Carbon-related Materials in Recognition of Nobel Lectures by Prof. Akira Suzuki in ICCE

Graphene is composed of a single layer of carbon atoms arranged in a sp²-bonded aromatic structure, which has become one of the most interesting research areas in the last 5 years. Graphene is also distinctly different from carbon nanotubes and fullerenes, exhibiting a range of unusual properties. It exhibits excellent serials of properties including magical optical, mechanical, electrical, thermal, and chemical performance. These features make graphene the go-to material for applications including photocatalysis, supercapacitors, photovoltaic devices, flexible displays, and nano-transistors.

In this chapter, we will introduce our research work focusing on the novel synthesis of high-quality graphene and graphene-based composites for renewable clean energy and environmental protection. The novel quenching process was developed to produce high-quality graphene on a large scale from cheap expanded graphite. Based on high-quality graphene sheets, Ag/graphene composite was synthesized as a promising antibacterial agent. In addition, we also developed small-size Pd@PdO clusters on nitrogen-doped graphene sheets by facile oxidation-reduction method, which was used in Suzuki-Miyaura reactions with high yields and good structural stability. The TiO₂/graphene with excellent photocatalytic performance was also synthesized for environmental protection application.

Carbon produces a wealth of different materials ranging from organic molecules to diamond crystals. One common challenge for the synthesis, application, and understanding of these materials is their characterization.

Graphene, a monoatomic layer of graphite, exemplifies the achievable diversity in properties of carbon materials and can serve as a model system for the analysis of complex molecules. Modifications, such as addition of heteroatoms, presence of edges, or interaction with adsorbates, significantly modify fundamental properties of graphene and allow inference to structure-property relations.

This contribution will demonstrate the ideal suitability of optical analysis techniques to provide complementary information on thus modified graphene. Even subtle changes in the mechanical, electronic, and chemical structure can be characterized by widely available and nondestructive optical spectroscopy methods.

We first provide an introduction of the available optical characterization techniques. Then, the ability of those techniques to elucidate changes of mechanical, electronic, and chemical properties of graphene will be described. To satisfy requirements from experimentalists, emphasis will be put on ease of access and quantitative relations.

Plasma-based technologies such as spark plasma, thermal and non-thermal plasma, plasma-enhanced chemical vapor deposition, etc., have been developed and extensively used for various forms of application. Plasma technologies provide an efficient and eco-friendly way to synthesize various forms of carbon nanomaterials, composites, and nanohybrids. Further, plasma reaction in aqueous and/or non-aqueous solutions facilitates powder synthesis of oxides and/or non-oxides, hydrogen production, disinfection, reduction of metal ions, medical applications, and analytical tools. Similarly, polymerization of organic gaseous precursors by gas plasma processes is a well-established synthetic route for the formation of unconventional polymers. Recently, plasma techniques have gained significant attention for the generation of ozone/hydrogen peroxide for water and wastewater treatment. Developments in novel plasma generating reactors also provide a sustainable solution to the treatment of emerging contaminant and toxic pollutants from drinking water system. This chapter provides a state-of-the-art overview and in-depth analysis of the various forms of carbon nanomaterials, synthesis of hybrids, and applications.

Graphene is a two-dimensional material that exhibits the highest carrier mobility of any known material. The unique characteristics of graphene allow graphene field-effect transistors (G-FETs) to respond sensitively when charged molecules contact the graphene channel. This response characteristic holds promise for biosensing, which requires the highly sensitive detection of target biomolecules. This article reviews our recent achievements in G-FET biosensing. First, the basic principle behind G-FET biosensing is described. Next, we report several examples of biosensing using G-FETs in which DNA molecules, antibodies, and other receptors were separately immobilized onto graphene channels to allow selective detection of the respective target molecule. Finally, we describe the further functionalization of G-FETs for wireless operation and to provide flexible sensors. Functionalization of G-FETs by receptors and device structures led to a biosensing platform that the authors have named “lab-on-a-graphene.”

