Graphene for energy solutions and its industrialization

Advances in solar energy harvesting integrated by van der Waals graphene heterojunctions

Graphene has garnered increasing attention for solar energy harvesting owing to its unique features. However, limitations hinder its widespread adoption in solar energy harvesting, comprising the band gapless in the molecular orbital of graphene lattice, its vulnerability to oxidation in oxidative environments, and specific toxic properties that require careful consideration during development. Beyond current challenges, researchers have explored doping graphene with ionic liquids to raise the lifespan of solar cells (SCs). Additionally, they have paid attention to optimizing graphene/Si Schottky junction or Schottky barrier SCs by enhancing the conductivity and work function of graphene, improving silicon's reflectivity, and addressing passivation issues at the surface/interface of graphene/Si, resulting in significant advancements in their power conversion efficiency. Increasing the functional area of graphene-based SCs and designing efficient grid electrodes are also crucial for enhancing carrier collection efficiency. Flaws and contaminants present at the interface between graphene and silicon pose significant challenges. Despite the progress of graphene/Si-based photovoltaic cells still needs to catch up to the efficiency achieved by commercially available Si p-n junction SCs. The low Schottky barrier height, design-related challenges associated with transfer techniques, and high lateral resistivity of graphene contribute to this performance gap. To maximize the effectiveness and robustness of graphene/Si-based photovoltaic cells, appropriate interlayers have been utilized to tune the interface and modulate graphene's functionality. This mini-review will address ongoing research and development endeavors using van der Waals graphene heterojunctions, aiming to overcome the existing limitations and unlock graphene's full potential in solar energy harvesting and smart storage systems.

Reduced graphene oxide/ionic liquid composites with tunable interlayer spacing for improved charge/discharge kinetics in supercapacitors

The large specific surface area and high conductivity of reduced graphene oxide (RGO) make it a promising material for supercapacitors. However, aggregation of graphene sheets into graphitic domains upon drying hampers supercapacitor performance by drastically impeding ion transport inside electrodes. Here, we present a facile approach to optimize charge storage performance in RGO-based supercapacitors by systematically tuning their micropore structure. To this end, we combine RGOs with room temperature ionic liquids during electrode processing to impede stacking of sheets into graphitic structures with small interlayer distance. In this process, RGO sheets function as the active electrode material while ionic liquid serves both as a charge carrier and a spacer to control interlayer spacing inside electrodes and form ion transport channels. We show that composite RGO/ionic liquid electrodes with larger interlayer spacing and more ordered structure exhibit improved capacitance and charging kinetics.

Graphene: A Path-Breaking Discovery for Energy Storage and Sustainability

The global energy situation requires the efficient use of resources and the development of new materials and processes for meeting current energy demand. Traditional materials have been explored to large extent for use in energy saving and storage devices. Graphene, being a path-breaking discovery of the present era, has become one of the most-researched materials due to its fascinating properties, such as high tensile strength, half-integer quantum Hall effect and excellent electrical/thermal conductivity. This paper presents an in-depth review on the exploration of deploying diverse derivatives and morphologies of graphene in various energy-saving and environmentally friendly applications. Use of graphene in lubricants has resulted in improvements to anti-wear characteristics and reduced frictional losses. This comprehensive survey facilitates the researchers in selecting the appropriate graphene derivative(s) and their compatibility with various materials to fabricate high-performance composites for usage in solar cells, fuel cells, supercapacitor applications, rechargeable batteries and automotive sectors.

A Review on Recent Advancements of Graphene and Graphene-Related Materials in Biological Applications

Graphene is the most outstanding material among the new nanostructured carbonaceous species discovered and produced. Graphene’s astonishing properties (i.e., electronic conductivity, mechanical robustness, large surface area) have led to a deep change in the material science field. In this review, after a brief overview of the main characteristics of graphene and related materials, we present an extensive overview of the most recent achievements in biological uses of graphene and related materials.

