Nickel Nanoparticles Research Articles

Conductive Nanocomposites Based on Graphene and Natural Polymers

This thesis focuses on the development of conductive nanocomposite materials based on graphene and natural polymers such as cellulose and chitosan. Graphene, a single layer of carbon atoms arranged in a honeycomb lattice, exhibits exceptional electrical, mechanical, and thermal properties, making it an attractive filler for polymer composites. However, the challenge lies in effectively dispersing graphene sheets within polymer matrices. The work presented explores new strategies for grafting polysaccharide chains onto oxidized graphite (graphene oxide) to improve its compatibility and dispersion in cellulose and chitosan matrices. The resulting composites were doped with gold or nickel nanoparticles to further enhance their electrical and catalytic properties. Detailed characterization techniques, including spectroscopic and microscopic methods, were employed to analyze the structure, morphology, and properties of the developed nanocomposites. The thesis is organized into three main parts: 1) a literature review on graphene, polysaccharides, and their biocomposites; 2) a description of the experimental materials and methods; and 3) a scientific discussion of the results, presented in the form of three research publications. The findings demonstrate the successful synthesis of conductive nanocomposites with improved compatibility and performance, opening up new avenues for the application of these sustainable and multifunctional materials in areas such as electronics, catalysis, and electromagnetic shielding.

A Flexible Organomagnetic Single-Layer Composite Film with Built-In Multistimuli Responsivity.

Materials possessing multiple properties and functionalities, that can be controlled or modulated by external stimuli, are a central focus of current research in materials sciences due to their potential to significantly enhance various future technological applications. Herein, we report a significant advancement in this field through the development of a smart, multifunctional organomagnetic composite material. By utilizing a thin layer of polydimethylsiloxane (PDMS) and polypyrrole (PPy) precursors, doped with nickel nanoparticles (NiNPs), we have created an innovative organomagnetic, PDMS/PPy/NiNPs (PPN), single-layer composite film that displays multistimuli responsivity. The study presents the first demonstration of a multifunctional flexible, three-component film structure integrating the structural and flexible PDMS component, together with a conductive polymer component and metal-based nanoparticles into a single-layer design, which displays enhanced and unprecedented responsivity properties against multiple different stimuli. Unlike typical stacked multilayered structures, that exhibit one or two functionalities at most, this novel configuration exhibits multiple functionalities, including magnetoresistance, mechanical stress response, piezoresistivity, and temperature change sensitivity. The as-prepared film demonstrates notable magnetoresistance responsivity, with a relative electrical resistance, ΔR/R0, changing under a weak magnetic field and under ambient conditions. The significance of our study lies in the film's versatility, stability, and sensitivity, especially within the physiological temperature range, making it highly relevant for future biomedical applications. Furthemore, the film's sensitivity to mechanical deformation reveals an impressive piezoresistance behavior. Unlike existing multilayer architectures of higher complexity, our single-layer thin film offers a simpler, more flexible, and reliable solution with a broad range of stimuli-sensing capabilities. The significance of this novel multiresponsive composite material is underscored by the growing demand for advanced materials in biomedical devices, magnetic switches, sensors, electronic skin, transistors, and organic spintronic devices. These promising organomagnetic self-standing layers provide a robust platform for future technological innovations.

The synergistic effects on the magnetic CoNi and Fe3O4 nanoparticles co-embedded porous carbon toward enhanced microwave absorbing performance

