Carbon Related Materials

The discovery of the carbon atom, an element forming the basis of life, had a great impact on technological development that continues to benefit from its valency that gives this element the ability to form many allotropes. Natural carbon allotropes, like diamond and graphite, have been under intense research, and many other synthetic allotropes are continuously being produced with extraordinary structural and chemical properties. When researching carbon-based nanostructures and their applications, numerous experiments are usually necessary to optimize laboratory protocols and achieve confidence in the overall approach. Furthermore, nanoscale laboratory approaches are time-consuming and expensive, and despite following consistent protocols, the results may be difficult to interpret and without clarity. In such cases, computational methods may be particularly helpful for understanding the interactions between carbon atoms and different biomolecules. This chapter focuses on updated carbonaceous materials that exist in various forms across all dimensions: 0D (e.g., fullerene—C₆₀, C₅₄₀, C₇₀, etc.), 1D (e.g., carbon nanotubes—single-walled, multi-walled), 2D (e.g., graphene, penta-graphene), and 3D (e.g., graphite, diamond, lonsdaleite). For each form of carbon allotrope, a brief description is provided along with the chemical structure and the most important properties of the materials. Also, interesting applications are discussed in order to emphasize the key novel properties of these carbonaceous materials. Moreover, state of the art and future prospects of carbon allotropes are presented, highlighting the novel carbon-based nanostructures. The reader will be introduced to the field of computational chemistry , followed by a brief introduction into ab initio methods and density functional theory. The chapter ends with a short presentation on carbonaceous materials that were researched using computational methods, either before or after being synthesized in the laboratory.

Exploiting low-cost and efficient electrocatalysts for hydrogen evolution reaction (HER) is an important route to solve the energy crisis and environmental pollution. HER process plays a vital role in many energy storage and conversion systems including water splitting, rechargeable metal–air batteries and the unitised regenerative fuel cells. The platinum-based catalysts are regarded as best electrocatalysts for the HER; nevertheless, they are very exorbitant and scarce. Therefore, it is necessary to develop efficient electrocatalysts based on carbon materials. Graphene oxide (GO), for instance, is a monolayer structure with a high contribution of sp² hybridised carbon atoms, and various oxygen-containing surface functional groups have attracted the attention of a worldwide research community in the last decades due to its various potential applications linked to the unique combination of properties, such as hardness, physical and chemical stability, high specific surface area, electron mobility and heat transfer. It can be easily manufactured by simple and scalable chemical oxidation approaches from graphite, the reduction of GO into reduced GO (rGO) is a widely used method to obtain graphene. In HER, GO can also be incorporated with metals and porous materials for synergetic effect as co-catalysts for enhancement of electrocatalytic activities. On the other hand, metal–organic frameworks (MOFs) are crystalline materials with porous network structure. They possess various compositions, large surface area, tunable pore structures and are easily functionalised. Recently, MOF‐based electrocatalysts have been rapidly developed with excellent catalytic performance, demonstrating a promising application prospect in HER. In this chapter, the background on hydrogen energy and HER structure, category and synthesis of GO and MOFs are discussed. The application of GO- and MOF-based electrocatalysts for HER is discussed in detail. Their HER parameters such as Tafel slope (b) and exchange current density (i₀) are emphatically discussed and followed by the synergetic effect of HER studies of GO/MOF composites as an alternative electrocatalyst for future hydrogen production and storage via HER mechanism.

Diamond-like carbon (DLC) films are an amorphous carbon film with sp² and sp³ bonding structures of carbons. The DLC films have been used widely in industry owing to have superior properties such as high mechanical hardness and low friction coefficient. The DLC films are divided into the following of four categories: ta-C and a-C films are hydrogen-free DLC with high and low C–C sp³ bonds, respectively, and ta-C:H and a-C:H films are hydrogenated DLC with high and low C–C sp³ bonds, respectively. As the industrial application of DLC films is expanding, it is important to clarify the definition of these DLC film types and to able to easily evaluate the types. There are various DLC deposition methods. Filtered arc deposition (FAD) method which is one of the vacuum arc deposition methods is a few deposition methods can form hydrogen-free DLC films with high hardness. In addition, hydrogenated DLC films can be prepared under the deposition condition in which a hydrogen or a hydrocarbon gas is introduced into the chamber on the FAD system. Various DLC films prepared using T-shape FAD system were characterized by the sp³ fraction and hydrogen content measured using near edge X-ray absorption fine structure spectroscopy and Rutherford back scattering/elastic recoil detection analysis, respectively. It was found that the sp³ fraction, nanoindentation hardness, and film density of DLC films have a correlation. Based on these results, DLC films were classified from the film density and hydrogen content.

