Surface Of Foam Research Articles

Fe2O3/NiO Interface for the Electrochemical Oxygen Evolution in Seawater and Domestic Sewage.

Hydrogen production from the electrolysis of seawater and domestic sewage is more attractive than that from pure water, especially in regions where freshwater resources are scarce. However, under such harsh conditions, higher requirements are put forward for the catalytic activity and adaptability of a catalytic electrode. Herein, we advance an ultrasimple dipping-and-heating method to engineer the surface of Ni foam (NF) into an interface-rich FeNi oxide layer and realize an exceptional oxygen evolution reaction (OER) performance. It only requires overpotentials of 182 and 267 mV to achieve current densities of 10 and 1000 mA cm-2 in 1 M KOH, respectively, which are significantly lower than those of the recently reported catalysts. The as-prepared FNE300||MoNi4/MoO2 electrolyzer realizes the industrial demand of 500 mA cm-2 at low voltages of ∼1.75 V for overall alkaline natural seawater and domestic sewage electrolysis, as well as satisfactory stability. Density functional theory (DFT) calculations indicate that modifying the electronic structure so as to optimize the intermediate adsorption is well achieved by constructing the interfaces between NiO and Fe2O3. The interaction of Fe with oxygen intermediates can be optimized by e--e- repulsion between Ni2+ and oxygen intermediates. This work provides a facile approach to fabricate an electrocatalyst for seawater and domestic sewage electrolysis, which is of great significance to the synergetic development of hydrogen economy and environmental science.

A multifunctional Cu6Sn5 interface layer for dendritic-free lithium metal anode

The unstable electrode/electrolyte interface of the lithium metal anode is one of the reasons that induce the formation of lithium (Li) dendrites. The Li dendrites will reduce the coulombic efficiency, and even pierce the separator to cause the safety problems. Herein, a tightly bonded and uniformly distributed Cu6Sn5 interface layer is formed on the surface of the Cu foam by a simple electroless plating method. The composite layer has multiple functions, such as high lithiophilicity, high carrier transport and high adaptability to mechanical strain. Based on the versatility of the Cu6Sn5 interface layer, the cycle life of Cu foam is increased from 150 h to 1000 h, and the deposition overpotential is as low as 18 mV. In-situ online observation proves that the existence of composite layer can make Li metal uniformly deposited to avoid the dendrites. Furthermore, Cu6Sn5@Cu foam also shows a higher capacity retention rate (increased from 65.2% to 78.6% after 300 cycles) and a more stable rate performance when it is used in full batteries. Compared with the single function improvement strategy proposed by the current lithium metal anode research. The Cu6Sn5 multifunctional composite layer modification method in this work provides a new strategy for constructing a stable electrode/electrolyte interface.

High capacitance for asymmetric supercapacitors based on one-step synthetic nanoflowers/nanocones arrays as cathode and pomelo peel as anode

In this work, NiCoO2 nanoflowers and nanocones are synthesized by one-step hydrothermal method. A layer of NiCoO2 nanoflowers is initially grown on the surface of Ni foam, followed by subsequent growth of NiCoO2 nanocones in order to obtain hierarchical NiCoO2/NiCoO2 nanoflowers/nanocones arrays (NNFC arrays). Various characterization methods are used to ensure the structure, morphology and composition of the materials. The results confirm that the as-prepared sample exhibits high specific surface area and voidage, low electrode internal resistance (0.5Ω), extremely fast diffusion and migration, and high electrochemical performance (1215.2 ​F ​g−1 at 5 ​mA ​cm−2). Furthermore, an all-solid-state supercapacitor (ASC) using NNFC arrays as a cathode, pomelo peel carbon (PPC) as an anode, and polyvinyl alcohol/KOH as separator is assembled. The ASC exhibits excellent specific capacitance (318.7 ​F ​g−1 at 5 ​mA ​cm−2) and large energy density (113.3 ​Wh·kg−1 at 396 ​W ​kg−1). Two ASCs in series can illume a red LED of 1.8 ​V for 30 ​min. The present work provides an effective approach to hydrothermally prepare two different morphologies in one-step, offering a facile and cost-efficient route to design outstanding supercapacitors (SCs).

