Carbon/NiO Compositional Fibers

This article presents the results of the synthesis of carbon-NiO composite fibers. Fibers doped with NiO particles are of practical interest for applications in sensors, energy storage systems, photocatalysts, etc. Four-component initial fibers based on polyacrylonitrile (PAN), activated carbon (AC), coal tar pitch (CTP), and NiO particles were obtained. CTP was obtained by thermal treatment of coal tar, AC by carbonization of apricot kernels, NiO by solution combustion synthesis. PAN, CTP, and AC are a source of carbon, but each of them plays a specific role. PAN is the basis of carbon fibers and a fiber-forming material, CTP is a technogenic waste added to replace polymer particles, AC is an additive that could increase the carbon content and the porosity of the final fibers. The fibers were obtained using the electrospinning method, which makes it possible to use complex suspensions and obtain fibers of various diameters. PAN:CTP:AC:NiO fibers were obtained. Next, the processes of stabilization and carbonization of the fibers were carried out. The fibers at each stage were examined by scanning electron microscopy and EDAX. The result of the synthesis was carbon/NiO fibers with a diameter of 100‒300 nm. The resulting fibers are promising for practical applications due to the one-dimensional structure of the fibers and better adhesion between the fiber and NiO particles.

CO2 Conversion into N-Doped Porous Carbon-Encapsulated NiO/Ni Composite Nanomaterials as Outstanding Anode Material of Li Battery

N-doped porous carbon encapsulated NiO/Ni composite nanomaterials (N-doped NiO/Ni@C) was successfully obtained by a one-step solution combustion method. This study demonstrates a one-step combustion method to synthesize n-doped porous carbon encapsulated NiO/Ni composite nanomaterials, using carbon dioxide as the carbon source, nickel nitrate as the nickel source, and hydrazine hydrate as the reaction solution. Spherical NiO nanoparticles with a particle size of 20 nm were uniformly distributed in the carbon matrix. The load of NiO/Ni can be controlled by the amount of nickel nitrate. The range of carbon content of recovered samples is 69-87 at%. The content of incorporated nitrogen for recovered samples is 1.94 at%. As the anode of lithium ion battery, the composite material exhibits high capacity, excellent multiplier performance and stable circulation performance. N-doped NiO/Ni@C-2 was applied to lithium ion batteries, and its reversible capacity maximum is 980 mAh g^-1 after 100 cycles at the current density of 0.1 A g^-1. Its excellent electrochemical properties imply its high potential application for high-performance lithium-ion battery anode materials.

An in situ electrospinning route to fabricate NiO-SnO2 based detectors for fast H2S sensing

Hydrogen sulfide (H₂S) is a toxic and flammable chemical, even in low concentration. In this study, an in situ electrospinning strategy was developed to directly deposit the sensitive materials of nickel oxide (NiO)-doped SnO₂ nanofiber on alumina substrates, resulting in the fast H₂S detection. The electrospun fiber could be deposited on to the alumina tube directly, and remain there during calcination. Using this method, the NiO-doped SnO₂ nanofibers fabricated and manifested a fast response, fast recovery, and high selectivity at a low temperature (150 °C). A 15% atom NiO-doped SnO₂ nanofiber-containing H₂S detector presented a high response (1352), low response time (23 s), and low recovery time (38 s) while detecting a concentration of 50 ppm H₂S at 150 °C. Compared to conventional methods, the H₂S detector based on the in situ electrospinning method showed a higher sensitivity, faster response, and faster recovery. Furthermore, the superior performance of the detector can be ascribed to the thinner film and non-interrupted fiber structure. Additionally, the transformation of NiO to Ni₃S₂, confirmed by the x-ray photoelectron spectroscopy under a H₂S atmosphere, suggested the main reason for the detector's high performance. The high performance of the NiO-doped SnO₂ suggests a strategy for gas detectors, biodetectors, and semiconductor devices.

Supercapattery and full-cell lithium-ion battery performances of a [Ni(Schiff base)]-derived Ni/NiO/nitrogen-doped carbon heterostructure

[Ni(Schiff base)]-derived Ni/NiO on the conductive carbon network is explored as an electrode material for high-performance supercapatteries and lithium-ion batteries.

Formation of Nanodimensional NiCoO2 Encapsulated in Porous Nitrogen-Doped Carbon Submicrospheres from a Bimetallic (Ni, Co) Organic Framework toward Efficient Lithium Storage

Recently, rock-salt NiCoO₂ (NCO) with desirable electronic conductivity has drawn enormous interest worldwide for energy-related applications. However, the intrinsically sluggish kinetics and electrode aggregation/volumetric change/pulverization during Li-insertion/-extraction processes hugely limit its applications in Li-ion batteries (LIBs). In the contribution, we first devise a bottom-up method for scalable fabrication of the nanodimensional NCO particles encapsulated in porous nitrogen-doped carbon submicrospheres (NCS), which are derived from a bimetal (Ni, Co) metal-organic framework. The porous NCS, as a flexible conductive skeleton, can buffer distinct volume expansion as an efficient buffering phase, restrain agglomeration of nanoscaled NCO, and enhance electronic conductivity and wettability of the electrode. Benefiting from the synergistic functions between the nanodimensional NCO and porous NCS, the obtained NCO@NCS anode (∼74.5 wt % NCO) is endowed with remarkable high-rate reversible capacity (∼403.0 mAh g^-1 at 1.0 A g^-1) and cycling behaviors (∼371.4 mAh g^-1 after being cycled for 1000 times at 1.0 A g^-1) along with a high lithium diffusion coefficient and remarkable pseudocapacitive contribution. Furthermore, the NCO@NCS-based full LIBs exhibit competitive lithium-storage properties in terms of energy density (∼217.0 Wh kg^-1) and cyclic stability. Furthermore, we believe that the methodology is highly promising in versatile design and construction of binary metal oxide/carbon hybrid anodes for advanced LIBs.

Flexible NiO-Graphene-Carbon Fiber Mats Containing Multifunctional Graphene for High Stability and High Specific Capacity Lithium-Ion Storage

An electrode's conductivity, ion diffusion rate, and flexibility are critical factors in determining its performance in a lithium-ion battery. In this study, NiO-carbon fibers were modified with multifunctional graphene sheets, resulting in flexible mats. These mats displayed high conductivities, and the transformation of active NiO to inert Ni(0) was effectively prevented at relatively low annealing temperatures in the presence of graphene. The mats were also highly flexible and contained large gaps for the rapid diffusion of ions, because of the addition of graphene sheets. The flexible NiO-graphene-carbon fiber mats achieved a reversible capacity of 750 mA h/g after 350 cycles at a current density of 500 mA/g as the binder-free anodes of lithium-ion batteries. The mats' rate capacities were also higher than those of either the NiO-carbon fibers or the graphene-carbon fibers. This work should provide a new route toward improving the mechanical properties, conductivities, and stabilities of mats using multifunctional graphene.

A new strategy of spray pyrolysis to prepare porous carbon nanosheets with enhanced ionic sorption capacity

We developed a new synthetic strategy to control the microstructure of carbon particles via ultrasonic spray pyrolysis. Porous carbon nanosheets with high ion-sorption capacitance were prepared by the one-pot spray pyrolysis process.

Electrospun In@C nanofibers as a superior Li-ion battery anode

In this communication, we have successfully obtained electrospun indium@carbon nanofibers. When applied as the Li-ion battery anode, the indium@carbon nanofibers could exhibit a high discharge capacity of 500 mA h g⁻¹ after 200 cycles at 100 mA g⁻¹.