Surface Of NF Research Articles

Ultrafast Room-Temperature Synthesis of Phosphate-Intercalated NiFe Layered Double Hydroxides for High-Performance Alkaline Seawater Oxidation.

Quick and easy synthetic methods and highly efficient catalytic performance are equally important to anodic oxygen evolution reaction (OER) electrocatalysts for alkaline seawater electrolysis. Herein, we report a facile one-step route to in situ growing PO43- intercalated NiFe layered double hydroxides (NiFe-LDH) on Ni foam (denoted as NiFe-P/NF) by a room-temperature immersion for several minutes. This ultrafast approach transforms the NF surface into a rough PO43- intercalated NiFe-LDH overlayer, which demonstrates outstanding OER performance in both alkaline simulated and natural seawaters owing to good hydrophilic interface and the electrostatic repulsion of PO43- against Cl- anions. Density functional theory calculations reveal that the intercalated PO43- can not only promote electron transfer but also prevent Cl- from entering the interlayer and simultaneously inhibit the migration of Cl- over the NiFe-LDH surface. In alkaline simulated and natural seawater electrolytes, NiFe-P/NF needs low overpotentials of 248 and 298 mV to achieve a current density of 100 mA cm-2, respectively. NiFe-P/NF can stably run over 42 h in an alkaline high-salty electrolyte (1 M KOH + 2.5 M NaCl) at 250 mA cm-2, more than 70 times that of NiFe/NF (0.6 h), emphasizing the critical role of the intercalated PO43- anions on the excellent durability. This study offers a new strategy to modify commercial NF to prepare efficient and stable OER catalysts for seawater electrolysis.

Polypyrrole-mediated construction of superhydrophobic photo/electro thermal composite fabric for efficient crude oil dehydration and recovery

During crude oil extraction, transportation, and oil spill recovery, rapid and effective removal of water from crude oil is a great challenge. Super-hydrophobic functional membranes with electrothermal/photothermal effects are considered to be an effective method. However, simply polymerizing photothermal/electrothermal nanomaterials on the membrane surface will lead to unstable thermal effects and easy shedding. Therefore, in this study we propose the synthesis of a novel superhydrophobic electrothermal/photothermal Nylon fabric (PSPPNF) by an innovative in situ polymerization method of Pyrrole (Py), to realize efficient viscosity reduction and dehydration of crude oil. In particular, by controlling FeCl3 solution from solid (−18 °C) to liquid state (0 °C), Py was polymerized on the fabric surface by slow oxidative process, which can effectively solve the problem of pore blocks to obtain a stable-conductive layer on the NF surface. The PSPPNF surface temperature can reach 80 °C under 1 kW m−2 sunlight intensity or by inputting 30 V, which brings a separation efficiency of 97 % for high-viscous crude oil/water mixture. We systematically analyzed the effects of PSPPNF with different pore sizes and oils with different viscosities on the separation flux, as well as the effects of the thermal properties of the membranes under different illumination conditions and voltages on crude oil permeation. Additionally, the PSPPNF combined with the roller can realize all-weather available crude oil spill recovery under solar and electrical energy. This work provides new insights into membrane materials that can realize the efficient dehydration and recovery of crude oil for day-night alternation and complex environments.

In situ constructed Bi5O7I/NiO-NF heterojunction on 3D nickel foam for photocatalytic sulfamerazine degradation: Structure-performance, application, and mechanism

