NiO Nanofibers Research Articles

Fabrication and characteristics study of self‐powered and UV–Vis–NIR photodetector based on p‐NiO:Eu nanofibers

AbstractHeterojunctions formed between undoped and Eu‐doped NiO nanofibers (NFs) and n‐Si were fabricated by electrospinning the NiO:Eu NFs onto Si. Since the photoresponse of the Eu‐doped NiO‐containing device was better than the undoped one, the study focused on the doped NiO‐containing device. This was explained by the increase in electron kinetics in terms of the active role of Eu in bonding with the 4f orbitals and the s, d, and f states of NiO. Electro‐optical measurements of the NiO:Eu NFs/n‐Si heterojunction were performed in the visible region depending on the light intensity and in the UV and NIR regions for 10 mW/cm2 powers. It was observed that the device exhibits a good level of rectification properties and responds very well to all lights. At all three light sources, the heterojunction photodetector exhibited self‐powered behavior. Furthermore, for 10 mW/cm2 light intensity, the NiO:Eu NFs/n‐Si photodetector achieved R values of 1.84 A/W at 365 nm, 0.98 A/W at 395 nm, and 1.54 A/W at 850 nm, while it is 0.12 A/W for visible light. Besides, the device showed an external quantum efficiency of 625% and this was attributed to the photocurrent gain. In self‐driven mode, D* values have been determined as 3.0 × 1012 Jones, 2.6 × 1012 Jones, and 2.9 × 1012 Jones for 365, 395, and 850 nm, respectively. The performance of NiO under UV light was attributed to the absorption of NiO under UV light, as well as the very good excitation of (Eu3+) ions by UV light.

Ultra-trace leakage detection of 1, 2-dimethoxyethane in Lithium-Ion battery electrolyte via lacunary polyoxometalates-driven synthesis of NiO/Si-NiWO4/WO3 heterostructure nanofibers

Early detection of electrolyte leakage is crucial to prevent thermal runaway in lithium-ion batteries (LIBs). Gas sensors offer a potential solution, however, designing sensing materials that can sensitively identify organic molecules from electrolyte leakage remains a great challenge. Herein, the heterostructured NiO/Si-NiWO4/WO3 nanofibers (NFs) were achieved as a sensing material for highly sensitive detection of 1, 2-dimethoxyethane (DME), a typical electrolyte organic molecule. This was accomplished using the highly negatively charged lacunary polyoxometalates (POMs) TBA4H6[SiW9O34]·2 H2O (α-SiW9) and Ni2+ as precursors, resulting in a series of uniform Si-NiWO4/WO3 decorated NiO NFs synthesized through a two-step process involving electrospinning followed by thermal oxidation. By utilizing the synergistic effect of abundant active interfaces, rapid carrier transfer, and a large specific surface area inherent to NFs, the sensor shows high sensitivity (1.87–300 ppb DME), reliable reproducibility and stability, and superior selectivity. Moreover, the sensor is highly responsive to electrolyte leakage simulations, making it a strong candidate for safety systems of LIBs. The study outlines a cost-effective method for preparing NiO/Si-NiWO4/WO3 NFs, setting a foundation for developing various heterostructured nanomaterials with POMs as precursors.

Growth kinetics of novel nickel oxide (NiO) nano fibers on glass substrates by SILAR process: A solution to remove AZO dye

This article presents the growth of uniformly distributed nickel oxide (NiO) nanofibers on a glass substrate by the Successive Ionic Layer Adsorption and Reaction (SILAR) process and explores its photocatalytic features towards an AZO dye. The nanofiber grown by the SILAR process is subjected to annealing at 400°C to decompose the hydroxide group into oxide. X-ray diffraction pattern divulges the Face-Centered Cubic (FCC) structure of NiO, and its average crystallite size (46–61 nm). The fibrous morphology with the width varying from 37.83 to 42.05 nm is confirmed through FESEM micrographs. The existence of nickel and oxide, with atomic percentages in the ratio 40:60 is confirmed by EDX analysis. From the UV–visible spectrum, the band gap energy Eg is determined using a Tauc plot and the values are varied between 3.38 eV and and 3.41 eV. Photocatalytic degradation efficiency for the Congo red dye is found to be 93% for reusable NiO nanofibers under the illumination of UV light. The photodegradation pathway of Congo red dye is presented based on gas chromatography-mass spectrometry (GC-MS) analysis. The prospective applications of the current work in wastewater treatment make it significant.

