3D Graphene Structures Research Articles

3D Porous Graphene Architecture Integrated with Cu2O for Enhanced Electrochemical Sensing Performance.

Construction and functionalization of a 3D graphene architecture are crucial to harness and extend the unique features of graphene and thus essential for its numerous conventional and novel applications. Herein, a 3D honeycomb-patterned porous graphene architecture is constructed through a facile and low-cost self-assembly process and then integrated with Cu2O nanoparticles via a simple electrodeposition procedure. The 3D porous graphene structure is prepared by the breath figure method using a graphene oxide (GO)-based complex in which GO is modified by a surfactant as the casting material. Benefiting from the intercalation of the surfactant between the GO nanosheets and the fabrication of a 3D porous structure, the aggregation inhibition of GO nanosheets and increases in accessible surface area are realized at both nano- and microscales, resulting in good electrochemical performance. Moreover, the deposition of Cu2O nanoparticles can further improve the electrochemical sensing performance of the porous reduced graphene oxide (rGO) structure. Extremely low detection limit (30.72 nM) with a linear range of 0 μM to 30 μM, excellent anti-interference, repeatability, reproducibility, stability, and high accuracy for actual sample testing are shown when the 3D porous Cu2O/rGO film is applied as an electrochemical sensor for DA detection. This work provides not only a superior electrochemical biosensor but also a simple, yet effective and general strategy for the construction and functionalization of a 3D graphene structure.

Nitrogen-Doped 3D-Graphene Advances Near-Infrared Photodetector for Logic Circuits and Image Sensors Overcoming 2D Limitations.

The limitations of two-dimensional (2D) graphene in broadband photodetector are overcome by integrating nitrogen (N) doping into three-dimensional (3D) structures within silicon (Si) via plasma-assisted chemical vapor deposition (PACVD) technology. This contributes to the construction of vertical Schottky heterojunction broad-spectrum photodetectors and applications in logic devices and image sensors. The natural nanoscale resonant cavity structure of 3D-graphene enhances photon capture efficiency, thereby increasing photocarrier generation. N-doping can fine-tune the electronic structure, advancing the Schottky barrier height and reducing dark current. The as-fabricated photodetector exhibits exceptional self-driven photoresponse, especially at 1550 nm, with an excellent photoresponsivity (79.6 A/W), specific detectivity (1013 Jones), and rapid response of 130 μs. Moreover, it enables logic circuits, high-resolution pattern image recognition, and broadband spectra recording across the visible to near-infrared range (400-1550 nm). This research will provide new views and technical support for the development and widespread application of high-performance semiconductor-based graphene broadband detectors.

Recent Progress in Electric‐field Enhanced 3D Graphene Electrodes using Laser Scribing for In‐plane Microsupercapacitors

AbstractThe increasing demand for miniature, flexible electronic devices have fueled the need for compact and high‐performing energy storage solutions. Microsupercapacitors (mSCs) with reduced dimension and novel electrode design have gained prominence. This concept paper summarizes and views the recent advancements in mSCs with a focus on 3D graphene electrodes and their novel electrode design to increase energy performance of the devices. Especially, we focus on these 3D graphene structures fabricated using a laser‐scribing method which offer an efficient, cost‐effective approach for enhanced mSC performance. Further, this work delves into the vital link between the electrical field effect and geometrically engineered interdigitated electrodes, which is pivotal for maximizing the ion transport and mSC energy storage performance. The insights presented here are promising for meeting the power requirements of future miniature electronics.

Ferroelectricity of ice nanotube forests grown in three-dimensional graphene: the electric field effect.

