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Background: The scientific and clinical interest of breath analysis for non-invasive disease diagnosis has been focused by the scientific community over the past decade. This was due to the exhalation of prominent volatile organic compounds (VOCs) corresponding to the metabolic activities in the body and their concentration variation. To identify these biomarkers, various analytical techniques have been used in the past and the threshold concentration was established between a healthy and diseased state. Subsequently, various nanomaterials-based gas sensors were explored for their demand in quantifying these biomarkers for real-time, low cost and portable breathalyzers along with the essential sensor performances. Methods: We focus on the classification of graphene derivatives and their composites’ gas sensing efficiency for the application in the development of breathalyzers. The review begins with the feasibility of the application of nanomaterial gas sensors for healthcare applications. Then, we systematically report the gas sensing performance of various graphene derivatives/semiconductor metal oxides (SMO) binary nanocomposites and their optimizing strategies in selective detection of biomarkers specific to diseases. Finally, we provide insights on the challenges, opportunity and future research directions for the development of breathalyzers using other graphene derivatives/SMO binary nanocomposites. Results: On the basis of these analyses, graphene and its derivatives/metal oxides based binary nanocomposites have been a choice for gas sensing material owing to their high electrical conductivity and extraordinary thickness-dependent physicochemical properties. Moreover, the presence of oxygen vacancies in SMO does not only alter the conductivity but also accelerates the carrier transport rate and influence the adsorption behavior of target analyte on the sensing materials. Hence researchers are exploring the search of ultrathin graphene and metal oxide counterpart for high sensing performances. Conclusion: Their impressive properties compared to their bulk counterpart have been uncovered towards sensitive and selective detection of biomarkers for its use in portable breathalyzers.

In the past few years, the outstanding properties of the best-known derivative of graphene, the graphene oxide (GO), have led to a wide increase of its spectra of application. GO-based composites have been reported as chemically and mechanically stable, presenting good biocompatibility and great antimicrobial potential. Also, GO's two-dimensional planar structure coupled with its large availability of oxygen-related functional groups can turn this material into a good candidate for several biomedical devices, including wound dressings (WD) and drug delivery systems (DDS). In this scenario, the present review compiles the most advanced and innovative research in WD and DDS containing GO, conducted in last 10 years. An overview of GO's global and specific biomedical properties was presented, alongside with a description of the current GO and GO-based composites producing methods for biomedical applications. In addition, the future challenges, and perspectives of the application of GO for WD and DDS were briefly analysed., FCT -Fundação para a Ciência e a Tecnologia(2C2T)

Micro-Supercapacitors (MSCs) are serving as potential candidates in the field of energy storage devices and applications. They have high capacitance and relatively small size and can be used as power storage for devices. The MSCs have many compartments and in recent years various forms of electrode materials are utilized in the MSCs. Graphene and its derivatives tagged with its unique properties are regarded as future flexible electronic and are widely explored electrode materials in many applications. Graphene can be used with other materials and forms hybrid structures to increase the capacitance of the devices. In this article, we briefly reviewed graphene and graphene derivatives used in the fabrication process of the MSC devices. The fabrication methods for the electrodes and the MSC devices are also evaluated. The various graphene-based MSCs and their capacitances are extensively summarized and compared in this review.

Water pollution by polycyclic aromatic hydrocarbons (PAHs) has lately received considerable attention due to their wide prevalence in the environment and deleterious effects on health. Naphthalene (NP), the simplest and most common PAH, has been extensively utilized for the production of important chemicals such as phthalic anhydride and methyl anthranilate. However, owing to its health-related concerns, NP has been classified as a hazardous pollutant, mandating its removal from water systems. Adsorption has been long the preferred approach for the removal of several pollutants including NP from wastewaters. In this review, we summarize the recent research articles evaluating the removal of NP from aqueous solutions and wastewaters by a series of adsorbents (i.e., activated carbons, graphene derivatives, clay minerals, wastes/by-products, and composites). It is clear from the literature that modified materials have exhibited remarkable performance toward the removal of NP. More importantly, we highlight the potential use of adsorption integrated with other processes for the enhancement of NP removal from wastewaters. Based on the studies published in the last decade (i.e., since 2010), we pinpoint out as well the main existing shortcomings, which need to be considered in future research endeavors.

Even though many graphene derivatives that are atomically thin two-dimensional structures, such as graphene oxide (GO), have triggered enormous interest in the scientific and industrial communities owing to their easy synthesis and mass production, there is inevitable degradation of their properties compared to pristine graphene. This is because the sp2-carbon lattice of chemically oxidized GO is transformed into sp3-defect sites with various oxygen-containing functional groups. However, from a synthetic chemistry perspective, GO can become a robust and versatile carbon scaffold with utilizable surface functional groups via a variety of synthetic methods. In this regard, covalent functionalization with a diverse set of molecules on the surface of GO can not only recover diminished electrical and physical properties but also improve its overall performance in applications. In this review, we focus on the covalent functionalization of GO and present various strategies to control its dispersibility, conductivity, and catalytic activity toward potential applications. We anticipate that graphene chemistry will offer opportunities for designing multifunctional nanocomposites for future development in the materials science and device engineering areas.