Abstract Lightweight and environmentally friendly three-dimensional biomass-derived porous carbon (3D BPC) holds great potential as a highly effective material for microwave absorption (MA) applications. However, the high complex permittivity and lack of magnetic loss in a single 3D BPC lead to impedance mismatching and a limited absorption bandwidth. Developing 3D BPC–based absorbers with multiple loss mechanisms and excellent impedance matching remains a notable yet challenging task. In this study, inspired by a synergistic composition and microstructure design, 3D BPC co-embedded with magnetic cobalt–nickel (CoNi) and iron(III) oxide (Fe3O4) nanoparticles (3D BPC@CoNi@Fe3O4) was developed. 3D BPC@CoNi@Fe3O4 exhibited consistently low complex permittivity, primarily due to the suppression of conductive loss, whereas the introduction of magnetic phases (CoNi and Fe3O4) enhanced the magnetic loss. Optimised impedance matching, achieved through the synergistic regulation of the electromagnetic parameters, emerged as the key mechanism for improving the MA properties. The as-synthesised 3D BPC@CoNi@Fe3O4 composite, with only 20 wt.% loading demonstrated a wide effective absorption bandwidth (reflection loss [RL] < −10 dB) of 6.08 GHz and an impressive minimum RL value of −40.08 dB. These findings offer valuable insights into the development of high-performance 3D BPC–based microwave absorbers through composition and microstructure optimisation.

Synthesis of Ecofriendly Bimetallic Pt/Ni Nanoparticles on KNbO3 via Hydrothermal Process for Sustainable Hydrogen Evolution from NaBH4

The performance of nickel and platinum bimetallic nanoparticles (NPs) supported on potassium niobate (KNbO3) is evaluated in the catalytic hydrolysis of sodium borohydride (NaBH4) to generate hydrogen (H2). KNbO3 was synthesized via a hydrothermal route using Nb2O5 and KOH as precursors. X-ray diffraction (XRD) confirmed the crystalline orthorhombic structure of KNbO3. The Ni/Pt NPs, with an average size of 4.66 nm and a spherical morphology, were uniformly dispersed on the surface of KNbO3 nanosheets. The N2 physisorption isotherms of KNbO3 and Ni/Pt NPs were classified as type V with H3 hysteresis, showing specific surface areas of 0.170 and 2.87 m2 g−1, respectively. Catalytic performance studies examined various Ni/Pt molar ratios, with the 1:3 ratio (mol/mol) demonstrating the highest efficiency. Kinetic analysis of NaBH4 hydrolysis showed that the data fit the pseudo-first-order model. An increase in temperature enhanced the hydrogen generation rate (HGR), reaching 2068.3 mL gcat−1 min−1 at 315.05 K. The apparent activation energy (Ea) was determined to be 29.9 kJ mol−1. Durability assays showed only an 11% decrease in activity after 11 catalytic cycles. Thus, a promising, easy-to-synthesize, and environmentally friendly catalyst for NaBH4 hydrolysis has been developed.

Rapid Synthesis of Uniformly Small Nickel Nanoparticles for the Surface Functionalization of Epitaxial Graphene

AbstractNickel nanoparticles (Ni NPs) combined with carbon nanomaterials are of significant interest due to their wide range of applications, including catalysis, hydrogen storage, and sensor technologies. However, it is challenging to develop an efficient process to produce small and stable Ni NPs ideal for functionalizing graphene or substrates with complex geometries. For this purpose, a rapid, simple, and cost‐effective method is presented for synthesizing uniformly small Ni NPs. The process involves cooling aqueous solutions of Ni(OAc)2 and cetyltrimethylammonium bromide (CTAB) to ≈1 °C, followed by the rapid addition of NaBH4. Crucial parameters, such as temperature and stirring rate, are precisely controlled to ensure uniform particle growth, with the reaction completing in just a few minutes. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) characterizations reveal spherical NPs with an average diameter of ≈11 nm and a narrow size distribution. Additionally, epitaxial graphene (EG) samples are functionalized with the synthesized NPs and their arrangement on the surface and their stability upon thermal annealing are investigated. X‐ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) measurements demonstrate the degradation of CTAB, along with the recovery of Ni(0) under mild conditions (below 350 °C), with the NPs maintaining structural stability up to approximately 550 °C.