Generating diverse ferroelectric ice nanotubes (NTs) efficiently has always been challenging, but matters in nanomaterial synthesis and processing technology. In the present work, we propose a method of growing ice NT forests in a single cooling process. A three-dimensional (3D) graphene structure was selected to behave as a representative container in which a batch of (5, 0) ice NTs was formed simultaneously under the cooling process from molecular dynamics simulation. Other similar 3D graphene structures but with different hole configurations, like uniform triangle or both triangle and pentagon, were also tested, revealing that ice NTs with different tube indices, i.e. both (3, 0) and (5, 0), could also be formed at the same time. Intriguingly, the orientations of the dipole moments of the water molecules of an ice NT formed were independent of each other, making the net ferroelectricity of the whole system weakened or even cancelled. An electric field could help change the orientation of the water molecules of the already obtained ice NTs and even twist the tube to be a spiral (5, 1) one if it was applied during the cooling process, such that the net ferroelectricity was greatly improved. The underlying physical mechanism of all phase transition phenomena, including the improvement of the ferroelectricity under an electric field, were explored in depth from the phase transition curves and structural point of view. The obtained results are of significant application value for improving the preparation efficiency of nano-ferroelectric materials, which are prosperous in nano-devices.

In Situ Synthesis of Doped Bio-Graphenes as Effective Metal-Free Catalysts in Removal of Antibiotics: Effect of Natural Precursor on Doping, Morphology, and Catalytic Activity.

Wastewater contaminated with antibiotics is a major environmental challenge. The oxidation process is one of the most common and effective ways to remove these pollutants. The use of metal-free, green, and inexpensive catalysts can be a good alternative to metal-containing photocatalysts in environmental applications. We developed here the green synthesis of bio-graphenes by using natural precursors (Xanthan, Chitosan, Boswellia, Tragacanth). The use of these precursors can act as templates to create 3D doped graphene structures with special morphology. Also, this method is a simple method for in situ synthesis of doped graphenes. The elements present in the natural biopolymers (N) and other elements in the natural composition (P, S) are easily placed in the graphene structure and improve the catalytic activity due to the structural defects, surface charges, increased electron transfers, and high absorption. The results have shown that the hollow cubic Chitosan-derived graphene has shown the best performance due to the doping of N, S, and P. The Boswellia-derived graphene shows the highest surface area but a lower catalytic performance, which indicates the more effective role of doping in the catalytic activity. In this mechanism, O2 dissolved in water absorbs onto the positively charged C adjacent to N dopants to create oxygenated radicals, which enables the degradation of antibiotic molecules. Light irradiation increases the amount of radicals and rate of antibiotic removal.

Growing of 2D/3D graphene structures on natural substrates from aromatic plastic wastes by scalable thermal-based upcycling process with a comparative CO2 footprint analysis

Recycling aromatic plastics, such as polystyrene (PS) and polyethylene terephthalate (PET), is complex and strongly sensitive to the process design and conditions due to the presence of polycyclic aromatic hydrocarbons and interunit CO and/or CC linkages. Herein, the upcycling process becomes crucial to attain high-value-added products from aromatic plastics. With this study, graphene growth was achieved on the natural substrates of talc and organically modified montmorillonite (OMMT), from waste PS and PET sources via a sustainable, affordable, and environment-friendly upcycling technique. This promising method promotes the formation of 2D and 3D graphene structures from waste PS and PET. This provides dimension-controlled graphene growth by tailoring the substrate type and size, surface composition of the substrate, and the degree of aromaticity in the polymer. In addition, polymer processing techniques of twin-screw extrusion and thermokinetic mixing, were investigated in the development of graphene-grown hybrid additives to tailor the degree of crystallinity. Regarding structural characterization results, a high shear rate mixer led to the change in crystalline planes of talc, whereas conventional twin screw extrusion preserved the structure of talc indicating that high shear rate triggered the exfoliation of talc. Furthermore, a systematic life cycle assessment was conducted to evaluate the CO2 footprint of upcycled graphenes grown on talc and OMMT compared to graphene produced from graphite. Upcycled graphene structures obtained by direct carbonization and even catalyst impregnated natural substrate-based graphene growth process with PS or PET source have comparably lower CO2 emission than graphene received from graphite. Therefore, these newly developed and upcycled hybrid additives opens a way for the conversion of aromatic complex plastic wastes into value-added nanomaterials being candidate as reinforcing agent by adopting a circular economy model.

