NiO Nanoplates Research Articles

Hydrogen storage properties of surface oxidized LiBH4 system catalyzed with NiO nanorods and nanoplates

This paper highlights the hydrogen storage performance of surface oxidized LiBH4 (Lithium borohydride) system incorporated with NiO nanostructures under 250 °C. Surface oxidized LiBH4 system was impregnated with hydrothermally synthesized mesoporous NiO nanorods (NiONR) and NiO nanoplates (NiONP) using simple ultrasonication method. Hydrogen sorption and desorption studies has been investigated for LiBH4/NiONR and LiBH4/NiONP systems for the first time. The Brunauer-Emmett-Teller results showed that the specific surface area of NiONR, NiONP, LiBH4/NiONR and LiBH4/NiONP systems were 77.92, 88.12, 96.67 and 101.65 m2/g, respectively. Hydrogenation followed by isothermal dehydrogenation at 250 °C revealed that the LiBH4/NiONR and LiBH4/NiONP systems released ∼3.44 wt% and 4.02 wt% of hydrogen respectively in 60 min. Using the Kissinger's relation, the activation energy (Ea) was calculated as 69.28 and 63.23 kJ/mol for LiBH4/NiONR and LiBH4/NiONP systems, respectively. The dehydrogenation rate of LiBH4/NiONP system was found to be greater than that of LiBH4/NiONR system due to its large surface area and lower activation energy. The reported results revealed that nickel oxide nanostructures incorporated surface oxidized LiBH4 systems provide new opportunities for the solid-state hydrogen storage applications.

Experimental investigations on morphology controlled bifunctional NiO nano-electrocatalysts for oxygen and hydrogen evolution

Developing a single electrocatalyst effective for both oxygen and hydrogen evolution remains challenging. Although an attempt to utilize a single electrocatalyst for overall water splitting is made, there still exist several issues of efficiency and stability of the electrocatalyst. Hence, the present study reports on morphology-controlled NiO electrocatalyst, a single electrocatalyst for oxygen and hydrogen evolution. The cubic phase NiO nanoparticles and nanoplates of diameter and thickness <10 nm delivered surface-to-volume ratios of 0.078 and 0.083, respectively. XRD and TEM confirm the formation of NiO nanostructures, where morphology transformed independently of the chemical composition. XPS and EXAFS confirm the 2+ oxidation state of Ni ions and its octahedral coordination with oxygen. The 0D nanoparticles providing a larger surface area and active sites offered the overpotentials of 373 and 268 mV for OER and HER activity, respectively, and performed well than the 2D porous NiO nanoplates. The chronoamperometry and repetitive LSV cyclic studies confirmed the excellent long-term stability of 0D NiO nanoparticles in basic and acidic mediums during electrocatalytic water splitting reactions, owing to its increased electrochemically exposed active sites.

The electrochemical reforming of glycerol at Pd nanocrystals modified ultrathin NiO nanoplates hybrids: An efficient system for glyceraldehyde and hydrogen coproduction

The electrochemical reforming of glycerol at Pd nanocrystals modified ultrathin NiO nanoplates hybrids: An efficient system for glyceraldehyde and hydrogen coproduction

NiO nanoplates for energy storage application: Role of electrolyte concentration on the energy storage property

Here in, synthesis of NiO nanoplates by employing a mixed solvent system under solvothermal method followed by calcining the obtained product nickel hydroxide in air is reported. Diffraction, microscopic, and spectroscopic results confirmed the formation of NiO phase. The as synthesized NiO nanoplates are tested as a robust material for energy storage applications. The effect of electrolyte concentration on the capacitive behavior of NiO is studied thoroughly. The outcome from the electrochemical analysis reveals that NiO nanoplates have a high specific capacity value of 108.4 C g−1 (270 F g−1) in 6 M KOH electrolyte and the value decreases to 85.0 C g−1 (212.5 F g−1) and 78.2 C g−1 (195.5 F g−1) for 4 M, and 2 M KOH electrolyte, respectively. The resistance values also decreased with increase in the KOH concentration. The better electrochemical performance depicted by the 6 M KOH electrolyte is mainly ascribed to the availability of plenty of OH− ions in the electrolyte solution, which helped in the proper wettability of the sample so that the OH− ions can participate to higher extent during the electrochemical redox reactions, due to which the observed charge storage capacity is more in higher electrolyte concentration and vice-versa. Thus, the results suggest the usefulness of this material for energy storage applications.