Synthesis and EMI shielding study of Ni (II) semicarbazone driven nickel nanoparticles

Herein, we report the synthesis of nickel nanoparticles (Ni-NPs) from Ni (II) complexes of cyclic semicarbazone derivatives and their electromagnetic interference (EMI) shielding behaviour. Ni (II) complexes of cyclic semicarbazones were synthesized and characterized by various spectroscopic tools. It was observed that such complexes are excellent precursors for the synthesis of Ni-NPs when reduced by hydrazine hydrate. It is expected that the reaction kinetics will be ably normalized by the presence of semicarbazone ligand and that upon dissociation and partial consumption during nano-particle formation, will provide an added advantage of mild functionality around the particles. Overall various nickel complexes obtained from cyclic semicarbazones were tested as an effective precursor for the synthesis of Ni-NPs which were characterized by XRD, TEM, SEM, and AFM, and their magnetic behaviour was studied by VSM. EMI shielding efficiency of flexible Ni/PVA composite films showed shielding efficiency of about minus (−) 30 dB in X-band (8–12 GHz) for about 25 % loading in the PVA matrix.

Experimental investigation of nickel-based nanofluid on the performance of evacuated tube solar collector

This paper conducts an experimental investigation of an evacuated tube solar collector type solar collector employing a unique Ni/water nanofluid to assess its exergetic and energy performance. The investigation sheds light on the intricate behavior of nanofluid and their consequential impact on the efficiency, thermal properties, and entropy generation within the framework of evacuated tube solar collector (ETSC). The study reveals that an escalation of nickel nanoparticles volumetric concentration results in a reduction of specific heat capacity, attributed in part to the clustering effect of nanoparticles mixed with working fluid. Nevertheless, higher temperatures counterintuitively lead to an augmentation in specific heat capacity. The study presents the comparative behavior of nanofluid and the parent base fluid. The study further elucidates that augmenting the volumetric concentration of nanoparticles causes a reduction in the temperature difference between the collector's both side inlet and outlet, affecting thermal efficiency positively. Moreover, with mass flow rate contribute and increased volumetric concentration to a diminished outlet temperature, thereby enhancing the efficiency of ETSC. The study also analyzed the thermophysical properties such as thermal conductivity, viscosity, and specific heat of the Ni/water nanofluid across different volumetric concentrations and temperature ranges from 25 °C to 50 °C. Furthermore, the thermal performance of the collector was evaluated at various mass flow rates ranging from 0.0085 kg/s to 0.051 kg/s. The findings revealed a maximum energy efficiency of 73.14% at a volumetric concentration of 1% and a mass flow rate of 0.041 kg/s.

Supported Nickel Nanoparticles as Catalyst in Direct sp3 C-H Alkylation of 9H-Fluorene Using Alcohols as Alkylating Agent.

Herein, we report an inexpensive first-row transition metal Ni heterogeneous catalytic system for the Csp3-mono alkylation of fluorene using alcohols as alkylating agents via borrowing hydrogen strategy. The catalytic protocol displayed versatility with high yields of the desired products using various types of primary alcohols, including aryl/hetero aryl methanols, and aliphatic alcohols as alkylating agents. The catalyst Ni NPs@N-C was synthesized via high-temperature pyrolysis strategy, using ZIF-8 as the sacrificial template. The Ni NPs@N-C catalyst was characterized by XPS, HR-TEM, HAADF-STEM, XRD and ICP-MS. The catalyst is stable even in the air at room temperature, displayed excellent activity and could be recycled 5 times without appreciable loss in its activity.