Graphene and Lithium-Based Battery Electrodes: A Review of Recent Literature

Graphene is a new generation material, which finds potential and practical applications in a vast range of research areas. It has unrivalled characteristics, chiefly in terms of electronic conductivity, mechanical robustness and large surface area, which allow the attainment of outstanding performances in the material science field. Some unneglectable issues, such as the high cost of production at high quality and corresponding scarce availability in large amounts necessary for mass scale distribution, slow down graphene widespread utilization; however, in the last decade both basic academic and applied industrial materials research have achieved remarkable breakthroughs thanks to the implementation of graphene and related 1D derivatives. In this work, after briefly recalling the main characteristics of graphene, we present an extensive overview of the most recent advances in the development of the Li-ion battery anodes granted by the use of neat and engineered graphene and related 1D materials. Being far from totally exhaustive, due to the immense scientific production in the field yearly, we chiefly focus here on the role of graphene in materials modification for performance enhancement in both half and full lithium-based cells and give some insights on related promising perspectives.

A framework for technology transfer success factors: validation for the Graphene4Life project

Purpose

The purpose of this paper is to develop a theoretical framework for technology transfer success factors from a technology provider viewpoint and to test this framework considering the perceptions of graphene researchers from a Romanian research project (Graphene4Life).

Design/methodology/approach

The authors conducted a literature review and a case study with three units of analysis. Semi-structured face-to-face interviews and content analysis were used.

Findings

The five-category framework for technology transfer success factors from a technology provider viewpoint, which portrays success factors in an expansive way from technology to the market (technology, organization, context, collaboration and customer absorptive capacity factors), is confirmed by the qualitative analysis, while new factors in all categories are discovered.

Research limitations/implications

The results are limited given the qualitative nature of this research. The extrapolation of the results to other technologies and contexts is a scientific challenge.

Originality/value

In this paper, the authors develop, based on a detailed literature review, a framework for technology success factors from a technology provider viewpoint, which classifies technology transfer success factors in an expansive way from technology to the market (technology, organization, context, collaboration and customer absorptive capacity factors). Technology itself is settled as the foundation of the framework, underlining the need for a technology-driven technology transfer process. In comparison to existing frameworks that analyze technology transfer success factors, the present framework is a more complex one, covering all facets of the technology process. The new factors discovered through the qualitative analysis are also an important contribution of this research.

Ethical, legal, social and economics issues of graphene

There are several applications and innovations of graphene that can change the world in the areas of energy, health, and electro-electronics. Graphene is ideal for bringing together the research sector and the industry, considering that the potential market is huge, as well as profitability. The purpose of this chapter is to present social, economic, ethical, and legal issues involving graphene. Among the existing research with the use of graphene, we can highlight an antibacterial role, acceleration of the internet, membranes that capture carbon dioxide. The global graphene market has an average annual growth of 32%. There is also a manual on processes for making graphene. However, intellectual property must be used in a way that respects its social function and further research on graphene is necessary due to the market trend and applications in several areas.

Recent advances in synthesis and biosensors of two-dimensional MoS2

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted tremendous research interests due to their exciting optical properties, large surface area, intercalatable morphologies and excellent electrochemically catalytic activity. Acting as the most typical member in TMDCs family, layer-dependent molybdenum disulfide (MoS₂) with particular direct bandgap of 1.8 eV in monolayer has been widely applied in various biosensors with high sensitivity and selectivity. In this review, the preparation methods of MoS₂, together with MoS₂-based biosensors for detecting cells and biomolecules (such as glucose, DNA and antigens) would be summarized. In addition, the current challenges and future perspectives are outlined for the applications of biosensors based on 2D MoS₂.

Mechanically robust nanocomposites from screen-printable polymer/graphene nanosheet pastes

Innovative methods for producing graphene-based polymer nanocomposites with excellent mechanical robustness have become a focus for their practical utilization, existing solutions suffer from drawbacks such as limited laboratory-scale fabrication, affordability, and inadequate processability. To address these issues, we proposed a screen printing approach utilizing formulated graphene-modified water-based printable pastes to achieve inexpensive and scalable manufacturing of graphene-reinforced polymer nanocomposites. Leveraging this simple and versatile manufacturing process, mass production, as well as personalized-patterned bulk materials, can be efficiently produced using easily obtainable substrates. The surface-tailored graphene (PEI-rGO) can improve the dispersion quality and strengthen the interfacial bonding with a waterborne polyurethane (WPU) matrix, yielding an optimized enhancement effect and enhancing the tensile strength and Young's modulus about 9.46 and 19.8 times higher than those of the pure WPU, respectively. In particular, their utility as an anti-wear modifier through direct printing on textile and wear-reduction performance were investigated. Our study establishes screen printing as a general strategy to achieve facile fabrication of polymer nanocomposites at an industrial-scale in an economically viable manner, which can to a great extent bridge the gap between scientific research and real-world applications.

