Electrokinetic-mechanism of water and furfural oxidation on pulsed laser-interlaced Cu_(2)O and CoO on nickel foam

The electrocatalytic oxidation of biomass-derived furfural(FF)feedstocks into 2-furoic acid(FA)holds immense industrial potential in optics,cosmetics,polymers,and food.Herein,we fabricated Co O/Ni O/nickel foam(NF)and Cu_(2)O/Ni O/NF electrodes via in situ pulsed laser irradiation in liquids(PLIL)for the bifunctional electrocatalysis of oxygen evolution reaction(OER)and furfural oxidation reaction(FOR),respectively.Simultaneous oxidation of NF surface to NiO and deposition of CoO and/or Cu_(2)O on NF during PLIL offer distinct advantages for enhancing both the OER and FOR.CoO/NiO/NF electrocatalyst provides a consistently low overpotential of~359 m V(OER)at 10 m A/cm^(2),achieving the maximum FA yield(~16.37 m M)with 61.5%selectivity,79.5%carbon balance,and a remarkable Faradaic efficiency of~90.1%during 2 h of FOR at 1.43 V(vs.reversible hydrogen electrode).Mechanistic pathway via in situ electrochemical-Raman spectroscopy on CoO/NiO/NF reveals the involvement of phase transition intermediates(NiOOH and CoOOH)as surface-active centers during electrochemical oxidation.The carbonyl carbon in FF is attacked by hydroxyl groups to form unstable hydrates that subsequently undergo further oxidation to yield FA products.This method holds promise for large-scale applications,enabling simultaneous production of renewable building materials and fuel.

Engineering of Self-Supported Electrocatalysts on a Three-Dimensional Nickel Foam Platform for Efficient Water Electrolysis

Economical water electrolysis requires highly active non-noble electrocatalysts to overcome the sluggish kinetics of the two half-cell reactions,oxygen evolution reaction,and hydrogen evolution reaction.Although intensive efforts have been committed to achieve a hydrogen economy,the expensive noble metal-based catalysts remain under consideration.Therefore,the engineering of self-supported electrocatalysts prepared using a direct growth strategy on three-dimensional(3D)nickel foam(NF)as a conductive substrate has garnered significant interest.This is due to the large active surface area and 3D porous network offered by these electrocatalysts,which can enhance the synergistic eff ect between the catalyst and the substrate,as well as improve electrocatalytic performance.Hydrothermal-assisted growth,microwave heating,electrodeposition,and other physical methods(i.e.,chemical vapor deposition and plasma treatment)have been applied to NF to fabricate competitive electrocatalysts with low overpotential and high stability.In this review,recent advancements in the development of self-supported electrocatalysts on 3D NF are described.Finally,we provide future perspectives of self-supported electrode platforms in electrochemical water splitting.

Compressive properties and energy absorption characteristics of open-cell nickel foams

Open-cell nickel foams with different relative densities and pre-stretching degrees were subjected to room temperature quasi-static compressive tests to explore their compressive properties. The compressive properties of the nickel foams including yield strength, elastic modulus, energy absorption density and energy absorption efficiency were calculated accurately. The results show that the compressive properties of yield strength, elastic modulus and energy absorption density increase with the increase of relative density of nickel foams. The compressive properties are sensitive to the pre-stretching degree, and the values of yield strength, elastic modulus and energy absorption density decrease with the increase of pre-stretching degree. However, the energy absorption efficiency at the densification strain state exhibits the independence of relative density and pre-stretching degree. The value of energy absorption efficiency reaches its peak when the strain is at the end of the collapse plateau region.

Preparations of TiO_2 film coated on foam nickel substrate by sol-gel processes and its photocatalytic activity for degradation of acetaldehyde

Anatase TiO2 films were successfully prepared on foam nickel substrates by sol-gel technique using tetrabutyl titanate as precursor. The characteristics of the TiO2 films were investigated by XPS, XRD, FE-SEM, TEM and UV-Vis absorption spectra. The photocatalytic activities of TiO2 films were investigated by photocatalytic degradation reactions of gaseous acetaldehyde, an indoor pollutant, under ultraviolet light irradiation. It was found that Ni^2＋ doping into TiO2 films due to the foam nickel substrates resulted in the extension of absorption edges of TiO2 films from UV region to visible light region. The pre-heating for foam nickel substrates resulted in the formation of NiO layer, which prevented effectively the injection of photogenerated electrons from TiO2 films to metal nickel. The TiO2 films displayed high photocatalytic activity for the degradation of acetaldehyde, and were enhanced by calcining the substrates and coating TiO2 films repeatedly. The high activity was mainly attributed to the improvement of the characteristics of substrate surface and the increase of active sites on photocatalyst.