Fast lithiation of NiO investigated by in situ transmission electron microscopy

As a lithium-ion battery anode material, NiO has attracted a lot of attention owing to its excellent theoretical capacity. In this work, the dynamic lithiation process of NiO nanoplates and nanoparticles was investigated by in situ transmission electron microscopy (TEM). The morphology evolution, phase transformation, and electrochemical reaction of NiO during the lithiation process have been probed in real time by in situ TEM combined with selected area electron diffraction and electron energy loss spectroscopy technologies. We found that the insertion of Li-ions led to huge volume expansion of NiO, resulting in structural changes and breakdown. Li2O formed during lithiation hinders electron transportation through NiO due to its low conductivity, which causes poor cycling performance of NiO. Our findings provide valuable theoretical guidance for the modification of NiO as anode material for next generation high-performance lithium-ion batteries.

Controllable synthesis of crescent-shaped porous NiO nanoplates for conductometric ethanol gas sensors

NiO has been widely used as building blocks for gas sensing because of its excellent physicochemical properties. However, the high working temperature of most NiO-based sensors (<200 °C) hinders their further applications. In this work, a novel nanostructure, crescent-shaped porous NiO nanoplates, has been synthesized via hydrothermal approach combining with calcination treatment, which shows low working temperature for ethanol gas sensing. The volume ratio of ethanol to distilled water, the adding amount of PVP, and annealing temperature have been investigated in detail for precisely controlling the morphology of NiO nanostructure. Subsequently, the crescent-shaped porous NiO nanoplates are employed to fabricate conductometric ethanol gas sensors. Under optimal experimental conditions, the NiO nanoplates based gas sensor demonstrates fast response and recovery speed (5 and 20 s, respectively) to 100 ppm ethanol at a low working temperature of 130 °C with excellent long-term stability and selectivity. Furthermore, the limit of detection is experimentally calculated to be as low as 200 ppb. The results show that the crescent-shaped porous NiO nanoplates has great potential in ethanol sensing applications and the feasibility of morphology control for high performance gas sensing.

Improved selectivity and low concentration hydrogen gas sensor application of Pd sensitized heterojunction n-ZnO/p-NiO nanostructures

Heterojunction based gas sensor was fabricated by forming two semiconductor nanostructures interface i.e. n-type ZnO nanorods and p-type NiO nanoplates. These nanostructures were synthesized via chemical routes. Palladium (Pd) nanoparticles (NPs) were synthesized and sensitized on the surface of heterojunction sensor material to enhance the gas response. Sensor materials were characterized using XRD, TEM, FESEM, EDS, Elemental mapping, and XPS techniques for their physicochemical properties. The n-ZnO/p-NiO heterojunction sensors with and without Pd NPs sensitization were investigated for low hydrogen gas concentration 2–100 ppm. Pd NPs sensitized n-ZnO/p-NiO heterojunction sensor showed higher response of 72% towards 100 ppm hydrogen (H2) gas concentration at the operating temperature 225 °C, whereas 53% response was noted by p-NiO/n-ZnO heterojunction sensor for 100 ppm concentration at 237 °C operating temperature. Both the sensors were investigated for selectivity studies using methane (CH4), carbon monoxide (CO), nitrogen dioxide (NO2), carbon dioxide (CO2) and H2 gases. Higher selectivity was observed towards H2 gas for both the sensors. The gas responses of both sensors were investigated at various operating temperatures and concentrations. Transient response, repeatability, and stability were also confirmed for both sensors. The gas sensing mechanism for heterojunction sensors was elucidated.

Konjac glucomannan-templated synthesis of three-dimensional NiO nanostructures assembled from porous NiO nanoplates for gas sensors.