This chapter discusses the emergence conditions of energy states arisen from the interaction of electromagnetic waves with an optically active planar slab covered by graphene sheets. All energy configurations inside and outside the graphene layers are explicitly revealed. In particular, we specialize to some certain cases of maximal energy storage by imposing the spectral singularity condition and show that energy density stored within graphene layers can be increased tremendously because of the presence of graphene layers surrounding the complex potential slab. Method presented here relies on the most fundamental principles embracing its power from Maxwell’s equations and employing the whole control of transfer matrix formalism of scattering theory. In this respect, various situations are discussed to see how graphene sheets can be handled in order to increase the energy storage within a slab. It is attained that both graphene layers are required and there must be currents flowing in the same direction in order to preserve the parity invariance. If the parity invariance is broken, energy stored inside the slab slumps to much lower values. Besides, it is illustrated that graphene features can be effectively used in order to enhance energy storage efficiently. Predictions proposed in this work are perceptibly supported by the corresponding graphical demonstrations. The suggested method is quite illustrative and instructive and gives rise to extend all other cases by following similar steps. These observations and predictions suggest a concrete and sound way of forming graphene-related energy storage devices.

Graphene is a two-dimensional nanocarbon material that exhibits unique physical properties. Graphene field-effect transistor (FET) has a strong potential for an electrical biosensor, because graphene FET transduces direct contact of the target on two-dimensional electron gas to large drain current change owing to graphene’s high carrier mobility. To achieve selective detection of the target, graphene surface needs to be immobilized with target-specific receptor molecules, and the receptor molecules must be smaller than the thickness of electrical double layer in sample solution to avoid Debye screening. In this article, we reviewed our recent achievements in biosensing applications of graphene FET immobilized with small receptor molecules such as aptamer, sialoglycan and others. The graphene FET biosensor, named “lab-on-a-graphene-FET,” showed high sensitivity at sub-nanomolar concentration of the target, immunoglobulin E, pseudo-influenza virus lectin, and others. With appropriate control of graphene surface, lab-on-a-graphene-FET provides attractive method for electrical biosensing.

Hydrogen is a clean and efficient energy source and has been considered as one of the best alternate energy carriers for transport sector. Development of cost-effective and safe storage system is one of the major challenges in hydrogen economy as specified by the Department of Energy (DOE). In this direction, multi-walled carbon nanotubes (MWCNTs) have received much attention as hydrogen storage medium due to their high surface area, pore tunability, and good reversibility at non-cryogenic temperatures. The hydrogen storage capacity can be further improved by decorating the MWCNT with nanoparticles of TiO₂, Cr₂O₃, Fe₂O₃, CuO, and ZnO through surface modification. This chapter provides the fundamental insights into strategies for development of nanoparticle decorated MWCNTs under different experimental conditions for better hydrogen storage. The surface morphology and structures of the synthesized samples were examined by scanning electron microscopy (SEM) coupled with EDS, transmission electron microscopy (TEM), and powder X-ray diffraction. The hydrogen storage performance of materials was examined at non-cryogenic temperatures, i.e., 253 and 298 K up to 70 bar pressure.

Technology scaling into the nanometer regime has forced the research community to revisit the choice of on-chip interconnect materials. Copper, which is a traditional material for interconnects, has started encountering several limitations in giga-scale integration. Carbon nanotube (CNT) interconnects have emerged as one of the promising candidates for future on-chip interconnect technology to sustain the performance and reliability of nanoscaled integrated circuits. The overall signal integrity not only depends on interconnect but also on the quality of drivers and repeaters, which may be designed with the help of multi-gate transistors (MGTs). The on-resistance and capacitance offered by MGTs are quite different from their conventional planar counterparts. This, along with the inherent variability in MGTs, which may be induced as a result of fabrication imperfections, impose challenges in adapting interconnects to such transistors. After presenting some electrical properties and modeling approaches of CNTs, this chapter is an effort to familiarize the reader with the various effects of using MGT-based driver circuits using gate-all-around (GAA) devices. Methods for improving interconnect delay using GAA devices in presence of device variability have also been presented.