Universal Strategy for Reversing Aging and Defects in Graphene Oxide for Highly Conductive Graphene Aerogels.

The production of highly stable, defect-free, and electrically conducting 3D graphene structures from graphene oxide precursors is challenging. This is because graphene oxide is a metastable material whose structure and chemistry evolve due to aging. Aging changes the relative composition of oxygen functional groups attached to the graphene oxide and negatively impacts the fabrication and properties of reduced graphene oxide. Here, we report a universal strategy to reverse the aging of graphene oxide precursors using oxygen plasma treatment. This treatment decreases the size of graphene oxide flakes and restores negative zeta potential and suspension stability in water, enabling the fabrication of compact and mechanically stable graphene aerogels using hydrothermal synthesis. Moreover, we employ high-temperature annealing to remove oxygen-containing functionalities and repair the lattice defects in reduced graphene oxide. This method allows obtaining highly electrically conducting graphene aerogels with electrical conductivity of 390 S/m and low defect density. The role of carboxyl, hydroxyl, epoxide, and ketonic oxygen species is thoroughly investigated using X-ray photoelectron and Raman spectroscopies. Our study provides unique insight into the chemical transformations occurring during the aging and thermal reduction of graphene oxide from room temperature up to 2700 °C.

Enhanced Energy Transfer between Nitrogen‐Vacancy Centers and 2D MoS2 Films Accurately Fabricated by Atomic Layer Deposition

AbstractEnergy transfer between 2D MoS2 films and fluorescent emitters is widely used in biological detection and imaging. In this paper, by regulating the thickness of the MoS2 film on the diamond surface through the number of atomic layer deposition (ALD) cycles, the energy transfer efficiency between the nitrogen vacancy (NV) center and the MoS2 film is improved and precisely controlled. When the number of ALD cycles is 8, the energy transfer efficiency between the 2D MoS2 film and the NV center is 86.35%. Furthermore, when the number of ALD cycles is more significant than 140, compared with 2D and 3D graphene structures, the energy transfer efficiency of the NV center is increased by 126.55% and 24.60%, respectively. Meantime, the fluorescence lifetime of the NV center is reduced in the presence of the MoS2 film, indicating that the MoS2 film provides a new, additional fluorescence decay channel for the NV center in the MoS2 film and the NV center system. Moreover, ALD can also effectively improve the tightness of the contact interface between the MoS2 film and the diamond. This paper provides a new method and experimental basis for regulating the photon emission behavior of emitters.

Digitization of Free‐Shapable Graphene Foam with Damage Tolerance

Abstract3D construction of 2D sheets is the key to the utilization of graphene for large scale industrial applications. The layer by layer approach of additive manufacturing enables a high degree of design freedom for the fabrication of 3D graphene structures with excellent mechanical flexibility. Herein, the excellent mechanical and functional properties of 3D nitrogen‐doped graphene (NG) foams fabricated is demonstrated via 3D printed templates and template‐directed chemical vapor deposition. The super‐elastic foam, consisting of interconnected networks of graphene sheets can make near complete strain recovery from load up to 62500 times its own weight, with extraordinary damage tolerance at a low density of 9.5 mg cm−3. Fast transport of charge carriers (5 S cm−1) highlights the potential of the NG foam for use in various functional applications. Observed temperature‐invariant reversible elasticity from −196 to 300 °C further emphasizes its value for use in demanding environments.

