Macroporous Nickel Foam Research Articles

Integrated cathode with in-situ grown MnCo2O4/NC/MnO2 catalyst layer for alkaline liquid fuel cells

This study was conducted to develop new fabrication techniques and achieve improved performance of the cathode in liquid fuel cells. An integrated electrode with a sandwich-structured MnCo2O4/NC/MnO2 catalyst was prepared by in-situ growth on nickel foam. The resulting integrated electrode was tested as the cathode of the alkaline direct methanol fuel cell (DMFC) and direct borohydride fuel cell (DBFC). The data indicated peak power density of 12.22 mW cm−2 for DMFC, and 33.65 mW cm−2 for DBFC. The in-situ growth of the MnCo2O4/NC/MnO2 catalyst layer, without an organic binder, indicated a superior catalytic activity to that of MnCo2O4 and MnCo2O4/NC. Moreover, stability test conducted at a constant-current discharge of 10 mA cm−2 for the integrated cathode-based DBFC revealed excellent stability for about 350 h. Compared to that of traditional cathode prepared by doctor-blade method, traditional cathode showed a significantly diminished discharge voltage. Thus, the highly dispersed nanocatalysts and the macroporous nickel foam accelerated the intrinsic catalytic activity and mass transfer in the cathode. This work provides a new strategy for the preparation and structure optimization of fuel cell electrodes.

Facile fabrication of Ni5P4-NiMoOx nanorod arrays with synergistic thermal management for efficient interfacial solar steam generation and water purification

Interfacial steam generation by harnessing renewable solar energy has been recognized as a sustainable solution to global freshwater crisis. A promising evaporator with key components of high spectral absorption, efficient thermal management and adequate water transport is highly desired. In the present study, an integrated design for three-in-one functionality is achieved by simply loading Ni5P4-NiMoOx (P-NMO) on a macroporous nickel foam (NF) carrier. In situ embedding broadband Ni5P4 absorber into insulating NiMoOx enables efficient photothermal conversion and heat localization. Benefiting from proper thermal management and abundant water transmission, P-NMO/NF exhibits the excellent performance for interfacial steam generation with a high evaporation rate of 1.49 kg m−2h−1 and evaporation efficiency of 93.0 % under one sun irradiation. Furthermore, the obtained P-NMO/NF is proven to be applicable for high-efficiency freshwater production in seawater desalination and wastewater purification, showing great potential for practical solar evaporator under natural environmental conditions.

Biomass template method for preparing macroporous nickel foam with tunable pore size and porosity

• A simple one-step strategy to prepare Ni foams. • Ni foam characterized by macropores in the range of 1–10 μm. • Versatile controllability of pore size and porosity. • Cotton fibers play roles of both template and reductant. A simple one-step biomass template method was reported to prepare macroporous Ni foams with tunable pore size and porosity by using basic nickel carbonate and cotton as Ni source and biomass template respectively. The cotton fibers also played a key role of reducing agent which enabled the simple one-step strategy without further treatment. The pore size and porosity of the products can be versatilely controlled by reactant concentrations.

Hierarchically porous nickel foam supported Co-NCNT arrays for efficient solar water evaporation, wastewater purification and electricity generation

Developing advanced solar-powered interfacial evaporators with three-dimensional porous configuration integrating key components of effective solar conversion, adequate water transmission, and flexible thermal modulation is highly demanded but remains a major challenge for solar steam generation. In this work, nitrogen-doped carbon nanotube@Co arrays are in situ grown on three-dimensional macroporous nickel foam (Co-NCNT/NF) to act as a hierarchically porous configuration for solar water evaporation. Synergistic cooperation between Co nanoparticles and NCNT leads to outstanding broadband absorption across whole solar spectrum. Under 1 sun irradiation, the Co-NCNT/NF can rapidly respond to solar light and generate a stable surface temperature as high as 41.5 °C during solar evaporation process. Benefiting from the multifunctional structure features, the Co-NCNT/NF achieves a high evaporation rate of 1.65 kg m−2 h−1 and an evaporation efficiency up to 97.5 % under 1 sun irradiation. Such performance facilitates the continuous production of clean water from seawater and the effective purification of various wastewater. Moreover, comprehensive utilization of additional heat loss during solar water evaporation for thermoelectric power generation is demonstrated as well.

