Graphene growth on silicon carbide: A review Mishra, Neeraj; Boeckl, John; Motta, Nunzio ...
Physica status solidi. A, Applications and materials science,
September 2016, Letnik:
213, Številka:
9
Journal Article
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Graphene has been widely heralded over the last decade as one of the most promising nanomaterials for integrated, miniaturized applications spanning from nanoelectronics, interconnections, thermal ...management, sensing, to optoelectronics. Graphene grown on silicon carbide is currently the most likely candidate to fulfill this promise. As a matter of fact, the capability to synthesize high‐quality graphene over large areas using processes and substrates compatible as much as possible with the well‐established semiconductor manufacturing technologies is one crucial requirement. We review here, the enormous scientific and technological advances achieved in terms of epitaxial growth of graphene from thermal decomposition of bulk silicon carbide and the fine control of the graphene electronic properties through intercalation. Finally, we discuss perspectives on epitaxial graphene growth from silicon carbide on silicon, a particularly challenging area that could result in maximum benefit for the integration of graphene with silicon technologies.
This article provides a comprehensive review of the scientific progress of epitaxial graphene on silicon carbide and sketches its future perspectives. Strong focus is dedicated to recent progress in graphene growth on silicon carbide films onto silicon substrates. Integration of graphene with silicon is of great interest not just because of lower fabrication costs, but also since it would offer seamless integration with a vast array of silicon micro‐ and nano‐ technologies for electronics, photonics, and micro‐electro‐mechanical systems.
The world is facing an energy crisis due to exponential population growth and limited availability of fossil fuels. Over the last 20 years, carbon, one of the most abundant materials found on earth, ...and its allotrope forms such as fullerenes, carbon nanotubes and graphene have been proposed as sources of energy generation and storage because of their extraordinary properties and ease of production. Various approaches for the synthesis and incorporation of carbon nanomaterials in organic photovoltaics and supercapacitors have been reviewed and discussed in this work, highlighting their benefits as compared to other materials commonly used in these devices. The use of fullerenes, carbon nanotubes and graphene in organic photovoltaics and supercapacitors is described in detail, explaining how their remarkable properties can enhance the efficiency of solar cells and energy storage in supercapacitors. Fullerenes, carbon nanotubes and graphene have all been included in solar cells with interesting results, although a number of problems are still to be overcome in order to achieve high efficiency and stability. However, the flexibility and the low cost of these materials provide the opportunity for many applications such as wearable and disposable electronics or mobile charging. The application of carbon nanotubes and graphene to supercapacitors is also discussed and reviewed in this work. Carbon nanotubes, in combination with graphene, can create a more porous film with extraordinary capacitive performance, paving the way to many practical applications from mobile phones to electric cars. In conclusion, we show that carbon nanomaterials, developed by inexpensive synthesis and process methods such as printing and roll-to-roll techniques, are ideal for the development of flexible devices for energy generation and storage - the key to the portable electronics of the future.
Measuring gases for environmental monitoring is a demanding task that requires long periods of observation and large numbers of sensors. Wireless Sensor Networks (WSNs) and Unmanned Aerial Vehicles ...(UAVs) currently represent the best alternative to monitor large, remote, and difficult access areas, as these technologies have the possibility of carrying specialized gas sensing systems. This paper presents the development and integration of a WSN and an UAV powered by solar energy in order to enhance their functionality and broader their applications. A gas sensing system implementing nanostructured metal oxide (MOX) and non-dispersive infrared sensors was developed to measure concentrations of CH4 and CO2. Laboratory, bench and field testing results demonstrate the capability of UAV to capture, analyze and geo-locate a gas sample during flight operations. The field testing integrated ground sensor nodes and the UAV to measure CO2 concentration at ground and low aerial altitudes, simultaneously. Data collected during the mission was transmitted in real time to a central node for analysis and 3D mapping of the target gas. The results highlights the accomplishment of the first flight mission of a solar powered UAV equipped with a CO2 sensing system integrated with a WSN. The system provides an effective 3D monitoring and can be used in a wide range of environmental applications such as agriculture, bushfires, mining studies, zoology and botanical studies using a ubiquitous low cost technology.
