A highly sensitive electrochemical sensor based on poly(3-aminobenzoic acid)/graphene oxide-gold nanoparticles modified screen printed carbon electrode for paraquat detection.

Herein, a modified screen printed carbon electrode (SPCE) based on a composite material, graphene oxide-gold nanoparticles (GO-AuNPs), and poly(3-aminobenzoic acid)(P3ABA) for the detection of paraquat (PQ) is introduced. The modified electrode was fabricated by drop casting of the GO-AuNPs, followed by electropolymerization of 3-aminobenzoic acid to achieve SPCE/GO-AuNPs/P3ABA. The morphology and microstructural characteristics of the modified electrodes were revealed by scanning electron microscopy (SEM) for each step of modification. The composite GO-AuNPs can provide high surface area and enhance electroconductivity of the electrode. In addition, the presence of negatively charged P3ABA notably improved PQ adsorption and electron transfer rate, which stimulate redox reaction on the modified electrode, thus improving the sensitivity of PQ analysis. The SPCE/GO-AuNPs/P3ABA offered a wide linear range of PQ determination (10-9-10-4 mol/L) and low limit of detection (LOD) of 0.45 × 10-9 mol/L or 0.116 µg/L, which is far below international safety regulations. The modified electrode showed minimum interference effect with percent recovery ranging from 96.5% to 116.1% after addition of other herbicides, pesticides, metal ions, and additives. The stability of the SPCE/GO-AuNPs/P3ABA was evaluated, and the results indicated negligible changes in the detection signal over 9 weeks. Moreover, this modified electrode was successfully implemented for PQ analysis in both natural and tapped water with high accuracy.

Effect of surface species on the alcohol-acid adsorption from FTS wastewater on graphene: A structure-capacity study.

Fischer-Tropsch synthesis (FTS) wastewater retaining low-carbon alcohols and acids are organic pollutants as a limiting factor for FTS industrialization. In this work, the structure-capacity relationships between alcohol-acid adsorption and surface species on graphene were reported, shedding light into their intricate interactions. The graphene oxide (GO) and reduced graphene oxide (rGO) were synthesized via improved Hummers method with flake graphite (G). The physicochemical properties of samples were characterized via SEM, XRD, XPS, FT-IR, and Raman. The alcohol-acid adsorption behaviors and adsorption quantities on G, GO, and rGO were measured via theoretical and experimental method. It was revealed that the presence of COOH, C=O and CO species on graphene occupy the adsorption sites and increase the interactions of water with graphene, which are unfavorable for alcohol-acid adsorption. The equilibrium adsorption quantities of alcohols and acids grow in pace with carbon number. The monolayer adsorption occurs on graphene was verified via model fitting. rGO has the highest FTS modeling wastewater adsorption quantity (110 mg/g) due to the reduction of oxygen species. These novel findings provide a foundation for the alcohol-acid wastewater treatment, as well as the design and development of high-performance carbon-based adsorbent materials.

Electrochemical Detection of Nucleic Acids Using Three-Dimensional Graphene Screen-Printed Electrodes.

Electrochemical approaches, along with miniaturization of electrodes, are increasingly being employed to detect and quantify nucleic acid biomarkers. Miniaturization of the electrodes is achieved through the use of screen-printed electrodes (SPEs), which consist of one to a few dozen sets of electrodes, or by utilizing printed circuit boards. Electrode materials used in SPEs include glassy carbon (Chiang H-C, Wang Y, Zhang Q, Levon K, Biosensors (Basel) 9:2-11, 2019), platinum, carbon, and graphene (Cheng FF, He TT, Miao HT, Shi JJ, Jiang LP, Zhu JJ, ACS Appl Mater Interfaces 7:2979-2985, 2015). There are numerous modifications to the electrode surfaces as well (Cheng FF, He TT, Miao HT, Shi JJ, Jiang LP, Zhu JJ, ACS Appl Mater Interfaces 7:2979-2985, 2015). These approaches offer distinct advantages, primarily due to their demonstrated superior limit of detection without amplification. Using the SPEs and potentiostats, we can detect cells, proteins, DNA, and RNA concentrations in the nanomolar (nM) to attomolar (aM) range. The focus of this chapter is to describe the basic approach adopted for the use of SPEs for nucleic acid measurement.