Rational engineering of hierarchical mesoporous CuxFeySe battery-type electrodes for asymmetric hybrid supercapacitors

Highly-ranked positive electrode materials with distinct electrochemical properties and appropriate designs of heterostructured porous architectures integrating mixed transition metal selenides are necessary to boost energy storage capability, which thus have been intensively investigated in the recent years. In this work, we develop a one-step chemical deposition method to grow 3D copper iron selenides (CuxFeySe) heterostructures on the surface of a nickel foam (NF) current collector. The macroporous skeleton of NF not only boosts the homogeneous growth of CuxFeySe architectures but also improves the electrical conductivity of resultant electrodes due to the robust mechanical strength at the junction. The effect of Cu2+/Fe2+ ions is also investigated and noticeably contributed to electrochemical performance. Benefitting from the synergetic effect of integrated Cu and Fe ions with different chemical states, improved electronic configuration, and effective electron/ion transport rate, the battery-type Cu7.5Fe7.5Se electrode delivers a high specific capacity of 186.1 mAh g−1 at a current density of 1 A g−1 with an enhanced capacity retention (63.7% at 50 A g−1). Moreover, the asymmetric supercapacitor (ASC) device fabricated with the self-standing Cu7.5Fe7.5Se electrode and benchmark activated carbon (AC) as the positive and negative electrodes, respectively realizes a large cell potential of 1.5 V and exhibits a high specific capacity of 70 mAh g−1 at 1 A g−1 and a good rate capability (61.6% at 25 A g−1). The assembled device reaches a maximum energy density of ~74.2 W h kg−1 at a power density of 1058.3 W kg−1 together with an appropriate lifespan (91.3% after 8000 cycles at 12 A g−1).

Energy storage properties of hydrothermally processed ultrathin 2D binder-free ZnCo2O4 nanosheets

High energy-density supercapacitors (SCs) with long operating life, cost-effective, and competitive cycling performance is attracted great research attention to competing in the requirements of the modern age. However, despite these benefits, SC hampers inadequate rate-capability and structural deterioration, which primarily affects its commercialization. Herein, ultra-thin two-dimensional (2D) ZnCo2O4 nanosheets are in situ anchored on the conductive surface of nickel foam (denoted as ZCO@NF) by hydrothermal process. The binder-free ZCO@NF is employed as an electrode for SCs and shows impressive charge storage properties. ZCO@NF electrode exhibited a high capacitance of 1250 (750) and 733 F g−1 (440 C g−1) at 2.5 and 20 A g−1, respectively, demonstrating the outstanding rate-capability of 58.6% even at 8 times larger current density. Furthermore, the ZCO@NF electrode exhibits admirable capacitance retention of 96.5% after 10 000 cycles. This impressive performance of the ZCO@NF electrode is attributed to the high surface area which gives a short distance for ion/electron transfer, a high conductivity with extensive electroactive cities, and strong structural stability. The binder-free approach provides a strong relationship between the current collector and the active material, which turns into improved electrochemical operation as an electrode material for SCs.

Improvement of Electrochemical Performance of ZnCo2O4@Co9S8 Nanosheets for Supercapacitors

ZnCo2O4@Co9S8 nanostructures were grown on the surface of Ni foam by facile hydrothermal method and subsequent thermal treatment process, thus increasing the active site on the surface of the material. After vulcanization treatment, the performance of the composite material has been significantly improved the product has a higher specific capacitance of 1018.2 F g−1 at 4 A g−1. This work demonstrates that ZnCo2O4@Co9S8 nanostructures are highly desirable for application as advanced electrochemical electrode materials.

Plasma mediated preparation of NiFeNx nanoparticles anchored on nickel foam for efficient oxygen evolution in alkaline solution

This paper reports a plasma mediated nitriding method to prepare transition metal nitrides (TMNs) for efficient oxygen evolution reaction (OER). Nickel foam (NF) dipped into FeCl3 solution is treated with N2 plasma, and a composite structure of NiFeN and Ni2Fe2N is obtained with nitride nanoparticles uniformly distributed on the surface of the nickel foam (donated as NiFeNx/NF). The prepared NiFeNx/NF shows a low overpotential of 286 mV at 10 mA cm−2 and 330 mV at 100 mA cm−2, which is lower than RuO2 loaded on NF (0.5 mg cm−2). There is no obvious increase in the overpotential after 20 h stability test. The excellent performance of NiFeNx/NF is attributed to the synergistic effect of NiFe bimetallic nitrides.

