Method For Synthesis Of Graphene Research Articles

Laser micro/nano structuring of three-dimensional porous gradient graphene: Advanced heater for antibacterial surfaces and ion-selective electrode for sweat sensing

The development of three-dimensional (3D) gradient porous graphene (GPG) patterns, leveraging the remarkable properties and unique structure of graphene, has garnered considerable attention owing to their excellent electrochemical and electrothermal performances. Among the numerous graphene synthesis methods, laser-induced graphene (LIG) stands out as an eco-friendly and practical approach for creating patterned graphene structures on commercial films, with synthetic details varying depending on the application. Unlike conventional LIG with uniform geometric characteristics, we developed an innovative approach for circular line-scribed ultraviolet (UV)-LIG patterning; these approaches utilize a high overlapping factor and low power to achieve uneven graphitization. A comprehensive analysis of the 3D GPG was conducted via specific surface area measurements, contact angle analyses, sheet resistance measurements, X-ray photoelectron spectroscopy, and Raman spectroscopy. These 3D GPG structures exhibit large surface areas, low sheet resistance, and superior ion transport, thus improving heater and ion-selective electrode (ISE) performances. The fabricated 3D GPG heaters were successfully applied to antibacterial surfaces, and the ISEs were applied in a sweat sensor was demonstrated owing to the remarkable combination of high surface area, low electrical resistance, and unique 3D porous structure.

Site-Selective Synthesis of Bilayer Graphene on Cu Substrates Using Titanium as a Carbon Diffusion Barrier.

Chemical vapor deposition (CVD) is a widely used method for graphene synthesis, but it struggles to produce large-area uniform bilayer graphene (BLG). This study introduces a novel approach to meet the demands of large-scale integrated circuit applications, challenging the conventional reliance on uniform BLG over extensive areas. We developed a unique method involving the direct growth of bilayer graphene arrays (BLGA) on Cu foil substrates using patterned titanium (Ti) as a diffusion barrier. The use of the Ti layer can effectively control carbon atom diffusion through the Cu foil without altering the growth conditions or compromising the graphene quality, thereby showcasing its versatility. The approach allows for targeted BLG growth and achieved a yield of 100% for a 10 × 10 BLG units array. Then a 10 × 10 BLG memristor array was fabricated, and a yield of 96% was achieved. The performances of these devices show good uniformity, evidenced by the set voltages concentrated around 4 V, and a high resistance state (HRS) to low resistance state (LRS) ratio predominantly around 107, reflecting the spatial uniformity of the prepared BLGA. This study provides insight into the BLG growth mechanism and opens new possibilities for BLG-based electronics.

Electrochemical exfoliation of graphene from pencil lead

Addressing an ever-increasing demand for graphene in recent years, simple, accessible, and effective graphene synthesis methods are essential. One of such methods is to use a highly oriented pyrolytic graphite (HOPG) to perform an electrochemical exfoliation. While this is one of the simplest and most cost-effective methods, the limited availability and price of HOPG hinders its usage. Our study proposed a simple and economical electrochemical exfoliation of pencil lead, producing graphene with properties comparable to that produced from HOPG. The electrical properties are determined by depositing graphene onto a screen-printed electrode. Graphene from pencil leads can achieve an electrical resistance as low as 1.86 kΩ, marking over 80% improvement in electrical performance compared to bare electrodes. This finding provides an alternative for the synthesis of graphene, increasing its availability and the cost-effectiveness as well as contributing towards a potential commercialization of the method in the future.