NiFe-based nanostructures on nickel foam as highly efficiently electrocatalysts for oxygen and hydrogen evolution reactions

Water splitting,as an advanced energy conversion technology,consists of two half reactions,including oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).However,the ideal electrocatalysts are noble metal based catalysts.Their high cost and scarcity in earth seriously restrict the large deployments.Ni Fe-based materials have attracted great attention in recent years due to their excellent catalytic properties for OER and HER.Nevertheless,their conductivity and electrochemical stability at high current density are unsatisfactory,resulting in ineffective water splitting due to high impedance and low stability.Recently,a series of catalysts coating Ni Fe-based materials on 3 D nickel foam were found to be extremely stable under the circumstance of high current density.In this review,we summarized the recent advances of NiFe-based materials on nickel foam for OER and HER,respectively,and further provided the perspectives for their future development.

Sound absorption performance of various nickel foam-base multi-layer structures in range of low frequency

Commercial3D reticular nickel foam and its composite structure were investigated on the sound absorption at200-2000Hz.The absorption performance of foam plates1?5layers(1-layer thickness:2.3mm;porosity:89%;average pore-diameter:0.57mm)was found to be poor,and could be improved by adding backed cavum or front perforated thin sheet.The absorption coefficient could reach about0.4at1000-1600Hz for the composite structure of5-layer foam with a backed5mm-thick cavum,and even0.68at about1000Hz for that of2-layer foam with the same cavum and a perforated plate closely in front of the foam.

Microstructure of nickel foam/Mg double interpenetrating composites

The magnesium matrix double interpenetrating composites reinforced by nickel foam were fabricated by pressureless infiltration technology.Then the morphology of the nickel reinforcement and the microstructures of composites were characterized by SEM.The results show that not only is the nickel foam reinforcement reticular in three dimensions,but also the struts of foam keep the network structure,which ensures that the Ni foam/Mg composites are double interpenetrating.The interface bonding of composites between magnesium matrix and nickel foam reinforcement is good,without reaction around the interface,which is the indispensable condition that advanced composites should possess.Magnesium matrix distributes in the windows of nickel foam,the triangle center holes and microhole of nickel struts,and the composites have double interpenetrating structure,which makes the composites have unique properties.

Highly-dispersed iron element decorated nickel foam synthesized by an acid-free and one-pot method for enzyme-free glucose sensor

The highly-dispersed iron element decorated Ni foam was prepared by simple immersion in a ferric nitrate solution at room temperature without using acid etching, and characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), EDAX spectrum(EDAX mapping) and Raman spectroscopy. The EDAX spectrum illustrated that iron element was highly-dispersed over the entire surface of nickel foam, and the Raman spectroscopy revealed that both Ni-O and Fe-O bonds were formed on the surface of the as-prepared electrode. Moreover, the iron element decorated Ni foam electrode can be used as non-enzymatic glucose sensor and it exhibits not only an ultra-wide linear concentration range of 1-18 mmol/L with an outstanding sensitivity of 1.0388 m A·mmol/(L·cm2), but also an excellent ability of stability and selectivity. Therefore, this work presents a simple yet effective approach to successfully modify Ni foam as non-enzymatic glucose sensor.

Sound absorption of several various nickel foam multilayer structures at aural frequencies sensitive for human ears

Using the three-dimensional reticular nickel foam as experimental material, the sound absorption performance was investigated for several various multilayer structures in the frequency range of 2000-4000 Hz, which is aurally sensitive for human ears. The results showed that the 7.5 mm-thick foam sample, which was formed by piling of 5-layer foam plate（thickness： 1.5 mm; porosity： 96%; average pore-diameter： 0.65 mm） could exhibit an excellent sound absorption effect at 4000 Hz, with the absorption coefficient about 0.8. Constituting alternate air gap with the total thickness of about 18.5 mm can greatly improve the absorption performance at relatively low frequencies of 2000-3150 Hz, with the absorption coefficient up to about 0.5 or more. In addition, the research showed that alternate piling up the perforated plate inside the foam plates can also achieve a quite good effect of sound absorption at relatively low frequencies.