Biopolymer template synthesis has attracted extensive interest for fabricating highly porous metal oxide nanostructures. In this report, a green template-based approach for the synthesis of three-dimensional (3D) NiO nanostructures assembled from porous NiO nanoplates is introduced using a konjac glucomannan (KGM) template. The Ni–KGM composites, which were formed by the immersion of KGM nanofibrils in nickel nitrate solution, were annealed in air at 600 °C to obtain the highly porous NiO nanoplates. The KGM nanofibrils were used as a sacrificial template, which was combusted at a high temperature for the formation of the porous nanostructures. The gas sensor properties of the porous NiO architecture were systematically investigated with four reduced gases including hydrogen sulfide, ammonia, carbon monoxide and hydrogen. The results indicate that the porous NiO nanoplates show a good detection of hydrogen sulfide with a rapid response and recovery speed at low concentrations.

In situ synthesis of mesoporous NiO nanoplates embedded in a flexible graphene matrix for supercapacitor electrodes

Scholars have attached increasing attention to Graphene nanosheet (hereinafter referred to as GNS)-loaded transition metal oxide composites owing to the ability of attaching inorganic nanoparticles with better capacity and capacitance and better capacity than GNS of conductive polymer materials. A novel mesoporous structure of NiO nanoplates encapsulated in graphene matrix was synthesized and designed rationally. The composite composed of GNS and mesoporous NiO nanoplates can expand the approximate specific surface area of electrolyte. It has various advantages, such as good charge transport and short ion diffusion path. In addition, the interconnected graphene conducting network, as an adhesive, can maintain structural stability and promote charge transport by encapsulating mesoporous NiO nanoplates. The specific capacity is increased to 1050 F g−1 through the improved optimized NiO/GNS hybrid electrodes. This study provides a new idea for the design and manufacture of high performance transition metal oxide energy storage devices.

Hydrothermal synthesis of p-type nanocrystalline NiO nanoplates for high response and low concentration hydrogen gas sensor application

High quality nanocrystalline NiO nanoplates were synthesized using surfactant and template free hydrothermal route. The gas sensing properties of NiO nanoplates were investigated. The nanoplates morphology of NiO with average thickness ~ 20 nm and diameter ~ 100 nm has been confirmed by FE-SEM and TEM. Crystalline quality of NiO has been studied using HRTEM and SAED techniques. Structural properties and elemental compositions have been analyzed by XRD and energy dispersive spectrometer (EDS) respectively. The detailed investigation of structural parameters has been carried out. The optical properties of NiO were analyzed from UV–Visible and photoluminescence spectra. NiO nanoplates have good selectivity towards hydrogen (H2) gas. The lowest H2 response of 3% was observed at 2 ppm, whereas 90% response was noted for 100 ppm at optimized temperature of 200 °C with response time 180 s. The H2 responses as functions of different operating temperature as well as gas concentrations have been studied along with sensor stability. The hydrogen sensing mechanism was also elucidated.

Satellite-like CdS nanoparticles anchoring onto porous NiO nanoplates for enhanced visible-light photocatalytic properties

Novel CdS/NiO nanocomposites assembled by satellite-like CdS nanoparticles anchoring onto porous NiO nanoplates have been fabricated by a step synthesis process, which involves a chemical bathing method followed by a heat treatment, and a microwave-assisted aqueous chemical reaction. The structure and photocatalytic properties of products were characterized by various techniques. More significantly, benefiting from the synergistic effect of CdS/NiO heterojunction, the as-prepared CdS/NiO architectures exhibited superior photocatalytic activity for decolorization of Congo red. The degradation rate on CdS/NiO nanocomposites achieves about 3.5 times higher than that of pure CdS nanocrystals under visible light irradiation for 30 min, suggesting a promising application in water purification.

Microwave assisted synthesis of [formula omitted] and NiO nanoplates and structural, optical, magnetic characterizations

The surfactant and template free Co3O4 and NiO nanoplates have synthesized using microwave assisted method. Synthesized Co3O4 and NiO nanoplates were characterized using X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive spectrometer (EDS) for their Structural, morphological and elemental analysis respectively. The Fourier transform infrared (FTIR) spectra of both samples were recorded for the oxide compound confirmation. Optical and magnetic characterizations were studied by using UV–Visible absorption spectroscopy, photoluminescence (PL) and vibrating sample magnetometer (VSM) respectively. Average crystallite sizes for Co3O4 and NiO nanoplates were found to be 21 nm and 17 nm respectively by using Debye–Scherrer’s formula. The energy band gaps for Co3O4 and NiO nanoplates were calculated using Tauc plot and values are 3.3 eV and 3.1 eV respectively. BET surface areas of Co3O4 and NiO nanoplates were measured to be 29 m2/g and 92 m2/g respectively. The magnetization of Co3O4 and NiO nanoplates as a function of magnetic field were recorded at room temperature showing a small hysteresis loop with coercivity of ∼534 and ∼152 Oe respectively. Microwave assisted method can be useful for the synthesis of Co3O4 and NiO nano morphological materials for supercapacitor application.