Repeated fast selective growth of prepatternable monolayer graphene of electronic quality

Pattern formation is becoming indispensable in many applications of high-quality synthetic graphene. Nevertheless, the use of multiple lithography and etching steps can often degrade the properties of graphene due to residual disorder. Here, we report a facile, selective, and recyclable method for graphene synthesis from acetylene (C2H2) via catalytic chemical vapor deposition on a bimetal catalyst (Cu–Ni alloy). The synergistic pairing of the Cu–Ni alloy and C2H2 facilitates a rapid (ca. 1 min) synthesis of high-quality graphene under an intermediate temperature condition, e.g., 800 °C, that is quite relaxed from the far-flung method based on a Cu–CH4 pair. Prepatterned Cu–Ni alloy not only produces monolayer graphene patterns without any postprocessing but is also detachable from the resultant graphene patterns electrochemically, hinting at catalyst recyclability. Our test device of an organic field-effect transistor based on the prepatterned monolayer graphene outperforms its top-down counterpart that has undergone lithography and etching. Our facile selective growth of prepatternable monolayer graphene at intermediate temperatures, along with catalyst recyclability, may altogether lend adaptability, productivity, and sustainability to graphene-incorporated applications.

Laser‐Induced Porous Graphene/CuO Composite for Efficient Interfacial Solar Steam Generation

AbstractInterfacial solar steam generation can produce clean water in an environmentally friendly and efficient way. The evaporator employing graphene as a photothermal conversion material represents an excellent paradigm within the realm of interfacial evaporators. However, existing graphene materials exhibit a certain degree of hydrophobicity and are associated with intricate manufacturing processes. Hence, the study proposes a hydrophilic composite graphene‐based material incorporating CuO, which is fabricated through a straightforward laser‐induced graphene synthesis method directly onto a polyimide film coated with CuCl2. Due to the fast capillary performance endowed by the enhanced hydrophilicity and hierarchical structural morphology, the assembled laser‐induced‐graphene evaporator achieves an evaporation rate of 2.54 kg m−2 h−1 under 1 sun irradiation with an evaporation efficiency of 91.1%, while also demonstrating excellent desalination capabilities. The as‐prepared graphene‐based evaporator has significant potential for desalination and wastewater treatment applications, offering an effective solution to address clean water challenges in remote areas.

Investigation of picosecond laser-induced graphene for dopamine sensing: Influence of laser wavelength on structural and electrochemical performance

This research focuses on a straightforward synthesis method for laser-induced graphene using green (532 nm) and UV (355 nm) picosecond laser irradiation of graphene oxide dispersion. Structural analysis revealed that the laser operating at 355 nm is more favorable to producing a product with a higher content of the restored sp2 network, a higher graphene in-plane crystallite size, a higher concentration of pyrrolic N, and higher values of the optical bandgap. Conversely, the 532 nm laser yielded a sample with higher concentrations of epoxy groups, sp3 defects, and amorphous carbon. Electrochemical analysis for dopamine determination showed potential for both samples as electrode materials. However, the analytical parameters of the sample treated with the 355 nm laser surpass those of the 532 nm laser. It was assumed that the enhanced electrochemical activity results from the presence of pyrrolic N and vacancies in the structure of the sample treated with the 355 nm laser.

Unconventional eco-friendly synthesis of graphene and its electrochemical analysis

In response to the growing demand for sustainable graphene synthesis methods, traditionally characterized by harsh conditions and prolonged processing, we present an innovative approach. Here, graphene is synthesized utilizing melaleuca alternifolia, a natural resource, under mild conditions of cold plasma. This method not only aligns with the increasing need for environmentally friendly processes but also boasts efficiency, producing graphene within seconds. Our investigation employs various analytical techniques, including Raman spectroscopy, confirming the successful synthesis of graphene. The distinctive peaks identified in the spectroscopic analysis validate the high quality of the graphene material produced. Beyond synthesis, our study delves into the electrochemical properties of the synthesized graphene. Rigorous testing with real biomolecules reveals enhanced current peaks, underscoring the potential applications of graphene in the realm of electrochemical sensing. This work contributes to advancing sustainable and efficient graphene synthesis while exploring its promising properties for practical applications.

Sensitive and selective detection of heavy metal ions and organic pollutants with graphene-integrated sensing platforms.