Sugar-cubic Fe2O3/nitrogen-doped graphene nanocomposite as high-performance anode material for oxygen evolution reaction

Industrial application of water electrolysis has called for the development of oxygen evolution electrocatalysts that are low-cost, stable and have low overpotential. Substituting the precious metal catalysts with more accessible transition metal oxide such as Fe2O3 is a key solution for applications in water electrolysis. Here, we show an efficient modified electrode for oxygen evolution, which be developed by co-electrodeposition of graphene oxide and Fe2O3 nanoparticles directly onto macroporous nickel foam substrate. Then, using an electrochemical procedure, in-situ electro-polymerization of pyrrole and graphene oxide reduction are performed on the electrode surface. The sugar-cubic Fe2O3 nanoparticles are also prepared by the hydrothermal method. The morphology and structure of the Fe2O3 nanoparticles and Fe2O3/ graphene nanocomposites are characterized by Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray spectroscopy (EDX), Fourier Transform Infra-Red spectroscopy (FT-IR), X-Ray Diffraction (XRD), Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS) methods. Moreover, the OER activities of the synthesized catalysts are investigated by using Linear Sweep Voltammetry (LSV), Chronopotentiometry (CP) and Electrochemical Impedance Spectroscopy (EIS) methods. The electrocatalytic activity of the sugar-cubic Fe2O3/nitrogen-doped graphene nanocomposite prepared by hydrothermal method in alkaline media shows outstanding advantages, so that its over potential was 313 mV and its Tafel slope was 81 mV/dec.

Construction of a binder-free non-enzymatic glucose sensor based on Cu@Ni core–shell nanoparticles anchored on 3D chiral carbon nanocoils-nickel foam hierarchical scaffold

Bimetallic nanostructures composited with carbonaceous materials are the potential contenders for quantitative glucose measurement owing to their unique nanostructures, high biomimetic activity, synergistic effects, good conductivity and chemical stability. In the present work, chemical vapors deposition technique has been employed to grow 3D carbon nanocoils (CNCs) with a chiral morphology on hierarchical macroporous nickel foam (NF) to get a CNCs/NF scaffold. Following, bimetallic Cu@Ni core–shell nanoparticles (CSNPs) are effectively coupled with this scaffold through a facile solvothermal route in order to fabricate a binder-free novel Cu@Ni CSNPs/CNCs/NF hybrid nanostructure. The constructed free-standing 3D hierarchical composite electrode guarantees highly efficient glucose redox activity due to core–shell synergistic effects, enhanced electrochemical active surface area, excellent electrochemical stability, improved conductivity with better ion diffusivity and accelerated reaction kinetics. Being a non-enzymatic glucose sensor, this electrode achieves highly swift response time of 0.1 s, ultra-high sensitivity of 6905 μA mM−1 cm−2, low limit of detection of 0.03 μM along with potential selectivity and good storage stability. Moreover, the proposed sensor is also tested successfully for the determination of glucose concentration in human serum samples under good recovery ranging from 96.6 to 102.1 %. The 3D Cu@Ni CSNPs/CNCs/NF composite electrode with unprecedented catalytic performance can be utilized as an ideal biomimetic catalyst in the field of non-enzymatic glucose sensing.

La-doped NiFe-LDH coupled with hierarchical vertically aligned MXene frameworks for efficient overall water splitting

The development of stable electrocatalysts with high hydrogen and oxygen evolution reactions (HER and OER) activity in alkaline electrolytes is critical to renewable energy conversion technologies, such as electrochemical water splitting. In this work, a novel strategy for engineering water splitting electrocatalysts in alkaline electrolyte was developed by synergistically coupling La-doped NiFe-layered double hydroxides (NiFe-LDH) nanosheets onto three-dimensional (3D) vertically aligned MXene nanosheets on macroporous nickel foam (NF) substrates (NiFeLa-LDH/v-MXene/NF). The electrocatalytic performance of the prepared NiFeLa-LDH/v-MXene/NF is enhanced by the synergy of strong electronic interaction among multiple metal centers and unique vertically aligned porous MXene with increased active surface area, accelerated reaction kinetics and improved water adsorption and dissociation ability. To reach the commercially required current density (500 mA cm−2), the NiFeLa-LDH/v-MXene/NF exhibits greatly reduced overpotentials of 233 and 255 mV for HER and OER, respectively, along with excellent durability. Moreover, an alkaline electrolyzer driven by NiFeLa-LDH/v-MXene/NF delivers a lower cell voltage (1.71 V) compared with that of Pt/C-RuO2 couple to achieve the current density of 500 mA cm−2.