LDH@MgSiO3 multi-core@shell catalyst for dry reforming of methane

In this paper, LDH@SiO2 catalyst was prepared via coating a layer of silica over LDH (Layered Double Hydroxide) nanoplates. Then it was calcined and further treated by hydrothermal method with magnesium acetate to convert silica layer into MgSiO3. After H2- reduction, a layer of branch-like MgSiO3 was observed as the shell and nickel nanoparticles with average diameter around 10 nm were encapsulated within the shell, which was called as LDH@MgSiO3 multi-core@shell catalyst. This catalyst was then tested in dry reforming of methane (DRM) at 675 °C and the CH4 conversion was kept stable around 25% for 30 h time on stream at GHSV of 360 L/gcat/h. Besides, the H2/CO ratio in the product gas was 0.85, much higher than that of LDH@SiO2 catalyst, indicating its superb selectivity. Characterization revealed that the formation of MgSiO3 was beneficial to reduce the nickel particle size, modify the porosity and improve the surface alkalinity, which enhanced the DRM activity and selectivity. More importantly, it enhanced the hydrothermal stability, thus preventing the reconstruction of the shell.

Pt–Ni–Co trimetallic nanoparticles anchored on graphene oxide: An effective catalyst for ammonia-borane hydrolysis and direct electrooxidation of ammonia-borane in alkaline solution

In this study, graphene oxide supported platin, nickel and cobalt trimetallic nanoparticles (PtNiCo@GO) were prepared by the impregnation/reduction method. The catalytic performances of PtNiCo@GO catalysts prepared with different atomic ratios were investigated for hydrogen production and electro-oxidation of ammonia-borane (AB). For hydrolysis of ammonia-borane, Pt0.8Ni0.1Co0.1@GO catalyst exhibited higher catalytic activity than Pt0.6Ni0.2Co0.2@GO, Pt0.4Ni0.3Co0.3@GO, and Pt0.2Ni0.4Co0.4@GO. The hydrogen generation rate and turnover frequency values were found to be 540 mL min−1g−1 and 42.8 min−1, respectively, in the experiment conducted at 35 °C, 0.5 mmol AB, and 50 mg Pt0.8Ni0.1Co0.1@GO catalyst. The activation parameters (Ea, ΔH#, and ΔS#) in the catalytic hydrolysis of AB were obtained at 42.22 kJ/mol, 31.95 kJ/mol and −114.82 J/(mol × K), respectively. The effects of the PtNiCo@GO catalyst on AB electro-oxidation were made at a scanning rate of 100 mV/s in the potential range of - 1V/+1V against Ag/AgCl, and chronoamperometry measurements were made at constant potentials of - 0.2V, 0.1V and 0.4V. For cyclic voltammetry and chronoamperometry measurements, 5 mM [Fe(CN)6]3/4 (1 M KCl) redox probe and 1 M NaOH + 50 mM AB solution were used.

Introducing nickel nanoparticles on boron-doped diamond electrode for realizing high performance electrochemical detection of azithromycin

The broad-spectrum antibiotic azithromycin (AZI) has been widely applied to suppress bacteria and fight infection. However, excessive use of AZI can cause serious side effects. It is greatly desirable to develop efficient and sensitive sensor devices for environmental monitoring and analysis of AZI. In this study, we develop the nickel (Ni) nanoparticle-modified boron-doped diamond (NiNPs-BDD) electrode to achieve high-performance electrochemical detection of AZI. The NiNPs-BDD electrode has square pits with Ni particles embedded in the pits, which provides higher sensitivity compared to unmodified BDD. The promoting performance is attributed to the synergistic effect of pitted features and Ni NPs on BDD electrode. The NiNPs-BDD electrode presents linear detection ranges in the wide concentration scales of 0.1–8 µM and 8–100 µM, and its limit of detection is 0.086 µM. In addition, the NiNPs-BDD electrode shows excellent repeatability, stability, and reproducibility with respect to most conventional electrodes.

Higher Sensitivity of Rat Testes to Nano Nickel than Micro Nickel Particles: A Toxicological Evaluation.