Development of Nanoporous Nickel Oxide Materials as Electrodes for Supercapacitors

As a potential electrochemical energy storage device, supercapacitor has been researched owing to its low weight, excellent power density, outstanding charging rate, and long durability. For the supercapacitor, the electrode material and its morphology determine its overall performance. Nickel oxide (NiO) is a promising material for the electrode because of its low cost, high specific capacitance, and eco-friendly manufacturing process. In this research, we developed a simple and cost-effective method to fabricate supercapacitor electrodes by electrospinning and thermal annealing, making porous nickel oxide nanofibers directly grow on 3D-nickel foam. The binder-free design and porous structure of electrodes enhance the ion transport and electron transfer in the supercapacitor. The crystal structure of NiO was identified by X-ray diffractometry (XRD). The morphological and microstructural characterization was analyzed by scanning electron microscopy (SEM). The electrochemical test was carried out in a three-electrode electrochemical cell with the obtained foamed NiO as the working electrode, the platinum sheet as the counter electrode, and the Ag/Cl electrode as the reference electrode. The electrochemical performance was evaluated by using cyclic voltammetry (CV), galvanostatic charge/discharge technique, and electrochemical impedance spectroscopy (EIS). Due to the large specific surface area and good electrical conductivity of the NiO electrode, the supercapacitor exhibited excellent electrochemical performance (591 F/g at 2 A/g). After 1500 cycles of charging and discharging at 10 A/g, the capacitance of the supercapacitor using the NiO electrode increased by 21.7% with excellent cycle stability.

Synthesis and characterization of rGO wrapped 1-D NiO nanofibers for ammonia gas sensing application

The fabrication of reduced graphene oxide (rGO) based metal oxide semiconductor (MOS) nanocomposites for applications at room temperature gas sensing have attracted growing interest in during recent years. The present work, one dimensional (1-D) rGO-NiO nano fibers were fabricated by employing electrospinning technique for detection of NH3 gas at room temperature. SEM, XRD, BET, DRS and XPS were used to analyse the surface morphology, structure, composition of materials and optical properties of rGO-NiO nanofibers. Ammonia gas is detected by the rGO-NiO sensor with an excellent response time of 32 s. and recovery time of 38 s. respectively for a concentration of 50 ppm at room temperature. The intrinsic charge transfer due to the synergistic effect of the heterostructure will enhance the sensing performance.

Synergistic effect of Pd and Fe2O3 nanoparticles embedded in porous NiO nanofibers on hydrogen gas detection: Fabrication, characterization, and sensing mechanism exploration

Pd and Fe2O3 nanoparticles (NPs)-embedded porous NiO nanofibers (NFs) with high specific surface area were prepared using a facile electrospinning method. Adjusting the amount of Fe2O3 NPs in the precursor solution of electrospinning regulates the morphological evolution and crystallization of oxide heterostructures at elevated temperatures and significantly contribute to the enhanced gas sensing performance for hydrogen (H2) gas testing. Synthesized composites present the highest response of 199.24 at the optimum operating temperature of 250 °C toward 1000 ppm H2 gas, which is 65 times higher than that of only Pd-decorated NiO NFs. The response/recovery times of the sensors decreased significantly from 39/323 s for the pure sample to 11/105 s, along with good selectivity and long-term stability toward H2. The excellent gas sensing properties of the sensors is mainly attributed to the flourishing porous one-dimensional (1D) microstructure containing closely connected p-n heterojunctions of NiO and Fe2O3, which provide large specific surface areas with many active sites to promote the reaction between H2 molecules and O ion on the surface and the catalytic effect of Pd. The results demonstrate the potential of the method to fabricate gas sensors for H2 detection at ppm levels at 250 ℃ environment.