Recently, graphene and carbon fibers have enticed extensive consideration in many scientific fields, they are considered by many scientists to be one of the most promising materials in the 21st century. Due to the uniqueness of their properties was attracted to be used to reinforce polyimide. Impressive graphene properties coupled with those excellent of polyimide composites produced composites materials with good tribological properties, different contents of graphene and its derivatives tend to improve polyimide composites properties particularly friction and wear. Furthermore, nanofillers decorated graphene derivatives showed also an effect on the tribological properties of composites. Carbon fibers coupled with polyimide composites also reviewed and showed a significance in the improvement of the properties of composites materials. The results nanofillers reinforced carbon fibers/polyimide exhibit enhanced tribological properties, which can be applied in various fields. Therefore, this survey article gives an enormous review study of the tribological properties under various conditions of graphene/polyimide and car- bon fibers/polyimide composites. Besides the effects of nanofillers size on tribological properties, preparation, and research challenges were also reviewed.

Biomedical application of graphene derivatives have been intensively studied in last decade. With the exceptional structural, thermal, electrical, and mechanical properties, these materials have attracted immense attention of biomedical scientists to utilize graphene derivatives in biomedical devices to improve their performance or to achieve desired functions. Surfaces of graphene derivatives including graphite, graphene, graphene oxide and reduce graphene oxide have been demonstrated to pave an excellent platform for antimicrobial behavior, enhanced biocompatibility, tissue engineering, biosensors and drug delivery. This review focuses on the recent advancement in the research of biomedical devices with the coatings or highly structured polymer nanocomposite surfaces of graphene derivatives for antimicrobial activity and sterile surfaces comprising an entirely new class of antibacterial materials. Overall, we aim to highlight on the potential of these materials, current understanding and knowledge gap in the antimicrobial behavior and biocompatibility to be utilized of their coatings to prevent the cross infections., Recent advances in the research of biomedical devices with coatings or highly structured polymer nanocomposites composed of graphene derivatives for self‐cleaning surfaces are reviewed. Overall, the authors aim to highlight the potential of these materials as well as the current understanding and knowledge gaps regarding their antimicrobial behavior and biocompatibility for use as biomedical coatings to prevent cross infections.

Graphene, a two-dimensional single layered carbon atoms crystal lattice has grabbed much attention due to its unique electronic, surface, mechanical and optoelectronic characteristics. Owing to its unique structure and properties, graphene has opened new opportunities for the future systems and devices, which has led to increase its demand in numerous applications. However, scaling up its production is still a challenging job. Although there is a huge body of literature on the graphene synthesis using various techniques but eco-friendly and cost–effective processes for mass scale production are still needed. In order to conceptualize and develop the processes fulfilling the growing concerns, it is important to overview the existing literature. The current review summarizes the production of graphene using several approaches as well as the potential of various waste materials as graphene precursors. The methods used for graphene synthesis have been categorized into top down techniques such as chemical exfoliation, mechanical exfoliation and chemical fabrication processes, and bottom up techniques including pyrolysis, plasma synthesis, epitaxial growth and chemical vapor deposition (CVD) processes. Conversely, several limitations are considerate for an individual procedure such as toxicity of chemicals, high-cost, time consumption or inadequate quality of the product. Furthermore, mass production of graphene derivatives under low-cost can also be considered by utilizing a variety of wastes precursors such as plastic and batteries waste, newspaper, biomass, chitosan, coal, insects waste etc. This review designates the current advances in wastes-derived graphene synthesis to relief synthetic difficulties as well as predicts the future development in this area.

Since the very first landmark report by Geim and Novoselov in 2004 on graphene [1], the interest of the scientific and technological communities for every form of this carbon-based nanomaterial has only grown and grown. In 2019, the hype for graphene turned fifteen years old and, after having experienced an intense infancy (with impressive results at laboratory scales in a myriad of different application fields), experts say that the following 15 years should be oriented towards its commercialization and day-to-day uses [2]. For this, some aspects are crucial and need to be understood, such as standardization or safety issues [2,3]. The broad family of graphene nanomaterials (including graphene nanoplatelets, graphene oxide, graphene quantum dots, and many more), go beyond and aim higher than mere single-layer (‘pristine’) graphene; thus, their potential has sparked the current Special Issue. In it, 18 contributions (distributed in 14 research articles and 4 reviews) have probably portrayed the most interesting lines as regards future and tangible uses of graphene derivatives.

This work is focused on determining whether two graphene derivatives: graphene oxide (GO) and reduced graphene oxide (RGO) can be used alone as a component of anticancer therapy. In this paper, we present the synthesis GO and RGO, their physicochemical characterization as well as an evaluation of their cytotoxic properties on cancer (HepG2 and MCF-7) and non-malignant (clone-9 and HMF) cells. We demonstrated that both tested graphene derivatives have a high affinity to cancer cells. We showed that cytotoxic properties of GO and RGO were different depending on the type of solvent in which they were prepared. Additionally, we observed that cytotoxic properties of GO and RGO were different depending on the origin of the cells (liver and breast) and the form of graphene material (GO and RGO). We showed that GO and RGO can be potential, selectively materials which in future can found application in anticancer therapy.