Sandwich structured Ni3S2-MoS2-Ni3S2@Ni foam electrode as a stable bifunctional electrocatalyst for highly sustained overall seawater splitting

The exploitation of cost-effective bifunctional seawater electrocatalyst is an attractive technology to generate hydrogen fuel. Sustainable seawater splitting requires catalysts with robust hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity as well as superior chloride corrosion resistance in the salty electrolyte. Here we designed a sandwich-like Ni3S2-MoS2-Ni3S2@Ni foam (NMN-NF) catalyst on the surface of Ni foam by stacking Ni3S2 coatings as top and bottom protective layers (chloride anti-corrosion), and MoS2 as an interlayer to trigger both HER and OER in salty water. The unique sandwich structure endowed NMN-NF catalysts with excellent bifunctional catalytic activity and long-term durability in alkaline seawater electrolytes. Taking advantage of the synergistic effect between MoS2 and Ni3S2, NMN-NF delivered a current density of 100 mA/cm2 at a low voltage of 1.82 V under operating over 100 h in alkaline seawater, allowing them a promising catalyst towards practical application for efficient seawater splitting.

In-situ growth of Ag particles anchored Cu foam scaffold for dendrite-free lithium metal anode

Metallic lithium is considered to be the potential anode for high energy density rechargeable Li batteries. Yet the growth of lithium dendrites impedes the industrial production of lithium metal batteries. Herein, we fabricate a dendrite-suppressed composite Li metal anode via introducing Ag particles as lithiophilic layer on the 3D copper foam (Cu-Ag). The Li ion prefers deposit on the surface of Cu-Ag foam, which is beneficial to the better adsorption of the Cu-Ag hierarchical heterojunction structure by the first-principles calculations. The heterojunction structure can further reduce the nucleation overpotential and surface current density of the composite Cu-Ag-Li anode to realize the homogeneous Li distribution for stable Li deposited/stripped. Thus, the Cu-Ag-Li composite electrode (CAL) presents better electrochemical performance in the symmetric battery and excellent rate performance in the full cell with a greatly enhanced capacity retention of 83% after 500 cycles. This strategy presents a general approach to suppress the growth of lithium dendrites and regulate the volume changes for long-life span lithium metal batteries.

High-Performance Foam-Shaped Strain Sensor Based on Carbon Nanotubes and Ti3C2Tx MXene for the Monitoring of Human Activities.

The flexible strain sensor is of significant importance in wearable electronics, since it can help monitor the physical signals from the human body. Among various strain sensors, the foam-shaped ones have received widespread attention owing to their light weight and gas permeability. However, the working range of these sensors is still not large enough, and the sensitivity needs to be further improved. In this work, we develop a high-performance foam-shaped strain sensor composed of Ti3C2Tx MXene, multiwalled carbon nanotubes (MWCNTs), and thermoplastic polyurethane (TPU). MXene sheets are adsorbed on the surface of a composite foam of MWCNTs and TPU (referred to as TPU/MWCNTs foam), which is prefabricated by using a salt-templating method. The obtained TPU/MWCNTs@MXene foam works effectively as a lightweight, easily processable, and sensitive strain sensor. The TPU/MWCNTs@MXene device can deliver a wide working strain range of ∼100% and an outstanding sensitivity as high as 363 simultaneously, superior to the state-of-the-art foam-shaped strain sensors. Moreover, the composite foam shows an excellent gas permeability and suitable elastic modulus close to those of skin, indicating its being highly comfortable as a wearable sensor. Owing to these advantages, the sensor works effectively in detecting both subtle and large human movements, such as joint motion, finger motion, and vocal cord vibration. In addition, the sensor can be used for gesture recognition, demonstrating its perspective in human-machine interaction. Because of the high sensitivity, wide working range, gas permeability, and suitable modulus, our foam-shaped composite strain sensor may have great potential in the field of flexible and wearable electronics in the near future.