Graphene/Si Schottky solar cells: a review of recent advances and prospects

Graphene has attracted tremendous interest due to its unique physical and chemical properties. The atomic thickness, high carrier mobility and transparency make graphene an ideal electrode material which can be applied to various optoelectronic devices such as solar cells, light-emitting diodes and photodetectors. In recent years, there has been a growing interest in developing graphene/silicon Schottky junction solar cells and the power conversion efficiency has reached up to 15.8% with an incredible speed. In this review, we introduce the structure and mechanism of graphene/silicon solar cells briefly, and then summarize several key strategies to improve the performance of the cells. Finally, the challenges and prospects of graphene/silicon solar cells are discussed in the development of the devices in detail.

The structure and mechanism of graphene/silicon solar cells, and several key strategies to improve the performance of the cells.

Autophagic flux induced by graphene oxide has a neuroprotective effect against human prion protein fragments

Graphene oxide (GO) is a nanomaterial with newly developing biological applications. Autophagy is an intracellular degradation system that has been associated with the progression of neurodegenerative disorders. Although induction of autophagic flux by GO has been reported, the underlying signaling pathway in neurodegenerative disorders and how this is involved in neuroprotection remain obscure. We show that GO itself activates autophagic flux in neuronal cells and confers a neuroprotective effect against prion protein (PrP) (106–126)-mediated neurotoxicity. GO can be detected in SK-N-SH neuronal cells, where it triggers autophagic flux signaling. GO-induced autophagic flux prevented PrP (106–126)-induced neurotoxicity in SK-N-SH cells. Moreover, inactivation of autophagic flux blocked GO-induced neuroprotection against prion-mediated mitochondrial neurotoxicity. This is the first study to demonstrate that GO regulates autophagic flux in neuronal cells, and that activation of autophagic flux signals, induced by GO, plays a neuroprotective role against prion-mediated mitochondrial neurotoxicity. These results suggest that the nanomaterial GO may be used to activate autophagic flux and could be used in neuroprotective strategies for treatment of neurodegenerative disorders, including prion diseases.

Critical Insight into the Relentless Progression Toward Graphene and Graphene-Containing Materials for Lithium-Ion Battery Anodes

Used as a bare active material or component in hybrids, graphene has been the subject of numerous studies in recent years. Indeed, from the first report that appeared in late July 2008, almost 1600 papers were published as of the end 2015 that investigated the properties of graphene as an anode material for lithium-ion batteries. Although an impressive amount of data has been collected, a real advance in the field still seems to be missing. In this framework, attention is focused on the most prominent research efforts in this field with the aim of identifying the causes of such relentless progression through an insightful and critical evaluation of the lithium-ion storage performances (i.e., 1^st cycle irreversible capacity, specific gravimetric and volumetric capacities, average delithiation voltage profile, rate capability and stability upon cycling). The "graphene fever" has certainly provided a number of fundamental studies unveiling the electrochemical properties of this "wonder" material. However, analysis of the published literature also highlights a loss of focus from the final application. Hype-driven claims, not fully appropriate metrics, and negligence of key parameters are probably some of the factors still hindering the application of graphene in commercial batteries.

Graphene enterprise: mapping innovation and business development in a strategic emerging technology

This paper explores enterprise development and commercialization in the field of graphene. Firm characteristics and relationships, value chain positioning, and factors associated with product entry are examined for a set of 65 graphene-oriented small and medium-sized enterprises located in 16 different countries. As well as secondary sources and bibliometric methods to profile developments in graphene, we use computerized data mining and analytical techniques, including cluster and regression modeling, to identify patterns from publicly available online information on enterprise web sites. We identify groups of graphene small and medium-sized enterprises differentiated by how they are involved with graphene, the materials they target, whether they make equipment, and their orientation toward science and intellectual property. In general, access to finance and the firms' location are significant factors that are associated with graphene product introductions. We also find that patents and scientific publications are not statistically significant predictors of product development in our sample of graphene enterprises. We further identify a cohort of graphene-oriented firms that are signaling plans to develop intermediate graphene products that should have higher value in the marketplace. Our findings suggest that policy needs to ensure attention to the introduction and scale-up of downstream intermediate and final graphene products and associated financial, intermediary, and market identification support. The paper demonstrates novel data methods that can be combined with existing information for real-time intelligence to understand and map enterprise development and commercialization in a rapidly emerging and growing new technology.

