and two-dimensional NiFe-LDH nanosheets is reported. The optimized Co3O4@NiFe-LDH/NF catalyst affords 79 and 215 mV at 10 mA cm−2 for catalyzing the hydrogen and oxygen evolution reaction in 1.0 M KOH, which also exhibits quick reaction kinetics and excellent durability. The self-supported electrode only requires 1.58 V to afford 10 mA cm−2 with astonishing stability for water splitting. The linked interfacial nanostructure between NiFe-LDH and Co3O4, which supports the enhancement of the electronic structure and increases catalytic active sites, is primarily responsible for the electrode’s remarkable catalysis performance. The Co3O4@NiFe-LDH/NF as an ideal electrocatalyst lays forth a broad technique for synthesizing electrocatalytic materials for efficient and scalable water splitting.

Triethanolamine-assisted synthesis of NiFe layered double hydroxide ultrathin nanosheets for efficient oxygen evolution reaction

Water electrolysis is a promising technique for producing high-quality hydrogen, the application of which is impeded by the sluggish oxygen evolution reaction (OER) process. In this study, ultrathin nickel–iron layered double hydroxide (NiFe LDH) nanosheets were successfully synthesized through a facile hydrothermal reaction with the assistance of triethanolamine (TEA). Morphological and structural characterizations revealed that the presence of TEA modified the morphology of NiFe LDH, facilitated the synthesis of high-purity NiFe LDH, improved the crystallinity of NiFe LDH and resulted in a slight decrease in specific surface area. X-ray photoelectron spectroscopy (XPS) analysis demonstrated the modulation of the electronic structure engendered by the addition of TEA, with nickel and iron appearing in high valence state in the resulting NiFe LDH nanosheets. The as-prepared NiFe LDH nanosheets possessed outstanding OER activity with fast kinetics, exhibiting a low overpotential of 261 mV to achieve a current density of 10 mA cm−2 and a small Tafel slope of 32.5 mV dec−1 in 1 M KOH. The excellent OER performance and rapid OER kinetics are mainly attributed to the high-valence Ni and Fe rather than the modification in the morphology and microstructure.

MnOx Film-Coated NiFe-LDH Nanosheets on Ni Foam as Selective Oxygen Evolution Electrocatalysts for Alkaline Seawater Oxidation.

Compared to freshwater electrolysis, seawater electrolysis to produce hydrogen is preferable and more promising, but this technology is plagued by the electrode's corrosion and oxidative reactions of the competitive Cl- ion on the anode. To develop efficient oxygen evolution reaction (OER) catalysts for seawater electrolysis, the ultrathin MnOx film-covered NiFe-layered double-hydroxide nanosheet array is directly assembled on Ni foam (MnOx/NiFe-LDH/NF) by hydrothermal and electrodeposition in turn. This catalyst demonstrates excellent OER-selective activity in alkaline saline electrolytes. In 1 M KOH/0.5 M NaCl and 1 M KOH/seawater electrolytes, MnOx/NiFe-LDH/NF exhibits lower overpotentials at 100 mA cm-2 (η100 values of 265 and 276 mV, respectively) and Tafel slopes (73 and 77 mV decade-1, respectively) than does the NiFe-LDH/NF electrode (η100 values of 298 and 327 mV and Tafel slopes of 91 and 140 mV decade-1, respectively). In alkaline saline solutions, the stability and durability of the former are also better than those of the latter. The good OER selectivity and catalytic performance are attributed to the MnOx overlayer that selectively blocks Cl- anions from approaching catalytic centers, and the good conductivity, fast kinetics, more oxygen vacancies, and abundant active sites of MnOx/NiFe-LDH/NF. The robust stability is due to the enhanced resistance for Cl- corrosion stemming from the MnOx protective film. Hence, MnOx/NiFe-LDH/NF can act as a promising OER electrocatalyst for alkalized natural seawater electrolysis.

A hierarchical nickel-iron hydroxide nanosheet from the high voltage cathodic polarization for alkaline water splitting

Developing efficient and stable oxygen evolution reaction (OER) electrocatalysts is a promising method to relieve the pressure of noble metals for catalyzing water splitting. Among the prominent candidates, nickel-iron layered double hydroxides (NiFe-LDH) have been found excellent catalytic activity, but their poor conductivity and stability seriously impede their performance. Herein, we report hierarchical NiFe-LDH nanosheets prepared from NiFe-Alloy on nickel mesh (NM) by high voltage cathodic polarization. The resultant NiFe-LDH/NM exhibits a remarkable OER activity and stability, which has a low overpotential of 340 mV at a current density of 10 mA cm−2, and maintains a current density of 15 mA cm−2 at a constant voltage of 1.56 V for 50 h if the NiFe-Alloy/NM is used as the cathode. The successful conversion of NiFe-LDH nanosheets originating from NiFe-Alloy nanoparticles would open a new avenue for synthesizing transition metal-based LDH compounds.