Photocatalysis is a promising technology for water purification, but the inadequate separation of photogenerated charge carriers and light utilization efficiency limits its practical application. Herein, a highly solar-responds photocatalyst Bi5O7I/preoxidized nickel foam (Bi5O7I/NiO-NF) with p-n heterojunction was constructed by impregnation and microwave-assisted co-precipitation method to remove typical antibiotic efficiently. The special pretreatment is conducive to the formation of NiO on the NF surface, which participates in the construction of p-n heterogeneous structures and strengthens the bonding force between NiO-NF and surface Bi5O7I. The macroscopic renewable Bi5O7I/NiO-NF could effectively degrade sulfamerazine (SMR) nearly 100 % under sunlight irradiation and be convenient for separating from aqueous. Variety pollutants are degraded with high efficiency in the solar Bi5O7I/NiO-NF system, and the system performs the resistance to co-existing ions (≥89 % removal efficiency) and water matrix interference (≥95 % removal efficiency). Quenching experiments and electron paramagnetic resonance spectroscopy characterization results indicate that h+, 1O2 and O2− are the dominant reactive substances in SMR elimination. Based on the DFT calculation and quadrupole-time of flight-liquid chromatography/mass spectrometry (Q-TOF-LC/MS) detection, C-S and N-S bonds tend to be attacked in the SMR degradation pathway. This work opens up novel insights for constructing efficient macroscopic photocatalysts for practical water treatment.

Versailles Santa Barbara-5 derived bifunctional one-dimensional electrocatalysts of hierarchical Ni3S2 nanoprism@nanosheets arrays for self-supporting and binder-free efficient supercapacitor and methanol oxidation reaction

We herein present a structure consisting of two-dimensional (2D) single-crystal Ni3S2 nanosheets designed on one-dimensional (1D) Ni3S2 nanoprism arrays (also known as Ni3S2 nanoprism@nanosheets). These arrays are directly synthesized over nickel foam, which is referred to as Ni3S2/NF. These structures can be used as binderless, self-supporting electrodes for bifunctional methanol oxidation reaction (MOR) applications and high energy density hybrid supercapacitors (HSC). Ni3S2/NF is synthesized through the two steps of hydrothermal processes. In step I, 1D hexagonal Versailles Santa Barbara-5 (VSB-5) nanorod arrays have been prepared onto the surface of NF (denoted as VSB-5/NF). The precursor for step II was 1D VSB-5 nanorod arrays, which were transformed into Ni3S2 using Na2S as a sulfur source via the Kirkendall effect. Electrochemical examination results show that as-synthesized Ni3S2/NF electrode exhibited a high specific capacitance (Cs) of 145.0 mA h g−1 at 5 A g−1, low series resistance (0.18 Ω) and charge-transfer resistance (0.05 Ω), small relaxation time constant (τ0 = 8 ms) and high frequency response at 125.8 Hz. Ni3S2/NF has a superior specific capacity of 145.0 mA h g−1 at 5 A g−1 as a SC electrode. The Ni3S2/NF//CNTs/NF HSC can be operated up to 1.6 V in a 3 M KOH electrolyte, delivering an impressive energy density of 256.35 W h kg−1 at a power density of 6400 W kg−1. The as-assembled Ni3S2/NF//CNTs/NF HSC device exhibited an impressive stability of 81 % even after undergoing 10,000 charge-discharge cycles. When compared to previously reported catalysts, Ni3S2/NF was proved to be an excellent electrocatalyst for MOR due to its ability to generate a current density of 215.0 mA cm−2 at 0.5 VSCE, while maintaining a superior and stable current density of 619.2 mA cm−2 at 0.8 VSCE.

Non-enzymatic Glucose Sensor Based on Ni(OH)2/NF Materials Using Different Pulse Voltammetry Technique

Non-enzymatic glucose sensors have gained significant attention owing to their potential for accurate and cost-effective glucose detection. Nanomaterials play a pivotal role in enhancing performance of non-enzymatic glucose sensor. In this study, a novel non-enzymatic glucose sensor based on Ni(OH)2/NF (nickel hydroxide/nickel foam) materials was developed using different pulse voltammetry technique. Chemical precipitation methods have been used to grow Ni(OH)2 nanostructures directly on a nickel foam electrode. The characterization of the synthesized materials was performed through field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), and X-ray diffraction (XRD). The performance of the Ni(OH)2/NF-based glucose sensor was evaluated through electrochemical measurements. Nanoscale hive-like structures of Ni(OH)2 with a diameter ranging from 450 to 530 μm and a thickness of 20 nm were formed on the NF surface. The sensor exhibited good performance, displaying a high sensitivity of 8.42mA.mM-1.cm-2 with a low detection limit of 0.84 μM. These results position the synthesized electrode as a promising contender for non-enzymatic electrochemical glucose sensors.