Shielding the chemical reactivity using graphene layers for controlling the surface properties of carbon materials

Graphene can efficiently shield chemical interactions and gradually decrease the binding to reactive defect areas. In the present study, we have used the observed graphene shielding effect to control the reactivity patterns on the carbon surface. The experimental findings show that a surface coating with a tiny carbon layer of 1-2 nm thickness is sufficient to shield the defect-mediated reactivity and create a surface with uniform binding ability. The shielding effect was directly observed using a combination of microscopy techniques and evaluated with computational modeling. The theoretical calculations indicate that a few graphene layers can drastically reduce the binding energy of the metal centers to the surface defects by 40-50 kcal mol(-1). The construction of large carbon areas with controlled surface reactivity is extremely difficult, which is a key limitation in many practical applications. Indeed, the developed approach provides a flexible and simple tool to change the reactivity patterns on large surface areas within a few minutes.

Three dimensional Graphene aerogels as binder-less, freestanding, elastic and high-performance electrodes for lithium-ion batteries

In this work it is shown how porous graphene aerogels fabricated by an eco-friendly and simple technological process, could be used as electrodes in lithium- ion batteries. The proposed graphene framework exhibited excellent performance including high reversible capacities, superior cycling stability and rate capability. A significantly lower temperature (75 °C) than the one currently utilized in battery manufacturing was utilized for self-assembly hence providing potential significant savings to the industrial production. After annealing at 600 °C, the formation of Sn-C-O bonds between the SnO₂ nanoparticles and the reduced graphene sheets will initiate synergistic effect and improve the electrochemical performance. The XPS patterns revealed the formation of Sn-C-O bonds. Both SEM and TEM imaging of the electrode material showed that the three dimensional network of graphene aerogels and the SnO₂ particles were distributed homogeneously on graphene sheets. Finally, the electrochemical properties of the samples as active anode materials for lithium-ion batteries were tested and examined by constant current charge–discharge cycling and the finding fully described in this manuscript.

Quality of graphene on sapphire: long-range order from helium diffraction versus lattice defects from Raman spectroscopy

We report a new method to produce high-quality, transparent graphene/sapphire samples, using Cu as a catalyst.

Large-scale synthesis of soluble graphitic hollow carbon nanorods with tunable photoluminescence for the selective fluorescent detection of DNA

A high-yield synthesis of water-soluble photoluminescent carbon nanorods is described. The wsCNRs were used for the selective determination of DNA molecules via a fluorescent turn-off/turn-on mechanism.

Spatial imaging of carbon reactivity centers in Pd/C catalytic systems

Gaining insight into Pd/C catalytic systems aimed at locating reactive centers on carbon surfaces, revealing their properties and estimating the number of reactive centers presents a challenging problem. In the present study state-of-the-art experimental techniques involving ultra high resolution SEM/STEM microscopy (1 Å resolution), high brilliance X-ray absorption spectroscopy and theoretical calculations on truly nanoscale systems were utilized to reveal the role of carbon centers in the formation and nature of Pd/C catalytic materials. Generation of Pd clusters in solution from the easily available Pd2dba3 precursor and the unique reactivity of the Pd clusters opened an excellent opportunity to develop an efficient procedure for the imaging of a carbon surface. Defect sites and reactivity centers of a carbon surface were mapped in three-dimensional space with high resolution and excellent contrast using a user-friendly nanoscale imaging procedure. The proposed imaging approach takes advantage of the specific interactions of reactive carbon centers with Pd clusters, which allows spatial information about chemical reactivity across the Pd/C system to be obtained using a microscopy technique. Mapping the reactivity centers with Pd markers provided unique information about the reactivity of the graphene layers and showed that >2000 reactive centers can be located per 1 μm2 of the surface area of the carbon material. A computational study at a PBE-D3-GPW level differentiated the relative affinity of the Pd2 species to the reactive centers of graphene. These findings emphasized the spatial complexity of the carbon material at the nanoscale and indicated the importance of the surface defect nature, which exhibited substantial gradients and variations across the surface area. The findings show the crucial role of the structure of the carbon support, which governs the formation of Pd/C systems and their catalytic activity.

