Multifunctional Carbon Nanostructures for Advanced Energy Storage Applications

Nanobioengineered surface comprising carbon based materials for advanced biosensing and biomedical application

Carbon-based nanomaterials (CNMs) are at the cutting edge of materials science. Due to their distinctive architectures, substantial surface area, favourable biocompatibility, and reactivity to internal and/or external chemico-physical stimuli, carbon-based nanomaterials are becoming more and more significant in a wide range of applications. Numerous research has been conducted and still is going on to investigate the potential uses of carbon-based hybrid materials for diverse applications such as biosensing, bioimaging, smart drug delivery with the potential for theranostic or combinatorial therapies etc. This review is mainly focused on the classifications and synthesis of various types of CNMs and their electroanalytical application for development of efficient and ultra-sensitive electrochemical biosensors for the point of care diagnosis of fatal and severe diseases at their very initial stage. This review is mainly focused on the classification, synthesis and application of carbon-based material for biosensing applications. The integration of various types of CNMs with nanomaterials, enzymes, redox mediators and biomarkers have been used discussed in development of smart biosensing platform. We have also made an effort to discuss the future prospects for these CNMs in the biosensing area as well as the most recent advancements and applications which will be quite useful for the researchers working across the globe working specially in biosensors field.

Industrial bioelectrochemistry for waste valorization: State of the art and challenges

Bioelectrochemistry has gained importance in recent years for some of its applications on waste valorization, such as wastewater treatment and carbon dioxide conversion, among others. The aim of this review is to provide an updated overview of the applications of bioelectrochemical systems (BESs) for waste valorization in the industry, identifying current limitations and future perspectives of this technology. BESs are classified according to biorefinery concepts into three different categories: (i) waste to power, (ii) waste to fuel and (iii) waste to chemicals. The main issues related to the scalability of bioelectrochemical systems are discussed, such as electrode construction, the addition of redox mediators and the design parameters of the cells. Among the existing BESs, microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) stand out as the more advanced technologies in terms of implementation and R&D investment. However, there has been little transfer of such achievements to enzymatic electrochemical systems. It is necessary that enzymatic systems learn from the knowledge reached with MFC and MEC to accelerate their development to achieve competitiveness in the short term.

Surfactant assisted reactive crystallization of cobalt oxide nanoparticles in a tubular microreactor: effects of precursor concentrations and type of surfactants

The particle size distributions in CTAB and Tween-80 assisted reactive crystallization of CoO nanoparticles using CoCl2·6H2O and NaBH4 at two molar ratios in a tubular microreactor were investigated for establishing suitability of surfactants.

Nano-Structured Carbon: Its Synthesis from Renewable Agricultural Sources and Important Applications

Carbon materials are versatile in nature due to their unique and modifiable surface and ease of production. Nanostructured carbon materials are gaining importance due to their high surface area for application in the energy, biotechnology, biomedical, and environmental fields. According to their structures, carbon allotropes are classified as carbon nanodots, carbon nanoparticles, graphene, oxide, carbon nanotubes, and fullerenes. They are synthesized via several methods, including pyrolysis, microwave method, hydrothermal synthesis, and chemical vapor deposition, and the use of renewable and cheaper agricultural feedstocks and reactants is increasing for reducing cost and simplifying production. This review explores the nanostructured carbon detailed investigation of sources and their relevant reports. Many of the renewable sources are covered as focused here, such as sugar cane waste, pineapple, its solid biomass, rise husk, date palm, nicotine tabacum stems, lapsi seed stone, rubber-seed shell, coconut shell, and orange peels. The main focus of this work is on the various methods used to synthesize these carbon materials from agricultural waste materials, and their important applications for energy storage devices, optoelectronics, biosensors, and polymer coatings.