This work presents the development of novel fluorinated graphene (FG)-based resistive humidity sensor. The humidity sensor was fabricated by drop-casting FG suspension, as the humidity sensing material, on silver (Ag)-based interdigitated electrodes (IDEs). The silver-based IDEs were screen printed on a flexible polyimide substrate. The FG suspension was synthesized by uniform dispersion of FG in isopropyl alcohol (IPA), using the ultra-sonication process. The resistive response of the fabricated humidity sensors towards varying relative humidity (RH) levels was investigated, when the RH was varied from 20% to 80%, in steps of 10%, and at a temperature of 24 °C. A relative resistance change of 13.3% was observed when the RH was changed from 20% to 80%, with a sensitivity of 0.22%/%RH for the FG-based humidity sensor. Response time and recovery time of 82 s and 125 s, respectively, was obtained for the fabricated sensor. In addition, the effect of varying operating temperatures on the response of the fabricated humidity sensors was investigated. The average temperature coefficient of resistance of sensors was obtained as approximately −0.3%/°C. A linear relation between the temperature and the relative resistance change of sensors was observed. Further, first-principles study, employing density functional theory calculations, was performed to investigate interactions between the fluorine atom and graphene substrate, as well as humidity sensing behavior of the FG. DFT calculations showed that hydrogen atoms of the water molecule move towards the fluorine atom of the FG during the relaxation process, confirming the hydrogen bonding between FG and water molecules. The Eads of −0.50 eV was calculated for the adsorption of water molecule on the FG, demonstrating the strong humidity sensing property of the FG. The results demonstrate that FG, a highly stable derivative of graphene, is a potential material for humidity sensing applications.

Two-dimensional graphene films and graphene derivatives have attracted broad interest because of the large potential in optoelectronic applications. However, improving the performance of photodetec...

Graphene is a potential candidate for applications in biomedical field. It is inevitable that graphene is in contact with the ubiquitous bacterial environment. More attention has been paid to the antimicrobial activity of graphene derivatives (graphene oxide, reduced graphene oxide) than the interaction between graphene and bacteria. Herein, we explore interaction between graphene micron-sheet and bacteria from micro (gene expression) and macro (colonies) perspectives. Results demonstrate that graphene micron-sheet accelerates the biofilm forming thus promoting pathogen expansion toward both Gram-negative bacteria E. coli and Gram-positive bacteria S. aureus. The graphene micron-sheet acts as a “habitat” for increasing bacterial attachment and biofilm forming. For E. coli, graphene micron-sheet, firstly changes the integrity of periplasmic and outer membrane components, then makes membrane-associated and cell division genes increased, and finally promotes bacterial proliferation; For S. aureus, graphene micron-sheet can accelerate biofilm forming and develop bacterial expansion owing to the regulation of the quorum-sensing system and global regulatory proteins. The work can shed new light on the range of possible mode of actions, developing a better understanding of the capabilities of graphene micron-structures.

The fact that some of solid materials with suitable phases possess higher thermal conductivity than liquids gave rise to their utilization in heat transfer processes. Fluids that contain nanopartic...

Among various 2D materials, graphene has received extensive research attention in the last 2-3 decades due to its fascinating properties. The discovery of graphene provided an immense boost up and new dimension to materials research and nanotechnology. The multidisciplinary characteristics of graphene havea wide range of applications from health to aerospace. Modern graphene research has been directed towards the exploration of new graphene derivatives and their utilisations for fabrication of products and devices. The enhancement of graphene properties by functionalization or surface modification is another innovative approach. However, like other 2D materials, graphene research also needs amendments and up-gradation in the light of recent scientific output. In this contribution, we have reassessed the recent research output on graphene and graphene-based materials for applications in different fields. For the reader's comfort and to maintain lucidity, first, some fundamental aspects of graphene are discussed and then recent overviews in graphene research are explored in a systematic manner. Overall, this review article provides an outline of graphene in terms of fundamental properties, cutting-edge research and applications. Keywords: Graphene, 2D materials, Graphene oxide, Engineering application of graphene

While noncovalent interactions between graphene derivatives and biosystems are extensively studied, less knowledge about their covalent multivalent interactions at biointerfaces is available. Due to the affinity of boronic acids towards cis-diol bearing biosystems, graphene sheets with this functionality were synthesized and their covalent interactions with the bacteria and nematode were investigated. As expected, graphene platforms with boronic acid functionality were able to wrap bacteria and destroy it in a short time. Surprisingly, body of nematodes was ruptured and their viability decreased to 30% after 24 h incubation with the functionalized graphene sheets. Because of their antibacterial and antiparasitic activities as well as their ability for wound dressing, graphene platforms with the boronic acid functionality were further investigated for diabetic wound healing. In vivo experiments showed that graphene platforms are more efficient than the commercially available drug, phenytoin, and restore both infected and non-infected diabetic wounds in ten days. Taking advantage of their straightforward synthesis, strong interactions with different biosystems as well as their ability to heal diabetic wounds, the boronic acid functionalized graphene sheets are promising candidates for a broad range of future biomedical applications.

Based on the extensive investigation on graphene and graphene derivatives asymmetrically functionalized with a variety of molecular groups and the concept of Janus materials with asymmetric facial properties, Janus two-dimensional (2D) materials as derivatives of the 2D material family, including Janus graphene, Janus transition metal chalcogenides, etc., have attracted much attention in recent years. Janus 2D materials have been demonstrated experimentally and theoretically to possess unique properties such as an out-of-plane piezoelectric polarization and strong Rashba effect due to their out-of-plane asymmetry. Here, the recent progress of emerging Janus 2D materials, including Janus graphene, prediction and fabrication of various different Janus 2D materials and Janus 2D van der Waals heterostructures, is presented. The investigations on the unique properties and potential device applications of Janus 2D materials are summarized. Finally, the conclusion and prospects for the future explorations on Janus 2D materials are also provided.