Intensive research has been carried out over the past few years to find industrial-scale methods for the preparation of monolayer or few-layer graphene. However, large-scale, economical production of graphene with a low level of defects remains challenging. In this chapter, we review the research on several techniques for production of single- and few-layer graphene, particularly concerning mechanical exfoliation of high-quality graphene. We report our production scheme for graphite nanosheets from natural graphite. Crystalline graphite nanosheets were successfully produced from natural graphite powder by solution-phase synthesis of graphite intercalation compounds, following wet planetary-ball milling. We emphasize the high potential of graphene as a conductive composite film. Some composite films derived from phenolic resin and graphite nanosheets displayed much higher electrical conductivities than those of films from natural graphite particles. We also show that the stage structure of synthetic graphite intercalation compounds affected film conductivity.

Among the most promising nanomaterials, an extensive emphasis was drawn onto graphene-based ones for biomedical applicability, being triggered by its exotic properties such as biocompatibility, electric conductivity, and transparency, excellent aqueous processability, amphiphilicity and surface functionalisation degree. The tuneable chemistry and the excellent mechanical, tribological, as well as corrosion properties of graphene-based materials have indicated their potential applications in implant material. Given the growing demand for designing advanced new implant surfaces to control the interactions with the surrounding biological environment in order to improve their biocompatibility and bioactivity and enhance their corrosion resistance, this chapter highlights the approaches for surface modification of dental implants with graphene nanomaterials as surface coatings.

Numerous papers have shown improvements in mechanical properties of epoxy and other resins and their composites, by introducing small amounts of carbon nanotubes (CNT). Most reports deal with lab scale and/or standard specimens. Lesser work has been done on full-scale composite parts, especially large parts for the aerospace industry. This chapter reviews what has been done in this area and also reveals an effort to demonstrate the effect of introducing multi-walled carbon nanotubes (MWCNT) to the resin in a series of full-scale carbon/epoxy filament wound pressure vessels. The study covers processing, physical properties, mechanical behavior, and failure modes during burst tests. A dispersion method was developed to achieve excellent dispersion of the CNT in the resin. The CNT-modified carbon/epoxy composite exhibits higher interlaminar shear strengths, compared to the neat composite. Following the improvements in standard samples, full-size pressure vessels with metallic bosses and rubber shear plies were produced and tested by a routine testing protocol. The vessels were designed to burst in the domes, where interlaminar stresses may lead to failure. Process parameters were adjusted for minimum resin viscosity and best processibility. However, CNT led to some increase in resin viscosity, thus slightly affecting resin content in the vessels, especially at the domes. All the vessels burst at the domes as expected. Failure occurred at very high tensile strains, and the interlaminar shear failure mode did not develop, as evidenced by high-speed video-camera frame-by-frame analysis. Tensile strains and burst pressures of the vessels containing CNT were very similar to those of the neat vessels. CNT in the epoxy resin interacted with the rubber surface and led to enhanced cohesive failure of the rubber/composite interface. Acoustic emission from the matrix supports a mechanism of crack arrest and energy dissipation, in agreement with previous results. Prediction of failure is apparent at pressures below proof.

Lightweight fiber-reinforced composites (FRPs) do not exhibit the ductile failure mechanism associated with metals. FRPs absorb lots of energy through progressive crushing modes by a combination of multi-micro-cracking, bending, delamination, and friction. However, FRPs have not been used as energy absorption components on a large scale, one of the most important reasons being their high manufacturing costs. In this study, carbon fiber, glass fiber, and aramid fiber were chosen as reinforcements and a commercial epoxy resin was chosen as matrix to manufacture nine types of different structures and reinforcement forms of hybrid fiber reinforced composite tubes through a highly productive and low-cost winding method. Then specimens were kept under 100 °C conditions for 100 h, 200 h, and 400 h, respectively. The effects of crushing speed, temperature treatment, reinforced forms and structures including hybrid ratio, fiber orientation, and thickness of tube wall on energy absorption capabilities were investigated by quasi static and dynamic compression tests. Optical microscope observations of cross section were taken to analyze the mechanism of failure. By optimizing different hybrid methods, ratio, and reasonable geometry shape of composites, low cost and high energy absorption components with specific energy absorption (E _s ) reaching 100 kJ/kg in quasi-static tests and 82 kJ/kg in dynamical tests could be manufactured for real applications in vehicles.

