Customization of FeNi alloy nanosheet arrays inserted with biomass-derived carbon templates for boosted electromagnetic wave absorption

Electromagnetic wave(EMW)-absorbing materials have considerable capacity in the military field and the prevention of EMW radiation from harming human health.However,obtaining lightweight,high-performance,and broadband EMW-absorbing material remains an overwhelming challenge.Creating dielectric/magnetic composites with customized structures is a strategy with great promise for the development of high-performance EMW-absorbing materials.Using layered double hydroxides as the precursors of bimetallic alloys and combining them with porous biomass-derived carbon materials is a potential way for constructing multi-interface heterostructures as efficient EMW-absorbing materials because they have synergistic losses,low costs,abundant resources,and light weights.Here,FeNi alloy nanosheet array/Lycopodium spore-derived carbon(FeNi/LSC)was prepared through a simple hydrothermal and carbonization method.FeNi/LSC presents ideal EMW-absorbing performance by benefiting from the FeNi alloy nanosheet array,sponge-like structure,capability for impedance matching,and improved dielectric/magnetic losses.As expected,FeNi/LSC exhibited the minimum reflection loss of-58.3 dB at 1.5 mm with 20wt%filler content and a widely effective absorption bandwidth of 4.92 GHz.FeNi/LSC composites with effective EMW-absorbing performance provide new insights into the customization of biomass-derived composites as high-performance and lightweight broadband EMW-absorbing materials.

A CuNi/C Nanosheet Array Based on a Metal–Organic Framework Derivate as a Supersensitive Non-Enzymatic Glucose Sensor

Bimetal catalysts are good alternatives for nonenzymatic glucose sensors owing to their low cost, high activity, good conductivity, and ease of fabrication. In the present study, a self-supported CuNi/C electrode prepared by electrodepositing Cu nanoparticles on a Ni-based metal–organic framework(MOF) derivate was used as a non-enzymatic glucose sensor. The porous construction and carbon scaffold inherited from the Ni-MOF guarantee good kinetics of the electrode process in electrochemical glucose detection. Furthermore, Cu nanoparticles disturb the array structure of MOF derived films and evidently enhance their electrochemical performances in glucose detection. Electrochemical measurements indicate that the CuNi/C electrode possesses a high sensitivity of17.12 mA mM^(-1) cm^(-2), a low detection limit of 66.67 nM,and a wider linearity range from 0.20 to 2.72 mM. Additionally, the electrode exhibits good reusability, reproducibility, and stability, thereby catering to the practical use of glucose sensors. Similar values of glucose concentrations in human blood serum samples are detected with our electrode and with the method involving glucose-6-phosphate dehydrogenase; the results further demonstrate the practical feasibility of our electrode.

Abundant heterointerfaces in MOF-derived hollow CoS_(2)-MoS_(2) nanosheet array electrocatalysts for overall water splitting

Rational coupling of hydrogen evolution reaction(HER) and oxygen evolution reaction(OER) catalysts is extremely important for practical overall water splitting,but it is still challenging to construct such bifunctional heterostructures.Herein,we present a metal-organic framework(MOF)-etching strategy to design free-standing and hierarchical hollow CoS_(2)-MoS_(2) heteronanosheet arrays for both HER and OER.Resulting from the controllable etching of MOF by MoO_(4)^(2-) and in-situ sulfuration,the obtained CoS_(2)-MoS_(2) possesses abundant heterointerfaces with modulated local charge distribution,which promote water dissociation and rapid electrocatalytic kinetics.Moreover,the two-dimensional hollow array architecture can not only afford rich surface-active sites,but also facilitate the penetration of electrolytes and the release of evolved H_(2)/O_(2) bubbles.Consequently,the engineered CoS_(2)-MoS_(2) heterostructure exhibits small overpotentials of 82 mV for HER and 266 mV for OER at 10 mA cm^(-2).The corresponding alkaline electrolyzer affords a cell voltage of 1.56 V at 10 mA cm^(-2) to boost overall water splitting,along with robust durability over 24 h, even surpassing the benchmark electrode couple composed of IrO_(2) and Pt/C The present work may provide valuable insights for developing MOF-derived heterogeneous electrocatalysts with tailored interface/surface structure for widespread application in catalysis and other energyrelated areas.

In Situ Growth of 3D Hierarchical ZnO@Ni_xCo_(1-x)(OH)_y Core/Shell Nanowire/Nanosheet Arrays on Ni Foam for High-Performance Aqueous Hybrid Supercapacitors

In this study, we designed and synthesized a novel battery-type electrode featuring three-dimensional(3D) hierarchical ZnO@Ni_xCo_(1-x)(OH)_y core/shell nanowire/nanosheet arrays arranged on Nifoam substrate via a two-step protocol including a wet chemical process followed by electro-deposition. We then characterized its composition, structure and surface morphology by X-ray diff raction, energy-dispersive X-ray spectrometry(EDS), X-ray photoelectron spectroscopy, scanning electron microscopy(SEM), transmission electron microscopy, EDS elemental mapping. Our electrochemical measurements show that the ZnO@Ni_(0.67)Co_(0.33)(OH)_y electrode material exhibited a noticeably high specific capacity of as much as 255(mA ·h)/g at 1 A/g. Additionally, it demonstrated a superior rate capability, as well as an excellent cycling stability with 81.6% capacity retention over 2000 cycles at 5 A/g. This sample delivered a high energy density of 64 W·h/kg and a power density of 250 W/kg at a current density of 1 A/g. With such remarkable electrochemical properties, we expect the 3D hierarchical hybrid electrode material presented in this work to have promising applications for the next generation of energy storage systems.