Graphene-based hybrid nanomaterials are interestingly being considered in expanding fields such as supercapacitors, biosensors, biomedicine, and pathogen deactivation. Surface properties of the two-dimensional (2D) hybrids are crucial in dictating their safety and efficacy. Therefore, concise and accurate functionalization of the pristine 2D nanomaterials is very important for facilitating their clinical trials. In this case, some of the promising candidates for effective and controllable functionalization of graphene derivatives are dendrimers and hyperbranched polymers because of their high density of tunable functional moieties and their ability to interact with biosystems. Herein, we have reviewed recent advances on designing graphene-dendritic polymer hybrids and their applications together with the challenges in the field.

Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq Studies that apply biochar as adsorbent material of contaminants present in the environment are growing and promising, mainly due to the environmental appeal in the use of this carbonaceous material. In this work, samples of biochar and graphene derivatives were used as adsorbents of Cr(VI) ions in aqueous media. The samples of biochar were obtained from the pyrolysis of the biomass of waterapple (Eichhornia crassipes) at 500 °C, forming the biochar B5. Subsequently, it was submitted to the activation process with nitric acid (HNO3), resulting in the formation of the activated biochar B5AT. The samples of graphene derivatives, known as graphene oxide (GO) and reduced graphene oxide (rGO), were synthesized from graphite. A hybrid material was also formed using biochar and rGO (B5ATM:rGOM) by maceration. Characterizations to determine the chemical composition of the biochar samples showed oxygenated and nitrogenated functional groups, especially for the sample activated with HNO3 acid. The synthesized graphene derivatives showed morphology and structural organization in agreement with the literature. The materials were applied for the adsorption of Cr(VI) ions and the macerated biochar B5M stood out in relation to the others, presenting a higher adsorption capacity of the metal ions in acid medium. The kinetic study showed a decrease in the adsorption rate at times greater than 5 hours of contact of the B5M adsorbent with the Cr(VI) solution. The nonlinear Elovich kinetic model applied to the B5M adsorbent showed the best fits for the adsorption rate, suggesting that the adsorption process occurs by chemisorption, while the Sips isotherm model provided the best adsorption equilibrium parameters, the maximum adsorption capacity was 97.25 mg g-1 . These results suggest that the adsorption process occurs in monolayer and that the adsorbent material B5M exhibits a high degree of heterogeneity. Estudos que aplicam biocarvão como material adsorvente de contaminantes presentes no meio ambiente são crescentes e promissores, principalmente devido ao apelo ambiental no aproveitamento desse material carbonáceo. Neste trabalho, foram utilizadas amostras de biocarvão e derivados de grafeno como adsorventes de íons Cr(VI) em meio aquoso. As amostras de biocarvão foram obtidas a partir da pirólise da biomassa de Aguapé (Eichhornia crassipes) a 500 °C, formando o biocarvão B5. Posteriormente foi submetido ao processo de ativação com ácido nítrico (HNO3), resultando na formação do biocarvão ativado B5AT. As amostras dos derivados de grafeno, conhecidos como óxido de grafeno (GO) e óxido de grafeno reduzido (rGO), foram sintetizadas a partir do grafite. Um material híbrido também foi formado utilizando biocarvão e rGO (B5ATM:rGOM) por meio de maceração. As caracterizações para a determinação da composição química das amostras de biocarvão apresentaram grupos funcionais oxigenados e nitrogenados, principalmente para a amostra ativada com ácido HNO3. Os derivados de grafeno sintetizados apresentaram morfologia e organização estrutural de acordo com a literatura. Os materiais foram aplicados para a adsorção de íons Cr(VI) e o biocarvão macerado B5M se destacou em relação aos demais, apresentando uma maior capacidade de adsorção dos íons metálicos em meio ácido. O estudo cinético apresentou uma diminuição da taxa de adsorção em tempos maiores que 5 horas de contato do adsorvente B5M com a solução de íons Cr(VI). O modelo cinético de Elovich não linear aplicado ao adsorvente B5M apresentou melhores ajustes para a taxa de adsorção, sugerindo que o processo adsortivo ocorre por quimissorção, enquanto o modelo de isoterma de Sips forneceu os melhores parâmetros de equilíbrio de adsorção, a capacidade máxima de adsorção foi de 97,25 mg g-1 . Estes resultados sugerem que o processo de adsorção ocorre em monocamada e que o material adsorvente B5M apresenta um alto grau de heterogeneidade. São Cristóvão

Trioxide Tungsten (WO3), an n-type semiconductor that exhibits a wide band gap of 2.5 to 3.6 eV, has attracted special attention from the scientific community. This attraction is due to its manifold properties, which not only follow the development of technologies, but accelerate it. There are several methods to synthesize WO3 nanostructures with various morphologies. In the present study, for the first time, a novel chemical method was developed for the preparation of WO3 nanostructures by using tungsten carbide (WC) as precursor. This novel approach has many advantages such as high yields, simple methodology and easy work up. Moreover, graphene oxide coated with WO3 nanostructured is prepared via in-situ and ex-situ chemical approaches followed by subsequent thermal treatment at 500°C. The obtained samples were characterized by different techniques to confirm the transformation of WC to WO3 nanostructures and the formation of their nanocomposites with graphene derivatives.