Electrokinetic-mechanism of water and furfural oxidation on pulsed laser-interlaced Cu2O 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 CoO/NiO/nickel foam (NF) and Cu2O/NiO/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 Cu2O 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 mV (OER) at 10 mA/cm2, achieving the maximum FA yield (∼16.37 mM) 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.

Hydrogen peroxide electrosynthesis with nickel foam electrodes: influence mechanism of surface oxidation

AbstractBACKGROUNDNickel foam (NF) is widely used as battery electrode matrix and electrochemical process cathode. However, the surface of NF is prone to oxidation, which may affect its ability to reduce oxygen and produce H2O2, but the influence mechanism is still unclear. In this paper, surface oxidation of the NF was regulated by pickling and drying pretreatment, and the surface oxides were characterized by X‐ray photoelectron spectroscopy (XPS) and energy dispersive X‐ray spectrometry (EDS). The NF was used as the substrate, graphite powder as the catalyst, and PTFE as the binder to prepare graphite‐coated NF composite electrodes. The effect of NF surface oxidation on their ability to generate H2O2 was investigated.RESULTSThe results demonstrated that after pickling and drying, the NF surface generated a large amount of NiO, which increased the charge transfer resistance of the NF by 20.3%, and accelerated further reduction decomposition of H2O2. The rotating ring‐disk electrode (RRDE) tests further confirmed that NiO can reduce the two‐electron oxygen reaction selectivity, which was detrimental to H2O2 electrosynthesis. The graphite‐coated NF composite electrode with pristine NF as the substrate can produce 869.1 mg L−1 of H2O2 and maintain relatively good reusability.CONCLUSIONOverall, the surface oxidation of NF is not conducive to H2O2 electrosynthesis, and it is necessary to prevent oxidation during electrode preparation. This study provides a valuable reference for the preparation of NF electrodes and can promote the further study of in situ H2O2 electrosynthesis. © 2023 Society of Chemical Industry (SCI).

Continuous flow degradation of Orange II by a dandelion-like NiCo2O4/NF activated peroxymonosulfate in a fixed-bed system

A novel dandelion-like catalyst, nickel foam supported NiCo2O4 (NiCo2O4/NF), was successfully synthesized and applied to the activation of peroxymonosulfate (PMS) in a fixed bed system for the degradation of Orange II (OII). The physicochemical properties of synthesis catalysts were identified by various characterization methods (SEM, EDS, XRD and XPS), revealing that the dandelion-like NiCo2O4 nanosheets were evenly distributed on the surface of NF. NiCo2O4/NF-250 showed excellent catalytic performance at a hydrothermal reaction time of 8 h, urea/metal ratio of 10:1, and Co/Ni concentration of 10 mM/5 mM. When PMS concentration was 5 mM, reaction temperature was 50 ℃, pH was 7.5, space velocity was 0.236 min−1, the conversion ratios of OII, PMS and COD were 99.8 %, 71.3 %, and 71.4 % at 240 min, respectively. In particular, NiCo2O4/NF still could reach 99.9 % OII conversion and 64.4 % COD conversion in the third cycle. DFT calculations implied that NiCo2O4/NF had excellent PMS activation performance.

Electrochemiluminescence Sensor with Controlled-Release Triggering Electrostatic Attraction Elimination Mechanism for Trenbolone Trace Detection.

