Ni Template Research Articles

The Morphology-Controllable Synthesis of Ni–Co–O Nanosheets on a 3D Porous Ni Template as a Binder-Free Electrode for a Solid-State Symmetric Supercapacitor

In this work, a porous Ni template (Ni–Co–O@3D Ni) with Ni–Co oxide nanosheets (Ni–Co–O)@3D was synthesized by incorporating Ni–Co oxide nanosheets within a 3D porous Ni template as a binder-free electrode for a supercapacitor. The 3D Ni template was synthesized with hydrogen bubble templates that possessed different applied voltages that marked differences in terms of physicochemical properties, as well as factors that affect the subsequent growth of Ni–Co–O nanosheets. Then, Ni and Co metal ion sources were introduced to produce the morphology adjustment of Ni–Co–O@3D Ni with a multiple hierarchical architecture with a hydrothermal process. Field emission scanning electron microscopy (FESEM), X-ray absorption spectroscopy (XAS), and an electrochemical analysis were employed to investigate the morphological, structural, and electrochemical characteristics. FESEM and XAS results evidenced that Ni–Co–O@3D Ni consists of a 3D, well-designed hierarchical interconnected network, and the local electronic structure change has a great influence on the capacitive performance. The electrochemical results of Ni–Co–O@3D Ni displayed an excellent electrochemical performance due to the synergistic effect of Ni and Co on Ni–Co–O@3D Ni, which possessed multiple oxidation states to enable various reversible Faradaic redox reactions. Remarkably, the solid-state symmetric supercapacitor fabricated with Ni–Co–O@3D Ni exhibited excellent capacitive behaviour at a wide operating voltage window and cycling performance. Also, the as-assembled solid-state symmetric supercapacitor (two devices in series) can successfully illuminate a desired parallel pattern consisting of 36 red LED lights, demonstrating its practical application as a supercapacitor.

Densified graphene-like carbon nanosheets with enriched heteroatoms enabling superior gravimetric and volumetric potassium storage capacities

Constructing carbon electrodes with abundant heteroatoms and appropriate graphitic interlayer spacing remains a major challenge for achieving high gravimetric and volumetric potassium storage capacities with fast kinetics. Herein, we constructed 3D graphene-like N, F dual-doped carbon sheets induced by Ni template (N, F-CNS-Ni) with dense structure and rich active sites, providing a promising approach to address the facing obstacles. Highly reversible K-ion insertion/extraction is realized in the graphitic carbon structure, and K-adsorption capability is enhanced by introducing N/F heteroatoms. As a result, the N, F-CNS-Ni electrode exhibits ultrahigh gravimetric and volumetric capacities of 404.5 mA h g−1 and 281.3 mA h cm−3 at 0.05 A/g, respectively, and a superb capacity of 259.3 mA h g−1 with a capacity retention ratio of 90 % even after 600 cycles at 5 A/g. This work presents a simple Ni-based template method to prepare graphene-like carbon nanosheets with high packing density and rich heteroatoms, and offers mechanism insight for achieving superior K-ion storage.

3D Porous Graphene Films with Large‐Area In‐Plane Exterior Skins

AbstractConstruction of macroscopic 3D architectures of graphene is crucial to harness the advantageous properties of planar 2D graphene and to enable integration to many conventional and novel applications. Ideally, the 3D structure of graphene should be free of defects, covalently interconnected, and can be produced at large‐scale. Among various assembly techniques, fabrication using chemical vapor deposition (CVD) enables the production of high‐quality graphene where selection of template is the key that determines its consequent crystalline quality and structural morphology. Herein, a new method is presented to synthesize high‐quality porous graphene film by incorporating an in situ reduction–oxidation cycling treatment to generate micrometer‐sized pores on commercial Ni foil using an all‐CVD process route. Owing to the unique morphological features of the modified Ni template, the graphene film exhibits a holey surface with large‐area exterior skin coverage of >94% and many interconnected ligaments within its porous interior. This extraordinary configuration gives rise to superior in‐plane electrical conductivity despite its low density. In comparison to state‐of‐the‐art materials for electromagnetic interference shielding, this porous graphene film is among the best performing materials with a specific shielding effectiveness of >550 dB cm3 g−1 and absolute effectiveness of >220 000 dB cm2 g−1.