Porous Cobalt Oxide@Layered Double Hydroxide Core-Shell Architectures on Nickel Foam as Electrode for Supercapacitor

The high performance of an electrode relies largely on a scrupulous design of nanoarchitectures and smart hybridization of electroactive materials.A porous core-shell architecture in which one-dimensional cobalt oxide(Co_3O_4)nanowire cores are grown on nickel foam prior to the growth of layered double hydroxide(LDH)shells is fabricated.Hydrothermal precipitation and thermal treatment result in homogeneous forests of 70-nm diameter Co_3O_4 nanowire,which are wrapped in LDH-nanosheet-built porous covers through a liquid phase deposition method.Due to the unique core-shell architecture and the synergetic effects of Co_3O_4and NiAl-LDH,the obtained Co_3O_4@LDH electrode exhibits a capacitance of 1 133.3F/g at a current density of 2A/g and 688.8F/g at 20A/g(5.3F/cm^(2 )at 9.4mA/cm^(2 )and 3.2F/cm^(2 )at 94mA/cm^2),which are better than those of the individual Co_3O_4nanowire.Moreover,the electrode shows excellent cycling performance with a retention rate of 90.4%after 3 000cycles at a current density of 20A/g.

Growth of Ag/g-C_(3)N_(4) nanocomposites on nickel foam to enhance photocatalytic degradation of formaldehyde under visible light

Formaldehyde is a pollutant that significantly affects the indoor air quality.However,conventional remediation approaches can be challenging to deal with low-concentration formaldehyde in an indoor environment.In this study,Photocatalysts of Ag/graphitic carbon nitride(g-C_(3)N_(4))/Ni with 3D reticulated coral structure were prepared by thermal polymerization and liquid phase photo-deposition,using nickel foam(NF)as the carrier.Experiments demonstrated that when the Ag concentration was 3%,and the relative humidity was 60%,the Ni/Ag/g-C_(3)N_(4)showed the maximum degradation rate of formaldehyde at 90.19%under visible light irradiation,and the formaldehyde concentration after degradation was lower than the Hygienic standard stated by the Chinese Government.The porous structure of Ni/Ag/g-C_(3)N_(4)and the formation of Schottky junctions promoted the Adsorption efficiency and degradation of formaldehyde,while the nickel foam carrier effectively promoted the desorption of degradation products.Meanwhile,the degradation rate was only reduced by3.4%after 16 recycles,the three-dimensional porous structure extended the lifetime of the photocatalyst.This study provides a new strategy for the degradation of indoor formaldehyde at low concentrations.

Promising supercapacitor electrodes based immobilization of proteins onto macroporous Ni foam materials

Immobilizing biocomponents on solid surfaces is a critical step in the development of new devices for future biological, medical, and elec- tronic applications. Therefore, numerous integrated films were recently developed by immobilizing different proteins or enzymes on electrode surfaces. In this work, hemeproteins were safely immobilized onto macroporous nickel-based electrodes while maintaining their functionality. Such modified electrodes showed interesting pseudo-capacitive behavior. Among hemeproteins, hemoglobin （Hb） film has a higher electro- chemical performance and greater charge/discharge cycling stability than myoglobin （Mb） and cytochrome C （CytC）. The heme group in an alkaline medium could induce the formation of superoxides on the electrode surface. These capacitive features of hemeprotein-Ni electrode were related to strong binding sites between hemeproteins and porous Ni electrode, the accumulation of superoxide or radicals on the Ni sur- face, and facile electron transfer and electrolyte diffusion through the three-dimensional macroporous network. Thus, these new protein-based supercapacitors have potential use in free-standing platform technology for the development of implantable energy-storage devices.

Apparent Electrical Conductivity of Porous Titanium Prepared by the Powder Metallurgy Method

Porous titanium is produced by thepowder metallurgy method. Dependence of the electrical conductivity on the porosity and pore size is investigated and the experimental results are compared with a number of models. It is found that the minimum solid area model could be successfully applied to describe the relationship between the electrical conductivity and the porosity of porous titanium. This kind of conductivity increases with increasing pore sizes.