Atomic Heterointerfaces and Electrical Transportation Properties in Self‐Assembled LaNiO3–NiO Heteroepitaxy

AbstractVertical nanostructure heteroepitaxy opens new opportunities for designing next‐generation electronic devices due to the enthralling multifunction combinations and the abundant heterointerfaces manipulated effects. In this study, self‐assembled heteroepitaxial thin films, vertically aligned metallic LaNiO3 (LNO) and semiconducting NiO with diverse heterointerfaces, are created and systematically investigated by advanced transmission electron microscopy. With the increase of LaNiO3 content, the LaNiO3 phases present as isolated islands encircled by the connected NiO nanoplates and eventually become the continuous matrix with embedded NiO nanopillars. The atomic heterointerface between NiO and LaNiO3 phases is determined to be [NiO2–LaO]LaNiO3–LaO–[NiO]NiO, in which an extra La–O layer is enriched at the heterointerface. Besides, the formation mechanism of the heterointerface and antiphase boundaries observed in LaNiO3 phase is discussed. The electrical transport properties at room temperature can be tuned gradually by changing the volume ratio of constituents. The correlation among the insulator‐to‐metal transition, the carrier types associated with transport behaviors, and the heterostructure evolutions are explored. This study offers a desirable platform to design new multifunctional electronic devices based on the oxide heterojunctions.

Synthesis, characterization, and study of the supercapacitive performance of NiO nanoplates prepared by the cathodic electrochemical deposition-heat treatment (CED-HT) method

NiO nanoplates were prepared through a method base on cathodic electrochemical deposition-heat treatment. The deposition mechanism of the hydroxide precursor (i.e. Ni(OH)2) during the CED step, and final oxide formation during the HT step were specified. The structural and morphological evolutions by XRD, SEM and TEM confirmed the production of pure β-Ni(OH)2 nanoplates and cubic crystalline NiO nanoplates as the CED and HT products, respectively. The supercapacitive performance of the prepared NiO nanoplates was further studied by techniques of cyclic voltammetry and galvanostatic charge–discharge within the potential window of −0.1 to 0.5 V in 1 M KOH electrolyte. The measurements revealed that the nanoplates have high reversibility (ΔEp = 22 mV), high specific capacitance (1345 F g−1 at the scan rate of 2 mV s−1) and proper long-term cycling stability of 89.1 % capacity retention after 3000 cycling at the current density of 1 A g−1.

H2S gas sensing properties of Fe2O3 nanoparticle-decorated NiO nanoplate sensors

Abstract Fe 2 O 3 nanoparticles and Fe 2 O 3 nanoparticle-decorated NiO nanoplates were synthesized via a facile solvothermal route using FeCl 3 , nickel acetate, and NaOH as starting materials. The structure and morphology of the synthesized nanoparticles were examined using X-ray diffraction and scanning electron microscopy, respectively. The gas sensing properties of the Fe 2 O 3 nanoparticles and Fe 2 O 3 nanoparticle-decorated NiO nanoplate sensors toward H 2 S gas were examined at different concentrations of H 2 S (5–200 ppm) gas at various temperatures (200–350 °C). The Fe 2 O 3 nanoparticle-decorated NiO nanoplate sensor exhibited a stronger response to H 2 S than the Fe 2 O 3 nanoparticle sensor. The response of the Fe 2 O 3 nanoparticle-decorated NiO nanoplate sensor was 26.55 for 200 ppm H 2 S at 300 °C, whereas the maximum response of the Fe 2 O 3 nanoparticle sensor was 7.46 under the same condition. The Fe 2 O 3 nanoparticle-decorated NiO nanoplate sensor also exhibited shorter response and recovery times than those of the Fe 2 O 3 nanoparticle sensor. The improved sensing performance of the Fe 2 O 3 nanoparticle-decorated NiO nanoplate sensor was attributed to the enhanced modulation of the conduction channel width and potential barrier height at the NiO–Fe 2 O 3 interface, catalytic activity of NiO in the oxidation of H 2 S, larger surface-to-volume ratio of the decorated sensor, and stronger adsorption of oxygen molecules by p-type NiO.