A controlled-release strategy can meet the needs of sensitive environmental monitoring for pollutants through a self-on/off mode. In this work, an electrochemiluminescence (ECL) biosensor with controlled-release triggering electrostatic attraction elimination and biomolecular stimulated response strategies was constructed to detect environmental steroid hormones sensitively. The blocked pores on the aminated mesoporous silica nanocontainers were opened by specific binding between the trenbolone (TB) antigen and the antibody. The released l-cysteine counteracted the negative charge on the MnO2 NF surface through the redox reaction between -SH and MnO2, making the electrostatic interaction between the MnO2 NFs and the Ru(dcbpy)32+ disappear. Ru(dcbpy)32+ released an ECL signal on the electrode, thus completing the controlled-release triggering electrostatic attraction elimination strategy. In addition, with the TB antibody as the target and the competition strategy between the TB antigen and the standard substance, the constructed controlled-release ECL biosensor was used to detect the TB standard substance. Moreover, MnO2 NFs as the substrate of the ECL biosensor increased the active specific surface area of the electrode, effectively catalyzing the production of OH• and O2•-, thus endowing the ECL biosensor with coreactant-catalytic enhancement characteristic and further improving its ECL performance. This sensitive signal response brought about a low limit of detection of 2.53 fg/mL for the constructed ECL biosensor, which contributed a feasible idea for efficient trace analysis of pollutants in the environment.

Cu doped Fe2O3 growing a nickel foam for sulfadiazine degradation in peroxymonosulfate assisting photo-electrochemical system: Performance, mechanism and degradation pathway

In this study, cost-effective and easily recovery Cu doped Fe2O3 in-situ growing on a nickel foam (Cu-Fe2O3/NF) was successfully fabricated and employed in peroxymonosulfate (PMS) assisting visible-light photoelectrochemical oxidation (VL + EC + catalyst + PMS) system for sulfadiazine (SD) removal. The optimum 2Cu-Fe2O3/NF exhibited excellent catalytic efficiency toward SD degradation in the VL + EC + catalyst + PMS system, 100% of SD being removed in 10 min and the firs-order reaction kinetic constant being 41.30 × 10-2 min−1. The excellent catalytic efficiency of 2Cu-Fe2O3/NF was due to the depressed recombination of photoinduced electron and hole, the enhanced electron transfer efficiency, more Fe2+, Cu+ and Ni2+ in sample resulting from Cu doping, and more active sites owing to the bulk thick petals-like of Fe2O3 being changed to thinner flakes after Cu doping. Therefore, a large number of reactive oxygen species including •OH, •O2− and h+ in the VL + EC + 2Cu-Fe2O3/NF + PMS system were produced to degrade SD. The mechanism of SD degradation in the system was explored in detail. The 2Cu-Fe2O3/NF displayed adaptation ability for a wide range, good anti-interference ability toward ions in real water. More inspiring, benefiting from the in-situ growth of Cu-Fe2O3 on NF surface, 2Cu-Fe2O3/NF exhibited good durability and recycle ability. This study provides a worthy reference for designing efficient and easily recycled catalysts and promotes the practical application possibility of low-cost Fe2O3 in antibiotics removal.

Achieving homogeneous Li deposition of 3D dendrite-free lithium metal anode through atomic layer deposition surface modification

Herein, two coating amorphous Al2O3 and Li3PO4 with different properties were firstly demonstrated for Li/Nickel Foam (Li/NF) composite anode via atomic layer deposition (ALD) method to form a free-standing Li host material for dendrite-free Li anode. Impedance test shows that Li nucleates easily on Li3PO4 surface compared with NF and Al2O3 surface. Significantly, scanning electron microscope (SEM) observation of tracing the same site shows that a large number of lithium dendrites were deposited on NF and Al2O3 surface, while no dendrite growth was observed on Li3PO4 surface. The test of cells shows that Li@Li3PO4@NF anode presents better cycling stability and rate capability. Li3PO4 reduces the nucleation overpotential and the surface energy barrier, which can increase the overall surface lithiophilic, so that the entire surface is deposited uniformly. This work promotes the uniform deposition of lithium and sheds light on the development of ultrastable lithium metal anode.

Synthesis of Ni3S2 and MOF-Derived Ni(OH)2 Composite Electrode Materials on Ni Foam for High-Performance Supercapacitors.