Recent Advances in Functional Polymer Materials for Energy, Water, and Biomedical Applications: A Review

Academic research regarding polymeric materials has been of great interest. Likewise, polymer industries are considered as the most familiar petrochemical industries. Despite the valuable and continuous advancements in various polymeric material technologies over the last century, many varieties and advances related to the field of polymer science and engineering still promise a great potential for exciting new applications. Research, development, and industrial support have been the key factors behind the great progress in the field of polymer applications. This work provides insight into the recent energy applications of polymers, including energy storage and production. The study of polymeric materials in the field of enhanced oil recovery and water treatment technologies will be presented and evaluated. In addition, in this review, we wish to emphasize the great importance of various functional polymers as effective adsorbents of organic pollutants from industrial wastewater. Furthermore, recent advances in biomedical applications are reviewed and discussed.

Electrode Effects on Flexible and Robust Polypropylene Ferroelectret Devices for Fully Integrated Energy Harvesters

This work presents a characterization study of the electrode interface in polypropylene ferroelectret nanogenerators. An emphasis is made on the comparison of carbon nanotube fiber electrodes with traditional metallic thin film electrodes. Multiple experiments were performed on samples with the same electrode dimensions for a range of applied pressures. Results showed higher open-circuit voltage peak values for the thin film metal electrodes, regardless of the applied pressure. Interestingly, the difference in short-circuit current values between metal and carbon nanotube-based fiber electrodes was not as significant. The carbon nanotube fiber electrode was further investigated by post-treating the fiber with acetone and comparing the results with untreated carbon nanotube film electrodes and thin film metal electrodes. In an effort to enable a monolithic integration of ferroelectret energy harvesters with flexible energy storage elements, this work also presents studies on generation and leakage of induced free charge in the electrodes of flexible ferroelectret energy harvesters. It was found the current leakage through parasitic elements is a faster process than dipole relaxation in the polypropylene film. Finally, an electrode reliability study shows no significant difference in the electrical output of the devices with metallic thin film electrodes after single folding but shows a significant deterioration after crumpling; meanwhile, these processes had no effect on the performance of similar devices with carbon nanotube fiber-based electrodes.

Carbon-Based Polymer Nanocomposite for High-Performance Energy Storage Applications

In recent years, numerous discoveries and investigations have been remarked for the development of carbon-based polymer nanocomposites. Carbon-based materials and their composites hold encouraging employment in a broad array of fields, for example, energy storage devices, fuel cells, membranes sensors, actuators, and electromagnetic shielding. Carbon and its derivatives exhibit some remarkable features such as high conductivity, high surface area, excellent chemical endurance, and good mechanical durability. On the other hand, characteristics such as docility, lower price, and high environmental resistance are some of the unique properties of conducting polymers (CPs). To enhance the properties and performance, polymeric electrode materials can be modified suitably by metal oxides and carbon materials resulting in a composite that helps in the collection and accumulation of charges due to large surface area. The carbon-polymer nanocomposites assist in overcoming the difficulties arising in achieving the high performance of polymeric compounds and deliver high-performance composites that can be used in electrochemical energy storage devices. Carbon-based polymer nanocomposites have both advantages and disadvantages, so in this review, attempts are made to understand their synergistic behavior and resulting performance. The three electrochemical energy storage systems and the type of electrode materials used for them have been studied here in this article and some aspects for example morphology, exterior area, temperature, and approaches have been observed to influence the activity of electrochemical methods. This review article evaluates and compiles reported data to present a significant and extensive summary of the state of the art.

Micro-Nano Carbon Structures with Platelet, Glassy and Tube-Like Morphologies

Carbon source precursors for high-grade, clean, and low-carbon refractories were obtained by in situ exfoliation of flake graphite (FG) and phenol–formaldehyde resin (PF) composites with three-roll milling (TRM) for the fabrication of graphite nanoplatelets. In addition, by using Ni(NO₃)₂·6H₂O as a catalyst in the pyrolysis process, multidimensional carbon nanostructures were obtained with coexisting graphite nanoplatelets (GNPs), glassy carbon (GC), and carbon nanotubes (CNTs). The resulting GNPs (exfoliated 16 times) had sizes of 10–30 μm, thicknesses of 30–50 nm, and could be uniformly dispersed in GC from the PF pyrolysis. Moreover, Ni(NO₃)₂·6H₂O played a key role in the formation and growth of CNTs from a catalytic pyrolysis of partial PF with the V–S/tip growth mechanisms. The resulting multidimensional carbon nanostructures with GNPs/GC/CNTs are attributed to the shear force of the TRM process, pyrolysis, and catalytic action of nitrates. This method reduced the production costs of carbon source precursors for low-carbon refractories, and the precursors exhibited excellent performances when fabricated on large scales.