Catalytic diesel soot elimination over potassium promoted transition metal oxide (Co/Mn/Fe) nanosheets monolithic catalysts

A series of potassium promoted transition metal oxide crossed nanosheets (KTMO-NS: KCo-NS, KMn-NS and KFe-NS) on the monolithic three-dimensional macroporous (3-DM) nickel foam substrate was prepared through the facile hydrothermal and wet impregnation methods, and utilized to evaluate for catalytic soot oxidation. The KTMO-NS catalysts display higher activity than that potassium-free catalysts (TMO-NS) for soot elimination. The results of XPS O1s, Soot-TPR and the amount of active oxygen species indicate that the interaction between potassium and transition metal oxides can generate more oxygen vacancies, so that the catalysts have more active oxygen species, especially for KCo-NS and KFe-NS. Under O2/N2 atmosphere, the KCo-NS and KFe-NS display the higher catalytic activity because of the more surface oxygen species and the stronger interaction between potassium and cobalt/ferric oxide. After introducing NO in the O2/N2 ambient, the KMn-NS possesses the similar catalytic activity with the KFe-NS owing to the higher oxidation ability of NO. Among these catalysts, the KCo-NS shows the highest catalytic soot performance with the lowest T10 (229 °C) and T50 (333 °C), which is higher than the Pt promoted transition metal oxide catalysts.

Confining self-standing CoSe2 nanostructures and Fe3C wrapped N-doped carbon frameworks with enhanced energy storage performances

Transition metal selenides have been explored as suitable candidates for sustainable energy systems. More specific, designing battery-type and capacitor electrodes with exceptional structural, compositional and physiochemical properties is of a great significance to build battery-type supercapacitor hybrid (BSH) devices with high energy and power performances. In this study, a novel binder free positive electrode-based on nanostructured CoSe2 is prepared on a macroporous nickel foam (NF) current collector (CoSe2/NF) via a one-step chemical deposition route. A time-dependent in-situ growth reaction is executed to optimize the structural and electrochemical properties of electrodes. Interestingly, the uniformly constructed CoSe2/NF-9 crystallized into vertically aligned nanosheet arrays with unique porous features shows a higher specific capacitance (231 mAh g−1 at a current density of 1 A g−1) and keeps about 83.7% of its initial capacitance after 3000 potential GCD cycles. As per strategy, Fe3C@N-CNTs composite is synthesized through a facile strategy and serves as a negative electrode material with a substantially high specific capacitance of 348 F g−1 at 1 A g−1 coupled with a remarkable rate capability. By paring the as-prepared CoSe2/NF-9 cathode and Fe3C@N-CNTs anode, an alkaline aqueous BSH system is fabricated with an enlarged potential window of 1.7 V. The integrated CoSe2/NF-9//Fe3C@N-CNTs BSH device exhibits a large energy density of 79.3 Wh kg−1 at a power density of 1023.6 kW kg−1. Moreover, the device has an improved cycling stability and retains around 80.7% of its initial capacitance after 8000 charge–discharge cycles. These results afford an effective rational guidance for developing materials with special compositional characteristics and electrochemical performances for energy storage applications.

Oxygen-deficient Cu doped NiFeO nanosheets hydroxide as electrode material for efficient oxygen evolution reaction and supercapacitor

The development of renewable energy conversion and storage has triggered the development of electrode materials for oxygen evolution reaction (OER) and supercapacitors. Here we report a highly active Cu doped NiFe nanosheets hydroxide electrode with rich oxygen vacancies (OVs) (denoted as H-NiFeCuO/NF) prepared by in situ anodic electrodeposition on the three-dimensional macroporous nickel foam (NF) substrate followed by heat treatment with H2. The as-prepared H-NiFeCuO/NF electrode showed the initial potential of 1.44 V (versus RHE) for OER and 980 F g−1 specific capacity as supercapacitor in 1 M KOH. Further investigation suggested that the tuning of composition and structure by doping copper ions and creating OVs helped accelerate the electrochemical reactions. This practice provides an efficient approach for the fabrication of heteromultimetallic hydroxide monolithic electrode with high performance in OER or supercapacitor application.