Improving photocatalytic hydrogen production via ultrafine-grained precipitates formed nearby surface defects of NiFe-LDH nanosheets

New types of photocatalytic systems formed by coupling annealed large-sized NiFe-LDH nanosheets with small-sized TiO2 nanosheets were used to facilitate the rapid separation of photo-generated electrons and holes. The photocatalytic hydrogen production for optimized photocatalytic systems can reach 209 mmol/g, which is 8 times of that for TiO2. To understand the photocatalytic mechanism, in-situ annealing transmission electron microscopy (TEM) investigation of the microstructural evolution of large-sized NiFe-LDH nanosheets identified typical microstructures at different annealing stages. The microstructure of the optimized system contains plentiful ultrafine grains distributed along surface delaminated defects, which can provide abundant active sites for photocatalytic hydrogen evolution. Electrochemical and spectroscopic techniques were further used to determine the Z-scheme mechanism, guiding photo-generated electrons to fast transfer onto large-sized NiFe-LDH nanosheets to achieve high efficient carrier separation.

Integrating trifunctional Co@NC-CNTs@NiFe-LDH electrocatalysts with arrays of porous triangle carbon plates for high-power-density rechargeable Zn-air batteries and self-powered water splitting

A structural engineering strategy is proposed to fabricate trifunctional electrocatalysts supported by carbon cloth, composed of NiFe-LDH nanosheets aligned on Co-embedded N-doped carbon triangle plates with interwoven carbon nanotubes (Co@NC-CNTs@NiFe-LDH), which is employed as a freestanding electrode for both flexible Zn-air batteries and self-powered water splitting. This unique 3D hierarchical structure and the strong interfacial coupling between the NiFe-LDH and Co@NC-CNTs facilitate the transport of oxygen species as well as electrons and achieve synergy between the integrated nano-scaled structures with different functional components. As expected, a large peak power density of 194 mW cm−2 and outstanding durability for 760 h are obtained in the as-assembled rechargeable Zn-air battery. The resultant water splitting device acquires a cell voltage of 1.66 V at 10 mA cm−2 and the as-assembled Zn-air battery has been successfully employed in a self-power water splitting system, demonstrating a great potential prospect for practical renewable energy applications.

Robust Fe2+-doped nickel-iron layered double hydroxide electrode for electrocatalytic reduction of hexavalent chromium by pulsed potential method

• A 3D porous Fe 2+ -NiFe LDH/NF was synthesized using a spontaneous redox reaction. • Pulsed potential remarkably improved electrocatalytic Cr(VI) reduction performance. • Anodic potential accelerated the adsorption of Cr(VI) and desorption of Cr(III). • Cathodic potential can regenerate Fe 2+ and reduced. • Bare Ni foam can reduce Cr(VI) directly under cathodic potential. Electrocatalytic reduction of Cr(VI) to less toxic Cr(III) is deemed as a promising technique. Conventional electrocatalytic reduction is always driven by a constant cathodic potential, which exhibits a repelling action to Cr(VI) oxyanions in wastewater and consequently suppresses reduction kinetics. In order to remarkably accelerate Cr(VI) electrocatalytic reduction, we applied a pulsed potential on an Fe 2+ -NiFe LDH/NF electrode synthesized by in situ growth of Fe 2+ -doped NiFe LDH nanosheets on Ni foam using a spontaneous redox reaction. Under anodic potential section, HCrO 4 – anions are adsorbed on the electrode surface and reduced to Cr(III) by Fe 2+ . Then, Cr(III) ions are desorbed from the electrode surface under coulombic force. The regeneration of Fe 2+ and direct reduction of Cr(VI) are achieved under cathodic potential section. The pulsed potential can achieve complete elimination of Cr(VI) within 60 min at an initial concentration of 10 mg L −1 , and the removal efficiency shows a 60% increase with respect to that under constant cathodic potential.