In the recent years, electrochemical double-layer capacitors (EDLC), also known as supercapacitors, have arisen as promising electrical energy storage systems (EEES) for applied technologies, due to their very high power density, fast response in time, unlimited cycle life and excellent efficiency. The chapter first summarizes the state of the art of these devices with a special emphasis on the operating principle, features and applications. The characterization of the electrodes is herein focused on the study of textural properties by gas adsorption and the capacitive behaviour by the main electrochemical techniques (i.e. cyclic voltammetry, galvanostatic charge–discharge cycles and electrochemical impedance spectroscopy). A wide variety of porous carbons which have been extensively investigated as active material of the electrodes are briefly described. Finally, this contribution discusses the importance of the reliable determination of porosity parameters involved in the formation of the double layer and the need of specific characterization protocols for this application with the objective of providing useful insights into the relationship between the specific surface area and the electrochemical capacitance.

Nowadays, solar photovoltaics systems have a significant contribution to the demand of electricity. The capacity of solar photovoltaics is increasing every year. Thus, the design and development of efficient photovoltaics are highly aimed in order to address the energy and global warming issues. The implementation of carbon nanomaterials such as fullerenes, carbon nanotubes, and graphene into photovoltaics attracted great interest due to the exciting properties including good mechanical strength, high thermal conductivity, transparency, high surface area, and remarkable charge transport properties. In this respect, their use has been shown to increase the electron mobility in the photoactive layers besides assisting the charge separation. This chapter presents the application and role of carbon-based nanomaterials in improving the efficiency and stability of solar cells and in components such as hole transport layer. We summarize the recent progress and general aspects of carbon nanomaterials in various photovoltaics including synthesis, structure, properties, and efficiency. Furthermore, challenges and future perspectives in this area are also discussed.

Nowadays, it has become clear that the critical demands of biosensor development can only be achieved with advanced nanoscale materials. The unique electronic and structural properties of carbon nanomaterials (CNs) and the recent advances in their design and synthesis methodology have enabled new high-performance electrochemical sensing platforms. Furthermore, the progress made towards the functionalization of these nanomaterials led to successful interfacing of biomolecules, such as DNA, and thus to an extensive development of CNs-based electrochemical DNA sensors. The transduction of DNA hybridization events into electrical signals has facilitated the development of rapid, highly sensitive, and highly specific sensing devices employed in important fields such as medical diagnosis, food analysis, and environmental monitoring. A broad range of CNs such as two-dimensional graphene, one-dimensional carbon nanotubes, and zero-dimensional graphene or carbon quantum dots are being explored for designing high-performance DNA-sensing devices. This chapter provides a comprehensive overview of the recent strategies for CNs incorporation into novel DNA-sensing schemes for medical, food, and environmental applications. Likewise, the issues required for an extensive implementation of CNs-based electrochemical DNA sensors in POC technology are critically presented.

In the last couple of decades, carbon nanomaterials have been a hot topic in research, and while they start appearing in commercial products, their environmental impacts are still far from being understood. The life-cycle assessment (LCA) is one way of assessing the environmental burdens of a product throughout its lifecycle on the environment and human beings. This chapter starts with an introduction to the LCA technique, from its origins to the ideas behind its holistic approach that, by investigating the whole lifecycle, avoids shifting the environmental burden from one life stage to the others (e.g. from production to disposal). The chapter then focuses then on a review of the published LCA studies on carbon nanomaterials evaluating commonalities among studies and limitations. Findings suggest that carbon nanomaterials production is more energy demanding than their traditional counterparts, but they can have a lower environmental profile when their whole lifecycle is considered. The last part focuses on the limitations of the LCA in relation to nanomaterials, and the difficulties in understanding their toxicological impacts when released to the environment.