Co-doped Ni_(3)S_(2) nanosheet array: A high-efficiency electrocatalyst for alkaline seawater oxidation

Developing efficient and durable oxygen evolution reaction(OER)catalysts holds great promise for green hydrogen production via seawater electrolysis,but remains a challenge.Herein,we report a Co-doped Ni_(3)S_(2) nanosheet array on Ni foam(Co-Ni_(3)S_(2)/NF)as a high-efficiency OER electrocatalyst for seawater.In alkaline conditions,Co-Ni_(3)S_(2)/NF requires an overpotential of only 368 mV to drive 100 mA·cm^(–2),superior to Ni_(3)S_(2)/NF(385 mV).Besides,it exhibits at least 50-h continuous electrolysis.

Self-supported CoMoS4 nanosheet array as an efficient catalyst for hydrogen evolution reaction at neutral pH

Development of earth-abundant electrocatalysts, particularly for high-efficiency hydrogen evolution reaction （HER） under benign conditions, is highly desired, but still remains a serious challenge. Herein, we report a high-performance amorphous CoMoS4 nanosheet array on carbon cloth （CoMoS4 NS/CC）, prepared by hydrothermal treatment of a Co（OH）F nanosheet array on a carbon cloth （Co（OH）F NS/CC） in （NH4）2MoS4 solution. As a three-dimensional HER electrode, CoMoS4 NS/CC exhibits remarkable activity in 1.0 M phosphate buffer saline （pH 7）, only requiring an overpotential of 183 mV to drive a geometrical current density of 10 mA·cm-2. This overpotential is 140 mV lower than that for Co（OH）F NS/CC. Notably, this electrode also shows outstanding electrochemical durability and nearly 100% Faradaic efficiency. Density functional theory calculations suggest that CoMoS4 has a more favorable hydrogen adsorption free energy than Co（OH）F.

In situ growth of NiS_(2) nanosheet array on Ni foil as cathode to improve the performance of lithium/sodium-sulfur batteries

The NiS;nanosheet array on Ni foil(NiS2/NF)was prepared using an in situ growth strategy and sulfidation method and was used as the cathode of lithium sulfur battery.The unique nanostructure of the NiS;nanosheet array can provide abundant active sites for the adsorption and chemical action of polysulfides.Compared with the sulfur powder coated pure NF(pure NF-S)for lithium sulfur battery,the sulfur powder coated NiS_(2)/NF(NiS_(2)/NF-S)electrode exhibits superior electrochemical performance.Specifically,the NiS_(2)/NF-S delivered a high reversible capacity of 1007.5 m Ah g^(-1) at a current density of 0.1 C(1 C=1675 mA g^(-1))and kept 74.5% of the initial capacity at 1.0 C after 200 cycles,indicating the great promise of NiS_(2)/NF-S as the cathode of lithium sulfur battery.In addition,the NiS_(2)/NF-S electrode also showed satisfactory electrochemical performance when used as the cathode for sodium sulfur battery.

Pt/TiO_(2) Nanosheets Array Dominated by {001} Facets with Enhanced Photocatalytic Activity

{001}facets dominated single crystalline anatase TiO_(2) nanosheet array(TNSA)was synthe-sized through an optimized organic solvothermal route on uorine-doped tin oxide substrate.The field emission scanning electron microscopy images and X-ray diffraction patterns re-vealed that the{001}synthesized facets dominated TNSA exhibited much higher orientation than that synthesized by hydrothermal route.The TNSAs were loaded with Pt nanoparti-cles in uniformly size by using a photodecomposition method,which were further con rmed by high resolution transmission electron microscopy(HRTEM).The HRTEM images also revealed that Pt nanoparticles preferred to deposit on{001}facets.With loading of Pt nanoparticles,the optical absorbance was significantly enhanced,while the photolumines-cence(PL)was inhibited.The photocatalytic activity of TNSA was signi cantly improved by Pt loading and reached the maximum with optimal amount of Pt loading.The optimal amount of Pt on{001}facets is far less than that on TiO_(2) nanoparticles,which may be attributed to the specific atom structure of reactive{001}facets.