Hierarchical nanocomposites of nickel/iron-layered double hydroxide ultrathin nanosheets strong-coupled with nanocarbon networks for enhanced oxygen evolution reaction

Nickel/iron-layered double hydroxide (NiFe-LDH) for oxygen evolution reaction (OER) was hindered insufficient active sites, low inherent conductivity and poor stability. Herein, we innovatively report a facile and cost-effective in situ synthesis strategy to prepare ultrathin NiFe-LDH nanosheets coupled onto hierarchical nanocarbon networks consisting of carbon nanotube and graphene nanoribbon (NiFe-LDH/CNT@GNR) forming a porous interconnected nanocomposite. Partial unzipping of CNT induced by strong oxidation leads to the creation of GNR nanolayers tightly attached to the retained CNT framework, where GNR achieves high surface areas to load NiFe-LDH nanosheets and inner CNT still enables high conductivity. The CNT@GNR nanocarbon network not only enhances accessible electrochemical active area and mass transfer, but also provides high-efficiency conductive brackets with interlinked electron transfer pathways and achieve the strong interface coupling with NiFe-LDH nanosheets, synergistically resulting in rapid electrocatalytic kinetics. Moreover, NiFe-LDH nanosheets are tightly anchored on the surface of nanocarbon networks, greatly enhanced the stability of NiFe-LDH. NiFe-LDH/CNT@GNR exhibits remarkable OER activity with a low overpotential of 261 mV at 10 mA cm−2, Tafel slope of 78 mV dec−1, and high stability for up to 17 h, superior to most LDH-based OER catalysts reported, and even better than commercial RuO2. Therefore, the facile synthesis and excellent hierarchical architecture endow NiFe-LDH/CNT@GNR nanocomposites as advanced electrocatalysts for outstanding OER performance. Most importantly, the design provides a simple but universal strategy to yield high performance of NiFe-LDH catalysts, facilitating the commercial process of non-noble catalysts for OER.

Sulfur-Incorporated Nickel-Iron Layered Double Hydroxides for Effective Oxygen Evolution Reaction in Seawater

Given the abundance of water on the surface of the Earth, water splitting using seawater may be an effective solution to the future energy crisis. However, oxygen evolution reaction (OER) electrocatalysts require several specific characteristics to be used in seawater electrolysis, such as high catalytic activity, selectivity, and resistivity against chlorine corrosion. This paper reports that sulfur incorporation into nickel– iron layered double hydroxide (NiFe-LDH-S) can fulfill the abovementioned requirements for seawater oxidation. Sulfidation was performed on NiFe-LDH nanosheets homogeneously grown on a porous carbon scaffold via a facile chemical vapor deposition (CVD) process. The best NiFe-LDH-S sample demonstrated excellent catalytic activity with a high corrosion resistance for seawater oxidation.

Heterostructured composite of NiFe-LDH nanosheets with Ti4O7 for oxygen evolution reaction

Developing oxygen evolution reaction (OER) electrocatalyst based on earth-abundant materials holds great promise for ascertaining water-splitting to surmount its deprived kinetics. In this regard, NiFe-LDH (layered double hydroxide) receives considerable attention owing to their layered structure. However, they still suffer from poor electronic conductivity and structural stability. We combined NiFe-LDH nanosheets with Magnéli phase Ti4O7 into a heterostructured composite. A series of analyses reveal that decorating Ti4O7 facilitates charge transfer to enhance the conductivity of NiFe-LDH-Ti4O7. During electrochemical measurement, Ni2+ is transformed to metastable Ni3+ (Ni (OH)→ NiOOH) before the OER onset potential. Thus, the presence of Ni3+ as the main active sites could improve the chemisorption of OH− to facilitate OER. As a result, the NiFe-LDH-Ti4O7 catalyst delivers as low as onset potential (1.43 V). Combining the holey structure (NiFe-LDH and Ti4O7) and the defect engineering generated on NiFe-LDH-Ti4O7 as a synergistic effect improves the OER performance. The inclusion of Ti4O7 in the composite leads to more vacancy sites, as evidenced by the extended X-ray absorption fine structure (EXAFS) analysis. The obtained defective structure with a low coordination environment would improve the electronic conductivity and facilitate the adsorption process of H2O onto metal cations, thereby increasing the intrinsic catalytic activity of NiOOH. The strong coupling of NiFe-LDH and Ti4O7 also increases the stability, and the heterostructured composite helps maintain the structural robustness of the LDH.