There is broad agreement among researchers that the next facing of the construction material industry is ‘geopolymer composites’, also called ‘green composites. Although geopolymer composites have been extensively investigated as a new sustainable building material in recent years, their acceptability is still limited owing to few critical fragilities as a commercial material for construction. However, recent progress on geopolymer composites by several scientists suggests that it could be designed at the nanoscale to significantly enhance the chemical and physiomechanical characteristics to overcome multiple limitations. Graphene, a 2D nanomaterial, has been reported to improve various crucial properties when combined with geopolymer composites. This review paper starts with a bibliometric investigation of the studies related to graphene reinforced geopolymer composites (GRGC) to provide useful insights into current research trends. The paper described the synthesis of suitable graphene derivatives and the manufacturing of different phases of GRGC, namely ink, paste, mortar, and composites. Then a critical review is provided on the mechanical and electrical properties enhancement of graphene geopolymer matrix systems through the modification of the composite matrix at the nano-micro structural level. The GRGC has the potential to be used in multiple applications, such as the recycling of industrial solid waste, and is addressed in this paper. Research gaps were identified in the areas of suitable forms of graphene materials synthesis, dispersion, geopolymer binder type, mixing design, microstructure, and acceptance as well as implementation. The review clarifies those challenging aspects and presents guided solutions for developing sustainable, resilient, and efficient geopolymer matrix-based future materials.

Additive manufacturing techniques established a new paradigm in the manufacture of composite materials providing a simple solution to build complex, custom designed shapes. In the biomedical field, 3D printing enabled the production of scaffolds with patient-specific requirements, controlling product architecture and microstructure, and have been proposed to regenerate a variety of tissues such as bone, cartilage, or the nervous system. Polymers reinforced with graphene or graphene derivatives have demonstrated potential interest for applications that require electrical and mechanical properties as well as enhanced cell response, presenting increasing interest for applications in the biomedical field. The present review focuses on graphene-based polymer nanocomposites developed for additive manufacturing fabrication, provides an overview of the manufacturing techniques available to reach the different biomedical applications, and summarizes relevant results obtained with 3D printed graphene/polymer scaffolds and biosensors., PC acknowledges the support of the Portuguese Foundation for Science and Technology (FCT) through the National Funds Reference UIDB/05256/ 2020 and UIDP/05256/2020. I3Bs acknowledges the support of FCT through the Project SeaJellyBone (PTDC/BTM-MAT/28123/2017). MS acknowledges FCT for the PhD Grant Reference SFRH/BD/138244/2018

Biosensors hold great potential for revolutionizing personalized medicine and environmental monitoring. Their construction is the key factor which depends on either manufacturing techniques or robust sensing materials to improve efficacy of the device. Functional graphene is an attractive choice for transducing material due to its various advantages in interfacing with biorecognition elements. Graphene and its derivatives such as graphene oxide (GO) are thus being used extensively for biosensors for monitoring of diseases. In addition, graphene can be patterned to a variety of structures and is incorporated into biosensor devices such as microfluidic devices and electrochemical and plasmonic sensors. Among biosensing materials, GO is gaining much attention due to its easy synthesis process and patternable features, high functionality, and high electron transfer properties with a large surface area leading to sensitive point-of-use applications. Considering demand and recent challenges, this perspective review is an attempt to describe state-of-the-art biosensors based on functional graphene. Special emphasis is given to elucidating the mechanism of sensing while discussing different applications. Further, we describe the future prospects of functional GO-based biosensors for health care and environmental monitoring with a focus on additive manufacturing such as 3D printing.

Graphene has accomplished huge notoriety and interest from the universe of science considering its exceptional mechanical physical and thermal properties. Graphene is an allotrope of carbon having one atom thick size and planar sheets thickly stuffed in a lattice structure resembling a honeycomb structure. Numerous methods to prepare graphene have been created throughout a limited span of time. Due to its fascinating properties, it has found some extensive applications to a wide variety of fields. So, we believe there is a necessity to produce a document of the outstanding methods and some of the novel applications of graphene. This article centres around the strategies to orchestrate graphene and its applications in an attempt to sum up the advancements that has taken place in the research of graphene.

The research and technological advancements observed in the latest years in the nanotechnology field translated into significant application developments in various areas. This is particularly true for the renewable polymers area, where the nano-reinforcement of biobased materials leads to an increase in their technique and economic competitiveness. The efforts were predominantly focused on materials development and energy consumption minimization. However, attention must also be given to the widespread commercialization and the full characterization of any particular potential toxicological and environmental impact. Some of the most important nanomaterials used in recent years as fillers in the bioplastic industry are graphene-based materials (GBMs). GBMs have high surface area and biocompatibility and have interesting characterizations such as strangeness and flexibility. In this paper, the current state of the art for these GBMs in the bioplastics area, their challenges, and the strategies to overcome them are analyzed. Scopus

Fluorinated graphene (FG), as an emerging member of the graphene derivatives family, has attracted wide attention on account of its excellent performances and underlying applications. The introduction of a fluorine atom, with the strongest electronegativity (3.98), greatly changes the electron distribution of graphene, resulting in a series of unique variations in optical, electronic, magnetic, interfacial properties and so on. Herein, recent advances in the study of FG from synthesis to applications are introduced, and the relationship between its structure and properties is summarized in detail. Especially, the functional chemistry of FG has been thoroughly analyzed in recent years, which has opened a universal route for the functionalization and even multifunctionalization of FG toward various graphene derivatives, which further broadens its applications. Moreover, from a particular angle, the structure engineering of FG such as the distribution pattern of fluorine atoms and the regulation of interlayer structure when advanced nanotechnology gets involved is summarized. Notably, the elaborated structure engineering of FG is the key factor to optimize the corresponding properties for potential applications, and is also an up-to-date research hotspot and future development direction. Finally, perspectives and prospects for the problems and challenges in the study of FG are put forward.