A self-powered theranostic DNA nanodevice for amplification of both intracellular microRNA imaging and photodynamic therapy.

While numerous methods exist for diagnosing tumors through the detection of miRNA within tumor cells, few can simultaneously achieve both tumor diagnosis and treatment. In this study, a novel graphene oxide (GO)-based DNA nanodevice (DND), initiated by miRNA, was developed for fluorescence signal amplification imaging and photodynamic therapy in tumor cells. After entering the cells, tumor-associated miRNA drives DND to Catalyzed hairpin self-assembly (CHA). The CHA reaction generated a multitude of DNA Y-type structures, resulting in a substantial amplification of Ce6 fluorescence release and the generation of numerous singlet oxygen (1O2) species induced by laser irradiation, consequently inducing cell apoptosis. In solution, DND exhibited high selectivity and sensitivity to miRNA-21, with a detection limit of 11.47 pM. Furthermore, DND discriminated between normal and tumor cells via fluorescence imaging and specifically generated O21 species in tumor cells upon laser irradiation, resulting in tumor cells apoptosis. The DND offer a new approach for the early diagnosis and timely treatment of malignant tumors.

Is Low Polydispersity Always Beneficial? Exploring the Impact of Size Polydispersity on the Microstructure and Rheological Properties of Graphene Oxide.

Graphene oxide (GO) is a promising material widely utilized in advanced materials engineering, such as in the development of soft robotics, sensors, and flexible devices. Considering that GOs are often processed using solution-based methods, a comprehensive understanding of the fundamental characteristics of GO in dispersion states becomes crucial given their significant influence on the ultimate properties of the device. GOs inherently exhibit polydispersity in solution, which plays a critical role in determining the mechanical behavior and flowability. However, research in the domain of 2D colloids concerning the effects of GO's polydispersity on its rheological properties and microstructure is relatively scant. Consequently, gaining a comprehensive understanding of how GO's polydispersity affects these critical aspects remains a pressing concern. In this study, we aim to investigate the dispersions and structure of GOs and clarify the effect of polydispersity on the rheological properties and yielding behavior. Using a rheometer, polarized optical microscopy, and small-angle X-ray scattering, we found that higher polydispersity in the same average size leads to overall improved rheological properties and higher flowability during yielding. Thus, our study can be beneficial in the employment of polydispersity in the processing of GO such as 3D printing and fiber spinning.

Fabrication of Self-Assembled Graphene Oxide Film and Its Application in Aqueous Zinc Metal Batteries.

Fabrication of well-dispersed thin graphene oxide (GO) films (GOFs) has always been a challenge. Herein, a quick preparation method for GOFs was developed using our homemade GO with a large lateral size. The film can be prepared in less than 2 h via a metal framework-induced self-assembly process. The thickness of the films can be as thin as ∼15.5 µm, which will be thinner with compression. When it is used as a flexible modification layer on the Zn metal for aqueous Zn-ion batteries, Zn can grow along the [010] direction in plane and stack orderly along the [002] direction even on the Cu substrate with GOF through epitaxial plating owing to negligible lattice mismatch between the (002) plane of Zn and the hexagonal ring [also (002) plane for graphite] of GO. Meanwhile, the rich O groups on the GO film can provide abundant zincophilic points and promote uniform distribution of Zn2+ around the anode. Finally, dendrite-free and dense Zn stripping/plating can be achieved and well remained. The GOF@Zn symmetric cell reveals long cyclic stability of 1300 h at 1 mA cm-2 and 1 mA h cm-2. It still can remain at 350 h even at a very high current density of 10 mA cm-2 accompanied by a high areal capacity of 10 mA h cm-2. With the same plating amount of 5 mA h cm-2, the thickness of the plated Zn is only ∼10 µm with GOF modification, very close to the theoretical value of 8.54 µm, much thinner than that without GOF (∼18 µm), indicating very dense deposition. Full cells assembled with the GOF@Zn anode and the MnO2 cathode exhibit a capacity retention rate of 71% over 1000 cycles at 0.7 A g-1, showing much better cycling performance than that using bare Zn.

Humidity Sensing Properties of Different Atomic Layers of Graphene on the SiO2/Si Substrate.