High-performance microwave absorption of MOF‐derived Co3O4@N-doped carbon anchored on carbon foam

Absorbing materials can convert electromagnetic wave (EMW) energy into heat and other energy and dissipate it. Carbon materials can attenuate EMW by generating large conduction losses due to their high conductivity. The introduction of low dielectric materials can improve impedance matching caused by high conductivity. However, the density of materials compounded with carbon materials is too large, which affects the overall density of composite materials. Therefore, this problem is solved by matching melamine foam with ZIF-67. As an ultra-light material, the melamine foam-based carbon material can significantly reduce the density of composite materials, and its developed three-dimensional structure can cause multiple scattering of EMW. The large specific surface area and evenly distributed metal oxides obtained after annealing of ZIF-67 can provide ultra-low-density carbon materials and abundant interfacial polarization to further attenuate EMW. So far, the methods of self-growing materials on the surface of melamine foam have not been reported. We prepared a 500 nm Co3O4 nanosheet/carbon foam (CF) composite material coated on the surface by a two-step method. The sample had a maximum reflection loss of −46.58 dB at 10.72 GHz, and an effective absorption bandwidth (EAB) of 5.4 GHz. This research provides a new idea for the growth of porous materials on the surface of melamine foam-based carbon materials.

Boron phenolic resin/silica sol coating gives rigid polyurethane foam excellent and long‐lasting flame‐retardant properties

AbstractIn this paper, a boron phenolic (BPR)/silica sol (Si‐sol) coated flame retardant was prepared, and the flame retardant was coated on the surface of rigid polyurethane foam (RPUF) to make it have excellent flame‐retardant effects. The molecular structure of BPR and Si‐sol was analyzed by FTIR, and the influence of the coating on the cells was observed with an optical microscope. It was evident from the test results of the cone calorimeter that the peak heat release rate (PHRR) and total heat release (THR) of RPUF were reduced by 45% and 37.7%, respectively. The limit oxygen index and vertical combustion test results indicated that the LOI reached 35%, and UL‐94 reached the V‐0 level. The aging experiment was conducted on the coated RPUF material, and the results showed that the material has long‐lasting flame‐retardant properties. The possible flame‐retardant mechanism was analyzed.

Stabilization and performance of a novel viscoelastic N2 foam for enhanced oil recovery

A novel viscoelastic N2 foam (0.12% sodium dodecyl sulfate + 0.18% erucyl dimethyl amidopropyl betaine) with ultra-low interfacial tension and alkali-free was developed. With the conditions of Xinjiang Oilfield (45℃, c (salinity) = 7880 mg/L), the foam performances were investigated by the modified Rose-Miles method. The modified Rose-Miles method is in non-shear action, in which N2 enters a porous media and pumps into the solution to produce foam. The stability mechanism was explained based on the dilatational surface viscoelasticity and liquid viscoelasticity. The EOR effect was evaluated by the displacement experiment. The results showed that the foam volume of viscoelastic N2 foam was five times compared with the initial solution. The foam half-life and the drainage half-life were 6.5 and 6.2 times higher compared with that of stabilized by the polyacrylamide, respectively. The surface of N2 foam possessed high elasticity modulus, and the solution had high viscoelasticity, so the particle size and drainage of liquid film changed slowly. Finally, the viscoelastic N2 foam flooding (0.4PV surfactant + 0.4PV N2) enhanced oil recovery by 22.95%, compared with the surfactant flooding (0.8PV surfactant) by 4.06%. The viscoelastic N2 foam could greatly reduce the amount of surfactant and had an excellent EOR application in the Xinjiang Oilfield.