Graphene is a bi-dimensional layer of carbon atoms bonded in a sp2 configuration forming a honeycomb structure. This material has attracted a lot of interested since it was first discovered by Novoselov and Geim and further applied in many fields due to its high theoretical surface area, high mechanical flexibility, good electrical conductivity and high theoretical capacitance. Graphene surface can be functionalized through covalent and non-covalent strategies, achieving different types of graphene derivatives that can be applied in different fields. The different types of functionalization give graphene-based structures a wide variety of different properties. All these characteristics make graphene and its derivatives highly promising materials to be used in many fields due to its great advantages mainly its great surface versatility. The effect of the functionalization in the final properties, of graphene surfaces are revised from an experimental and theoretical point of view and the possible applications of graphene and its derivatives are discussed in this chapter.

Since the first discovery of graphene in 2004, the scientific and industrial community is still finding fields to bring the excellent mechanical performance of graphene into full play. Herein, this review summarizes the recent advances in graphene and graphene derivatives toughened polymer nanocomposites, which gives full play to the unique two-dimensional nanostructure, extra specific surface area and ultrahigh mechanical properties of graphene and graphene derivatives. Using graphene and graphene derivatives as toughening modifier of polymers can not only enhance the toughness of the polymer matrix but also endow the polymer nanocomposites with enhanced strength. The preparation, performance and mechanism of graphene and graphene derivatives toughened polymer nanocomposites are highlighted in this review. The factors influencing the efficiency of graphene and graphene derivatives toughening polymers are discussed in detail. Current challenge and future direction in graphene and graphene derivatives toughened polymer nanocomposites are proposed for promoting the application of graphene in toughening polymers. This review provides a guidance for fabricating high-performance polymer/graphene nanocomposites.

Domestic and foreign literature on methods for obtaining graphene and its derivatives [graphene oxide (GO) and reduced GO] as representatives of the family of 2D layered materials is analyzed. Particular attention is paid to GO. Great potential of post-synthetic modification as well as unique properties of the material and its derivatives make them promising for a variety of applications including biomedicine, ecology, optoelectronics, etc. Chemical and physical methods for the reduction of GO to obtain graphene-like materials similar in structure and properties to pure graphene obtained by direct mechanical cleavage are considered. Functionalization strategies of graphene materials are discussed. The preparation of hydro- and organogels as well as Pickering emulsions from graphene derivatives as precursors of porous monoliths are considered. The formation of aerogels based on graphene materials and methane adsorption on these porous structures are discussed. Basic information about hybrid materials containing graphene derivatives and metal-organic frameworks is given and their adsorption characteristics with respect to methane are evaluated. Covalent and noncovalent interactions in graphene – porphyrin hybrids are considered from the standpoint of formation of porphyrin architectures on the surface of graphene materials. Examples of the use of porphyrin – graphene composite materials in photo- and electrocatalysis, fuel cells and gas separation membranes are given. The bibliography includes 243 references.

Recent findings of atomic-scale modelling studies are reviewed on graphene derivatives and metamaterials fabricated through chemical functionalization and/or defect engineering of graphene sheets. ...

We present a simple and facile approach to creating asymmetrically modified graphene oxide sheets by grafting polymers with different polarities. Single-layered Janus graphene derivatives were prep...

In recent years, graphene oxide (GO) and reduced graphene oxide (r-GO) are being produced using graphite powder as precursor material but the preparation of graphene derivatives from a non-graphiti...

In search of alternate procedures and raw materials to manufacture graphene oxide and graphene derivatives that could be scaled up to be industrially implemented, we have developed a simple thermal treatment of petroleum asphalt that gives rise to graphite oxide-like materials in high yield. Subsequent treatment of the oxide at higher temperature gives rise to graphene-like products similar to those obtained by conventional top-down methods based on graphite. The method offers economy in manufacturing time and energy spent, allowing the valorization of a waste material.

Thanks to their remarkable mechanical, electrical, thermal, and barrier properties, graphene-based nanocomposites have been a hot area of research in the past decade. Because of their simple top-down synthesis, graphene oxide (GO) and reduced graphene oxide (rGO) have opened new possibilities for gas barrier, membrane separation, and stimuli-response characteristics in nanocomposites. Herein, we review the synthesis techniques most commonly used to produce these graphene derivatives, discuss how synthesis affects their key material properties, and highlight some examples of nanocomposites with unique and impressive properties. We specifically highlight their performances in separation applications, stimuli-responsive materials, anti-corrosion coatings, and energy storage. Finally, we discuss the outlook and remaining challenges in the field of practical industrial-scale production and use of graphene-derivative-based polymer nanocomposites. Keywords: Graphene oxide, Reduced graphene oxide, Graphene quantum dots polymer, Nanocomposites, Synthesis, Properties of graphene and graphene oxide, Applications

In the last decade, a great deal of research has been devoted to the design and development of graphene-based polymer nanocomposites characterized by a prescribed arrangement of the graphene-based nanosheets into spatially segregated 3D architectures. The formation of a continuous filler network obtained by confining the nanosheets into a constrained volume of the polymeric matrix is particularly attractive from a technological point of view. The preparation of segregated 3D graphene-based architectures facilitates the proper tailoring of the overall performance of the resulting polymer nanocomposites, providing significant improvements in terms of structural (i.e., mechanical properties) and functional (electrical properties, sensing ability, and adsorption/absorption capacity) features. This review focuses on polymer-based nanocomposites in two categories, namely bulk and porous (foam and aerogels) systems. These all share the common distinctive feature that relies on the peculiar arrangement of the graphene-based nanosheets in the form of a segregated yet continuous 3D assembly. For each class of materials, the main preparation strategies are presented and the resulting structure-property correlations are highlighted and discussed, together with the technological implications, and possible future directions.