Sn2+ doped NiO hollow nanofibers to improve triethylamine sensing characteristics through tuning oxygen defects

The triethylamine (TEA) sensors with high response and selective detection have been widely reported. However, sluggish kinetics of recovery process, high operating temperature, unsatisfied long-term stability and high detection limit still restrict their further application. In this work, NiO nanofibers with different contents of Sn2+ are prepared via electrospinning method. Gas sensing investigation indicates that the sensor based on 6 at% Sn2+ doped NiO nanofibers with an elevated baseline resistance exhibits the highest gas response and excellent recovery characteristic to TEA at 200 °C. The sensor shows a low detection limit at ppb level and good long-term stability within three months. In addition, the sensor only has a small variation on baseline resistance, gas response and response/recovery speed under different relative humidity. The promising gas sensing performance can be mainly attributed to the increase of the oxygen vacancies defects caused by the difference of Sn2+ and Ni2+, resistance changes and the hollow structure of as-prepared nanofibers.

On the beneficial effect of Rh2O3 modification of Sn doped NiO nanofibers for conductometric triethylamine gas sensing

In this work, Sn4+ doped NiO nanofibers are modified by different contents of Rh2O3 through a facile electrospinning method to improve the gas sensing properties, especially the humidity tolerance, response value and detection limit. The morphological characterization indicates that the hollow nanostructures are still maintained after loading Rh2O3. Gas sensing investigation demonstrates that 6 at% Sn4+ doped NiO nanofibers modified with 6 at% Rh2O3 exhibit the highest response to triethylamine (28.3–20 ppm) with low detection limit (50 ppb) at a relatively low working temperature (165 °C), which are obviously superior to those (16.6–100 ppm, 500 ppb and 180 °C) of 6 at% Sn4+ doped NiO nanofibers without Rh2O3 modification. The response value to 20 ppm triethylamine is only changed about 35.7% as the relative humidity increases from 35% to 95%. The humidity tolerance of the optimal sensor is also improved after Rh2O3 modification including the baseline resistance and gas response changes. Furthermore, the baseline resistances of the optimal gas sensors don’t become higher after Rh2O3 modification. These phenomena can be mainly attributed to the improved catalytic effect and increased surface defects caused by Rh2O3 modification.

Conductivity features of ZnO and NiO nanofiber composites

In this work, composites of ZnO and NiO nanofibers with n- and p-type conductivity, respectively, were studied. It is shown that the conductivity of the studied composites strongly depends on the arrangement of ZnO and NiO nanofibers. In the case of a mixture of ZnO and NiO nanofibers (with their random arrangement relative to each other and electrical contacts), conduction can occur only along ZnO fibers, which have a higher conductivity compared to NiO. However, the presence of the ZnO/NiO p-n heterojunction leads to the formation of depleted regions in ZnO, as a result, the conductivity of the mixture becomes several orders of magnitude lower than the conductivity of ZnO nanofibers. In the case of a two-layer composite, in which one layer consists of NiO nanofibers and the other layer consists of ZnO nanofibers, charge carriers move through the p-n NiO/ZnO heterojunction, which leads to a rectifying current-voltage characteristic and opens up broad prospects for the use of such systems in electronic devices. Keywords: metal oxides, zinc oxide, nickel oxide, heterostructures, conductivity.

Особенности проводимости композитов нановолокон ZnO и NiO

In this work, composites of ZnO and NiO nanofibers with n- and p-type conductivity, respectively, were studied. It is shown that the conductivity of the studied composites strongly depends on the arrangement of ZnO and NiO nanofibers. In the case of a mixture of ZnO and NiO nanofibers (with their random arrangement relative to each other and electrical contacts), conduction can occur only along ZnO fibers, which have a higher conductivity compared to NiO. However, the presence of the ZnO/NiO p-n heterojunction leads to the formation of depleted regions in ZnO, as a result, the conductivity of the mixture becomes several orders of magnitude lower than the conductivity of ZnO nanofibers. In the case of a two-layer composite, in which one layer consists of NiO nanofibers and the other layer consists of ZnO nanofibers, charge carriers move through the p-n NiO/ZnO heterojunction, which leads to a rectifying current-voltage characteristic and opens up broad prospects for the use of such systems in electronic devices.