Supercapacitors are electric storage devices which can be recharged very quickly and release a large amount of power. In the automotive market they cannot yet compete with Li-ion batteries in terms ...of energy content, but their capacity is improving every year. They are already used as ancillary devices to store energy from braking and to provide the necessary boost during quick accelerations, ultimately increasing the efficiency of the vehicle.
This paper will introduce the basic physics of supercapacitors and provide a brief review of state-of-the art of materials, technological advances and applications, with an eye to their future usage in cars should the present trends in electrical storage continue.
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Electrospun one-dimensional (1D) nanostructures are rapidly emerging as key enabling components in gas sensing due to their unique electrical, optical, magnetic, thermal, mechanical and chemical ...properties. 1D nanostructures have found applications in numerous areas, including healthcare, energy storage, biotechnology, environmental monitoring, and defence/security. Their enhanced specific surface area, superior mechanical properties, nanoporosity and improved surface characteristics (in particular, uniformity and stability) have made them important active materials for gas sensing applications. Such highly sensitive and selective elements can be embedded in sensor nodes for internet-of-things applications or in mobile systems for continuous monitoring of air pollutants and greenhouse gases as well as for monitoring the well-being and health in everyday life. Herein, we review recent developments of gas sensors based on electrospun 1D nanostructures in different sensing platforms, including optical, conductometric and acoustic resonators. After explaining the principle of electrospinning, we classify sensors based on the type of materials used as an active sensing layer, including polymers, metal oxide semiconductors, graphene, and their composites or their functionalized forms. The material properties of these electrospun fibers and their sensing performance toward different analytes are explained in detail and correlated to the benefits and limitations for every approach.
•Synthesis methods and placement of gold nanoparticles in organic solar cells.•Plasmonic effect of the nanoparticles and its influence on the efficiency.•Choice of size and distance of the ...nanoparticles to improve efficiency.•Efficiency improvement in our novel plasmonic device.
Light trapping, due to the embedding of metallic nanoparticles, has been shown to be beneficial for a better photoabsorption in organic solar cells. Researchers in plasmonics and in the organic photovoltaics fields are working together to improve the absorption of sunlight and the photon–electron coupling to boost the performance of the devices.
Recent advances in the field of plasmonics for organic solar cells focus on the incorporation of gold nanoparticles. This article reviews the different methods to produce and embed gold nanoparticles into organic solar cells. In particular, concentration, size and geometry of gold nanoparticles are key factors that directly influence the light absorption in the devices. It is shown that a careful choice of size, concentration and location of gold nanoparticles in the device result in an enhancement of the power conversion efficiencies when compared to standard organic solar cell devices.
Our latest results on gold nanoparticles embedded in on organic solar cell devices are included. We demonstrate that embedded gold nanoparticles, created by depositing and annealing a gold film on transparent electrode, generate a plasmonic effect which can be exploited to increase the power conversion efficiency of a bulk heterojunction solar cell up to 10%.
In this work, the covalent attachment of an amine functionalized metal‐organic framework (UiO‐66‐NH2 = Zr6O4(OH)4(bdc‐NH2)6; bdc‐NH2 = 2‐amino‐1,4‐benzenedicarboxylate) (UiO‐Universitetet i Oslo) to ...the basal‐plane of carboxylate functionalized graphene (graphene acid = GA) via amide bonds is reported. The resultant GA@UiO‐66‐NH2 hybrid displayed a large specific surface area, hierarchical pores and an interconnected conductive network. The electrochemical characterizations demonstrated that the hybrid GA@UiO‐66‐NH2 acts as an effective charge storing material with a capacitance of up to 651 F g−1, significantly higher than traditional graphene‐based materials. The results suggest that the amide linkage plays a key role in the formation of a π‐conjugated structure, which facilitates charge transfer and consequently offers good capacitance and cycling stability. Furthermore, to realize the practical feasibility, an asymmetric supercapacitor using a GA@UiO‐66‐NH2 positive electrode with Ti3C2TX MXene as the opposing electrode has been constructed. The cell is able to deliver a power density of up to 16 kW kg−1 and an energy density of up to 73 Wh kg−1, which are comparable to several commercial devices such as Pb‐acid and Ni/MH batteries. Under an intermediate level of loading, the device retained 88% of its initial capacitance after 10 000 cycles.