The application of enzymes is a crucial issue for current biotechnological application in pharmaceutical, as well as food and cosmetic industry. Effective platforms for enzyme immobilization are necessary for their industrial use in various biosynthesis procedures. Such platforms must provide high yield of immobilization and retain high activity at various conditions for their large-scale applications. Graphene derivatives such as hydrogenated graphene (graphane) and fluorographene can be applied for enzyme immobilization with close to 100 % yield that can result to activities of the composites significantly exceeding activity of free enzymes. The hydrophobic properties of graphene stoichiometric derivatives allowed for excellent non-covalent bonding of enzymes and their use in various organic solvents. The immobilized enzymes retain their high activities even at elevated temperatures. These findings show excellent application potential of enzyme biocatalysts immobilized on graphene stoichiometric derivatives.

Graphene oxide (GO) is one of the most well-known graphene derivatives which, due to its outstanding chemical, electrical and optical properties as well as its high oxygen content, has been recently applied in several fields such as in the construction of sensors, as antimicrobial agent for biomedical applications, as well as nanofiller material for membranes applied in wastewater treatment. In this last-mentioned field, the synthesis and functionalization of membranes with GO has proven to improve the performance of membranes applied in the treatment of wastewater containing dyes, regarding antifouling behavior, selectivity and flux. In this review, an overview of water pollution caused by effluents containing synthetic dyes, the advantages and limitations of GO-based membranes and the latest research advances on the use of GO-based membranes for dyes removal, including its impact on membrane performance, are discussed in detail. The future panorama of the applicability of GO-based membranes for the treatment of water contaminated by dyes is also provided.

Population-driven socioeconomic urban expansion, industrialization and intensified modern agricultural practices are interlinked to environmental challenges which induce harmful repercussions on the health of human beings. Consequently, these challenges have culminated in compromised water quality due to pollution by toxic, persistent and bioaccumulative heavy metal ions, pesticides, and emerging pollutants. Most pollutants cause severe health dilemma including impairment of vital body organs like lungs, liver, kidneys, reproductive and nervous systems. Besides, some organic contaminants interfere with natural enzyme and hormonal functioning such as the endocrine system. Considering the detrimental impact of pollutants, their detection in different media including water is paramount. Notably, electrochemical techniques are more appealing owing to their facileness, sensitivity, portability, the potential for being used instantaneously, in situ and onsite comparative to conventional methods. Electrochemical sensing utilizing graphene derived nanocomposites have become attractive based on mechanical strength, electric conduction, and huge surface area to volume ratio of graphene. Apart from that, graphene-based materials are functionalisable owing to the prevalence of oxygen-rich entities. Thus, they are amenable for the incorporation of different components for modifying electrodes. Ultimately, combinational synergistic aftermaths in electrochemical sensor behaviour are being realized following functionalization and electrode modification with nanocomposites. This review summarizes graphene and its derivatives synthesis pathways. Besides that, the review describes the functionalization of graphene derived materials exploiting properties of metal (oxides) nanoparticles, conducting polymers, organic or inorganic materials, and other carbon materials like carbon nanotubes. Furthermore, the review evaluates the recent electrochemical detection of heavy metal ions, pesticides and emerging pollutants founded on hybridized graphene. For natural organic matter, the absence of reports on their sensing based on functionalized graphene derivatives is highlighted. In reckoning, current challenges related to graphene applicability, envisaged opportunities and future perspectives are outlined.

Multivalent carbohydrate-mediated interactions are key to many biological processes including disease mechanisms. In order to study these important glycan-mediated interactions at a molecular level, carbon nanoforms such as fullerenes, carbon nanotubes or graphene and their derivatives have been identified as promising biocompatible scaffolds that can mimic the multivalent presentation of biologically relevant glycans. In this mini-review, we will summarize the most relevant examples of the last few years in the context of their applications.

The main properties of graphene derivatives facilitating optical and electrical biosensing platforms are discussed, along with how the integration of graphene derivatives, plastic, and paper can lead to innovative devices in order to simplify biosensing technology and manufacture easy-to-use, yet powerful electrical or optical biosensors. Some crucial issues to be overcome in order to bring graphene-based biosensors to the market are also underscored., The authors acknowledge the support from H2020-EU (INTCATCH Project, Ref. 689341), MINECO (Spain, MAT2014-52485-P, RTC-2014-2619-7 and Severo Ochoa Program, Grant SEV-2013-0295) and Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (2014 SGR 260).

Waterborne poly(urethane urea)s (PUDs) containing graphene derivatives with different morphologies and surface polarities were synthesized via in situ polymerization by using the acetone method. Small amounts (0.04–0.30 wt.%) of graphene oxide (GO), graphite nanoplatelets (GP) or milled graphite (MG) were mixed with polyadipate of 1,4-butanediol polyol and added during synthesis of the PUDs. The addition of graphene derivatives changed differently the degree of micro-phase separation of the poly(urethane urea)s (PUs) depending on the balance between the extent of covalent interactions between the surface functional groups on the graphene sheets and the isocyanate groups, and the number of stacked graphene sheets. Whereas MG mainly intercalated between the soft segments showing a typical behavior of nanofiller, GP and, particularly, GO showed different degrees of micro-phase separation due to more net covalent interactions with the poly(urethane urea) chains which caused higher crystallinity. The addition of graphene derivative decreased the glass transition temperature of the hard segments and increased the percentages of associated by hydrogen bond urethane and urea groups, more noticeably by adding GP and MG. Lower temperatures of decomposition and higher amounts of urethane and urea hard domains, and soft domains were found in PU + GO and PU + MG, and they showed an additional structural relaxation at 11–16 °C. PU and PU + GP had higher thermal stabilities than PU + GO and PU + MG and the addition of GP and, more markedly, GO imparted toughening to the poly(urethane urea). The T-peel strength values were higher in the joints made with PUD + GO due to the more net covalent interactions between the surface functional groups on the GO sheets and the poly(urethane urea) chains. On the other hand, the lap-shear strength of the joints made with PUD + MG and, in less extent, with PUD + GP noticeably increased.