3D Free-Standing Graphene: Influence of Etching Solution and Etching Time on Chemical Vapor Deposition on the Graphene/Nickel Foam

Three-dimensional (3D) structures made of graphene sheets have been developed recently, and have resulted in the development of a new class of graphene materials known as 3D graphene materials. High-quality free-standing 3D graphene foam has been synthesized by chemical vapor deposition (CVD) on nickel foam followed by a chemical etching process to remove the nickel foam as a template. Field-emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), and Raman spectroscopy measurements were performed to investigate the morphologies, crystal phase, and the structure of nickel foam (NF), graphene/nickel foam (Gr/NF), and 3D graphene (3D Gr). In this study, the influence of etching solution and etching time on Gr/NF to produce free-standing 3D Gr was investigated. XRD spectroscopy showed that the mixed solutions of 1M FeCl<sub>3</sub>:1M HCl at 80 °C for 3 h can significantly remove the NF and no peaks of NF are observed, thus indicating a high crystal quality of 3D Gr was obtained. In addition, XRD spectroscopy revealed that by increasing the etching time beyond 3 h, the intensity of diffraction peaks decreases, thus degrading graphene quality. This research emphasizes the significance of proper selections of etching solution and etching time in removing the NF to maintain the characteristic, quality, and surface morphology of 3D Gr after the etching process.

On the computational modeling, additive manufacturing, and testing of tube-networks TPMS-based graphene lattices and characterizing their multifunctional properties

Lattices based on triply periodic minimal surfaces (TPMSs), which have been receiving increasing interest due to advances in additive manufacturing, are known now to be outperforming other cellular materials in several properties, enabling wider multifunctional applications. In this work, we focus on fabricating graphene TPMS lattices, viz., Gyroid, Schoen's I-WP (IWP), and Diamond, and investigate their multifunctional properties experimentally and computationally. The three-dimensional (3D) graphene structures were synthesized using a self-assembly hydrothermal-assisted dip-coating technique and the resulting lattices were tested for their mechanical, thermal, and electrical properties and compared to finite element simulation results. The graphene TPMS lattices resulting from the fabrication take the topology of a new class of TPMS architectures that are referred to here as the TPMS tube-networks. IWP demonstrated the highest elastic modulus as well as electrical and thermal conductivities. This study shows that 3D porous tube graphene can be utilized in designing new lightweight structural materials of low density with controllable thermal and electrical properties and mechanical strength with a potential to be employed in multifunctional engineering applications.

Anisotropic bending of graphene with grain boundaries: Insights from tight-binding simulations

Graphene grain boundaries (GBs) are associated with distinct mechanical and physical properties. To utilize these properties requires comprehensive investigation of the GB-controlled nanomechanics. Currently, there is short of fundamental understanding of the out-of-plane bending of graphene in the presence of GBs and the mechanical properties of related curved structures. Here with density functional theory-based tight-binding objective molecular simulations, we revealed anisotropic nonlinear bending of graphene with tilt GBs. The anisotropy and nonlinearity are caused by the dislocation cores which display out-of-plane protrusions. In addition, we investigated the GB-controlled elastic responses of curved graphene configurations, and established the coupling between the elastic modulus and local curvature near the GBs. Our findings serve as useful references for 3D graphene structure design utilizing GBs and can be generalized to other 2D materials.

Flexible Graphene-Copper Nanocomposite for Potential Wearable Electronics Applications

The demand for flexible and wearable electrochemical sensors has surged due to their low cost and portability. This study produces and characterizes low-cost and environmentally friendly flexible laser engraved graphene/Cu nanoparticles composite materials as a potential electrode for electronic applications. The electrode is fabricated by directly engraving Polyimide substrate using a CO2 laser machine to produce Laser Engraved Graphene (LEG). The electrode is then modified with copper nanoparticles via a one-step pulse electrodeposition technique to be characterized structurally, mechanically, and electrochemically using SEM, XRD, bending test, electrochemical impedance spectroscopy, and cyclic voltammetry to assess their stability and electrocatalytic activity. The laser irradiation of PI results in 3D porous graphene structure formation that increases electron transfer rate and the electrochemically active surface area. Copper deposition improves the sensitivity of LEG by its high conductivity.