Present investigations were undertaken to record the vulnerability of testis to nickel oxide nano and microparticles in Wistar rat with special reference to their preferred bioaccumulation, consequent generation of reactive species, reciprocal influence on testosterone synthesis, DNA damage in spermatids and histopathological changes. Suitable numbers of rats were gavaged NiONPs or NiOMPs (5mg/kg b.w.each) for 15 and 30days. Testes en bloc were removed and processed for the estimation of selected parameters. Results showed that rat testes could accumulate nickel in an exposure time dependent manner. Generation of malondialdehyde, a denominator of ROS, increased significantly in the testes of NiONPs treated rats. Moreover, serum testosterone values also increased in NiONPs treated rats. Higher DNA damage in sperms was also recorded. Nano and microparticles of nickel, both could induce specific dose and time dependent lesions in the testis of rat. Histopathological results revealed degeneration of germinal epithelium and spermatocytes; hypertrophy of seminiferous tubules and necrosis. SEM results also indicated specific morphological changes in cellular components of tubules. This study suggests that testis is also vulnerable to the adverse effects of NiONPs alike liver and kidney. Both micro and nanoparticles of nickel elicited differential effects in a dose and exposure time dependent manner. However, NiONPs induced greater overall toxicity than NiOMPs. The results are expected to be helpful in determining the human reproductive health risks, associated with environmental/ occupational exposure to nanoparticles of nickel.

Comparative study of Ni nanoparticles synthetized using electroless Ni plating waste and an analytical Ni reagent. Characterization and possible application in magnetic fluids

Wastewater from the electroless industry represents a potential danger to the environment and health, mainly due to its heavy metal content. In this study, nickel nanoparticles were synthesized through chemical reduction precipitation by using an electroless nickel plating waste and hydrazine sulfate as reducing agent. The aim of the present work is twofold. First we want to extract the metal from the aqueous medium, minimizing its content to levels allowed by environmental regulations. Second, we aim to valorize the residue by recovering the precipitated nickel to be applied as a solid phase in a magnetic fluid (MF). It is found that the present synthesis method using N2H4 as reducing agent, allowed us to minimize the Ni concentration in the aqueous waste in 97.49 %. The properties of the recovered Ni precipitate is compared with the Ni nanoparticles (NPs) obtained from a solution prepared with analytical grade nickel sulfate. The synthesized materials from both the waste (Ni-R) and analytical reagent (Ni-A) were characterized by comparing their chemical, physical, and morphological properties. In both cases, the Ni-R and Ni-A precipitates, spherical Ni NPs of 8–10 nm crystallite sizes are obtained, agglomerated in a bimodal size distribution centered at 174.6 and 383.4 nm, and a monomodal size distribution centered at 63.6 nm, respectively. Both Ni precipitated samples are ferromagnetic, but the Ni-R sample has a higher magnetic saturation of 40 emu/g compared to 8 emu/g of the Ni-A sample. The difference in the rheological behavior of both precipitates could be attributed to the presence of surface oxidation having a relatively less contribution in the case of the Ni-R particles due to the higher average size of the particles. The Fe content, probably coming from the nickel-plated parts in spent baths, is slightly higher in the Ni-R sample. Thus, the present work shows that it is possible to valorize an industrial Ni-based residue, by obtaining Ni precipitates that in magnetic fluids give even better results than those expected under more rigorous experimental conditions, i.e., in cases where the quality of the chemical precursors is usually a determining factor.

Ruddlesden-Popper perovskite anode with high sulfur tolerance and electrochemical activity for solid oxide fuel cells