Graphene is the last known allotropy of carbon that has fascinated the scientific community with its outstanding physical, electrical, optical, and mechanical properties. This two-dimensional, atomically thin, and the strongest known material possesses immense industrial potential in the field of surface coatings. This chapter outlines the important coating properties of graphene derivatives with an up-to-date progress in the field of functional coatings. The area of graphene-based coatings covered in this chapter includes antireflection and self-cleaning action, self-lubricating, and hard coatings for wear resistance, anticorrosion, fire-retardant, antibiofouling and pollutant adsorption, and antibacterial applications.

Smart materials have been the subject of interest for decades because of their unique structural features and impressive physicochemical properties. Cellulose nanocrystals/fibrils, a class of fascinating bio-based nanoscale materials, is a promising candidate for a wide range of applications in biomedical, pharmaceuticals, electronics, nanocomposites, membranes, supercapacitors, etc. These materials have been extensively studied both in industry and academia due to their specific characters such as biocompatibility, adaptable surface chemistry, biodegradability, low density, optical transparency, improved mechanical properties, and renewability. Similarly, graphene and its derivatives in combination with biopolymers have received much attention in designing nanocomposites with improved electrical, mechanical, and thermal properties. This chapter presents the state of the art research on the synthesis and applications of nanoscale cellulose-graphene hybrid composites. A brief summary of new observations and findings related to the available methods and materials in this area will be helpful for the readers to understand the progress on cellulose nanocrystals/fibrils, graphene derivatives, and their composite materials. The practical application of cellulose-graphene materials along with the current trends in this field is also discussed to show the future prospects for the development and applications of these materials.

Tribological performance of three ionic liquids (ILs), trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate (IL1), tributylethylphosphonium diethylphosphate (IL2) and trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate (IL3) combined with graphene nanoplatelets (GnP) as hybrid additives for a polyalphaolefin (PAO 32) base oil was studied. For this purpose, several dispersions were prepared by mixing, stirring, and then sonicating according to the following combinations: PAO 32 + (a wt%) IL + (b wt%) GnP, where a and b represent the concentration of the additives added to the PAO 32 base oil. In this study a is 0 or 1 and b is 0.05 or 0.1. Three PAO 32 + 1 wt% IL mixtures were also prepared. Thermophysical properties and stability against sedimentation of the dispersions were studied by means of a rotational viscometer and visual observation, respectively. Furthermore, friction and wear behaviors were analyzed using a ball-on-disk configuration tribometer operating in rotational mode and both a 3D optical profiler and a scanning electronic microscope, respectively. Confocal Raman microscopy was used to identify compounds in the tribofilms formed on the wear tracks. The hybrid combinations of PAO 32/ILs/GnP improved the friction reduction of the corresponding binary PAO 32/GnP nanolubricants and PAO 32/IL mixtures. Interestingly, the hybrid dispersions with low concentrations of GnP (with 0.05 wt% GnP) are more effective than those of 0.1 wt% GnP. Results also show that the addition of both 0.05 wt% graphene nanoplatelets and 1 wt% IL led to friction reductions up to 36% and wear reductions up to 27%, compared with the capabilities of neat PAO 32. IL1 and IL3, containing the trihexyltetradecylphosphonium cation, generate the hybrid lubricants with the best combined properties (stability, viscosity and tribological properties) of all the lubricants tested This work was supported by the Spanish Ministry of Science, Innovation and Universities and the ERDF programme (FEDER in Spanish) through ENE2017-86425-C2-2-R project, and by the Xunta de Galicia (ED431D 2017/06, ED431E 2018/08 and ED431C 2020/10) SI

Tissue engineering is able to produce, reconstruct, restore tissue, and organ through the scaffold. Tissue engineering formations are scaffold, cells, and growth factors. Graphene derivatives have opportunities to become materials promote endurance cells growth for tissue engineering forming a scaffold with specific characteristic in proper mechanical properties, physicochemical ability, enhance adhesion, proliferation, differentiation, and signaling to cells. Graphene and its derivatives are divided into three common types are pristine graphene as pure graphene, graphene oxide, and reduced graphene. Graphene derivatives have been used for various applications in tissue engineering, particularly for the use of induced osteogenesis, chondrogenesis, and drug delivery systems. Drug delivery is a new method to a vehicle the drugs through the site and control the drug loads inside using a scaffold. This review will demonstrate the progressive developments of the graphene derivatives scaffold-based in tissue engineering. In Preferential, we critically discuss and analyze the application of graphene derivatives in bone, cartilage tissue engineering, drug delivery system, and graphene biocompatibility. We hope the summary of this review will inspire others to studies on graphene derivatives in tissue engineering application so that it can be implemented in the next future clinical treatment.