PEO-PPO-PEO induced holey NiFe-LDH nanosheets on Ni foam for efficient overall water-splitting and urea electrolysis

Exploring the transition-metal-based bifunctional electrocatalysts with high performance for efficient water-splitting and urea electrolysis is significant but challenging. This work presents the in situ preparation of holey NiFe-LDH nanosheets on Ni foam (H-NiFe-LDH/NF) via a one-step hydrothermal method in the presence of PEO-PPO-PEO as the soft template. The holey NiFe-LDH nanosheets provide a high electrochemical surface area, more edge catalytic sites, and abundant oxygen vacancies. Consequently, H-NiFe-LDH/NF exhibits excellent catalytic activity to oxygen evolution, urea oxidation, and hydrogen evolution reactions (OER, UOR, and HER) with good stability in alkaline electrolytes. This electrode requires an overpotential of 261 mV for the OER, a potential of 1.480 V for the UOR to achieve a current density of 100 mA cm−2 in alkaline solutions. By employing the self-supported electrode as both the anode and cathode, this electrolysis cell (H-NiFe-LDH/NF||H-NiFe-LDH/NF) gains current densities of 10 and 100 mA cm−2 at low cell voltages of 1.575 and 1.933 V in the 1.0 M KOH solution. After adding 0.33 M urea, the voltages to deliver 10 and 100 mA cm−2 respectively decrease to 1.418 and 1.691 V. The H-NiFe-LDH/NF electrode also shows excellent stability for water-splitting and urea electrolysis. This work not only contributes to developing a low-cost, high-efficiency, bifunctional electrocatalyst but also provides a practically feasible approach for urea-rich wastewater electrolysis.

Metal-Organic Framework-Derived Hollow CoSx Nanoarray Coupled with NiFe Layered Double Hydroxides as Efficient Bifunctional Electrocatalyst for Overall Water Splitting.

For effective hydrogen production by water splitting, it is essential to develop earth-abundant, highly efficient, and durable electrocatalysts. Herein, the authors report a bifunctional electrocatalyst composed of hollow CoSx and Ni-Fe based layered double hydroxide (NiFe LDH) nanosheets for efficient overall water splitting (OWS). The optimized heterostructure is obtained by the electrodeposition of NiFe LDH nanosheets on metal-organic framework-derived hollow CoSx nanoarrays, which are supported on nickel foam (H-CoSx @NiFe LDH/NF). The unique structure of the hybrid material not only provides ample active sites, but also facilitates electrolyte penetration and gas release during the reactions. Additionally, the strong coupling and synergy between the hydrogen evolution reaction (HER) active CoSx and the oxygen evolution reaction (OER) active NiFe LDH gives rise to the excellent bifunctional properties. Consequently, H-CoSx @NiFe LDH/NF exhibits remarkable HER and OER activities with overpotentials of 95 and 250 mV, respectively at 10 mA cm-2 in 1.0 M KOH. Even at 1.0 A cm-2 , the electrode requires small overpotentials of 375 mV (for HER) and 418 mV (for OER), respectively. An electrolyzer based on H-CoSx @NiFe LDH/NF demonstrates a low cell voltage of 1.98 V at a current density of 300 mA cm-2 and good durability for 100 h in OWS application.

Interfacial interaction between NiMoP and NiFe-LDH to regulate the electronic structure toward high-efficiency electrocatalytic oxygen evolution reaction

Development of low-cost, high-efficiency electrocatalysts for the oxygen evolution reaction (OER) is challenging, even though it is critical for the overall electrochemical splitting. Herein, we report a NiMoP@NiFe-LDH heterostructure electrode supported on nickel foam. The study shows that the electrocatalytic activity for the OER can be improved by coupling NiMoP and NiFe-LDH. The resulting NiMoP@NiFe-LDH heterostructure exhibited remarkable catalytic performance with an ultralow overpotential of only 299 mV at a current density of 150 mA cm −2 and a Tafel slope of 23.3 mV dec −1 in 1.0 M KOH solution. Electron transfer from NiFe-LDH to NiMoP at the nanointerface reduces the energy barrier of the catalytic process, thus improving the OER activity performance. Thus, high-efficiency electrocatalysts can be utilised by constructing heterojunctions to regulate the electronic structure at the interface of the electrocatalysts. Interfacial electronic structure Regulation: The NiMoP@NiFe-LDH heterostructure electrode was successfully fabricated by a series of successive procedures (hydrothermal, phosphorisation, and electrodeposition). The enhanced OER activity of the electrocatalyst was attributed to nanointerfacial interaction between the NiMoP nanowires and the NiFe-LDH nanosheets, which reduces the energy barrier of the catalytic process, thus improving the electrocatalytic performance. • Heterostructure electrocatalyst that NiMoP nanowires coupled with NiFe-LDH nanosheets was constructed. • This heterostructure electrocatalyst exhibits very remarkable OER activity and shows excellent stability. • Electronic interaction at the nanointerface of the heterojunction enhances the intrinsic activity of electrode.