Three-dimensional self-folding assembly of multi-layer graphene at the interface with a polymeric film

Three-dimensional (3D) architectures of graphene are of great interest for applications in flexible electronics, supercapacitors, and biointerfaces. Here, we demonstrate that multi-layer graphene (MLG), like single-layer graphene (SLG), can self-fold to form 3D architectures at the interface with a polymeric film. Bilayers composed of graphene and polymeric film tightly adhere to each other and possess a sloped internal strain, which leads to spontaneous rolling to predetermined 3D microscale architectures. The curvature radii of self-folding films can be controlled by changing the thicknesses of the polymeric film and the stacking order. In contrast to single-layer graphene, multi-layer graphene shows no strain in most of the outer graphene layers and linear ohmic current characteristics after self-folding. Throughout the self-folding process, the conductance of MLG decreases but remains higher than that of SLG. This versatile way of forming a 3D multi-layer graphene structure is potentially applicable for fabrication of practical carbon devices without the changes in their conductive properties.

Structure–property relations of three-dimensional nanoporous template-based graphene foams

Recently, much attention has been directed to 3D graphene structures due to their potential of retaining intrinsic 2D graphene properties, in combination with structural flexibility and tunable porosity. From a theoretical point of view, however, it is challenging to build 3D graphene foam structures that accurately represent experimental topological configurations. Here, we generate open-cell 3D graphene structures that closely reflect template-based manufacturing techniques and investigate their mechanical properties. We use all-atom molecular dynamics simulations to relate the overall stiffness, collapse stress and fracture properties to the underlying graphene microstructure represented by the graphene relative density, template relative density and number of graphene layers. We do so for four different template morphologies: gyroids, regular foam (BCC), random foam and nanoporous gold. The overall mechanical properties as a function of graphene relative density are analyzed in terms of power law relations to probe the microstructural deformation modes. Our results show that the open-cell 3D graphene structures feature bending as the dominant deformation mode, with regular graphene foams having the highest stiffness and strength and random foams the lowest. For gyroids we found that a higher template relative density leads to reduced mechanical properties but improved ductility. A similar trend was observed when the number of graphene layers was increased: enhanced ductility but at the expense of a reduced strength. Interestingly, we found that for low graphene density, the gyroids feature a strong self-stiffening response, leading to improvements in both strength as well as ductility. Our findings can be used as a guideline for the experimental design of innovate and lightweight graphene structures with strongly enhanced mechanical properties.

In situ laser synthesis of Pt nanoparticles embedded in graphene films for wearable strain sensors with ultra-high sensitivity and stability

Carbon-based materials have recently attracted tremendous attention for their applications in highly sensitive wearable devices for human motion monitoring. Embedding rare metal nanoparticles such as Au, Ag, and Pt has been proved to significantly improve the sensitivity of the carbon-based strain sensors. However, the existing method to prepare nanoparticles usually involves multi-step, time-consuming procedures. Here, we report a facile one-step laser process to synthesize porous 3D graphene structures embedded with Pt nanoparticles. This is achieved by irradiating an ultraviolet (355 nm) picosecond laser on a film formed with a mixture of polybenzimidazole (PBI) and Pt(acac)2 solution to simultaneously induce the formation of graphene and reduction of the Pt precursor. The assembled strain sensor with loaded Pt nanoparticles in laser-induced graphene (Pt/LIG) demonstrates ultra-high sensitivity (a gauge factor, GFmax ≈ 489.3) and a wide strain range up to 20%. Additionally, the strain sensor with an optimized concentration of Pt(acac)2 has low hysteresis, minor lag errors, and a highly stable response (>5000 cycles). Various human motion signals are detected, from subtle physical activities (including chewing muscles movement, pulse beating) to large-scale limb track (finger bending, knee movement, and waist extending). This one-step laser process is facile, rapid, and potentially scalable for the mass production of high-performance wearable strain sensors.