Transition‐Metal Phosphide/Sulfide Nanocomposites for Effective Electrochemical Non‐Enzymatic Detection of Hydrogen Peroxide

AbstractIn this work, we clearly demonstrate the use of a transition‐metal phosphide/sulfide nanocomposite to set up an electrochemical reduction analysis platform for the sensitive and selective non‐enzymatic detection of H2O2. With the help of a macroporous nickel foam (NF) as the substrate, the noble‐metal‐free electrocatalyst nanocomposites of Ni3P and Ni3S2 were directly synthesized in one step on the surface of the NF. The Ni3P‐Ni3S2/NF based electrochemical sensors present excellent electrocatalytic activity for H2O2 reduction with a detection limit of approximately 0.3 μM and a large detection range, which guarantees the possibility of sensitive and reliable detection of H2O2.

Bi-metallic MOFs possessing hierarchical synergistic effects as high performance electrocatalysts for overall water splitting at high current densities

Bi-metallic metal organic framework (MOF) compounds, FeNi(BDC)(DMF,F), adequately modulated through alloying of Ni and Fe, were demonstrated outstanding electrocatalysts for overall water splitting. It was composed of two well mixed bi-metallic MOF phases, Fe-rich FeNi(BDC)(DMF,F) and Ni-rich FeNi(BDC)(F), each containing two molecularly well mixed metallic clusters, to give pronounced hierarchical synergistic effects toward overall water splitting, delivering current densities of 10 and 400 mA cm−2 at ultralow cell voltages of 1.58 and 1.90 V, respectively, outperforming the pairing of benchmark electrodes, Pt-C//IrO2. The stability of the electrodes was also excellent, experiencing only minor chronoamperometric decay after a continuous operation at 400 mA cm−2 for 30 h. The success may be attributed to the MOF/substrate synergistic effects between the FeNi(BDC)(DMF,F) and the conductive macroporous nickel foam, the inter-molecular synergistic effects between the two constituent MOF phases, and the intra-molecular synergistic effects between the FeO6 and NiO6 clusters of the Fe-rich FeNi(BDC)(DMF,F).

Hollow mesoporous nickel dendrites grown on porous nickel foam for electrochemical oxidation of urea

The macroporous nickel foam (NF) with attached hollow mesoporous nickel dendrites (NF@p-Ni) was prepared through electrochemical deposition of copper-nickel dendrites on the NF (NF@CuNi) followed by selective removal of the copper cores. The deposition process under high cathodic current density in an acidic solution favored the formation of hydrogen bubbles which acted as a template for the subsequent growth of macroporous dendritic copper-nickel film with 10 μm scale pores. The copper appeared to play an important part in the growth of dendritic shape and hollow porous structure on the porous and conductive NF framework. In the electrochemical oxidation of urea, the NF@p-Ni electrode could offer abundant electroactive sites and porous channels for increasing the oxidation current density and efficiency compared to the NF@CuNi electrode. The NF@p-Ni electrode featuring macroporous catalyst layer of hollow dendrites on highly conductive NF framework expedited the charge-transfer reaction of urea electrooxidation and the evolution of gaseous products. Thus, the current density and efficiency of NF@p-Ni could reach 141 mA cm−2 and 82%, respectively, higher than those of NF@CuNi (110 mA cm−2 and 72%, respectively) in catalyzing the electrochemical oxidation of urea molecules at 0.60 V versus saturated calomel electrode.