Graphene has great potential to be used for humidity sensing due to its ultrahigh surface area and conductivity. However, the impact of different atomic layers of graphene on the SiO2/Si substrate on humidity sensing has not been studied yet. In this paper, we fabricated three types of humidity sensors on the SiO2/Si substrate based on one to three atomic layers of graphene, in which the sensing areas of graphene are 75 µm × 72 µm and 45 µm × 72 µm, respectively. We studied the impact of both the number of atomic layers of graphene and the sensing areas of graphene on the responsivity and response/recovery time of the prepared graphene-based humidity sensors. We found that the relative resistance change of the prepared devices decreased with the increase of number of atomic layers of graphene under the same change of relative humidity. Further, devices based on tri-layer graphene showed the fastest response/recovery time, while devices based on double-layer graphene showed the slowest response/recovery time. Finally, we chose devices based on double-layer graphene that have relatively good responsivity and stability for application in respiration monitoring and contact-free finger monitoring.

Unraveling the Spin-to-Charge Current Conversion Mechanism and Charge Transfer Dynamics at the Interface of Graphene/WS2 Heterostructures at Room Temperature.

We report experimental investigations of spin-to-charge current conversion and charge transfer (CT) dynamics at the interface of the graphene/WS2 van der Waals heterostructure. Pure spin current was produced by the spin precession in the microwave-driven ferromagnetic resonance of a permalloy film (Py=Ni81Fe19) and injected into the graphene/WS2 heterostructure through a spin pumping process. The observed spin-to-charge current conversion in the heterostructure is attributed to the inverse Rashba-Edelstein effect (IREE) at the graphene/WS2 interface. Interfacial CT dynamics in this heterostructure was investigated based on the framework of the core-hole clock (CHC) approach. The results obtained from spin pumping and CHC studies show that the spin-to-charge current conversion and charge transfer processes are more efficient in the graphene/WS2 heterostructure compared to isolated WS2 and graphene films. The results show that the presence of WS2 flakes improves the current conversion efficiency. These experimental results are corroborated by density functional theory (DFT) calculations, which reveal (i) Rashba spin-orbit splitting of graphene orbitals and (ii) electronic coupling between graphene and WS2 orbitals. This study provides valuable insights for optimizing the design and performance of spintronic devices.

Impact of Graphene Oxide Nanoparticles on In Vitro Development of a Mouse Preimplantation Embryo and Interaction With the Zona Pellucida.

The development of assisted reproductive technologies increases the likelihood of nanoparticles' (NPs) direct contact with gametes and embryos in in vitro conditions. Analyzing the influence of nanomaterials on the early mammalian embryo becomes increasingly relevant. This work is devoted to the effect of graphene oxide (GO) NPs on the in vitro development of mammalian embryos. Mouse 2-cell embryos were preincubated with GO NPs. The interaction of GO with the Zona Pellucida (ZP) of the embryo was investigated using fluorescence lifetime imaging with two-photon excitation (2p-FLIM). During embryo development, the NPs penetration into ZP (blastocyst stage) and perivitelline space (blastocyst hatching stage) was observed. Despite this, GO did not affect the embryo's ability to develop till late and hatching blastocysts. The mechanism of the NPs getting into the perivitelline space and the consequences of NP-embryo direct contact are discussed. The 2p-FLIM efficiency for studying NP interaction with mammalian embryos is evaluated.

Visible Light-Triggered Catalytic Performance of Reduced Graphene Oxide Decorated With Copper Oxide Nanocomposite for Degradation of Rhodamine B Dye and Kinetics Studies.

Herein, novel nanocomposites based on reduced graphene oxide decorated copper oxide nanoparticles (rGO/CuO) were prepared by the in situ co-precipitation method. The structural, morphological, and optical characterization of as-prepared nanocomposites was performed by powdered x-ray diffraction (p-XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR), Raman, and ultraviolet-visible (UV-Vis) spectroscopy, respectively. The as-prepared nanocomposites exhibited better photocatalytic activity of rhodamine B dye with maximum ~94% degradation in 120 min with a rate constant of 0.2353 min-1 under optimized conditions. Furthermore, the effects of solution pH and catalyst loading are studied on the degradation process. Therefore, this state-of-the-art strategy for the decoration of CuO nanoparticles onto the surface of rGO nanosheets could be an ideal platform for fabricating highly efficient photocatalysts.