Boosting charge transfer via interface charge reconstruction between amorphous NiFe-LDH and crystalline NiCo_(2)O_(4)for efficient alkaline water/seawater oxidation

Electrocatalysts with optimal efficiency and durability for the oxygen evolution reaction(OER)are becoming increasingly important as the demand for alkaline water/seawater electrolysis technology grows.Herein,a novel rose-shaped NiFe-layered double hydroxide(LDH)/NiCo_(2)O_(4)composed of amorphous wrinkled NiFe-LDH and highly crystalline NiCo_(2)O_(4)was synthesized with rich heterointerfaces.Many unsaturated metal sites are generated due to significant charge reconstruction at the heterointerface between the crystalline and amorphous phases.These metal sites could trigger and provide more active sites.The density functional theory(DFT)reveals that a new charge transfer channel(Co-Fe)was formed at the heterointerface between NiFe-LDH as electron acceptor and NiCo_(2)O_(4)as electron donor.The new charge transfer channel boosts interfacial charge transfer and enhances catalytic efficiency.The NiFe-LDH/NiCo_(2)O_(4)/nickel foam(NF)drives current densities of 10 and 100 mA·cm−2 with overpotentials of 193 and 236 mV,respectively.The composite electrode demonstrates a fast turnover frequency(0.0143 s−1)at 1.45 V vs.RHE(RHE=reversible hydrogen electrode),which is 5.5 times greater than pure NiCo_(2)O_(4),suggesting its superior intrinsic activity.Additionally,NiFe-LDH/NiCo_(2)O_(4)/NF electrode exhibited negligible degradation after 150 h of uninterrupted running in alkaline seawater oxidation.This study introduces a method for preparing high-efficiency electrocatalysts utilized in alkaline water/seawater electrolysis.

Remarkably enhanced water splitting activity of nickel foam due to simple immersion in a ferric nitrate solution

The development of a facile method to construct a high-performance electrode is of paramount importance to the application of alkaline water electrolysis. Here, we report that the activity of nickel foam （NF） towards the oxygen evolution reaction （OER） can be enhanced remarkably through simple immersion in a ferric nitrate （Fe（NOs）s） solution at room temperature. During this immersion process, the oxidation of the NF surface by NOs- ions increases the near-surface concentrations of OH- and Ni2＋, which results in the in situ deposition of a highly active amorphous Ni-Fe hydroxide （a-NiFeOxHy） layer. Specifically the OER overpotential of the NF electrode decreases from 371 mV （bare NF） to 270 mV （@10 mA-cm-2 in 0.1 M KOH） after immersion in a 20 mM Fe（NOs）s solution for just I min. A longer immersion time results in further increased OER activity （196 mV@10 mA,cm-2 in 1 M KOH）. The overall water splitting properties of the a-NiFeOxHy@NF electrode were evaluated using a two-electrode configuration. It is worth noting that the current density can reach 25 mA.cm-2 in 6 M KOH at an applied voltage of 1.5 V at room temperature.

Interwoven nickel(II)-dimethylglyoxime nanowires in 3D nickel foam for dendrite-free lithium deposition

Metal skeletons,such as Nickel Foam(NF) has attracted worldwide interests as stable host for lithium metal anode because of its high stability,large specific surface area and high conductivity.However,most metal skeletons have lithophobic surface and uneven current distribution that result in sporadic lithium nucleation and uncontrolled dendrites growth.Herein,we describe a sequential immersing strategy to generate interwoven Nickel(Ⅱ)-dimethylglyoxime(Ni-DMG) nanowires at NF to obtain composite skeleton(NDNF),which can be used as an stable host for Li metal storage.The Ni-DMG has proved effective to realize uniform lithium nucleation and dendrite-free lithium deposition.Combing with the three dimensional(3 D) hierarchical porous structure,the composite host shows a significantly improved coulombic efficiency(CE) than pristine commercial nickel foam.Moreover,the corresponding Li‖Li symmetrical cells can run more than 700 h with low voltage hysteresis 22 mV at 1.0 mA/cm^(2),and Li@NDNF‖LiFePO;full-cell exhibits a high capacity retention of 82.03% at 1.0 C during 630 cycles.These results proved the effectiveness of metal-organic complexes in governing Li metal growth and can be employed as a new strategy for dendrite-free Li metal anode and safe Li metal batteries(LMBs).