Highly flexible, high-performance radio-frequency antenna based on free-standing graphene/polymer nanocomposite film

A facile approach was developed for producing highly conductive and free-standing graphene/polymer nanocomposite films for flexible radio-frequency (RF) antenna applications. Highly ordered macroporous and three-dimensional (3D) graphene-based nanocomposite films were obtained by growing graphene on Ni foam via chemical vapor deposition, Ni etching, and subsequent polymer infiltration into the graphene foam (GF). The film exhibited a surface resistance of 5 Ω/sq, which was 4,000 times lower than that of the reduced graphene oxide foam/polymer nanocomposite film. The large domain size provides a short electron transport pathway and good compatibility and interfacial adhesion between the GF and polymer matrix, resulting in an extremely flexible and conductive graphene-based film with high reliability. The free-standing GF-based RF antenna has a low return loss (−37.5 dB), as well as a high radiation efficiency (76.7%), making it commercially viable, and maintained its performance even under mechanical deformation over 1,000 bending cycles. The dimensions of the antenna were adjusted by controlling the size of the Ni template to achieve frequency tunability. These results demonstrate the potential of 3D graphene-based antennas for applications in wireless communications for Bluetooth and Wi-Fi technology.

Hollow bimetallic selenide derived from a hierarchical MOF-based Prussian blue analogue for urea electrolysis

PBA@MOF–Ni/Se with a nanocube structure grown on a flower-shaped MOF–Ni template exhibits better performance in urea electrolysis.

Sulfidation and selenidation of nickel nanoparticles

AbstractTransition metal chalcogenide nanoparticles (NPs) are of interest for energy applications, including batteries, supercapacitors, and electrocatalysis. Many methods have been established for synthesizing Ni NPs, and conversion chemistry to form Ni oxide and phosphides from template Ni NPs is well‐understood. Sulfidation and selenidation of Ni NPs have been much less explored, however. We report a method for the conversion of Ni template NPs into sulfide and selenide product NPs using elemental sulfur, 1‐hexadecanthiol, thiourea, trioctylphosphine sulfide, elemental selenium, and selenourea. While maintaining mole ratios of 2 mmol sulfur/selenium precursor: mmol Ni, products with phases of Ni3S2, Ni9S8, NiS, NiSO4·6H2O, Ni3S4, Ni3Se2, and NiSe have been obtained. The products have voids that form through the Kirkendall effect during interdiffusion. Trends relating the chemical properties of the precursors to the phases of the products have been identified. While some precursors contained phosphorus, there was no significant incorporation of phosphorus in any of the products. An increase of the NP size during sulfidation and selenidation is consistent with ripening. The application of Ni sulfide and selenide NPs as electrocatalysts for the hydrogen evolution reaction is also demonstrated.

Highly Sensitive Flexible Poly(dimethylsiloxane) Composite Sensors Based on Flame-Synthesized Carbon Foam Made of Vertical Carbon Nanosheet Arrays

A simple approach for flame synthesis of carbon foam (FCF) via one-step catalytic deposition of carbon on Ni template was developed. FCF was deposited within 5min at ~500 oC in an alcohol flame and...

Si nanoparticles veiled with ultrathin rGO film reduced directly by precoated Ni template: Fabrication and electrochemical performance

Si/graphene composite has been considered as a promising structure to limit the volume expansion and improve poor conductivity of silicon anode. Herein, a novel method to prepare Si/reduced graphene oxide (Si/rGO) composite anode was proposed. With this approach, nickel shell was pre-coated on Si particles via electroless deposition before used as a template to in-situ reduce GO. During the reduction process, the nickel template can as well promote the self-assembly of graphene sheets on the surface of Si nanoparticles. Following these facile and convenient processes, a Si/rGO hybrid-structure can be directly fabricated. Compared with pure Si anode, this Si/rGO composite displays a greatly improved electrochemical performance in both cycling stability and rate capability. It delivers a reversible capacity as high as 975 mA h g−1 and 717 mA h g−1 after 300 cycles under the current densities of 1 A g−1 and 3 A g−1, respectively. Meanwhile, its capacity can still maintain at 602 mA h g−1 even at a rather higher current of 5 A g−1.