Integrated Ni-P-S nanosheets array as superior electrocatalysts for hydrogen generation

Searching for efficient and robust non-noble electrocatalysts for hydrogen generation is extremely desirable for future green energy systems.Here, we present the synthesis of integrated Ni-P-S nanosheets array including Ni_2P and NiS on nickel foam by a simple simultaneous phosphorization and sulfurization strategy. The resultant sample with optimal composition exhibits superior electrocatalytic performance for hydrogen evolution reaction(HER) in a wide pH range. In alkaline media, it can generate current densities of 10, 20 and 100 mA cm^(-2) at low overpotentials of only-101.9,-142.0 and-207.8 mV with robust durability. It still exhibits high electrocatalytic activities even in acid or neutral media. Such superior electrocatalytic performances can be mainly attributed to the synergistic enhancement of the hybrid Ni-P-S nanosheets array with integration microstructure. The kind of catalyst gives a new insight on achieving efficient and robust hydrogen generation.

Iron-doped nickel disulfide nanoarray： A highly efficient and stable electrocatalyst for water splitting

Developing efficient water-splitting electrocatalysts, particularly for the anodic oxygen evolution reaction （OER）, is an important challenge in energy conversion technologies. In this study, we report the development of iron-doped nickel disulfide nanoarray on Ti mesh （Fe0.1-NiS2 NA/Ti） via the sulfidation of its nickel-iron-layered double hydroxide precursor （NiFe-LDH NAFFi）. As a three-dimensional OER anode, Fe0.1NiS2 NA/Ti exhibits remarkable activity and stability in 1.0 M KOH, with the requirement of a low overpotential of 231 mV to achieve 100 mA·cm^-2. In addition, it exhibits excellent activity and durability in 30 wt.% KOH. Notably, this electrode is also efficient for the cathodic hydrogen evolution reaction under alkaline conditions.

One-step synthesis of Fe-Ni hydroxide nanosheets derived from bimetallic foam for efficient electrocatalytic oxygen evolution and overall water splitting

The research of superior water oxidation electrodes is essential for the green energy in the form of hydrogen by way of electrolytic water splitting, and still remains challenging. Based upon dealloying foam, Fe-Ni hydroxide nanosheets network structure is designed on the surface of Fe-Ni alloy foam. The ratio of Ni/Fe elements was adjusted to realize the optimal catalytic activities for oxygen evolution reaction（OER） and hydrogen evolution reaction（HER）. The obtained electrode of Fe-Ni hydroxide nanosheets/Fe-Ni alloy foam-60% Fe（FN LDH/FNF-60, 60 is the percentage of Fe content） possess low overpotential of 261 mV to reach 10 mA/cm;, small Tafel slope（85.5 mV/dec）, and superior long-term stability（remaining 10 mA/cm;for over 14 h without attenuation） toward OER in 1.0 mol/L KOH.Moreover, an alkaline water electrolyzer is constructed with the FN LDH/FNF-60 as anode and Ni（OH）;/Fe-Ni alloy foam-25% Fe(Ni（OH）;/FNF-25) as cathode, which displays superior electrolytic performance（affording 10 mA/cm;at 1.62 V） and lasting durability.

Ultrasmall Ag nanoclusters anchored on NiCo-layered double hydroxide nanoarray for efficient electrooxidation of 5-hydroxymethylfurfural

Electrochemical oxidation of 5-hydroxymethylfurfural(HMF)has shown promising prospects in producing highly valuable chemicals.Herein,we report the synthesis of ultrasmall Ag nanoclusters anchored on NiColayered double hydroxide(NiCo-LDH)nanosheet arrays(Agn@NiCo-LDH)via a facile electrodeposition strategy.The prepared Agn@NiCo-LDH nanosheet arrays exhibit excellent electrocatalytic HMF oxidation performance with a current density of 10 mA cm^(−2) at 1.29 VRHE and the Faraday efficiency of nearly 100%for 2,5-furandicarboxylic acid production.This study offers an effective approach to rationally design nanoclusters to achieve high catalytic activity for sustainable energy conversion and production.

In situ electrochemically converting Fe_2O_3-Ni(OH)_2 to NiFe_2O_4-NiOOH:a highly efficient electrocatalyst towards water oxidation

To develop low-cost, earth-abundant NiFe- based materials as highly efficient oxygen evolution reaction （OER） electrocatalysts and to probe new catalytic species are still great challenges to now. Here, an in situ forma- tion of OER active NiFe2O4-NiOOH nanosheet arrays is demonstrated as a highly efficient OER electrocatalyst by the anodization of Fe203 domains anchored on Ni（OH）2 nanosheet arrays. The as-converted product can deliver the current density of 30 mA cm-2 with a small overpotential of 240 mV, and only requires an overpotential of 410 mV to achieve an amazing huge current density of 3000 mA cm-2. In situ potential-dependent Raman spectroscopy reveals that Ni（OH）2 in the composite is easier to be oxidized to NiOOH than pure Ni（OH）2, and the newly formed NiOOH reacts with the nearby Fe2O3 to produce hybrid NiFe2O4-NiOOH. It is found that the cooperative effect of the in situ formed NiFe2O4 and NiOOH as well as the hydrophilic and aero- phobic electrode surface make main contribution to the outstanding OER activity of the catalyst. This work will bring new perspectives to the recognition of the origin of NiFe composite materials for OER and provide a mild method to synthesize amorphous spinel materials at room temperature.