Joule Heating and mechanical properties of epoxy/graphene based aerogel composite

While polymer composites are anticipated as a promising alternative for Joule heating materials, constructing a continuous conductive network of fillers remains an open challenge to obtain high-performance Joule heating properties with the high steady-state surface temperature at low power input, rapid heating/cooling rate, and excellent cycle stability. Herein, we designed a three-dimensional graphene-based aerogel, infiltrated epoxy into it, and demonstrated a key role of 2D materials-based three-dimensional filler on the anisotropic Joule heating performances of the final aerogel composite. The aerogel composite with the highest graphene loading of 4.7 wt% shows outstanding Joule heating performance with a steady-state temperature of 213 °C at a relatively low applied voltage of 5 V. Benefiting from the 3D graphene structure, the epoxy/graphene-based aerogel composites show an excellent electrical conductivity of 48.7 S/m and thermal conductivity of 1.1 W/mK along the parallel direction to the lamellar structure growth. The Joule heating performance of epoxy/graphene-based aerogel composite is correlated with the morphology, electrical conductivities, and thermal conductivities. Importantly, the induced steady-state temperature follows a linear relationship with both the electrical and thermal conductivities of materials. Mechanical properties of aerogel composite is also studied. The obtained results indicate that the epoxy/graphene-based aerogel composite can be a promising material for thermal management applications.

A 3D honeycomb graphene structure for wearable piezoresistive pressure sensor with high sensitivity

A 3D honeycomb graphene structure for wearable piezoresistive pressure sensor with high sensitivity

Effect of annealing time on chemical vapor deposition growth of 3D graphene for photoelectrochemical water splitting

Graphene, a two-dimensional (2D) carbon material that has a zero bandgap with a symmetric band structure, has drawn extensive attention, owing to its exceptional electrical, mechanical, thermal and electron mobility properties. However, 2D graphene sheets encounter an aggregation and restacking issues, which affect the electron transport and charge separation. Therefore, a three-dimensional (3D) graphene structure has been explored to address these problems. The fabrication of 3D graphene via chemical vapor deposition (CVD) has intrigued comprehensive attention in photoelectrochemical (PEC) water splitting. It can produce high-quality graphene with a minimal defects of 3D graphene structures that can exhibit an outstanding performance for PEC water splitting. In this study, we investigated the effect of annealing time during CVD growth of 3D graphene/nickel (Ni) foam where the Ni foam was annealed with various annealing times (20–60 min). The coverage area of graphene on Ni foam has improved, based on characterization using field emission scanning electron microscope (FESEM). Raman and EDX analysis further confirmed the presence of graphene layer on Ni foam. The optimum annealing time was obtained at 50 min. The sample was tested for PEC water splitting and the current performance for 50 min annealing sample was found higher than the pure Ni foam, 596.46 mA and 429.33 mA, respectively. Thus, improved coverage area of graphene on Ni foam resulted in higher generated current that has a potential for PEC water splitting.

Arginine-functionalized graphene oxide for green and high-performance symmetric supercapacitors

The present paper intends to show how a graphene-based composite has effortlessly been synthesized utilizing the arginine amino acid (Arg) as a supercapacitor electrode via a green process with neither organic nor toxic substances in aqueous electrolyte (KOH 6 M). Arg amino acid molecules were used as interfacial spacer of graphene sheets to obstruct aggregation. Hence, the surface area increased and the efficient diffusion of electrolyte ions was facilitated in consequence of generating a 3D porous graphene structure. Besides, the surface chemistry of graphene is tuned as amine and carboxylic acid groups are present in the Arg structure which results in high capacitance through electrode wettability and improved diffusion of electrolyte ions into the electrode structure as well as through pseudo-faradic reactions. The as-fabricated electrode provides an exceptional specific capacitance of 295 F g−1 in 1 A g−1 and effective cycling stability (94% after 4000 cycles) in the design of two-electrode configuration. Considering environmental compatibility as well as the superior power and energy density (2204 W kg−1 and 50 Wh Kg−1, respectively), the striking ability of Arg/GO composite to become an appropriate choice for future generations of energy storage devices is proven.