In Situ Grown Bimetallic MOF‐Based Composite as Highly Efficient Bifunctional Electrocatalyst for Overall Water Splitting with Ultrastability at High Current Densities

AbstractA newly designed water‐stable NH2‐MIL‐88B(Fe2Ni)‐metal–organic framework (MOF), in situ grown on the surface of a highly conducting 3D macroporous nickel foam (NF), termed NFN‐MOF/NF, is demonstrated to be a highly efficient bifunctional electrocatalyst for overall water splitting with ultrastability at high current densities. The NFN‐MOF/NF achieves ultralow overpotentials of 240 and 87 mV at current density of 10 mA cm−2 for the oxygen evolution reaction and hydrogen evolution reaction, respectively, in 1 m KOH. For the overall water splitting, it requires only an ultralow cell voltage of 1.56 V to reach the current density of 10 mA cm−2, outperforming the pairing of Pt/C on NF as the cathode and IrO2 on NF as the anode at the same catalyst loading. The stability of the NFN‐MOF/NF catalyst is also outstanding, exhibiting only a minor chronopotentiometric decay of 7.8% at 500 mA cm−2 after 30 h. The success of the present NFN‐MOF/NF catalyst is attributed to the abundant active centers, the bimetallic clusters {Fe2Ni(µ3‐O)(COO)6(H2O)3}, in the MOF, the positive coupling effect between Ni and Fe metal ions in the MOF, and synergistic effect between the MOF and NF.

Synthesis of macroporous ZnO-graphene hybrid monoliths with potential for functional electrodes

The favorable optoelectronic and catalytic properties of zinc oxide, combined with the large specific surface area of graphene molded in 3D network, are able to offer a promising pathway towards the development of hybrid structures with improved electrical, optical, and catalytic properties, that are well suited as active elements for a wide range of applications, especially those related to energy storage and conversion. Using a template-assisted method we demonstrate the synthesis of 3D, porous network monoliths of hybrid ZnO-graphene thin-films in various controlled configurations. The thin-film composites are realized by thermal CVD growth of few-layers graphene on macroporous nickel foam, followed by an ALD coating process of the ZnO film. Notably, the graphene shell fully preserved its network structure after performing complete chemical etching of the nickel scaffold. The challenge of ZnO layer deposition directly on the graphene surface was solved by hydrophobicity adjustment using UV-ozone treatment prior to the atomic layer deposition process. Structural and morphological characterization revealed the formation of hexagonal crystalline zinc oxide films, conformally deposited on the few-layer graphene surface, while the electrical conduction analysis indicates excellent conductivity and interlayer electrical contact for these hybrids. Our results demonstrate that this controlled fabrication process is able to provide highly functional materials with great potential for various electrode applications.

Macroporous Ni foam-supported Co3O4 nanobrush and nanomace hybrid arrays for high-efficiency CO oxidation

Herein, we reported the synthesis of well-defined Co3O4 nanoarrays (NAs) supported on a monolithic three-dimensional macroporous nickel (Ni) foam substrate for use in high-efficiency CO oxidation. The monolithic Co3O4 NAs catalysts were obtained through a generic hydrothermal synthesis route with subsequent calcination. By controlling the reaction time, solvent polarity and deposition agent, these Co3O4 NAs catalysts exhibited various novel morphologies (single or hybrid arrays), whose physicochemical properties were further characterized by using several analytical techniques. Based on the catalytic and characterization analyses, it was found that the Co3O4 NAs-6 catalyst with nanobrush and nanomace arrays displayed enhanced catalytic activity for CO oxidation, achieving an efficient 100% CO oxidation conversion at a gas hourly space velocity (GHSV) 10,000hr−1 and 150°C with long-term stability. Compared with the other Co3O4 NAs catalysts, it had the highest abundance of surface-adsorbed oxygen species, excellent low-temperature reducibility and was rich in surface-active sites (Co3+/Co2+=1.26).