The influence of heterosubstitution on carbon foams characteristics as electrode materials for lithium-ion batteries

Undoped and nitrogen-doped carbon foams (CF) were synthesized by CVD via pyrolysis of hexane or acetonitrile over an Ni template. Undoped CF was also post-doped with nitrogen by hydrothermal treatment with ammonia solution. All samples were analyzed by scanning and transmission electronic microscopy, Raman spectroscopy and XPS. CVD-doped CF showed higher defectiveness than the undoped CF because of the deformation of carbon layers, while post-doped CF predominantly contained nitrogen species on its surface. These differences in the structure and composition of the foams strongly affect the electrochemical characteristics of lithium-ion battery anodes produced from these materials.

Fabrication of Hierarchical N-doped Carbon Nanotubes for CO2 Adsorption

Hierarchical N-doped carbon nanotubes (NCTs) with controllable aspect ratios were developed for CO2 adsorption. In this work, NCTs were synthesized by coating different amounts of 3-aminophenol/formaldehyde resin (APF) on the outer layer of silica nanotubes, carbonizing in N2 at 700∘C and removing the silica and Ni template by hydrofluoric acid etching. The obtained NCTs were activated by K2CO3. After activation, micropores on the activated N-doped carbon nanotubes (ANCTs) were enriched, the micro-surface area and pore volume of ANCT-1.0 reached 1195[Formula: see text]m2[Formula: see text]g[Formula: see text] and 0.45[Formula: see text]cm3[Formula: see text]g[Formula: see text], respectively, and the corresponding adsorption capacity increased by 50% (4.50[Formula: see text]mmol[Formula: see text]g[Formula: see text] at 0∘C and 1 bar). Moreover, ANCT-1.0 maintained a high stability throughout consecutive adsorption–desorption cycles. The advantages of hierarchical N-doped carbon nanotubes, including their meso–microporous structures, high geometric aspect ratio and good stability, make them valuable and promising materials to capture carbon dioxide.

Wafer-scale and selective-area growth of high-quality hexagonal boron nitride on Ni(111) by metal-organic chemical vapor deposition

We demonstrate wafer-scale growth of high-quality hexagonal boron nitride (h-BN) film on Ni(111) template using metal-organic chemical vapor deposition (MOCVD). Compared with inert sapphire substrate, the catalytic Ni(111) template facilitates a fast growth of high-quality h-BN film at the relatively low temperature of 1000 °C. Wafer-scale growth of a high-quality h-BN film with Raman E2g peak full width at half maximum (FWHM) of 18~24 cm−1 is achieved, which is to the extent of our knowledge the best reported for MOCVD. Systematic investigation of the microstructural and chemical characteristics of the MOCVD-grown h-BN films reveals a substantial difference in catalytic capability between the Ni(111) and sapphire surfaces that enables the selective-area growth of h-BN at pre-defined locations over a whole 2-inch wafer. These achievement and findings have advanced our understanding of the growth mechanism of h-BN by MOCVD and will contribute an important step toward scalable and controllable production of high-quality h-BN films for practical integrated two-dimensional materials-based systems and devices.

NiO-induced synthesis of PdNi bimetallic hollow nanocrystals with enhanced electrocatalytic activities toward ethanol and formic acid oxidation

Noble-metal hollow nanocrystals possess numerous unique advantages such as high surface-to-volume ratio and high utilization of noble metals, which make them a promising electrocatalyst for electro-oxidation of small molecules in fuel cells. Herein, we prepared bimetallic PdNi hollow nanocrystals (PdNi-HNCs) by taking advantage of the galvanic replacement reaction in an aqueous solution and developed a facile NiO-induced strategy for the controlled synthesis of PdNi-HNCs with dendritic or smooth outer shell architectures. A very short oxidation time of an amorphous Ni template is demonstrated to be the key factor to successful fabrication of the dendritic morphology. The results of electrochemical testing indicate that the electrocatalytic activities of PdNi-HNCs are highly dependent on their morphologies. The PdNi-HNCs with a rough and dendritic shell exhibit a mass activity of 1201.5 and 768.0mAmgPd−1 toward ethanol oxidation reaction (EOR) and formic acid oxidation reaction (FAOR), respectively, much greater than those of the commercial Pd black catalyst (502.6 and 266.3mAmgPd−1, respectivlely). In particular, the 1500 cyclic voltammetry cycles in alkaline solution and the 30,000s chronoamperometry tests in acid solution suggest an enhanced long-term durability of PdNi-HNCs with dendritic nanoarchitectures. We ascribe the better catalytic activity to the hollow feature, higher specific electrochemical surface area, more abundant active sites and more appropriate electronic structure of the PdNi-HNCs with a rough and dendritic shell.