Nowadays, rubber is widely used in our daily life. Developing different types of rubber with high performance is an urgent need for the high-tech modern industry. Graphene, as an excellent nanofiller, can effectively improve the properties of rubber in many aspects. Therefore, the graphene/rubber composites are widely studied by researchers from all over the world, to improve the performance and expand the application of rubber. Dispersing the graphene well in the rubber matrix is the main challenge to prepare the well-performed graphene/rubber composites. Investigating how graphene will improve the properties of rubber is also significant to us. In this chapter, we will review the different preparation methods and applications of the graphene-rubber composites and summarize how graphene will improve the mechanical, electrical, barrier, and thermal properties of the different rubber materials. Furthermore, in order to make a better understanding for graphene effect as a 2D filler for rubber, the chapter also illustrates the reinforcing, vulcanization, and barrier mechanism of the graphene-rubber composites.

Highly filled graphite and graphene polybenzoxazine (PBA) composites as bipolar plate materials for polymer electrolyte membrane fuel cell (PEMFC) are developed in this work. For graphite-filled PBA, the maximum graphite loading in the PBA composite was observed to be as high as 80 wt% which is significantly higher than that of graphene-filled PBA, i.e., 65 wt%. Mechanical properties, i.e., flexural modulus and flexural strength of both types of composites at their maximum contents, were much greater than the requirements of Department of Energy targets for bipolar plate materials. Electrical conductivity of the highly filled PBA composites was 255 S/cm for graphite composite and 357 S/cm for graphene composite. Furthermore, the graphite-filled PBA composite provides a thermal conductivity value up to 10.2 W/mK. Interestingly, thermal conductivity value of the PBA composite having 75.5 wt% of graphite in combination with 7.5 wt% of graphene loadings was found to be as high as 14.5 W/mK. The obtained properties of the graphite- and graphene-filled PBA composites exhibit various characteristics suitable for PEMFC applications.

Amorphous carbon nitride (a-CN_x) films are well-known coating materials that provide excellent mechanical and chemical properties such as a low friction coefficient, high wear resistance, high hardness, low chemical inertness, and biocompatibility. Based on initial theoretical results, a-CN_x was found to possess impressive properties such as a large bulk modulus of crystalline carbon nitride than that of the diamond. Apart from the mechanical properties, in recent years, unique electrical and optical properties of the a-CN_x film have been reported. These properties include deformation under visible-light illumination, tunable bandgap, and photoconductivity. In this chapter, electrical properties of a-CN_x films corresponding to the ambient pressure and gas species are presented. By conducting I-V measurements in a vacuum chamber, it was revealed that the electrical resistance value of the a-CN_x film prepared via reactive sputtering fluctuates with changes in ambient pressure. The fluctuation range varies with gas species of N₂, O₂, CO₂, and Ar. The gas sensitivity of approximately 3 % is obtained from an exposure area of 0.03 mm². Based on these results, an economical small pressure sensor fabricated using a-CN_x films is proposed.

Multicomponent reactions (MCRs) are convergent chemical processes that involve condensation of more than two reactants to form a product, in which basically all or most of the atoms contribute to the newly formed molecule. Usually, MCRs involve the formation of multiple bonds in a single operation without isolating the intermediates or changing the reaction conditions, allowing the straightforward creation of molecular diversity and complexity from simple and readily available substrates. Moreover, the sustainable aspects of MCRs have been recently highlighted: atom economy and step efficiency reduce the number of intermediate steps, functional group manipulations, and use of protecting groups. All these characteristics explain the renewed interest of the synthetic community for MCRs in recent years.