Carbon-Based Nanomaterials for Biomedical Applications: A Recent Study

The study of carbon-based nanomaterials (CBNs) for biomedical applications has attracted great attention due to their unique chemical and physical properties including thermal, mechanical, electrical, optical and structural diversity. With the help of these intrinsic properties, CBNs, including carbon nanotubes (CNT), graphene oxide (GO), and graphene quantum dots (GQDs), have been extensively investigated in biomedical applications. This review summarizes the most recent studies in developing of CBNs for various biomedical applications including bio-sensing, drug delivery and cancer therapy.

Polymer network-derived nitrogen/sulphur co-doped three-dimensionally interconnected hierarchically porous carbon for oxygen reduction, lithium-ion battery, and supercapacitor

Rational design and simple synthesis of carbon-based materials with high electrocatalytic activity are essential for their practical applications in electrochemical energy conversion and storage devices. Herein, we report the synthesis of nitrogen, sulfur co-doped three-dimensional interconnected hierarchically porous carbon (NSHPC) by zinc acetate assisted pyrolysis of polymer networks. The thus-synthesized NSHPC has a specific surface area of 1057 cm² g⁻¹ with the coexistence of micro- and meso-pores. As metal-free electrocatalyst, the NSHPC exhibits a promising activity towards oxygen reduction reactions as evidenced by the slightly negative shift of half-wave potential compared with commercial Pt/C catalyst. The assembled lithium ion battery using NSHPC as anode delivers the reversible capacity of 740 and 470 mA h g⁻¹ at current densities of 2 and 5 A g⁻¹ without performance decay after 1000 charge–discharge cycles. Moreover, the assembled supercapacitor using NSHPC as electrode has the capacitance of 203 F g⁻¹ at 1 A g⁻¹.

Polymer networks are efficient precursors for large scale production of hierarchical porous carbon.

Enhanced Conductivity of Composite Membranes Based on Sulfonated Poly(Ether Ether Ketone) (SPEEK) with Zeolitic Imidazolate Frameworks (ZIFs)

The zeolitic imidazolate frameworks (ZIFs) ZIF-8, ZIF-67, and a Zn/Co bimetallic mixture (ZMix) were synthesized and used as fillers in the preparation of composite sulfonated poly(ether ether ketone) (SPEEK) membranes. The presence of the ZIFs in the polymeric matrix enhanced proton transport relative to that observed for SPEEK or ZIFs alone. The real and imaginary parts of the complex conductivity were obtained by electrochemical impedance spectroscopy (EIS), and the temperature and frequency dependence of the real part of the conductivity were analyzed. The results at different temperatures show that the direct current (dc) conductivity was three orders of magnitude higher for composite membranes than for SPEEK, and that of the SPEEK/ZMix membrane was higher than those for SPEEK/Z8 and SPEEK/Z67, respectively. This behavior turns out to be more evident as the temperature increases: the conductivity of the SPEEK/ZMix was 8.5 × 10-3 S·cm-1, while for the SPEEK/Z8 and SPEEK/Z67 membranes, the values were 2.5 × 10-3 S·cm-1 and 1.6 × 10-3 S·cm-1, respectively, at 120 °C. Similarly, the real and imaginary parts of the complex dielectric constant were obtained, and an analysis of tan δ was carried out for all of the membranes under study. Using this value, the diffusion coefficient and the charge carrier density were obtained using the analysis of electrode polarization (EP).