The unusual intermediate species in the formation of Ni(II) complexes of unsymmetrical Schiff bases by Elder’s method: Structural, electrochemical and magnetic characterizations

During the synthesis of unsymmetrical salen type Schiff base ligand using Ni(II) template by Elder’s method, we isolated three isostructural dinuclear Ni(II)-complexes as possible intermediates of the reaction upon decreasing the reaction time. These three complexes [Ni2(L1)2(o-Hap)2] (2), [Ni2(L1)2(o-Hnap)2] (3) and [Ni2(L1)2(Sal)2] (4) [where HL1=2-((E)-(3-aminopentylimino)methyl)phenol is a monocondensed tridentate NNO-donor Schiff base ligand, o-Hap=o-hydroxyacetophenone, o-Hnap=o-hydroxynapthaldehyde, and Sal=salicylaldehyde] have been synthesized by putting the precursor complex, [Ni(L1)2] (1) and the respective carbonyl compound under reflux in methanol for two hours. The single crystal structural analyses reveal that intriguingly in all three complexes, the primary amine group of the mono-condensed Schiff base (L11−) and the carbonyl group remain uncondensed although they are present as coordinated ligands at the same Ni(II) center. In these complexes, Ni(II) centers possess a distorted octahedral geometry with centrosymmetric phenoxido bridged dinuclear Ni2O2 core. Electrochemical and mass-spectrometric studies revealed that these dinuclear complexes are stable in solution. However, removal of Ni(II) ions by dimethylglyoxime leads to exclusive formation of the desired unsymmetrical N2O2-donor Schiff base. The variable-temperature magnetic susceptibility measurements on solid samples reveal that all the compounds are antiferromagnetically coupled with exchange coupling constants (J) of −16.87, −10.14 and −13.78cm−1 for 2, 3 and 4, respectively. These values are in accordance with the magnetostructural correlation of previously reported phenoxido bridged polynuclear Ni(II) complexes. The nature and magnitude of exchange interactions are further corroborated by density functional calculations.

Synthesis of sulfur encapsulated 3D graphene sponge driven by micro-pump and its application in Li–S battery

Because of advantages such as excellent conductivity and high theoretical specific surface area, 3D graphene sponge (3D-GS) grown on Ni template via chemical vapor deposition (CVD) is receiving increasing attention as a conducting template to improve the conductivity of electrode in lithium sulfur (Li–S) battery. However, loading sulfur on the surface of 3D-GS is not a feasible approach to remit the dissolution of polysulfides in cathodes or improve the cycling of batteries. Here, we report a novel design inspired from micro-pump and synthesize a sulfur encapsulated 3D graphene sponge (3D-GS@S) material for Li–S battery for the first time. Under the oil–water two phase liquid seal system, consisting of sulfur-containing organic phase and etching water phase, the vacuum cavities would generate from Ni etching. Tactfully, the pressure differences between vacuum cavities and sulfur-containing solution were converted into driving force for pumping the sulfur-containing solution into 3D-GS. As a result, the sulfur particles uniformly anchored on the inner surface of 3D-GS after the volatilization of sulfur-containing solution. Serving 3D-GS@S as cathode material does not require any additional conducting additives, current collector or binders thus increasing the loading contents of sulfur. A Li–S battery with 3D-GS@S material cathode shows good electrochemical stability and high rate discharge capacity retention for up to 160 discharge/charge cycles at a high rate of 1C. Our results demonstrate the promising suitability of 3D-GS@S for efficient and high performance rechargeable Li–S batteries.

Three-Dimensional Bicontinuous Graphene Monolith from Polymer Templates.

The two-dimensional single-layer and few-layered graphene exhibit many attractive properties such as large specific surface area and high charge carrier mobility. However, graphene sheets tend to stack together and form aggregates, which do not possess the desirable properties associated with graphene. Herein, we report a method to fabricate three-dimensional (3D), bicontinuous graphene monolith through a versatile hollow nickel (Ni) template derived from polymer blends. The poly(styrene)/poly(ethylene oxide) were used to fabricate a bicontinuous gyroid template using controlled phase separation. The Ni template was formed by electroless metal depositing on the polymer followed by removing the polymer phase. The resulting hollow Ni structure was highly porous (95.2%). Graphene was then synthesized from this hollow Ni template using chemical vapor deposition and the free-standing bicontinuous graphene monolith was obtained in high-throughput process. Finally, the bicontinuous graphene monolith was used directly as binder-free electrode in supercapacitor applications. The supercapacitor devices exhibited excellent stability.