3D NiO nanowalls grown on Ni foam for highly efficient electro-oxidation of urea

3D NiO nanowalls are homogeneously grown on macroporous nickel foam by a hydrothermal method. The morphology of the NiO nanowalls are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the phase structure of NiO nanowalls is characterized by X-ray diffraction (XRD) analysis. The results indicate that the NiO nanowalls are uniformly distributed on the entire nickel foam framework. And ammonia fluoride has significant influence on the height and thickness of NiO nanowalls. With the presence of ammonia fluoride, NiO nanowalls with height of 4.6 (±0.4) μm and thickness around 50 nm were obtained, while the height and thickness decreased to 1.7 (±0.2) μm and around 20 nm without the presence of ammonia fluoride. The NiO nanowalls were used as electrodes for urea oxidation in alkaline condition. The electro-oxidation activity the catalyst is investigated by cyclic voltammetry and potential step chronoamperometry. The electrocatalytic performance of NiO electrodes depends strongly on the sample preparation condition. The 3D NiO nanowalls electrode exhibit excellent electro-oxidation activity towards urea oxidation. The morphology of the electrodes has significant influence on their activity. The current density of 3D NiO nanowalls electrode prepared with NH4F at 0.7 V reached 800 mA cm−2, which was over 4 times than that of sample prepared without NH4F. Moreover, NiO nanowalls prepared with NH4F was more stable than the one prepared without NH4F, which did not show any appreciable morphology change after being used for urea electro-oxidation for 12 h. While the one prepared without NH4F collapsed after used.

Radially Aligned Hierarchical Nickel/Nickel–Iron (Oxy)hydroxide Nanotubes for Efficient Electrocatalytic Water Splitting

Designing well-controlled hierarchical structures on micrometer and nanometer scales represents one of the most important approaches for upgrading the catalytic abilities of electrocatalysts. Although NiFe (oxy)hydroxide has been widely studied as a water oxidation catalyst due to its high catalytic capability and abundance, its structural manipulation has been greatly restricted due to its inherent crystallographic stacking feature. In this work, we report for the first time the construction of a nanotube structure of NiFe (oxy)hydroxide with an inner Ni-rich layer, which was radially aligned on a macroporous nickel foam. Such a hierarchically structured material realized several crucial factors that are essential for excellent catalytic behaviors, including abundant catalytic sites, a high surface area, efficient ionic and electronic transport, etc., and the designed catalyst exhibited competitive electrocatalytic activity for reaction of not only oxygen evolution but also hydrogen evolution, which is very rare. As a result, this novel material was well-suited for the use as a bifunctional catalyst in an integrated water-splitting electrolyzer, which could be even driven by a single AA battery or a 1.5 V solar cell, outperforming a benchmark catalyst of noble-metal ruthenium-platinum combinations and most state-of-the-art electrocatalysts. The work provided important suggestions for the rational modulation of catalysts with new structures targeted for high-performance electrodes used in electrochemical applications.

Electrocatalytic oxidation of urea in alkaline solution using nickel/nickel oxide nanoparticles derived from nickel-organic framework

Nickel-organic framework (NiOF) compound with layered structure was prepared by solvothermal synthesis using nickel chloride and bezenedicarboxylic acid precursors. NiOF could be converted into nickel with a face-centered cubic structure and nickel oxide with a cubic rock-salt crystal structure after heating above 425°C in air atmosphere. The organic units played a key role in the formation of well-dispersed nickel/nickel oxide nanoparticles. Primary particle size could be decreased by lowering the calcination temperature. Electrophoresis allowed for depositing a thin layer of nickel/nickel oxide nanoparticles on the skeleton of macroporous nickel foam (NF) as a catalyst electrode for electrooxidation of urea. Nickel/nickel oxide nanoparticles derived from NiOF at 425°C possessed large amounts of redox active sites (Ni2+/Ni3+), and thus was capable of enhancing the current density and efficiency in urea electrolysis. NF substrate with unique macroporous conductive structure exhibited electrocatalytic behavior towards urea electrolysis and allowed for rapid transport of electron, electrolyte, and gaseous products. Therefore, coating of nickel/nickel oxide nanoparticles on NF provided a possible way for further enhancing the electrocatalytic ability of electrode in urea electrolysis, making it favorable for large-scale applications.

Stable Janus superhydrophilic/hydrophobic nickel foam for directional water transport

Janus superhydrophilic/hydrophobic macroporous nickel foam for directional water transport has been demonstrated via a simple floating strategy. Water can transport from hydrophobic to superhydrophilic layer through Janus nickel foam, but cannot transfer from superhydrophilic to hydrophobic layer. This “3D water diode” Janus nickel foam shows extremely high transport rate and outstanding stability. After damaged by abrasion, its directional water transport property retains well.