Effect of Annealing Temperature on Morphology, Structural and Magnetic Properties of Electrospun Nickel Oxide Nanofibers

Objectives: To find how annealing temperature affected the morphological, structural, and magnetic properties of nickel oxide (NiO) nanofibers (NFs). Also to establish a link between magnetic characteristics and the vacancy defects generated by particle size effects. Methods: Cost-effective electrospinning method is used to fabricate NiO NFs by using Nickel nitrate hexahydrate Nickel (II) nitrate as a precursor and polyvinylpyrrolidone (PVP) as a polymer. Annealing of precursor NFs helps it to transform to NiO NFs. Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) are used to study the morphological and structural properties of NiO NFs. We inspected elemental composition and molecular interactions with an X-ray photoelectron spectrometer (XPS) and Raman spectra. Vibrating sample magnetometer (VSM) measurements probe the magnetic properties. Findings: Changing the annealing temperature allows us to tune the particle size. The average NF diameter was reduced with annealing from 17330 nm for as-spun NFs to 11013 nm for 800◦C annealed NiO NFs. With a rise in annealing temperature from 400◦C to 800◦C, the particle diameter increased from 9.16 nm to 27 nm. We observed field-dependent magnetization for NiO NFs annealed at 400◦C, i.e. ferromagnetic (FM) with susceptibility of 0.3341 at lower magnetic fields and antiferromagnetic (AF) with susceptibility of 0.0096 at higher applied magnetic fields. With the rise in annealing temperature, the magnetization reduced. As shown in XPS studies, we estimated the variation in Ni vacancies and oxygen concentration with annealing temperature may be the reason for a change in the magnetic properties of NiO NFs, because of its particle size variation with annealing. Novelty: From the experimental results, we inferred a probable cause for the FM properties in the AF material. Because of their anomalous magnetic property, i.e. field-dependent magnetization, we can use NiO NFs annealed at 400◦C as a material for spintronic switching devices. Keywords: Electrospinning; Nanofibers; Magnetic properties; Annealing temperature; Particle size

Camphene-derived hollow and porous nanofibers decorated with hollow NiO nanospheres and graphitic carbon as anodes for efficient lithium-ion storage

A synthesis strategy for hollow and porous nanofibers comprising hollow NiO (H-NiO) nanospheres formed via nanoscale Kirkendall diffusion and supported over a porous graphitic carbon matrix (H-NiO@HNFs) is reported herein to enable the fabrication of advanced anodes for stable lithium-ion batteries (LIBs). The H-NiO@HNFs comprising 1D longitudinal hollow channels ensured efficient diffusion of charged species via effective electrolyte percolation besides providing sufficient space to accommodate the large volume variations during repeated cycling. The hollow NiO nanospheres acted as chemical sites for lithiation and delithiation. Additionally, the H-NiO@HNFs exhibited improved lithium-ion storage properties, such as reasonable rate capability, stable prolonged cyclability at a high current density (1.0 A g-1), and a high lithium-ion diffusion coefficient, primarily owing to their enhanced structural integrity compared to that of filled NiO nanofibers (F-NiO NFs). This facile synthesis approach could broaden the current understanding of 1D hollow nanostructures decorated with conventional hollow metal-oxide nanoparticles for various applications.

1D NiO–3D Fe2O3 mixed dimensional heterostructure for fast response flexible broadband photodetector