In this chapter, recent advances in the MCRs involving metal carbenes via metal carbene migratory insertion will be discussed, based on significant examples appeared in the literature. We will also focus on the recent developments on the integration of this type of reaction with traditional cross-coupling processes. In recent years, different groups have developed such type of reactions combining classical cross-coupling transformations and metal-stabilized carbene processes with the aim to develop novel strategies for the formation of C-C and C-heteroatom bonds.

Stereoregular monosubstituted polyacetylenes (SPAs) can be prepared by polymerizing the corresponding monosubstituted acetylene monomers using a bidentate rhodium–diene complex with either an amine or alcohol cocatalyst. SPAs have advantages over polyacetylene (PA) in terms of handling and application because SPAs are stable in air and soluble in organic solvents, whereas PA is unstable in air and insoluble. The main chains of SPAs form unique helical structures because of the steric hindrance between neighboring monomers. SPAs can be switched between stretched and contracted helices by controlling the polymerization solvents, substituents, and temperature, leading to color changes in the solid-state materials. An “accordion-like helix oscillation” (HELIOS) was observed in a solution of a SPA with aliphatic ester groups, where the restricted rotation of the ester O–C bond was dynamically synchronized with changes in the helical pitch of the SPA molecules.

The Heisenberg spin Hamiltonian is the quantitative expression of the heuristic idea that the chemical bonding is made by the pairing of two electrons with opposite spins. It is also the parametric phenomenological form of the valence bond (VB) method, the first theory of the electronic molecular structure. This frame is well suited to account the structure and properties of aromatic hydrocarbons. The issue of aromaticity was revisited with modern VB calculations and numeric experiments with other techniques, such as density functional theory (DFT) complemented with analyses in the frame of natural bond orbitals (NBOs) and natural resonance theory (NRT). The aromatic delocalization is a molecular facet of the same mechanisms that are determining electron conduction in carbon-based materials. The linear polyacenes were approached in the spin-coupling paradigm as molecular models of conductions. The same methodology was applied to the hydrocarbons with triangular shape, which are carrying unpaired electrons because of topological reasons. Known small members of the series are the phenalenyl radical and the triangulene biradical. Extrapolating the analysis to extended systems, one may speculate about a spintronics based on triangular-shaped graphenes.

Polyaniline-based metal-organic framework (PANI/MOF) composite was synthesized by chemical oxidation of aniline monomer in the presence of MOF content for practical usages as effective hydrogen production. PANI and composite were characterized by ultraviolet visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopy, atomic absorption spectroscopy (AAS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS, EDX), selected area electron diffraction (SAED) and cyclic voltammetry (CV). Detailed structural and morphological characterizations established that PANI is wrapping MOF. The XRD, Raman and FTIR analyses showed that MOF was incorporated on the backbone of PANI through electrostatic interactions. This was supported by AAS analysis, revealing the amount of copper metal present in the composite. The determined energy band gap of the composite was in good agreement with previously reported catalysts for hydrogen evolution reaction (HER). Experiments probing the thermal, electrochemical, HER and photophysical properties revealed that the composite was very stable and robust and had exceptionally properties. Significant HER was generated by the composite in dimethyl sulphoxide/tetrabutylammonium perchlorate (DMSO/TBAP) supporting electrolyte in the presence of hydrogen source by applying a negative potential to the electrode. PANI and MOF also generated a weak HER as compared to composite.

This article reviews “plasma bonding” of plastic films. Polyethylene terephthalate (PET) films can be bonded directly by oxygen plasma irradiation and heat-press at low temperatures of 100–160 °C. Functional groups of COOH and OH are detected on the irradiated surface. The irradiated films are kept in the atmosphere for 6 years, yet they can be bonded tightly. The irradiated surface is extremely active just after the irradiation, and it is still considerably active after 5 years.