Synthesis of Amorphous Carbon Film in Ethanol Inverse Diffusion Flames

Recently, carbon nanomaterials have attracted significant attention due to their remarkable physical and chemical properties. The preparation methods and applications of the carbon nanomaterials have developed rapidly. In this study, the flame synthesis of amorphous carbon film grown on copper foil in an ethanol inverse diffusion flame was presented. The effects of ethanol flow rate, the copper foil location in flame and growth time were investigated in detail. The growth status of the synthetic amorphous carbon film was analyzed by an optical microscope and HRTEM (high resolution transmission electron microscope). Raman spectroscopy and XRD (X-ray diffraction) were used to characterize the structure of the carbon film. The roughness of the carbon film was determined by AFM (atomic force microscopy). As the ethanol flow rate increased and the copper foil moved upwards in the flame, the area of the synthetic amorphous carbon film increased. The roughness of carbon films with the growth time of 30 s and 2 min were smaller. In addition, the synthetic amorphous carbon film exhibited a certain degree of flexibility and visual transparency. Through the study, a reference could be provided to find the optimum condition for the flame synthesis of satisfactory amorphous carbon film. For these experiments, when the ethanol flow rate reached 2 mL/min, the copper foil was located on the top of the flame and the growth time was 2 min, an amorphous carbon film with higher quality could be obtained.

Understanding Heteroatom-Mediated Metal–Support Interactions in Functionalized Carbons: A Perspective Review

Carbon-based materials show unique chemicophysical properties, and they have been successfully used in many catalytic processes, including the production of chemicals and energy. The introduction of heteroatoms (N, B, P, S) alters the electronic properties, often increasing the reactivity of the surface of nanocarbons. The functional groups on the carbons have been reported to be effective for anchoring metal nanoparticles. Although the interaction between functional groups and metal has been studied by various characterization techniques, theoretical models, and catalytic results, the role and nature of heteroatoms is still an object of discussion. The aim of this review is to elucidate the metal–heteroatoms interaction, providing an overview of the main experimental and theoretical outcomes about heteroatom-mediated metal–support interactions. Selected studies showing the effect of heteroatom–metal interaction in the liquid-phase alcohol oxidation will be also presented.

Micromachined Planar Supercapacitor with Interdigital Buckypaper Electrodes

In this work, a flexible micro-supercapacitor with interdigital planar buckypaper electrodes is presented. A simple fabrication process involving vacuum filtration method and SU-8 molding techniques is proposed to fabricate in-plane interdigital buckypaper electrodes on a membrane filter substrate. The proposed process exhibits excellent flexibility for future integration of the micro-supercapacitors (micro-SC) with other electronic components. The device's maximum specific capacitance measured using cyclic voltammetry was 107.27 mF/cm² at a scan rate of 20 mV/s. The electrochemical stability was investigated by measuring the performance of charge-discharge at different discharge rates. Devices with different buckypaper electrode thicknesses were also fabricated and measured. The specific capacitance of the proposed device increased linearly with the buckypaper electrode thickness. The measured leakage current was approximately 9.95 µA after 3600 s. The device exhibited high cycle stability, with 96.59% specific capacitance retention after 1000 cycles. A Nyquist plot of the micro-SC was also obtained by measuring the impedances with frequencies from 1 Hz to 50 kHz; it indicated that the equivalent series resistance value was approximately 18 Ω.

Graphene-Based Inverted Planar Perovskite Solar Cells: Advancements, Fundamental Challenges, and Prospects

Metal halide based perovskite solar cells (PSCs) are considered among the most promising photovoltaic technologies, and already present certified efficiencies that surpass 22 %. The high performance and low fabrication cost make this technology competitive with that of state-of-the-art thin-film photovoltaics. However, PSCs present some striking disadvantages that hinder their commercialization, including short operational lifetimes, high toxicity, and hysteresis effects, which lower both the performance and long-term stability of the devices. Herein, work conducted within the last two years is summarized with regard to addressing the challenges of low-temperature-processed planar inverted PSCs composed of graphene-based materials. In addition, critical challenges and the prospects of this field are discussed and some prospects for future research directions are proposed.