Au nanoparticles decorated graphene/nickel foam nanocomposite for sensitive detection of hydrogen peroxide

The Au nanoparticles decorated graphene（AuNPs@Gr）/nickel foam（Gr/NiF） nanocomposite（AuNPs@Gr/NiF） was prepared by chemical vapor deposition followed by electrophoretic deposition of AuNPs on Gr/NiF. The morphology, microstructure and sensing performance of the as-prepared AuNPs@Gr/NiF nanocomposite were characterized and measured, respectively by scanning electron microscope, transmission electron microscope, ultraviolet visible spectroscopy and chemical workstation. The asprepared AuNPs@Gr/NiF nanocomposite was used as the electrode to construct a chemical sensor for the detection of hydrogen peroxide（H2O2）. The results showed that the AuNPs distributed homogenously and stably on the surface of Gr/NiF. The chemical sensor exhibits a sensitive and selective performance to the detection of H2O2.

Electrochemical capacitors based on the composite of graphene and nickel foam

An improved Hummers method was developed for the simple and efficient production of high-quality graphene oxide （GO）, and the composite of GO and nickel foam （NF） （GO/NF） was fabricated by ultrasonication-vacuum-assisted deposition of an aqueous solution of GO on NF. After chemical or thermal reduction, the composite of reduced GO and nickel foam （rGO/NF） was obtained. The electrochemical capacitance performance of rGO/NF was investigated using cyclic voltammetry and gal- vanostatic charge/discharge measurements. The chemically reduced rGO/NF composite （C-rGO/NF） exhibited high specific capacitance of 379 F/g at 1.0 A/g and 266.5 F/g at 10 A/g. We also prepared thermally reduced graphene oxide at 473 K in or- der to illuminate the difference in effect between the chemical and low-temperature thermal reduction methods on electro- chemical properties. The cycling performance of thermally reduced rGO/NF composite （T-rGO/NF） and C-rGO/NF had ~91% and ~95% capacitance retention after 2000 cycles in a 6 mol/L KOH electrolyte, respectively. Electrochemical experiments in- dicated that the obtained rGO/NF has very good capacitive performance and could be used as a potential application of elec- trochemical capacitors. Our work revealed high electrochemical capacitor performance of rGO/NF composite and provided a facile method of rGO/NF preparation.

Super-Capacitive Performances of Nickel Foam Supported CeO_2 Nanoparticles

This paper designs and fabricates CeO_2 nanoparticles on a large scale by hydrolysis and oxidation of cerium carbide.The electrochemical supercapacitor behavior of CeO_2 nanoparticles was investigated.The nickel foam(NF) supported CeO_2 nanoparticles show a high areal capacitance of 119 mF/cm^2,demonstrating a strong synergistic effect between NF and CeO_2 nanoparticles.The high capacitance of the CeO_2/NF nanoparticles is possibly due to an improved conductivity by NF and a better utilization of CeO_2 nanoparticles.

Trace ruthenium promoted dual-reconstruction of CoFeP@C/NF for activating overall water splitting performance beyond precious-metals

At present,Ru dopants mainly enhance electrocatalytic performance by inducing strain,vacancy,local electron difference,and synergy.Surprisingly,this work innovatively proposes that trace Ru atoms induce dual-reconstruction of phosphide by regulating the electronic configuration and proportion of Co–P/Co–O species,and ultimately activate superb electrocatalytic performance.Specifically,Ru-CoFeP@C/nickel foam(NF)is reconstructed to generate hydrophilic Co(OH)_(2)nanosheets during the hydrogen evolution reaction(HER)process,further accelerating the alkaline HER kinetics of phosphide.And the as-formed CoOOH during the oxygen evolution reaction(OER)process directly accelerates the oxygen overflow efficiency.As expected,the overpotential at 100 mA·cm^(−2)(η100)values of the reconstructed Ru-CoFeP@C/NF are 0.104 and 0.257 V for HER and OER,which are greatly lower than that of Pt/C-NF and RuO_(2)-NF benchmarks,respectively.This work provides guidance for the construction of highperformance catalysts for HER and OER dual reconstruction.This work provides a new idea for the optimization of catalyst structure and electrocatalytic performance.