Honeycomb-like Ni(OH)2/Ni3S2/Ni foam (NF) was fabricated via a two-step hydrothermal process and subsequent alkalization. Ni3S2 with a honeycombed structure was in-situ synthesized on the NF surface by a hydrothermal process. MOF-derived Ni(OH)2 nanosheets were then successfully grown on the Ni3S2/NF surface by a second hydrothermal process and alkaline treatment, and a large number of nanosheets were interconnected to form a typical honeycomb-like structure with a large specific surface area and porosity. As a binder-free electrode, the prepared honeycomb-like Ni(OH)2/Ni3S2/NF exhibited a high specific capacitance (2207 F·g-1 at 1 A·g-1, 1929.7 F·g-1 at 5 mV·s-1) and a remarkable rate capability and cycling stability, with 62.3% of the initial value (1 A·g-1) retained at 10 A·g-1 and 90.4% of the initial value (first circle at 50 mV·s-1) retained after 5000 cycles. A hybrid supercapacitor (HSC) was assembled with Ni(OH)2/Ni3S2/NF as the positive electrode and activated carbon (AC) as the negative electrode and exhibited an outstanding energy density of 24.5 Wh·kg-1 at the power density of 375 W·kg-1. These encouraging results render the electrode a potential candidate for energy storage.

Cerium ferrite @ molybdenum disulfide nanozyme for intracellular ROS generation and photothermal-based cancer therapy

Two-dimensional (2D) nanomaterial hybrid with metal nanoferrite nanoparticles will enhance their catalytic activity and photothermal therapy (PTT) through their synergistic coupling effects. This strategy also increases the photothermal conversion efficiency (PCE), blood circulation time, biostability, and cellular uptake efficiency of 2D materials. Herein, we first time report a new class of cerium ferrite (CeFe2O4) nanoparticles (NPs) decorated onto branched polyethyleneimine (bPEI) coated flower-like molybdenum disulfide nanoflowers (MoS2 NFs). The CeFe2O4 NPs on the MoS2 NF surface could be designed rationally to improve deficiencies and refine the PCE of MoS2 NFs and tumor ablation effectiveness in the treated MDA-MB-231 breast cells. Importantly, MoS2-bPEI-CeFe2O4 NFs consist of MoS2 in the inner core and CeFe2O4 in the outer shell, designed to generate heat efficiently and enhanced intracellular reactive oxygen species (ROS) generation in the tumor environment. Furthermore, using sheep blood cells, bare MoS2 and MoS2-bPEI-CeFe2O4 NFs showed hemolytic activity levels of 6 and 2.7 %, respectively. Moreover, MoS2-bPEI-CeFe2O4 NFs exhibit 53.6 % of PCE, which effectively induced up to 80 % cytotoxicity and higher levels of ROS generation in the MDA-MB-231 cells when exposed to the 808 nm NIR laser (1.5 W/cm2, 5 min). These findings demonstrate the unique CeFe2O4 NPs with MoS2 NF as a powerful nanozyme for dual-performance cancer therapies (PTT and ROS generation) and reveal a novel PCE refinement strategy for MoS2 NFs. It was successfully established as a new cancer therapeutic platform.

Electrochemical fabrication of interleaved vanadium oxide nanosheets coated nickel foam 3D electrode with improved oxygen evolution reaction performance

An interleaved vanadium oxide nanosheets coated on nickel foam (V/NF) is proposed as an excellent 3D electrode for oxygen evolution, which exhibits high activities with overpotential of 232 mV at 10 mA cm−2 and the Tafel slope is 50.1 mV dec−1, showing catalytic activity comparable to that of noble metals. The V/NF material are designed by a one-step facile electrodeposition method at low temperature in ethaline deep eutectic solvent and XRD analysis indicates that these nanosheets are mainly made up of VO(OH)2, V2O5 and NiVO3. The formation of these V-containing compounds on the surface of NF is regarded to be responsible for the electrocatalytic activity.