A Versatile Metal-Organic-Framework Pillared Interlayer Design for High-Capacity and Long-Life Lithium-Sulfur Batteries.

Developing high-performance lithium-sulfur batteries is a promising way to attain higher energy density at lower cost beyond the state-of-the-art lithium-ion battery technology. However, the major issues blocking their practical application are the sluggish kinetics and parasitic shuttling reactions for sulfur and polysulfides. Here, pillaring multilayer graphene with the metal-organic framework (MOF) demonstrates the substantial impact of a versatile interlayer design in tackling those issues. Unlike regular composite separators reported so far, the participation of tri-metallic Ni-Co-Mn MOF (NCM-MOF) as pillars supports the construction of an ion-channel interconnected interlayer structure, unexpectedly balancing the interfacial concentration polarization, spatially confining the soluble polysulfides and vastly affording lithiophilic sites for highly efficient polysulfide sieving/conversion. As a demonstration, we show that the MOF-pillared interlayer structure enables outstanding capacity (1634 mAh g-1 at 0.1C) and longevity (average capacity decay of 0.034% per cycle in 2000 cycles) of lithium-sulfur batteries. Besides, the multilayer separator can be readily integrated into the high-nickel cathode (LiNi0.91Mn0.03Co0.06O2)-based lithium-ion batteries, which efficiently suppresses the undesired phase evolution upon cycling. These findings suggest the potential of "gap-filling" materials in fabricating multi-functional separators, bring forward the pillared interlayer structure for energy-storage applications.

Effectively Sieving Alkali Metal Ions Using Functionalized Graphene Oxide Membranes by Exploiting Water-Repellent Interactions.

Sieving membranes capable of discerning different alkali metal ions are important for many technologies, such as energy, environment, and life science. Recently, two-dimensional (2D) materials have been extensively explored for the creation of sieving membranes with angstrom-scale channels. However, because of the same charge and similar hydrated sizes, mostly laminated membranes typically show low selectivity (<10). Herein, we report a facile and scalable method for functionalizing graphene oxide (GO) laminates by dually grafting cations and water-repellent dimethylsiloxane (DMDMS) molecules to achieve high selectivities of ∼50 and ∼20 toward the transport of Cs+/Li+ and K+/Li+ ion pairs, surpassing many of the state-of-the-art laminated membranes. The enhanced selectivity for alkali metal ions can be credited to a dual impact: (i) strong hydrophobic interactions between the incident cations' hydration shells and the water-repellent DMDMS; (ii) the efficient screening of electrostatic interactions that hamper selectivity.

Modality-Tunable Exfoliated N-Doped Graphene as Effective Electrolyte Additive for High-Performance Lithium-Sulfur Batteries.

While chemically doped graphene has shown great promise, the lack of cost-effective manufacturing has hindered its use. This study utilizes a facile fabrication approach for modality-tunable N-doped graphene via thermal annealing of aqueous-phase-exfoliated few-layered graphene from a Taylor-Couette reactor. This method demonstrates a high level of N-doping (27 atom % N) and offers modality tunability of the C-N bond without foregoing scalability and green chemistry principles. The resulting N-doped graphene, with varying N content and doping modality, is utilized in the lithium-sulfur battery electrolyte to address low ionic conductivity, lithium polysulfide (LiPS) shuttling, and Li anode instability. The study reveals that higher N content and pyridinic N modality graphene in the electrolyte positively influence battery performance. The results are 2-fold: higher overall N content improves capacity retention (73%) after 225 cycles at 0.2 C, and pyridinic-type nitrogen demonstrates the best performance at high C rates, exhibiting a 4-fold capacity increase relative to the reference cell at 2 C. Further, the computational study validates the adsorption affinity of LiPS to pyridinic nitrogen and improved Li+ mobility on the graphene backbone observed experimentally. This first experimental study on the impact of N-dopant concentration and modality on electrochemical performance provokes insights into tailoring N functionalization to achieve superior electrochemical performance.

Schottky Junction-Driven Photocatalytic Effect in Boron-Doped Diamond-Graphene Core-Shell Nanoarchitectures: An sp3/sp2 Framework for Environmental Remediation.