Synthesis of Multi-Walled Carbon Nanotubes from Plastic Waste Using a Stainless-Steel CVD Reactor as Catalyst

The disposal of non-biodegradable plastic waste without further upgrading/downgrading is not environmentally acceptable and many methods to overcome the problem have been proposed. Herein we indicate a simple method to make high-value nanomaterials from plastic waste as a partial solution to the environmental problem. Laboratory-based waste centrifuge tubes made of polypropylene were chosen as a carbon source to show the process principle. In the process, multi-walled carbon nanotubes (MWCNTs) were synthesized from plastic waste in a two-stage stainless steel 316 (SS 316) metal tube that acted as both reactor vessel and catalyst. The steel reactor contains Fe (and Ni, and various alloys), which act as the catalyst for the carbon conversion process. The reaction and products were studied using electron probe microanalysis, thermogravimetric analysis, Raman spectroscopy and transmission electron microscopy and scanning electron microscopy. Optimization studies to determine the effect of different parameters on the process showed that the highest yield and most graphitized MWCNTs were formed at 900 °C under the reaction conditions used (yield 42%; Raman I_D/I_G ratio = 0.48). The high quality and high yield of the MWCNTs that were produced in a flow reactor from plastic waste using a two stage SS 316 chemical vapor deposition (CVD) furnace did not require the use of an added catalyst.

MOF-derived multifractal porous carbon with ultrahigh lithium-ion storage performance

Porous carbon is one of the most promising alternatives to traditional graphite materials in lithium-ion batteries. This is not only attributed to its advantages of good safety, stability and electrical conductivity, which are held by all the carbon-based electrodes, but also especially ascribed to its relatively high capacity and excellent cycle stability. Here we report the design and synthesis of a highly porous pure carbon material with multifractal structures. This material is prepared by the vacuum carbonization of a zinc-based metal-organic framework, which demonstrates an ultrahigh lithium storage capacity of 2458 mAh g-1 and a favorable high-rate performance. The associations between the structural features and the lithium storage mechanism are also revealed by small-angle X-ray scattering (SAXS), especially the closed pore effects on lithium-ion storage.

High-rate-capability asymmetric supercapacitor device based on lily-like Co3O4 nanostructures assembled using nanowires

In this paper, high-rate-capability asymmetric supercapacitor device assembled by lily-like Co₃O₄ nanostructures and active carbon was presented.

Graphene Oxide Bionanocomposite Coatings with High Oxygen Barrier Properties

In this work, we present the development of bionanocomposite coatings on poly(ethylene terephthalate) (PET) with outstanding oxygen barrier properties. Pullulan and graphene oxide (GO) were used as main polymer phase and nanobuilding block (NBB), respectively. The oxygen barrier performance was investigated at different filler volume fractions (ϕ) and as a function of different relative humidity (RH) values. Noticeably, the impermeable nature of GO was reflected under dry conditions, in which an oxygen transmission rate (OTR, mL·m⁻²·24 h⁻¹) value below the detection limit of the instrument (0.01 mL·m⁻²·24 h⁻¹) was recorded, even for ϕ as low as 0.0004. A dramatic increase of the OTR values occurred in humid conditions, such that the barrier performance was totally lost at 90% RH (the OTR of coated PET films was equal to the OTR of bare PET films). Modelling of the experimental OTR data by Cussler’s model suggested that the spatial ordering of GO sheets within the main pullulan phase was perturbed because of RH fluctuations. In spite of the presence of the filler, all the formulations allowed the obtainment of final materials with haze values below 3%, the only exception being the formulation with the highest loading of GO (ϕ ≈ 0.03). The mechanisms underlying the experimental observations are discussed.