Three-dimensional porous nanosheets array FeVO4/NF-a catalyst for oxygen evolution reaction at industrially relevant current densities

Electrochemical water splitting is a vital means of producing hydrogen in the future. However, the sluggish kinetics of the oxygen evolution reaction (OER) at the anode of the water electrolysis limits its efficiency. Moreover, high current density (≥500 mA/cm2) hydrogen production that meets industrial requirements and remains relatively stability is the trend currently. Herein, we reported a three-dimensional porous nanosheets array electrocatalyst FeVO4/NF-a synthesized by electrochemical activation and hydrothermal method. The developed FeVO4/NF-a electrode represents excellent OER performance at high current densities, which allows a low overpotential of 376 mV to achieve 1000 mA/cm2 and keeps its durability for 50 h. Structural characterizations and electrochemical analyses show that the NF surface was converted to the active phase NiOOH for OER during electrochemical activation. The introduction of Fe3+ and V3+ changes the electron distribution of elements on the catalyst surface and optimizes its intrinsic activity. Additionally, the three-dimensional network structure of FeVO4/NF-a facilitates the gas diffusion and the contact between the catalyst with the electrolyte. This work will provide new ideas for hydrogen production from water electrolysis toward high current density.

Synergistic effect stemming from vertically anchored seamless 2D MoSe2 nanosheets on 1D NiTiO3 nanofibers toward CO2 photoreduction

Herein, nickel titanate nanofiber/molybdenum diselenide nanosheet (NiTiO3 NF/MoSe2) heterostructures were prepared and their photocatalytic CO2 photoreduction performance was assessed. The heterostructures were synthesized via a facile two-step synthesis route combining an electrospinning technique followed by a solvothermal method. The MoSe2 nanosheets were vertically anchored to the surface of NiTiO3 NF, thereby increasing the number of exposed active edges that are pivotal to photocatalytic performance. By tuning the loading of MoSe2 in the heterostructure, the optimal condition was obtained for the fabrication of the NiTiO3 NF/MoSe2 heterojunctions. The as-prepared heterojunctions exhibited higher photocatalytic activity than pure NiTiO3 NF and MoSe2 for the photocatalytic reduction of CO2 under ultraviolet-visible light irradiation. Among the several hybrid samples, the optimal sample displayed a 6.6- and 7.7-fold enhanced production of CO (386 µmol g–1) compared with that of pure NiTiO3 NF (58 µmol g–1) and pure MoSe2 (50 µmol g–1), respectively, with overall CO2 selectivity of 86%. This enhanced photocatalytic activity was attributed to synergy created by tailored loading of MoSe2 nanosheets onto the 1D NiTiO3 NF. This hierarchical growth of MoSe2 over NiTiO3 NF provided more exposed edge sites, enhanced light absorption over the entire spectrum, and improved separation of photogenerated electrons and holes at the NiTiO3 NF/MoSe2 heterojunction interface. Such NiTiO3 NF/MoSe2 heterojunctions with broad spectral photocatalytic performance have potential applications in water splitting and water treatment.

Co-NiSe2/NF nanosheet for efficient hydrogen evolution reaction

Developing highly efficient electrocatalysts is yet an important challenge for water electrolysis. Herein, the in-situ growth of Co-doped NiSe2 on nickel foam (Co-NiSe2/NF) has been synthesized. Co-NiSe2/NF exhibited an overpotential of 136 mV at 10 mA cm−2 with a Tafel slope of 80.9 mV dec−1. In addition, the stability testing showed 92.4% of its initial HER activity after 60 h at 10 mA cm−2. The results showed that the introduction of Co tunes the electronic structure of Co-NiSe2/NF, resulting in fast reaction kinetics, and an enhanced stability due to the in situ growth of NiSe2 on the NF surface.