Solid oxide fuel cells (SOFCs) are regarded as attractive electrochemical energy conversion devices owing to their exceptional efficiencies and superb fuel flexibility. However, their widespread implementations are remarkably restricted by the inferior sulfur tolerance of state-of-the-art nickel-based cermet anodes under practical conditions. Herein, a layered NaLaTiO4 (NLTO) perovskite oxide with Ruddlesden-Popper structure is designed as a new anode for SOFCs operating on sulfur-containing fuels. After impregnating NLTO into a samaria-doped ceria (SDC) scaffold, such impregnated nanocomposite anode exhibits high electrochemical activity, sulfur tolerance and stability in H2S-containing fuels due to the polar layered structure, abundant oxygen vacancies, superior surface basicity and water storage capability, leading to the efficient removal of the deposited/adsorbed sulfur on the surface of this nanocomposite anode. The electrochemical activity of the NLTO-based composite anode for fuel oxidation is further improved by adding nickel nanoparticles through impregnation, showing enhanced power outputs and considerable operational stability in H2S-containing fuels. This study provides a new, high-performing and sulfur-resistant anode for SOFCs, which may promote the commercialization of this technology.

Uniform nickel nanoparticles decorated porous carbon nanofibers for efficient electrochemical nitrite sensing

One-dimensional carbonaceous materials exhibit significant promise for sensing applications driven by their attractive properties. Herein, nickel/nitrogen-doped carbon (Ni/N–C) nanofibers were fabricated via a novel electrospinning-carbonization strategy. The distribution of Ni nanoparticles (NPs) in the carbon nanofibers was crucially affected by the carbonization temperatures. Various techniques were employed to characterize the fabricated Ni/N–C-X (X = 700, 800, and 900 °C, representing the carbonization temperatures) nanofibers, followed by an evaluation of their electrochemical sensing response to nitrite. The Ni/N–C-800-based sensor outperformed those based on the Ni/N–C-700 and Ni/N–C-900 catalysts in detecting nitrite, by merits of the relatively superior conductivity and more exposed active sites. The Ni/N–C-800-based sensor, delivered detected concentrations of 0.2–7000 μM, along with a sensitivity value of 0.991 μA μM−1 cm−2, and a detection limit of 0.1 μM. Furthermore, this Ni/N–C-800-based sensor demonstrated notable selectivity and stability, affirming its practicality in nitrite detection within sausage samples. The findings of this research illustrate that Ni/N–C materials hold great promise for monitoring nitrite.

A Smart Design of Non-noble Catalysts for Sustainable Propane Dehydrogenation.

Propane dehydrogenation (PDH), an important process for propylene synthesis, relies on expensive noble metals or highly toxic oxides as catalysts. In a recent publication in Science, Gong and coworkers report a breakthrough discovery for PDH by introducing a sustainable catalyst composed of titanium oxide overlayers encapsulating nickel nanoparticles, termed Ni@TiOx. This innovative catalyst showcases exceptional performance in PDH, exhibiting high propylene selectivity and stability under industrially relevant conditions. The study elucidates the role of defective TiOx overlayers and the electronic promotional effect of subsurface Ni in enhancing catalytic activity, translating a traditional model catalyst system into a sustainable industrial catalyst for low-carbon energy and the chemical industry.

Plasma surface treatment for enhanced supercapacitor and oxygen evolution reaction: Single-step preparation of carbon-coated nickel nanoparticles

Developing porous electrode materials with highly conductive for advanced electrochemical energy storage and conversion devices poses significant challenges, particularly in achieving single-step, impurity-free large-scale production for commercialization. This study investigates a method for synthesizing carbon-coated metallic nickel nanoparticles directly in the gas phase, using the plasma arc discharge method in an argon-methane atmosphere. The study meticulously examines the developed samples' phase, crystal type, morphology, elemental presence, and chemical state. The synthesized C@Ni NPs exhibit a core-shell morphology with high surface area, as confirmed by TEM and BET analysis. The C@Ni electrode underwent surface modification to enhance its electrochemical performance. In this context, the original C@Ni electrode and a plasma-treated version (C@Ni PT) were extensively investigated for their suitability in supercapacitor and oxygen evolution reaction applications. The C@Ni PT electrode demonstrated remarkable performance characteristics. In supercapacitor tests, it achieved a significantly higher specific capacitance of 313 F/g at a current density of 1 A/g, coupled with superior cyclic stability. It exhibited outstanding electrocatalytic activity for the OER, requiring only 312 mV of overpotential to reach a current density of 20 mA cm−2. The reduced overpotential and increase in specific capacitance suggest that C@Ni PT electrodes as promising materials for both OER and supercapacitor applications. Further, the plasma arc discharge method and dielectric barrier discharge are suitable for the large-scale production of nanoparticles and surface modification.