Self-formation of boron-doped diamond (BDD)-multilayer graphene (MLG) core-shell nanowalls (BDGNWs) via microwave plasma-enhanced chemical vapor deposition is systematically investigated. Here, the incorporation of nitrogen brings out the origin of MLG shells encapsulating the diamond core, resulting in unique sp3/sp2 hybridized frameworks. The evolution mechanism of the nanowall-like morphology with the BDD-MLG core-shell composition is elucidated through a variety of spectroscopic studies. The photocatalytic performance of these core-shell nanowalls is examined by the deterioration of methylene blue (MB) and rhodamine B (RhB) dyes beneath low-power ultraviolet (UV) light irradiation. Starting with 5 ppm dye solutions and employing BDGNWs as the photocatalyst, remarkable degradation efficiencies of 95% for MB within 100 min and 91% for RhB within 220 min are achieved. The effect of varying dye concentrations was also examined. The enhanced photocatalytic activity is driven by carrier photogeneration and mediated by the Schottky junction formed between BDD and MLG, promoting efficient photoinduced charge separation. The stability of the BDGNW photocatalyst is examined, and after five test runs, the photocatalytic behavior for MB and RhB degradation decreases to 87 and 85%, respectively, from initial values of 96 and 91%, demonstrating excellent photostability. These findings underscore the significance of diamond-graphene nanoarchitectures as promising green carbonaceous photocatalysts.

Laser-Induced Solid-Phase Strategy to Synthesize Single-Atomic Lithiophilic Sites Enabled Dendrite-Free Lithium Deposition on Graphene Matrix.

The introduction of metal Single-atom (SA) to construct lithium-philic active sites shows the ability to guide uniform lithium deposition and improve the stability of lithium hosts. Nevertheless, the development of facile and expedient methods for synthesizing SA remains a considerable challenge. Herein, The SA metal loaded on graphene (Bi@LrGO) is designed by laser-induced solid-phase strategy. The bismuth salts simultaneously decompose under the high local temperature and in the reductive atmosphere induced by laser to form SA metal. Simultaneously, graphene oxide (GO) nanosheets absorb photon energy to be reduced/graphitized into graphene, which serves as anchoring sites for Bismuth Sing-atom (Bi SA) immobilization. The SA metals, supported on the graphene not only provide sufficient lithiophilic sites but also significantly increase the adsorption energy (-2.11 eV) with lithium atoms, promote the uniform nucleation and deposition of lithium, and inhibit the growth of lithium dendrites. Additionally, the layered structure of the graphene film adapts to the volume change during the repeated lithium plating/stripping process. Therefore, the symmetrical battery-based Li deposited on Bi@LrGO (Bi@LrGO@Li) achieves an ultra-long stable cycle life of ≈2400 h at 1 mA cm-2. In particular, a full cell with LiFePO4 cathode provides a good capacity retention of 81.2% at 4 C after 600 cycles.

Closed-Loop Recycling of Wearable Electronic Textiles.

Wearable electronic textiles (e-textiles) are transforming personalized healthcare through innovative applications. However, integrating electronics into textiles for e-textile manufacturing exacerbates the rapidly growing issues of electronic waste (e-waste) and textile recycling due to the complicated recycling and disposal processes needed for mixed materials, including textile fibers, electronic materials, and components. Here, first closed-loop recycling for wearable e-textiles is reported by incorporating the thermal-pyrolysis of graphene-based e-textiles to convert them into graphene-like electrically conductive recycled powders. A scalable pad-dry coating technique is then used to reproduce graphene-based wearable e-textiles and demonstrate their potential healthcare applications as wearable electrodes for capturing electrocardiogram (ECG) signals and temperature sensors. Additionally, recycled graphene-based textile supercapacitor highlights their potential as sustainable energy storage devices, maintaining notable durability and retaining ≈94% capacitance after 1000 cycles with an areal capacitance of 4.92 mF cm⁻2. Such sustainable closed-loop recycling of e-textiles showcases the potential for their repurposing into multifunctional applications, promoting a circular approach that potentially prevents negative environmental impact and reduces landfill disposal.

3D Network of Liquid Metal-Embedded Graphene via Surface Coating for Flexible Thermal Management.