Lactic acid production from rice straw in alkaline hydrothermal conditions in presence of NiO nanoplates

The research study is based on alkaline hydrothermal liquefaction of rice straw using NiO nanoplates where temperature, reaction time and molar concentrations of alkali (NaOH) were varied to optimize lactic acid (LA) production. The highest yield of 58.81% for lactic acid was obtained at 260°C for 2h with 1M NaOH and 0.052g NiO nanoplates attributing to complete degradation of cellulosic rice straw. Influence of different morphological forms of NiO like nanoparticles, nanoplates and porous nanosheets were also investigated in this perspective where nanoplates had better catalytic activity. Lactic acid production was found to be highly dependent on and sensitive to slight changes in alkaline conditions in the existence of NiO nanoplates as catalyst.

Hierarchical flower-like NiO hollow microspheres for non-enzymatic glucose sensors

Abstract Hierarchical flower-like NiO hollow microspheres were controllably prepared by a facile hydrothermal method using carbon spheres as the template. Their structure and properties for non-enzymatic glucose sensors were investigated. The results showed that the hierarchical flower-like NiO hollow microspheres are composed of the interconnecting porous NiO nanoplates and each nanoplate is assembled by NiO nanoparticles with the length of about 12.5 nm and the width of about 10 nm. Furthermore, the hierarchical flower-like NiO hollow microspheres obtained at different temperatures were analyzed with the electro-catalytic activity toward the oxidation of glucose in alkaline solution, and the glucose sensor with hierarchical flower-like NiO hollow microspheres obtained at 550 °C exhibits the best performance with the linear range of 5 μM–364 μM and sensitivity of 288.87 mA mM− 1 cm− 2. The sensor is also used for detection of glucose with a relative concentration ranging from 2.96 mM to 7.46 mM and sensitivity of 37.82 mA mM− 1 cm− 2. More importantly, long-term stability and favorable anti-interference were obtained as a result of the hierarchical hollow structure.

In situ growth of mesoporous NiO nanoplates on a graphene matrix as cathode catalysts for rechargeable lithium–air batteries

NiO/graphene nanocomposites are fabricated via a solvothermal method. Scanning and transmission electron microscopy results indicate that the NiO nanoplates (length, ~100nm) were homogeneously distributed on the graphene sheets. The electrochemical properties of the samples as active cathode catalysts for rechargeable Li–air batteries are evaluated by constant current charge–discharge cycling. The composites exhibit a reversible capacity of 1160mAhg−1 after 50 cycles at a discharge current density of 50mAg−1; this reverse capacity is much higher than that of pure NiO nanoplates (30mAhg−1). Using graphene as a conductive matrix, a homogeneous distribution of NiO nanoplates is accomplished and graphene serves as a framework for loading as produced Li2O2 during the discharge process, resulting in the excellent electrochemical performance of the composites. The mesoporous structure of the NiO nanoplates is suitable for the transfer of O2 and deposition of Li2O2 produced by the electrochemical reaction. NiO/graphene nanocomposites are a candidate material for high-capacity, low-cost, and nontoxic cathode catalysts in rechargeable Li–air batteries.

&lt;i&gt;In Situ&lt;/i&gt; Growth of Mesoporous NiO Nanoplates on Graphene Matrix as Anode Material for Lithium-Ion Batteries

Graphene-NiO nanocomposites were prepared via a solvothermal method. The nanostructure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). SEM and TEM results indicated that NiO nanoplates distributed homogeneously on graphene sheets. The electrochemical properties of the samples as active anode materials for lithium-ion batteries were examined by constant current charge-discharge cycling. With graphene as conductive matrix, homogeneous distribution of NiO nanoplates can be ensured and volume changes of thenanocomposite during the charge and discharge processes can be accomodated effectively, which results in good electrochemical performance of the composites.

Fe3+ facilitating the response of NiO towards H2S

Fe2O3-loaded NiO nanoplates were prepared by immersing NiO nanoplates in aqueous Fe(NO3)3 solution and annealing the corresponding as-immersed NiO nanoplates.