Graphene-based sensors have emerged as promising tools for environmental monitoring due to their exceptional properties such as high surface area, excellent electrical conductivity, and sensitivity to various analytes. This paper presents a review of recent advancements in the development and application of graphene-based sensors for the detection of heavy metal ions and organic pollutants. These sensors employ either graphene or its derivatives, often in combination with graphene hybrid nanocomposites, as the primary sensing material. The synthesis methods of graphene and sensing mechanisms of graphene-based sensors are discussed. Furthermore, performance metrics including the determination range and detection limits of these sensors are itemized. The potential challenges and future directions in the field of graphene-based sensors for environmental monitoring are also highlighted. Overall, this review provides valuable insights into the current state-of-the-art technologies and paves the way for the development of highly efficient and reliable sensors for environmental monitoring purposes.

Graphene and Its Derivatives: Properties, Synthesis, and Applications in Wearable and Transparent Sensors

Graphene is a 2-D carbon-based material consisting of a single layer or few layers that has revolutionized the scientific world with its potential applications in various types of sensors, especially wearable and transparent devices. This material possesses astonishing thermal, electrical/electronic, optical, and excellent mechanical properties. It has the potential to replace carbon nanotubes (CNTs) due to its low cost and relatively similar properties. There is a need to work on different graphene synthesis methods, optimize various parameters, reduce costs, and achieve large-scale production. This study discusses in detail graphene, graphene oxide, reduced graphene oxide, their properties, various synthesis methods, and potential applications. Among these methods, we have found that Hummer’s method is relatively better for producing low-cost graphene on an industrial scale. However, there is a need to optimize Hummer’s method parameters, such as finding the right chemical to reduce graphene oxide and synthesizing few layers of graphene with high conductivity.

Methods of obtaining graphene

Graphene was first obtained at the beginning of the 21st century, and since then various methods have been developed for its synthesis. This variety is explained by the natural layered structure of graphite. A large number of methods is based on the idea of separating graphite layers. They are considered relatively cheap, productive and available in almost all laboratories. Another group of graphene synthesis methods is based on the concept of creating graphene sheets from individual carbon atoms. These methods are technologically more complex and require appropriate specialized equipment. Due to the wide range of graphene synthesis methods and their availability, researchers from all over the world can conduct experiments with this unique material in various scientific fields. This makes graphene an extremely promising object for further scientific research.

Research on the important properties of Graphene/AgNWs composites

Nano-material refers to small particles with a size within 100nm. It has received widespread attention from many industries because of its different performances of the light, electricity, heat and other industries that are different from conventional materials. In recent years, new nanomaterials such as AgNWs and graphene have attracted considerable attention worldwide due to their extremely high electrical conductivity and light transmission. However, AgNWs are less stable and graphene is less homogeneous in terms of resistance; thus, improving the performance by hybridizing the two composites has become a major research goal. In this paper, the synthesis methods of graphene and graphene/AgNWs composites are presented, and various properties of the composites, such as electrical conductivity, flexibility, and stress-strain capability, are also presented. The comparative analysis of these properties concludes that the excellent properties of graphene/silver nanowire composites have great potential for development and still need to be explored continuously.

Green fabrication of unoxidized graphene by combination of frozen dispersion and multimode microwave thermal shock

Next-generation electronic materials must be produced and used sustainably. Nanocarbon materials have attracted much attention as next-generation materials because they have excellent properties and can be made from readily available and inexpensive raw materials. Among them, graphene is highly expected as a material that realizes high performance and energy saving in electric devices. It has excellent properties such as high electrical conductivity, high strength, and light weight. However, the current synthesis method for graphene requires the use of toxic chemicals such as strong oxidants and a large amount of energy consumption due to use of high vacuum and high temperature. Those requirements increases the environmental impact and cost. Therefore, a simple, environmentally friendly, inexpensive, and innovative process is required for the practical use of graphene. We have developed a novel process with a new mechanism using inexpensive and safe raw materials such as graphite, ice, and simple organic solvents and general equipment such as a microwave oven. The combination of the thermal expansion properties of graphite and the selective heating properties of microwaves created the new process. This paper shows that graphene synthesis can be achieved easily and cost-effectively using familiar equipment and materials by combining fundamental physical properties and phenomena.