A facile method for the preparation of graphene/metal–organic framework (MOF) hybrids with an amine‐functionalized MOF and carboxylate‐functionalized graphene via amide bonds for capacitance applications is demonstrated.
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•Hybrid sensors were developed using SnS2 nanoflakes and a thin layer of rGO.•Sensors were tested towards different analytes: NO2, CH4, NH3, C2H6O, C3H6O, H2O.•The sensor showed ...exclusive selectivity and reversibility to NO2.•low detection limit of 0.6 ppm and a response of 9.8% to NO2 was recorded at 80 °C.•A sensing mechanism for the hybrid film based on the sensor behaviour is proposed.
The excellent sensing capabilities of SnS2 and the electrical properties of reduced graphene oxide (rGO) are combined to achieve a low-operating temperature NO2 gas sensor. Conductometric gas sensors based on hybrid films of 2D SnS2-rGO are fabricated and evaluated for humidity and different target gases including NO2, CH4, NH3, C2H5OH (ethanol), (CH3)2CO (acetone) at different operating temperatures ranging from 25 °C to 100 °C. The sensor shows exclusive selectivity and reversibility to NO2 as compared to the other analytes, with a low detection limit of 0.6 ppm and a response of 9.8% at 80 °C. The sensing mechanism of the hybrid SnS2-rGO system is described by analysing the effect of NO2 gas on the depletion region established at the interface between SnS2 and rGO layers.
Supercapacitors are a highly promising class of energy storage devices due to their high power density and long life cycle. Conducting polymers (CPs) and organic molecules are potential candidates ...for improving supercapacitor electrodes due to their low cost, large specific pseudocapacitance and facile synthesis methods. Graphene, with its unique two-dimensional structure, shows high electrical conductivity, large specific surface area and outstanding mechanical properties, which makes it an excellent material for lithium ion batteries, fuel cells and supercapacitors. The combination of CPs and graphene as electrode material is expected to boost the properties of supercapacitors. In this review, we summarize recent reports on three different CP/graphene composites as electrode materials for supercapacitors, discussing synthesis and electrochemical performance. Novel flexible and wearable devices based on CP/graphene composites are introduced and discussed, with an eye to recent developments and challenges for future research directions.
Enabling fast ion diffusion in thick electrodes (100–200 µm, ~ 10 mg cm−2) is critical for their practical application in state-of-the-art supercapacitors (SCs). We developed a three-dimensional (3D) ...boron, nitrogen, and phosphorus ternary-doped holey graphene hydrogel (BNP-HGH) film to achieve an optimized porous structure with a high electrical conductivity, large ion accessible surface area, efficient electron and ion transport pathways, as well as high ion adsorption capacity. The binder-free BNP-HGH electrode can deliver a specific capacitance of 350 F g−1 and a volumetric capacity of 234 F cm−3, which are the best performance reported so far for graphene-based SCs using an organic electrolyte. Fully packaged SCs using the BNP-HGH electrodes with a commercial level graphene mass loading (150 µm, ~ 10 mg cm−2) can deliver ultrahigh stack gravimetric and volumetric energy densities of 38.5 Wh kg−1 and 57.4 Wh L−1, respectively, which are comparable to those of lead-acid batteries (35–40 Wh kg−1 and 50–90 Wh L−1) while maintaining an ultrahigh power density of 83 kW kg−1 (~ 55 kW L−1) as well as a long cycle life (81.3% capacitance retention over 50,000 cycles). The high energy and power densities bridge the gap between traditional SCs and batteries, and should be very useful in practical applications.
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•A three-dimensional ternary doped holey graphene hydrogel (BNP-HGH) film is developed.•The BNP-HGH film electrode delivers a superior capacitance of 350 F g−1 (234 F cm−3).•It exhibits ultrahigh energy density even with a high mass loading of 10 mg cm-2.•The assembled device shows an impressive stack energy density of 57.4 Wh L−1.
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