The rapid growth of flexible electronics has led to significant demand for relevant accessories, particularly highly efficient flexible heat dissipators. The fluidity of liquid metal (LM) makes it a candidate for realizing flexible thermal interface materials (TIMs). However, it is still challenging to combine LM with a conductive thermal network to achieve the synchronous improvement of thermal conductivity and flexibility. In this work, highly conductive flexible LM@GN/ANF films are made by coating LM nano-droplets with graphene nanosheets (GN) via sonication, and then they are combined with aramid nanofibers (ANF). The LM@GN/ANF film is found to have a thermal conductivity of 5.67 W m-1 K-1 and a 24.5% reduction in Young's modulus, making it suitable for various flexible electronic applications such as wearable devices and biosensors.

Development and challenge of coal-based nanocarbon materials and their application in water treatment: a review.

Under the dual pressures of environmental protection and energy security, the development and application of coal-based nanocarbon materials, supported by the technical concepts of molecular chemical engineering and nanomaterial science, is of significant importance for achieving the high-value clean utilization of coal. Furthermore, it serves as an effective means to assist in the realization of dual carbon goals. Coal, with its abundant reserves, high carbon content, and aromatic and hydrogenated aromatic groups, exhibits great advantages and potential in the synthesis of nanocarbon materials. In addition to its applications in traditional power and chemical industries, coal-based nanocarbon materials also demonstrate significant value in the field of environmental pollution control. This article succinctly summarizes the preparation methods and properties of coal-based carbon nanotubes, coal-based carbon quantum dots, and coal-based graphene, elucidates their current applications in water pollution control and governance, and anticipates their development trends in water pollution control, aiming to provide support for the clean and efficient utilization of coal and water pollution control.

Synergistic Nanoscale Mn3O4-CoO-Co Heterojunctions for Boosting the Selectivity in Hydrogenation of Nitrostyrenes and Nitroarenes.

Metal-metal oxide interface catalysts are in high demand for advanced catalytic applications due to their multi-component active sites, which facilitate synergistic cooperation where a single component alone cannot effectively promote the desired reaction. Demonstrated herein graphene oxide-supported nanoscale Mn3O4-CoO-Co as highly efficient catalysts for hydrogenation of nitro styrenes/nitro arenes to amino styrenes/arenes under mild reaction conditions (0.5 MPa and 100 °C in 1:1 THF/water). Charge relocalization at the Co-CoO-Mn3O4 heterojunction interfaces, primarily driven by Mn3O4, significantly improves reaction selectivity. Replacing Mn3O4 with MnO or using other supported bimetallic CoMnOx catalysts decreases selectivity, leading to the formation of a mixture of products. The catalyst demonstrated remarkable selectivity in converting nitro groups to amines, even in the presence of highly reactive functional groups such as C=C, O-C=O, C=O, C≡N, chalcones, and halides. It also exhibited high yields, multiple reusability, and a broad substrate scope. This study demonstrates how Mn3O4, in synergy with CoO-Co, fine-tunes selectivity, paving the way for the development of advanced metal-metal oxide interface catalysts to enhance both selectivity and efficiency in organic transformations.

Tough Monolayer Silver Nanowire-Reinforced Double-Layer Graphene.

Mixed-dimensional nanomaterials composed of one-dimensional (1D) and two-dimensional (2D) nanomaterials, such as graphene-silver nanowire (AgNW) composite sandwiched structures, are promising candidates as building blocks for multifunctional structures and materials. However, their mechanical behavior and failure mechanism have not yet been fully understood. In this work, we have performed integrated experimental, theoretical, and numerical studies to explore the performance and failure modes of graphene-AgNW composite under tensile and impact loading conditions. In situ tensile tests using a nanoindenter, implemented with a push-to-pull device and a laser-induced projectile impact test system, are used to shed light on load-bearing mechanisms in graphene-AgNW composites. Multiple failure modes have been observed in both experimental setups and analyzed with numerical and theoretical models. Results show that in the tensile loading the distribution of AgNW, as characterized by the effective free length, is the key parameter determining the failure mode. As for the impact failure scenarios, compared with failure modes observed in pure graphene cases, the mechanical reinforcing effect of AgNW will transform the failure mode from a scattered tensile fracture along radial directions to a shear failure that is constrained in a relatively local domain. Theoretical analysis using shear lag modeling, Timoshenko plate theory, molecular dynamics modeling, and finite element modeling approaches are adopted to further establish the failure modes.