Strategies and Applications of Graphene and Its Derivatives-Based Electrochemical Sensors in Cancer Diagnosis.

Graphene is an emerging nanomaterial increasingly being used in electrochemical biosensing applications owing to its high surface area, excellent conductivity, ease of functionalization, and superior electrocatalytic properties compared to other carbon-based electrodes and nanomaterials, enabling faster electron transfer kinetics and higher sensitivity. Graphene electrochemical biosensors may have the potential to enable the rapid, sensitive, and low-cost detection of cancer biomarkers. This paper reviews early-stage research and proof-of-concept studies on the development of graphene electrochemical biosensors for potential future cancer diagnostic applications. Various graphene synthesis methods are outlined along with common functionalization approaches using polymers, biomolecules, nanomaterials, and synthetic chemistry to facilitate the immobilization of recognition elements and improve performance. Major sensor configurations including graphene field-effect transistors, graphene modified electrodes and nanocomposites, and 3D graphene networks are highlighted along with their principles of operation, advantages, and biosensing capabilities. Strategies for the immobilization of biorecognition elements like antibodies, aptamers, peptides, and DNA/RNA probes onto graphene platforms to impart target specificity are summarized. The use of nanomaterial labels, hybrid nanocomposites with graphene, and chemical modification for signal enhancement are also discussed. Examples are provided to illustrate applications for the sensitive electrochemical detection of a broad range of cancer biomarkers including proteins, circulating tumor cells, DNA mutations, non-coding RNAs like miRNA, metabolites, and glycoproteins. Current challenges and future opportunities are elucidated to guide ongoing efforts towards transitioning graphene biosensors from promising research lab tools into mainstream clinical practice. Continued research addressing issues with reproducibility, stability, selectivity, integration, clinical validation, and regulatory approval could enable wider adoption. Overall, graphene electrochemical biosensors present powerful and versatile platforms for cancer diagnosis at the point of care.

Scalable Production of 2D Material Heterostructure Textiles for High-Performance Wearable Supercapacitors.

Wearable electronic textiles (e-textiles) have emerged as a promising platform for seamless integration of electronic devices into everyday life, enabling nonintrusive monitoring of human health. However, the development of efficient, flexible, and scalable energy storage solutions remains a significant challenge for powering such devices. Here, we address this challenge by leveraging the distinct properties of two-dimensional (2D) material based heterostructures to enhance the performance of wearable textile supercapacitors. We report a highly scalable and controllable synthesis method for graphene and molybdenum disulfide (MoS2) through a microfluidization technique. Subsequently, we employ an ultrafast and industry-scale hierarchical deposition approach using a pad-dry method to fabricate 2D heterostructure based textiles with various configurations suitable for wearable e-textiles applications. Comparative analyses reveal the superior performance of wearable textile supercapacitors based on 2D material heterostructures, demonstrating excellent areal capacitance (∼105.08 mF cm-2), high power density (∼1604.274 μW cm-2) and energy density (∼58.377 μWh cm-2), and outstanding capacitive retention (∼100% after 1000 cycles). Our findings highlight the pivotal role of 2D material based heterostructures in addressing the challenges of performance and scalability in wearable energy storage devices, facilitating large-scale production of high-performance wearable supercapacitors.

Advancements in Plasma-Enhanced Chemical Vapor Deposition for Producing Vertical Graphene Nanowalls.