Mechanical properties of bulk carbon nanostructures: effect of loading and temperature

Carbon-based bulk nanostructures are believed to entail certain advantages over their parent low-dimensional materials and are promising candidates for supercapacitors due to their unique properties such as extremely high specific surface area and high conductivity. Herein the mechanical and structural properties of four types of carbon nanopolymorph-based nanomaterials were calculated using molecular dynamics simulations. Bulk carbon nanostructures composed of structural units of bent graphene flakes, short carbon nanotubes, fullerenes and their mixture were considered. The effect of the loading scheme and temperature was studied and constitutive relationships describing the deformation of the materials were given. The simulation results revealed that the effect of the loading scheme significantly depends on the type of structural units, and was slightly affected by the temperature especially for high densities. The constitutive equations obtained in this work can be applied to describe the mechanical behavior of new bulk carbon nanostructures.

3D graphene nanomaterials for binder-free supercapacitors: scientific design for enhanced performance

Because of the excellent intrinsic properties, especially the strong mechanical strength, extraordinarily high surface area and extremely high conductivity, graphene is deemed as a versatile building block for fabricating functional materials for energy production and storage applications. In this article, the recent progress in the assembly of binder-free and self-standing graphene-based materials, as well as their application in supercapacitors are reviewed, including electrical double layer capacitors, pseudocapacitors, and asymmetric supercapacitors. Various fabrication strategies and the influence of structures on the capacitance performance of 3D graphene-based materials are discussed. We finally give concluding remarks and an outlook on the scientific design of binder-free and self-standing graphene materials for achieving better capacitance performance.

High density decoration of noble metal nanoparticles on polydopamine-functionalized molybdenum disulphide

Here, we report a highly stable colloidal suspension of nanoparticles (i.e., Pt and Au)-deposited MoS2 sheets, in which polydopamine (PD) serves as surface functional groups. The adoption of polydopamine coating onto the MoS2 surface enables homogeneous deposition of nanoparticles in an aqueous solution. As-synthesized nanohybrids are thoroughly characterized by transmission electron microscopy (TEM), Raman spectroscopy, and X-ray diffraction (XRD) measurement. These intensive investigations reveal that noble metal nanocrystals are uniformly distributed on the surface of ultrathin MoS2 sheets (∼4 layers). Moreover, as-prepared Au/PD/MoS2 nanohybrids can be applied as a heterogeneous catalyst for reduction of 4-nitrophenol to 4-aminophenol, and they exhibit an excellent catalytic activity.

Three dimensional metal oxides–graphene composites and their applications in lithium ion batteries

The review focuses on the effects of morphology, composition and interaction of 3d metal oxide–graphene composites on the performances of libs.

A general strategy to create RNA aptamer sensors using "regulated" graphene oxide adsorption

Aptamers have been used as molecular recognition elements for sensor development in combination with graphene oxide (GO), a nanomaterial with properties including fluorescence quenching, and selective adsorption of single-stranded nucleic acids. However, previous sensor designs based on aptamer-GO adsorption have not demonstrated wide applicability, and few studies have explored the potential of RNA aptamers. Herein, we present a new sensing strategy based on "regulated" GO adsorption that can accommodate various RNA aptamers. First, adsorption of a fluorophore-labeled RNA aptamer to GO results in fluorescence quenching due to close proximity of the fluorophore to GO. The addition of a complementary, "blocking" DNA strand (BDNA) that hybridizes to the 3'-end of the aptamer, weakens aptamer-GO interaction, and enables increased fluorescent signal generation upon the addition of target, as the sensing system becomes completely separated from GO. Our findings can be applied toward different aptamers, and adapted to enhance generality of existing sensing applications.