One-step preparation of 3D binder-free electrode of porous Co-Mo-S nanostructures grown on Ni foam for supercapacitors

Transition metal chalcogenides have wide studied as active electrode materials for electrochemical storage devices. In this study, we successfully fabricated a binder-free electrode of hierarchical Co-Mo-S nanosheets on nickel foam (CMS/NF) by a facile hydrothermal method under microwave irradiation. The CMS layer, with a thickness of a few nanometers, was decorated on the NF's surface. Taking advantage of the large specific surface area of NF and the high capacitance and porosity of CMS, the prepared electrode is believed to have a rapid electron and ion transport, large electroactive sites, and excellent cycle stability. The specific capacitance of 1080 F g−1 at 1 A g−1 and excellent cycling stability (90.4% retention in specific capacitance after 5000 cycles) were obtained. For further practical applications, an asymmetric supercapacitor was assembled using the CMS/NF as the cathode and the activated carbon as anode material. The prepared device exhibited a high capacitance of 47 F g−1 at 1 A g−1 and a high energy density of 42.6 Wh kg−1 at a power density of 850.3 W kg−1 at a wide operating voltage of 1.6 V. This current method could provide a rapid one-step process for other 3D porous electrodes for high-performance supercapacitors.

Template confined strategy for constructing nickel cobalt selenide nanoarrays for efficient oxygen evolution reaction

Developing high-efficient and earth-abundant metals for the oxygen evolution reaction catalyst is of significant and promising but still challenging. Prussian blue analogs (PBAs) show great potential for the dispersion and exposure of OER catalysts due to their adjustable element compositions and easily decomposable structures. Herein, bimetallic Ni–Co Prussian blue analogs grown on the conductive nickel foam supported by Ni(OH)2 nanosheets are designed and constructed. Firstly, the uniform dispersion of Ni–Co Prussian blue analogs has been realized on the surface of NF. By means of the confined decomposition of PBAs at calcination temperature, NiSe2/CoSe with the smaller particle size and good dispersion supported on NF can provide the more active sites when containing high electron transfer rate. The oxygen evolution reaction (OER) measurements show that the as-prepared NiSe2/CoSe/NF exhibits the very impressive OER activity with low overpotential of 270 mV to reach the current density of 100 mA/cm2. The special nanoarrays structure, abundant active sites and high intrinsic activity may contribute to the excellent performance. The synergistic effect of nickel-cobalt selenide and support enable superior stability toward OER. This confined decomposition strategy may provide a promising way to controlled assembly of transition metal-based electrocatalyst for OER.

Strongly coupling of amorphous/crystalline reduced FeOOH/α-Ni(OH)2 heterostructure for extremely efficient water oxidation at ultra-high current density

Development of Fe-Ni-based electrocatalysts with high efficiency and stability remains a foremost challenge in the research for oxygen evolution reaction (OER) under high-current–density. Herein, a fast reduction strategy is developed for synthesis of strongly coupled crystalline α-Ni(OH)2 with amorphous reduced FeOOH (r-FeOOH) heterostructure grown on Ni foam (r-FeOOH/α-Ni(OH)2/NF). The obtained r-FeOOH/α-Ni(OH)2 with particle sizes around ~ 10 nm is coated orderly on the 3D NF surface in this hybrid. Benefitting from the strong coupling effects between r-FeOOH and α-Ni(OH)2, low potentials of 1.62 and 1.66 V at ultra-high current densities of 1,000 and 1,500 mA cm−2, as well as a robust stability over 10 h at 1,500 mA cm−2 in alkaline electrolyte are achieved in 3D r-FeOOH/α-Ni(OH)2/NF. Such a high OER performance is almost the best among all previously reported Fe-Ni-based OER electrocatalysts. Experimental results revealed that the NiOOH species is the real OER active phase in the 3D r-FeOOH/α-Ni(OH)2/NF. Further, bifunctional 3D r-FeOOH/α-Ni(OH)2 in alkaline electrolyzer delivers low cell voltages of 2.32 and 2.78 V to attain 500 and 1,000 mA cm−2 toward the overall-water-splitting, surpassing the benchmark Pt/C-Ir/C/NF system.