Conventional heterojunction photodetectors rely on planar junction architecture which suffer from low interfacial contact area, inferior light absorption characteristics and complex fabrication schemes. Heterojunctions based on mixed dimensional nanostructures such as 0D-1D, 1D-2D, 1D-3D etc have recently garnered exceptional research interest owing to their atomically sharp interfaces, tunable junction properties such as enhanced light absorption cross-section. In this work, a flexible broadband UV–vis photodetector employing mixed dimensional heterostructure of 1D NiO nanofibers and 3D Fe2O3 nanoparticles is fabricated. NiO nanofibers were synthesized via economical and scalable electro-spinning technique and made composite with Fe2O3 nanoclusters for hetero-structure fabrication. The optical absorption spectra of NiO nanofibers and Fe2O3 nanoparticles exhibit peak absorption in UV and visible spectra, respectively. The as-fabricated photodetector displays quick response times of 0.09 s and 0.18 s and responsivities of 5.7 mA W−1 (0.03 mW cm−2) and 5.2 mA W−1 (0.01 mW cm−2) for UV and visible spectra, respectively. The fabricated NiO–Fe2O3 device also exhibits excellent detectivity in the order of 1012 jones. The superior performance of the device is ascribed to the type-II heterojunction between NiO–Fe2O3 nanostructures, which results in the localized built-in potential at their interface, that aids in the effective carrier separation and transportation. Further, the flexible photodetector displays excellent robustness when bent over ∼1000 cycles thereby proving its potential towards developing reliable, diverse functional opto-electronic devices.

Fabrication and Characterization of Nickel Oxide Nanofibers by Electrospinning Technique

Nickel Oxide nanofibers were successfully prepared by electrospinning with a precursor mixture of Ni acetate/polyvinylpyrrolidone (PVP), followed by calcination treatment of the electrospun composite nanofibers. The parameter of solution and effect of applied voltage to the morphology of nanofibers were studied. Both Ni acetate/PVP and NiO NFs, nanofibers were characterized by FESEM and XRD. The results found that the nanofibers form with smooth surface without beads and the calcination temperature was at 500°C to produce NiO nanofibers.

Nickel oxide nanofibers manufactured via sol-gel method: synthesis, characterization and use it as a photo-anode in the dye sensitized solar cell

A modified method with sol-gel nickel oxide (NiO) nano fibers was used for current research synthesized. FE‐ SEM, AFM,and UV visible spectroscopy were used to investigate the morphology and optic properties of the synthesized nano. The synthesized nickel oxide structure has been demonstrated with X-ray diffraction (XRD),average crystalline size was 10.08 nm while particle size ~23 nm with fiber structure from FE‐ SEM and 16.87 nm from AFM. Nanofiber was used to produce a new solar cell (ITO/ NiO/ Rhodamina 6 G/iodide/Al nanofilm/ITO) with a photo-sensitization of approximately 0.973%.

Evaluation and Comparison of Nio/Cuo Nanocomposite and Nio Nanofibers as Non-Enzymatic Electrochemical Cholesterol Biosensor

Evaluation and Comparison of Nio/Cuo Nanocomposite and Nio Nanofibers as Non-Enzymatic Electrochemical Cholesterol Biosensor

Preparation of Nanostructured SnO2-NiO Composite Semiconductor for Gas Sensor Applications

Electro spinning technology combined with chemical precipitation method and high-temperature calcination was used to prepare SnO2-NiO composite semiconductor nanofibers with different Sn content. Scanning electron microscope (SEM), X-ray diffractometer (XRD) and energy dispersive X-ray spectrometer (EDS) were used to characterize the morphology, structure and content of various elements of the sample. Using ethanol as the target gas, the gas sensing properties of SnO2-NiO nanofibers and the influence of Sn content on the gas sensing properties of composite nanofibers were explored. The research results show that SnO2-NiO composite nanofibers have a three-dimensional network structure, and the SnO2 composite can significantly enhance the gas sensitivity of NiO nanofibers. With increase of SnO2 content, the response sensitivity of composite fibers to ethanol gas increases, and the response sensitivity of composite nanofibers with the highest response to ethanol gas with a volume fraction of 100×10-6 at the optimal working temperature of 160℃ are13.4;It is 8.38 times the maximum response sensitivity of NiO nanofibers. Compared with the common ethanol gas sensor MQ-3 on the market, SnO2-NiO composite nanofibers have a lower optimal working temperature and higher response sensitivity, which has certain practical application value

Effects of Precursors and Carbon Nanotubes on Electrochemical Properties of Electrospun Nickel Oxide Nanofibers-Based Supercapacitors.