In recent years, vertical graphene nanowalls (VGNWs) have gained significant attention due to their exceptional properties, including their high specific surface area, excellent electrical conductivity, scalability, and compatibility with transition metal compounds. These attributes position VGNWs as a compelling choice for various applications, such as energy storage, catalysis, and sensing, driving interest in their integration into next-generation commercial graphene-based devices. Among the diverse graphene synthesis methods, plasma-enhanced chemical vapor deposition (PECVD) stands out for its ability to create large-scale graphene films and VGNWs on diverse substrates. However, despite progress in optimizing the growth conditions to achieve micrometer-sized graphene nanowalls, a comprehensive understanding of the underlying physicochemical mechanisms that govern nanostructure formation remains elusive. Specifically, a deeper exploration of nanometric-level phenomena like nucleation, carbon precursor adsorption, and adatom surface diffusion is crucial for gaining precise control over the growth process. Hydrogen's dual role as a co-catalyst and etchant in VGNW growth requires further investigation. This review aims to fill the knowledge gaps by investigating VGNW nucleation and growth using PECVD, with a focus on the impact of the temperature on the growth ratio and nucleation density across a broad temperature range. By providing insights into the PECVD process, this review aims to optimize the growth conditions for tailoring VGNW properties, facilitating applications in the fields of energy storage, catalysis, and sensing.

Two-Step Thermal Transformation of Multilayer Graphene Using Polymeric Carbon Source Assisted by Physical Vapor Deposited Copper.

Direct in situ growth of graphene on dielectric substrates is a reliable method for overcoming the challenges of complex physical transfer operations, graphene performance degradation, and compatibility with graphene-based semiconductor devices. A transfer-free graphene synthesis based on a controllable and low-cost polymeric carbon source is a promising approach for achieving this process. In this paper, we report a two-step thermal transformation method for the copper-assisted synthesis of transfer-free multilayer graphene. Firstly, we obtained high-quality polymethyl methacrylate (PMMA) film on a 300 nm SiO2/Si substrate using a well-established spin-coating process. The complete thermal decomposition loss of PMMA film was effectively avoided by introducing a copper clad layer. After the first thermal transformation process, flat, clean, and high-quality amorphous carbon films were obtained. Next, the in situ obtained amorphous carbon layer underwent a second copper sputtering and thermal transformation process, which resulted in the formation of a final, large-sized, and highly uniform transfer-free multilayer graphene film on the surface of the dielectric substrate. Multi-scale characterization results show that the specimens underwent different microstructural evolution processes based on different mechanisms during the two thermal transformations. The two-step thermal transformation method is compatible with the current semiconductor process and introduces a low-cost and structurally controllable polymeric carbon source into the production of transfer-free graphene. The catalytic protection of the copper layer provides a new direction for accelerating the application of graphene in the field of direct integration of semiconductor devices.

Ultrafast synthesis of novel coal-based graphene and its anticorrosion properties of epoxy/graphene nanocomposite coatings

Graphene has a wide range of applications in anti-corrosion coatings due to its excellent barrier, shielding, and mechanical properties. However, traditional graphene synthesis methods, including the production of graphene oxide (GO) using Homer's method and then its reduction in the form of reduced graphene oxide (rGO) are time-consuming, energy-consuming, and environmentally polluting, which limits their application in anti-corrosion coatings. This study leveraged the capabilities of flash Joule heating (FJH) to synthesize flash coal-based graphene (FCBG) from Taixi anthracite (TA) within 200 ms without pretreatments or chemical reagents. The FJH had the advantages of low energy consumption and being environmentally friendly. Compared with the rGO, the FCBG prepared by FJH was characterized by fewer defects, larger carbon sheets, and a turbostratic structure. Moreover, carbon steel Q235 was used as the substrate to prepare anti-corrosion coatings by mixing FCBG at different flash voltages with epoxy resin (EP). Based on this, the electrochemical performance of different coatings was compared before and after salt spray corrosion. The results demonstrated that the FCBG composite anti-corrosion coating (EP/FCBG190) prepared using EP and FCBG synthesized at 190 V in the FJH, displayed stronger corrosion resistance than the EP and rGO composite coating (EP/rGO). The FJH synthesis process provides a feasible route for improving the synthesis process of the anti-corrosion coatings and the high value-added utilization of coal.