Enhanced hydrogen desorption from Mg(BH4)2 by combining nanoconfinement and a Ni catalyst

Magnesium borohydride (Mg(BH4)2) has been infiltrated into highly ordered mesoporous carbon (CMK3) containing dispersed Ni nanoparticles (Ni NPs) to investigate the possible synergetic effects of nanoconfinement and catalysis by Ni NPs. Ni NPs (5 wt%) were introduced into the CMK3 nanoscaffold (CMK3–Ni) then Mg(BH4)2 was slowly infiltrated into this prepared CMK3–Ni template to synthesize a CMK3–Ni confined (Mg(BH4)2) system (denoted as CMK3–Ni–Mg(BH4)2). Solid-state 11B NMR and FT-IR spectra confirmed that Mg(BH4)2 was in the pores of CMK3–Ni. Temperature-programmed desorption-mass spectroscopy (TPD-MS) and pressure–composition–temperature (PCT) measurements were utilized to study the hydrogen desorption properties for this nanoconfined CMK3–Ni–Mg(BH4)2 system, which was demonstrated to be remarkably improved, e.g. the hydrogen desorption temperature was dramatically decreased and the release rate was significantly enhanced. The hydrogen started to be released from the CMK3–Ni–Mg(BH4)2 at a temperature of only 75 °C (measured by TPD) and reached its peak release rate at a temperature of 155 °C, compared with 270 °C and above 350 °C respectively from pure Mg(BH4)2. To the best of our knowledge, this is the first time Mg(BH4)2 decomposition has been realized at a temperature below 100 °C, which is of great significance for the use of this material for practical hydrogen storage for proton exchange membrane fuel cells (PEMFCs).

Enhanced Light Output of InGaN-Based Light Emitting Diodes with Roughed p-Type GaN Surface by Using Ni Nanoporous Template

Roughened surfaces of light-emitting diodes (LEDs) provide substantial improvement in light extraction efficiency. By preparing the self-assemble nanoporous Ni template through rapid annealing of a thin Ni film, followed by a low damage dry etching process, a p-side-up LED with a roughened surface has been fabricated. Compared to a conventional LED with plane surface, the light output of LEDs with nanoporous p-GaN surface increases up to 71% and 36% at applied currents of 1 mA and 20 mA, respectively. Meanwhile, the electrical characteristics are not degraded obviously after surface roughening.

Highly conductive three-dimensional graphene for enhancing the rate performance of LiFePO 4 cathode

In this paper, three-dimensional (3D) graphene network was prepared by chemical vapor deposition (CVD) on 3D porous Ni template. The as-prepared 3D graphene showed high conductivity of ∼600 S cm −1 and low square resistance of 1.6 Ω sq −1. With the aid of 3D graphene network, the poorly conductive LiFePO 4 exhibited high conductivity and good rate performance of 109 mA h g −1 at 10 C, indicating potential application in high rate lithium ion batteries.

Graphitic carbon film formation under Ni templates by radio-frequency sputtering for transparent electrode applications

An alternate approach to the preparation of transfer-free graphitic carbon films is proposed in this paper. Using a standard radio-frequency sputtering system and a high-temperature annealing procedure, graphitic carbon films are prepared under Ni templates. The results demonstrate that carbon precipitation occurs at both Ni template interfaces. With repeated annealing procedures at 1100 °C, a sheet resistance of 1.36 × 104 Ω/□ can be achieved. Selective carbon film deposition has also been developed via pattern formation on the Ni templates. The results indicate the potential application of this method to transparent electrode formation.

Fabrication and Application of Copper Sub-Microdoughnut with Electroplating Method on Patterned Nickel Template

The sub-microdoughnut-like copper periodic structure is fabricated by an electroplating method on a patterned Ni template. The diameter of the cover Cu doughnut hole can be controlled by plating duration. This structure can be applied in a biosensor due to surface plasmonic resonance, and for a novel optical device with a variable hole diameter and period of that array. The magnetic force microscope was used for evaluating the biosensing response under the addition of magnetic proteins (metallothionein, metallothionein, and ferritin) on that sample before and after magnetization. In addition, the optical properties before and after magnetization were measured and scanned by Fourier transform IR spectroscopy. Some interesting behaviors were observed in the spectra and transmitting ratio under different polarization incident conditions.