Dry- and wet-peel tests on the bonded films suggest that there are two elements, hydrogen bonding and chemical bonding. The films are bonded weakly by these two elements at lower press temperatures because of the major hydrogen bonding, while they are bonded strongly at higher press temperatures because of the major chemical bonding. The hydrogen bonding is broken by water penetration into the interface, causing smaller peel strength under the wet-peel test.

FTIR results on the non-irradiated, irradiated, and bonded samples indicate that the COOH and OH groups are created at the irradiated surface, and they are responsible for the both of hydrogen and chemical bondings. The OH is consumed during the heat-press bonding; then dehydrated condensation reaction can be proposed for the chemical bonding. Cross-linking layer may be the origin for the long lifetime of the irradiated active surface.

The irradiated films are soaked in various liquids, but they do not lose the plasma effects and bonding ability. Only the films soaked in AlCl₃ and FeCl₃ solutions lose the bonding ability. Then we can keep the irradiated films in the atmosphere without special cares.

It is mentioned on feasible applications of laminated plastic films for back-sheets in solar cell and insulator sheets in EV motor.

In 1959, the Nobel Laureate Professor Richard Feynman delivered the signal of “there is plenty of room at the bottom” at his lecture in Caltech (Feynman RP, There’s plenty of room at the bottom: an invitation to enter a new field of physics. First published in engineering and science magazine XXIII(5), 1960). He described the people’s perspectives to establish the capability for manipulating individual atoms and/or molecules. When stepping into this century, our society has been in high demand of miniature devices (Westervelt RM, Science 320:324–325, 2008; Madou MJ, Fundamentals of microfabrication and nanotechnology, Volume III: from MEMS to Bio-MEMS and Bio-NEMS: manufacturing techniques and applications. CRC Press, Boca Raton, 2011). With the scale down on critical dimensions of the devices, there will be a great deal of the beauty happening in mechanical, electrical, chemical, thermal, and optical domains (Cumings J, Zettl A, Science 289:602–604, 2000; Klinke C, Hannon JB, Afzali A, Avouris P, Nano Lett 6:906–910 2006; Lucas M, Zhang XH, Palaci I, Klinke C, Tosatti E, Riedo E, Nat Mater 8:876–881, 2009). As one most profound application within nanotechnology, nanocomposite has been indispensable in many segments of our society, spanning from packaging, automotive, medicine, energy harvesting and storage, and avionics (Youssef AM, Plast Technol Eng 52:635–660 2013; Maiti M, Bhattacharya M, Bhowmick AK, Rubber Chem Technol 81:384–469, 2008; Pushparaj VL, Shaijumon MM, Kumar A, Murugesan S, Ci LJ, Vajtai R, Linhardt RJ, Nalamasu O, Ajayan PM, PNAS 104:13574–13577, 2007) to name a few. In surveying design and characterization of nanocomposites, atomic force microscopy (AFM) as invented in 1986 by Binnig, Gerber, and Quate (Binnig G, Quate CF, Gerber C, Phys Rev Lett 56:930–933, 1986) is extremely important and has been quickly developed as a multifunctional tool to probe rich information on the surfaces related to mechanical, electrical, magnetic, chemical, and capacitive properties (Muller DJ, Dufrene YF, Nat Nanotechnol 3:261–269, 2008; Brennan B, Spencer SJ, Belsey NA, Faris T, Croninb H, Silva SRP, Sainsbury T, Gilmorea IS, Stoevab Z, Pollard AJ, Appl Surf Sci 403:403–412, 2017; Huang H, Dobryden I, Ihrner N, Johansson M, Ma HY, Pan JS, Claesson PM, J Colloid Interf Sci 494:204–214, 2017). This chapter is organized for providing a review on AFM imaging techniques being useful for studying nanocomposites and their relevance.