Hierarchical Core‐Shell N‐Doped Carbon@FeP4‐CoP Arrays as Robust Bifunctional Electrocatalysts for Overall Water Splitting at High Current Density

AbstractExploring non‐precious metal‐based electrocatalysts at high current density and stability is an urgent issue for sustainable H2 production. Here, hierarchical core‐shell N‐doped carbon encapsulated array‐like FeP4 and CoP active components have been fabricated in situ on the surface of nickel foam (NC@FeP4‐CoP/NF) by etching sheet‐like ZIF‐67 arrays, Prussian analog formation, and phosphating in turns. The crystallinity, hierarchical heterostructure, and chemical state have been carefully discussed. Electrochemical studies demonstrate that the catalyst displays excellent electrocatalytic activity and durability in electrochemical oxygen evolution reaction (η20 = 218 mV) and hydrogen evolution reaction (η10 = 116 mV), better than most previously reported bifunctional catalysts. Moreover, the bifunctional catalyst only needs 1.72 and 1.80 V cell voltages at 500 and 1000 mA cm−2 respectively, together with a good catalytic stability at 500 mA cm−2 for 48 h, implying potential commercialization prospects. This excellent electrocatalytic performance is mainly attributed to the distinctive hierarchical structure as well as core‐shell NC encapsulated FeP4‐CoP active sites, which can enhance the charge transport rate, inhibit the exfoliation of the active materials, provide a larger active surface area, and facilitate electrolyte diffusion and gas release.

Synthesis of activated carbon foams with high specific surface area using polyurethane elastomer templates for effective removal of methylene blue

Abstract Carbon foams have gained significant attention due to their tuneable properties that enable a wide range of applications including catalysis, energy storage and wastewater treatment. Novel synthesis pathways enable novel applications via yielding complex, hierarchical material structure. In this work, activated carbon foams (ACFs) were produced from waste polyurethane elastomer templates using different synthesis pathways, including a novel one-step method. Uniquely, the produced foams exhibited complex structure and contained carbon microspheres. The ACFs were synthesized by impregnating the elastomers in an acidified sucrose solution followed by direct activation using CO2 at 1000 ℃. Different pyrolysis and activation conditions were investigated. The ACFs were characterized by a high specific surface area (SBET) of 2172 m2/g and an enhanced pore volume of 1.08 cm3/g. Computer tomography and morphological studies revealed an inhomogeneous porous structure and the presence of numerous carbon spheres of varying sizes embedded in the porous network of the three-dimensional carbon foam. X-ray diffraction (XRD) and Raman spectroscopy indicated that the obtained carbon foam was amorphous and of turbostratic structure. Moreover, the activation process enhanced the surface of the carbon foam, making it more hydrophilic via altering pore size distribution and introducing oxygen functional groups. In equilibrium, the adsorption of methylene blue on ACF followed the Langmuir isotherm model with a maximum adsorption capacity of 592 mg/g. Based on these results, the produced ACFs have potential applications as adsorbents, catalyst support and electrode material in energy storage systems.

Structural design of cobalt phosphate on nickel foam for electrocatalytic oxygen evolution

The elaborate design and synthesis of low-cost, efficient and stable electrocatalysts for the oxygen evolution reaction (OER), which may alleviate the current energy shortage and environment pollution, is still a great challenge. Herein, metal phosphonate precursors with controllable morphologies were synthesized in situ on the surface of nickel foam with different solvents, and could be easily converted into carbon- and nitrogen-doped cobalt phosphate through a calcination method. The OER catalytic performance of the final products was studied in detail. The results showed that the nanowire shaped samples of CoPiNF-800 synthesized with deionized water under hydrothermal conditions had the strongest electrochemical performance. They exhibited extraordinary catalytic activity with a very low overpotential of 222 mV at 100 mA cm−2, the smallest impedance and excellent electrochemical stability. These results not only demonstrate the possibility of preparing low-cost OER catalysts based on transition metal phosphate, but also aid our understanding of the controllable synthesis process of different morphologies.