An electrochemical approach for bulk production of reduced graphene oxide from graphite oxide followed by thermal reduction

A high-quality, bulk synthesis of graphene that is inexpensive, and environmentally safe is highly desired because of the broad range of applications. In comparison to the chemical vapor deposition (CVD) method, epitaxial growth on silicon carbide, etc., the electrochemical approach is thought to be the most straightforward and eco-friendly way for the cost-effective bulk production of graphene from graphite. Moreover, the thermal reduction method appears to be a particularly cost-effective way to eliminate oxygen-containing functional groups when compared to chemical reduction. The yield of graphene is also impacted by the choice of cathode low-cost, which is extremely important and played a critical role during the synthesis process. In this work, we demonstrate a green, eco-friendly, and cost-effective electrochemical method for the synthesis of reduced graphene oxide (RGO) followed by thermal reduction. To accomplish electrochemical exfoliation for the graphene synthesis, a constant DC power of 65[Formula: see text]W ([Formula: see text][Formula: see text]V and [Formula: see text][Formula: see text]amp) has been supplied within an electrolytic cell that contains 2[Formula: see text]M of sulphuric acid as an electrolytic solution. The aluminium has been utilized as a cathode in place of the platinum, carbon cathode, etc. Moreover, to prepare the electrolytic solution and for the sonication process, sterilized water has been used in place of DI (deionized water). Thereafter, previously oxidized graphite oxide has been thermally reduced at a temperature of [Formula: see text]C. The phase, crystallinity, and interatomic distance were investigated using X-Ray diffraction (XRD) analysis. X-Ray data show that the RGO crystal structure has been recovered following high-temperature annealing. The diffraction peak seems to be at [Formula: see text] with an interplaner distance of 3.48[Formula: see text]Å. The intensity of the defect, as measured by the [Formula: see text] ratio (intensity ratio), was analyzed using Raman spectra, and the result of that investigation was found to be 0.196. The findings of the Raman study unambiguously reveal that the severity of the defects is judged to be on the lower end of the spectrum. The surface texture, microstructure, and elemental analysis were performed using atomic force microscopy (AFM), Field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and EDX analysis. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were used to determine the number of oxygen-containing functional groups that existed in the RGO sample and their thermostability. The results of FTIR and TGA analysis clearly demonstrate that the reduction temperature has a major role in determining the proportion of oxygen that is present in the graphene. This study presents a large-scale, cost-effective, and eco-friendly graphene synthesis method for industrial applications.

Recent advances on the development of graphene‐based field‐effect transistors, electrochemical biosensors and electrochemiluminescence biosensors

AbstractGraphene, a honeycomb lattice of carbon material with single‐atom‐layer structure, demonstrates extraordinary mechanical, thermal, chemical and electronic properties. Thus, it has sparked tremendous interests in various fields, such as energy storage and conversion devices, field‐effect transistors (FET), chemical sensors and biosensors. In this review, we will first focus on the synthesis method of graphene and the fabrication strategy of graphene‐based materials. Subsequently, the construction of graphene‐based biosensors are introduced, in which three kinds of biosensors are discussed in details, including the FET, electrochemical biosensors and electrochemiluminescence (ECL) biosensors. The performances of the state‐of‐the‐art biosensors on the detection of biomolecules are also displayed. Finally, we also highlight some critical challenges remain to be solved and the development in this field for further research.

State-of-the-Art Graphene Synthesis Methods and Environmental Concerns

Graphene, a 2D sp2 hybridized carbon sheet consisting of a honeycomb network, is the building block of graphite. Since its discovery in 2004, graphene’s exceptional electronic and mechanical properties have peaked interest in various applications. However, the inability to mass produce high-quality graphene affordably currently limits the practical application of the material. Researchers are continuously working on advancing graphene synthesis methods to alleviate these limitations. Therefore, this review looks at the overview of established graphene synthesis methods and characterization techniques, and then highlights an in-depth review of graphene production through flash joule heating. The environmental concerns related to graphene synthesis are also presented in this review paper.