Noble metal, oxide and chalcogenide-based nanomaterials from scalable phototrophic culture systems

Phototrophic cell or tissue cultures can produce nanostructured noble metals, oxides and chalcogenides at ambient temperatures and pressures in an aqueous environment and without the need for potentially toxic solvents or the generation of dangerous waste products. These "green" synthesized nanobiomaterials can be used to fabricate biosensors and bio-reporting tools, theranostic vehicles, medical imaging agents, as well as tissue engineering scaffolds and biomaterials. While successful at the lab and experimental scales, significant barriers still inhibit the development of higher capacity processes. While scalability issues in traditional algal bioprocess engineering are well known, such as the controlled delivery of photons and gas-exchange, the large-scale algal synthesis of nanomaterials introduces additional parameters to be understood, i.e., nanoparticle (NP) formation kinetics and mechanisms, biological transport of metal cations and the effect of environmental conditions on the final form of the NPs. Only after a clear understanding of the kinetics and mechanisms can the strain selection, photobioreactor type, medium pH and ionic strength, mean light intensity and other relevant parameters be specified for an optimal bioprocess. To this end, this mini-review will examine the current best practices and understanding of these phenomena to establish a path forward for this technology.

Macroscopic fibres of CNTs as electrodes for multifunctional electric double layer capacitors: from quantum capacitance to device performance

In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m(2) g(-1), high electrical conductivity (3.5 × 10(5) S m(-1)) and mechanical properties in the high-performance range including toughness (35 J g(-1)) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg(-1) and 14 Wh kg(-1), respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10,000 cycles of charge-discharge at 3.5 V.

Simultaneous Reduction and Functionalization of Graphene Oxide by 4-Hydrazinobenzenesulfonic Acid for Polymer Nanocomposites

Graphene oxide (GO) was functionalized and reduced simultaneously by a new reductant, 4-hydrazinobenzenesulfonic acid (HBS), with a one-step and environmentally friendly process. The hydrophilic sulfonic acid group in HBS was grafted onto the surface of GO through a covalent bond. The successful preparation of HBS reduced GO (HBS-rGO) was testified by scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopic (XPS) and thermogravimetric analysis (TGA). The interlayer space of HBS-rGO was increased to 1.478 nm from 0.751 nm for GO, resulting in a subdued Van der Waals' force between layers and less possibility to form aggregations. The aqueous dispersibility of graphene was improved to 13.49 mg/mL from 0.58 mg/mL after the functionalization. The viscosity of the epoxy resin based HBS-rGO composite could be regulated by an adjustment of the content of HBS-rGO. This study provides a new and applicable approach for the preparation of hydrophilic functionalized graphene, and makes it possible for the application of graphene in some functional polymer nanocomposites, such as specialty water-based coatings.

High yield synthesis of amine functionalized graphene oxide and its surface properties

High yield amination of GO showing improved dispersion in epoxy resin.

Polycrystalline iron oxide nanoparticles prepared by C-dot-mediated aggregation and reduction for supercapacitor application

A facile strategy to directly prepare three-dimensional, multicomponent, multiphase oxide by solvothermal method and C-dots-mediated aggregation and reduction is demonstrated.

Engineering of Iron-Based Magnetic Activated Carbon Fabrics for Environmental Remediation

Magnetic Fe₃O₄, Fe and Fe/Pd nanoparticles embedded within the pores of activated carbon fabrics (ACF) were prepared by impregnation of the ACF in iron acetylacetanoate (Fe(acac)₃) ethanol solution, followed by thermal decomposition of the embedded iron precursor at 200, 400 and 600 °C in an inert atmosphere. The effect of the annealing temperature on the chemical composition, shape, crystallinity, surface area, pore volume, and magnetic properties of the various functionalized ACF was elucidated. The Fe nanoparticles within the ACF were also doped with tinier Pd nanoparticles, by impregnation of the Fe/ACF in palladium acetate ethanol solution. The potential use of the functionalized ACF for removal of a model azo-dye, orange II, was demonstrated. This study illustrated the enhanced removal of the dye from an aqueous solution according to the following order: Fe/Pd/ACF > Fe/ACF > ACF. In addition, the enhanced activity of Fe₃O₄/ACF in the presence of increasing concentrations of H₂O₂ (Fenton catalysts) was also illustrated.