Improvement of Interfacial Bonding Force between PMI Foam and CFRP in PMI Foam-Cored CFRP Sandwich Composites

In the polymethacrylimide (PMI) foam-cored carbon fiber reinforced polymer (CFRP) sandwich composite, PMI foam is the core material and CFRP is the surface material. The interfacial bonding force between the foam core and the skin layer is an important factor that determines the mechanical properties of the foam-cored sandwich composite. This study improved the interfacial bonding force between the PMI foam core and the CFRP skin layer in the PMI foam-cored sandwich CFRP composite. This was achieved by fabricating holes of a constant volume on the surface of the PMI foam; in addition, an epoxy, the matrix of CFRP, was filled to increase the bonding area of the interface between the PMI foam and the CFRP skin layer. Then by processing holes with constant distance, it was confirmed that the interfacial bonding force according to the intervals of the holes. As a result, the interfacial bonding force of samples with holes increased on average up to 63.5 % compared with the samples without the processed holes.

One-step synthesis of amino acid-derived HTC/NiO/Ni(OH)2@Ni cathode for high performance supercapacitors

Binder-free nano-sized structure composed of pseudocapacitive materials covered by carbon is concerned to be the next-generation electrode for supercapacitor due to the avoidance of binder and additional electrode preparation, high capacitance of the pseudocapacitive materials, and high conductivity of carbon. Here, a serial of amino acids chosen as hydrothermal carbon (HTC) source were loaded on conductive substrate surface of Ni foam (NF), which constructed binder-free electrodes by a one-step hydrothermal process. Because of its weak oxidative and acid properties, an in-situ redox reaction occurred in the existence of L-glutamic acid, in which Ni is also simultaneously converted into nanostructured NiO/Ni(OH)2 (HTC/NiO/Ni(OH)2@NF). It is discovered that HTC/NiO/Ni(OH)2@NF electrode derived from L-glutamic acid at 2 g L-1 and 160 °C exhibited a battery-like behavior and superior charge/discharge performances, i.e., a specific capacitance of 2586 F g−1 (1293 C g−1) at 2.8 A g−1, and an excellent stability of 91.30% retention after 20,000 cycles.

Effect of silica‐coated TiO2 nanorods on the foamability of polypropylene and photostability of foamed polypropylene

Researches about the heterogeneous nucleation ability of nanorods and the weather resistance of polypropylene (PP) foams were very limited. In this study, the well‐defined rutile TiO2 nanorods with UV‐absorbing function were coated with silica and then calcined. The obtained nanorods (denoted as “TS”) could be uniformly dispersed in PP matrix by melt blending. The foaming behavior of linear PP and its composites was investigated by using supercritical carbon dioxide (scCO2) as a physical foaming agent. The results demonstrated that the addition of 5 wt% TS made PP/TS‐5% foam have higher cell density, regular cell structure and uniform cell distribution owing to the large numbers of nucleation sites provided by well‐dispersed TS nanorods. At the same time, the aging performance of PP foam samples was evaluated by the changes of macro or micro morphology, melting and crystallization behavior before and after UVB irradiation. It was intuitively found that the damage to the surface of PP foams caused by UV light, involving the erosion of surface, the collapse of cells and the degradation of PP chains could be significantly suppressed by the incorporation of TS nanorods. These findings indicated that TS nanorods could be used as multifunctional nanofillers to achieve the PP foams with improved foamability and photostability.

A self-supporting electrode with in-situ partial transformation of Fe-MOF into amorphous NiFe-LDH for efficient oxygen evolution reaction

Metal-organic frameworks (MOFs) have been extensively researched in recent years benefiting from the large surface area, abundant active centers, and adjustable structure. However, low conductivity and inaccessible active sites severely hinder its application in water electrolysis. Herein, a self-supporting electrocatalyst by developing MOF derivative on the surface of iron foam (IF) was synthesized through a self-templated partial transformation strategy. In addition, a series of catalysts with different morphologies were synthesized by adjusting the amount of Ni and the reaction time. Profiting from the unique hierarchical structure with large active area and abundant active sites, strong combination of highly active amorphous NiFe-LDH and Fe-MOF, and high conductivity and stability of the MOFs array in situ growth on IF, the resulting NiFe-LDH@Fe-MOF/IF-2 shows excellent oxygen evolution reaction (OER) activity in alkaline electrolyte with required overpotentials of 183, 237 and 257 mV to achieve current densities of 10, 100, and 200 mA cm−2, respectively, and long-term stability for at least 20 h. This work provides new insights for the design and development of self-supporting MOFs derived high performance electrocatalysts.