Supercapacitors have been considered as one of the main energy storage devices. Recently, electrospun nanofibers have served as promising supercapacitor electrodes because of their high surface area, high porosity, flexibility, and resistance to aggregation. Here, we investigate the effects of electrospinning parameters and nickel precursors on the nanostructure of electrospun nickel oxide (NiO), as well as on their electrochemical performance as supercapacitor electrodes. In contrast to the case of using nickel nitrate, increasing the nickel acetate molar concentration maintains the flexible fibrous sheet morphology of the as-spun sample during the polycondensation and calcination of NiO. As a result, our flexible electrode of NiO nanofibers derived from nickel acetate (NiO-A) exhibits much better electrochemical performance values than that of nickel nitrate-derived NiO. To further improve the electrochemical storage performance, we combined NiO-A nanofibers with single-walled carbon nanotubes (CNTs) as a hybrid electrode. In both half-cell and full-cell configurations, the hybrid electrode displayed a higher and steadier areal capacitance than the NiO-A nanofibers because of the synergetic effect between the NiO-A nanofibers and CNTs. Altogether, this work demonstrates the potency of the hybrid electrodes combined with the electrospun NiO-A nanofibers and CNTs for supercapacitor applications.

Sn doping effect on NiO hollow nanofibers based gas sensors about the humidity dependence for triethylamine detection

• Hollow Sn-doped NiO nanofibers are synthesized through a facile electrospinning approach. • The Sn-doped NiO sensor with suitable Sn content (6 at%) shows the highest gas response to triethylamine. • Sn doping concentrations can significantly influence the resistance of sensors in air and in target gas under different RH. • The resistances of the sensor change slightly in target gas under different RH with suitable Sn doping content (6 at%). High stable triethylamine gas sensors under different relative humidity are highly desirable in order to correctly detect the concentrations of target gas. In this study, a series of Sn-doped NiO hollow nanofibers were prepared through a facile electrospinning process followed by heat treatment. Sn doping could inhibit the crystal growth, and the crystal sizes would decrease with the increase of Sn doping concentration. Gas sensing investigation indicates that Sn doping could significantly enhance the gas response towards triethylamine at a relative low temperature. Especially, the gas sensor exhibits the highest response to triethylamine when the doping content of Sn reaches to 6 at%. The response value is about 16.6–100 ppm triethylamine, and it is ∼9.2 times higher than that of pure NiO nanofibers at the same operating temperature. In addition, the resistances of the gas sensors with different doping contents of Sn would change differently in air or in target gas under variable relative humidity. The resistances in target gas are almost unchanged with the increase of relative humidity with the Sn doping content of 6 at%. It is reasonable to speculate that Sn doping can heavily alter the surface state of NiO nanofibers, which is beneficial for the improvement of the gas response and humidity dependence properties.

NiO nanofibers clad nickel foam as binder-free electrode with ultrahigh mass loading: boosting performance of hybrid supercapacitor and overall water-splitting

Although NiO has attracted intensive attention as promising active materials for hybrid supercapacitor (HSC) and HER/OER electrocatalysts, efficiently utilizing the NiO-based electrodes with high mass loading is still a challenge. Herein, we design a battery-type electrode, i.e., NiO nanofibers clad nickel foam (NiO/NF), by facile, low-cost, and eco-friendly etching and oxidation under ambient conditions. Thanks to the in-situ growth of NiO nanofibers on NF and its ultrahigh mass loading of 17.4 mg cm−2, the binder-free NiO/NF electrode shows excellent performance in HSC and overall water-splitting. An ultrahigh areal capacity (CA) of 3.84 mAh cm−2 (gravimetric capacity of 220.7 mAh g−1) is obtained at 2 mA cm−2, which is 1255 times more than pristine NF (0.00306 mAh cm−2). Even at 100 mA cm−2, CA can reach 1.38 mAh cm−2. Hybrid supercapacitor assembling with graphene oxide (GO) delivers a peak energy density of 2572.2 Wh m−3 and possesses good cycling stability of 110% retention after 6000 cycles. Moreover, NiO/NF electrode displays low overpotentials of 69.9 mV and 262 mV at 10 mA cm−2 for HER and OER, respectively. NiO/NF||NiO/NF electrolyzer outputs 10 mA cm−2 at only 1.57 V with long-term durability for 50 h.