In a layered carbon fiber reinforced thermoplastic polymer (CFRTP) composite composed of 3 cross-weave carbon fiber (CF) cloth sheets between 4 polypropylene (PP) mats, [PP]₄[CF]₃ (55 vol%-CFs), effects of: (1) factory provided sized CF (sizing film (SF) coated CFs with nano-scale rough surface after anodic oxidization), and (2) electron beam irradiation (EBI) under protective nitrogen gas atmosphere to SFF-CF (sizing film free and bare CFs with nano-scale rough surface after anodic oxidation) prior to assembly with PP layers and hot-press, on bending strength (σ_b) at median-accumulative probability (P_f = 0.50) were investigated. Firstly, the sizing film (SF) improved the σ_b 36% from 38 to 52 MPa over that of SFF-CF. Improvements by the SF itself could be explained by acting as a buffer adhering to both PP and CFs increasing fiber pullout and delamination resistance with friction force (F_f) of entangling of PP and SF polymer on CF with weak molecular bonds at SF/CF interface, larger than that of point contacts of PP and CF at PP/CF interface. Secondly, applying 0.22 and 0.30 MGy-EBI treatments to CF surfaces with and without sizing film under protective N₂ gas atmosphere prior to assembly and hot-press improved σ_b, 6% from 52 to 55 MPa and 45% from 38 to 55 MPa, respectively. Improvements of CFs with and without sizing film treated by EBI in N₂ gas can be explained by strong covalent bonds formation at PP/CF interface as direct (CF:\(\boxed{\text{C:C}}\):PP), and indirect (CF:\(\boxed{\text{N:N}}\):PP and CF:\(\boxed{\text{C:O:C}}\):PP) contacts induced by N₂ gas molecules and trace gaseous impurities, in addition to weak molecular bonds CF–(H₂O, N₂, O₂)–PP.

Light-driven actuators, which can convert light energy into mechanical energy, are a key component of photonic switches, pumps, robotics, and sensors. Recent studies of amorphous carbon nitrides, a-CN_x, have yielded interesting insights into the nature of the photomechanical response, resulting in the creation of novel light-driven systems. In this report, we examine the photomechanical response of a-CN_x films prepared from graphite and pure N₂ gas by reactive radio frequency magnetron sputtering. Under visible-light illumination, photoinduced deformation of an a-CN_x/SiO₂ system is observed by a cantilever technique. The photoinduced deformation is found to increase with the number of C≡N triple bonds and depends on the size of graphite clusters in the films. Furthermore, it is discovered that the photomechanical responses of a-CN_x films depends on the structure of the actuators and substrate materials as well as the chemical bonding states. Light-driven pumps based on these films are demonstrated.

The current interest in energy storage systems (ESSs) is primarily due to the environmental concerns of the harmful carbon print emissions from the fossil fuels used presently. The development of energy storage systems (ESSs) comes as a crucial factor when it comes to addressing the energy problems arising due to the rapid development of the global economy and the depletion of fossil fuels that brings the increase of environmental pollution. The innovation brought about by the discoveries in nanotechnology on the production of nanostructured materials has driven the rapid growth in the research of novel carbon nanomaterials towards various applications. Through these research efforts, various carbon-based nanomaterials have been discovered to possess unique properties such as high surface area, high electrical conductivity, as well as a range of shapes, sizes and pore-size distributions that are exploited extensively for electrochemical energy storage applications. Supercapacitors (SCs), also called ultracapacitors or electrochemical capacitors, are electrochemical energy storage (EES) devices that store electrical charge on high-surface-area conducting materials. This chapter explores the fundamental electrochemical properties of various nanostructured carbon materials with a great interest based on the synthesis and supercapacitive behaviour of carbon-based nanomaterials such as carbon nano-onions (CNO), carbon nanotubes (CNTs), activated carbon (AC), carbon nanofibres (CNFs), graphene and graphene oxide (GO) and their composites.

There are concerns regarding the depletion of the fossil-fuel resources and the destruction of the environment accompanied with drastic climate changes. Hence, researchers have derived attention on looking for an alternative clean, sustainable renewable, highly efficient energy conversion and storage technologies/systems. The fuel cell is one of the most promising renewable energy source that can provide a stable and constant energy output as long as fuel is supplied continuously. Currently, platinum-based metals are the best electrocatalysts for fuel cells applications. However, due to high cost of platinum, the large-scale synthesis and commercialisation of these electrocatalysts is challenging. Apart from its high cost, the Pt-based electrode also suffers from its susceptibility to time-dependent drift and CO deactivation, and it is unselective. For these reasons, many research groups are developing non-platinum electrocatalysts that are more active, stable and more economical. Carbon-based nanostructured and nanosized materials are widely applied to tackle these demanding challenges associated with energy conversion. Nanostructured carbon-based materials have received interest due to their fascinating physical and chemical properties. They have electronic behaviour ranging from metallic to semiconducting that depends on their structure, composition and chirality. In this chapter, numerous types of carbon nanomaterials such as carbon black, carbon nanofibers, carbon nanotubes and graphenes applied in the electrochemical activity of fuel cells are conversed.