Transition metal nickel nanoparticle-decorated g-C3N4 photocatalyst for improving tetracycline hydrochloride degradation

Metallic nickel nanoparticles (Ni0 NPs)-supported g-C3N4 have been developed using a solvothermal technique in N,N-dimethylformamide solvent. A uniformly dispersion of Ni0 NPs anchored on a g-C3N4 photocatalyst can improve the photocatalytic efficiency. The optimized Ni/g-C3N4 catalyst demonstrated a high photodegradation rate of TCH at 6.0 × 10−3 min−1 under LED light irradiation, which was approximately three times greater than that of the bare g-C3N4 catalyst. This superior performance originates from the capable separation of electron-hole pairs, facilitated by the strong interaction between Ni0 NPs and the host g-C3N4, as supported by optical and electrochemical property analysis. Our work provides a facile manner for the effective degradation of pollutants using heterojunction photocatalysts.

Agarose derived carbon based nanocomposite for hydrogen storage at near-ambient conditions

Nanocomposites of high surface area adsorption materials and nanosized transition metals have emerged as a promising strategy for hydrogen storage applications. However, their potential use in both transport and stationary applications depends on reaching the ultimate storage capacity at near-ambient conditions along with scalable synthesis protocols. Herein, a direct and simple thermal decomposition technique is reported to synthesize carbon-based nanocomposite, where nickel nanoparticles are dispersed in a porous carbon matrix. It is also demonstrated that the storage capacity can be enhanced at near-ambient conditions by effectively engineering the microstructure and synergistically combining the ‘physisorption’ and ‘spillover’ mechanism. The structure, composition and morphology of the samples were investigated using X-ray diffraction, energy dispersive spectroscopy, transmission and scanning electron microscopy. Sorption-desorption isotherms were obtained to study the hydrogen storage capacity at a moderate H2 pressure of 20 bar. The nanocomposite showed a promising storage capacity of 0.73 wt% at 298 K with reversible cyclability. It is shown that the uniform dispersion of catalytic nanoparticles leads to an increase in the spillover efficiency, which further helps in the enhancement of hydrogen storage capacity by a factor of 6.5 over pure carbon.

Lightweight composites derived from carbonized taro stems for microwave energy attenuation and thermal energy storage

A novel strategy has been developed for preparing porous carbon materials derived from taro stems, aimed at enhancing electromagnetic wave (EMW) attenuation and thermal energy storage. The materials were synthesized through the carbonization of taro stems to form a porous carbon structure, subsequently enhanced with polyethylene glycol (PEG) containing carbon nanotubes (CNTs) and nickel (Ni) nanoparticles. By adjusting the carbonization temperature and the loading of CNTs and Ni, the resulting carbon materials exhibited exceptional EMW attenuation performance. Specifically, the PC-800 sample demonstrated a remarkable minimum reflection loss of −61.4 dB across the frequency range of 8.2–11 GHz, with a low density of 0.054 g/cm³. The PC-1200 sample exhibited EMI SE values of 23.6 dB axially and 21.5 dB radially in the X-band, with an ultra-low density of 0.033 g/cm³. Further enhancements were observed in the PC/CNT2 and PC/CNT2-Ni15 composites, achieving EMI SE values of 26.3 dB and 26.8 dB, respectively. Additionally, these composites exhibited effective thermal energy storage and release, as confirmed by heating experiments. This study not only introduces a method for creating absorption-dominated biomass electromagnetic shielding materials but also provides a dual-functional solution for enhancing the performance of electronic devices.