Graphene Oxide Research Articles

Nano‐Multiactive Sites Pd/PdO/CuO/PdCu3 Formed In Situ on the Surface Hetero‐Organometallic Pd(II)/Cu(II) Nanosheet: Investigation on the Formation of Active Sites, Synergistic, and Catalytic Activity

ABSTRACTExploring the relationship between the structure of active site and the activity in molecular level and investigating the reason for deactivation are extremely important in designing the highly active catalyst. In this paper, new self‐assembly Schiff‐base Pd/Cu nanosheets supported on the surface of graphene oxide (GO) (called as GO@Hpmaba‐Pd/Cu) were fabricated and characterized. Among them, GO@Hpmaba‐Pd0.2/Cu0.8 exhibited a high activity with a TOF value of up to 95,357 h−1 and substrate suitability in Suzuki cross‐coupling reaction. GO@Hpmaba‐Pd0.2/Cu0.8 could be reused at least 13 times. GO@Hpmaba‐Pd0.2/Cu0.8 was a heterogeneous catalyst and the catalysis occurred on the surface. The truly active sites included Pd/PdO/CuO/PdCu3 formed in situ on the surface of the hetero‐organometallic Pd/Cu nanosheet during catalysis. The synergistic effects among these active sites could be described as that the electrons transferred from GO to CuO (PdO) or to Pd via ligand (Hpmaba) and subsequently electrons transferred from CuO (PdO) to Pd. These made more electron negative palladium, enhancing the oxidation addition between palladium and aryl halide and prompting the activity. The deactivation of catalyst was mainly caused by some destroyed organometallic in the nanosheet, residues adsorbed on catalytic surface, loss of active Pd due to the leaching with increase of recycling, and the aggregation of active metals.

Sustainable hydrogen production with synergistic electron transfer enhancement in nickel-based alkaline HER electrocatalyst empowered by graphene oxide

The hydrogen evolution reaction (HER) plays a crucial role in driving forward the transition to a hydrogen-based economy by providing a means to generate pure hydrogen. However, the efficient and cost-effective production of hydrogen via HER faces significant challenges, particularly at the cathode. To address these challenges, we produced a hybrid material – 2D graphene oxide (GO) sheets coated onto nickel sulfide (NiS) microspheres anchored on Ni Foam (GO@NiS/Ni Foam) using a straightforward synthesis technique. Our research highlights the significant influence of the interaction between GO and NiS on the performance of HER, attributed to the enhancement of electron transport at the interface. Furthermore, the GO@NiS/Ni Foam composite exhibits remarkable durability over extended periods, maintaining its superior functionality for up to 40 h of continuous operation. This underscores its potential for practical implementation in efficient water-splitting processes, offering a promising solution to the challenges hindering widespread adoption of hydrogen technology.

Bottom-up stripping of graphene with controlled oxidation behaviors towards supercapacitors energy storage

Due to its distinctive two-dimensional planar structure, room temperature quantum Hall effect, and high strength, graphene has garnered significant interest in the fields of energy storage and conversion. In order to achieve high efficiency in the production of graphene, electrochemical peeling has been extensively investigated. Nevertheless, the intermolecular forces between graphite layers are disrupted during ion intercalation in solution, leading to inconsistent bonding forces and low yields. In order to address the issues above, this study introduces a novel bottom-up electrochemical peeling method, wherein graphite expansion occurs above the electrolyte. By preventing contact between the peeled graphene and the electrolyte, the oxidation of graphene is significantly minimized, resulting in a substantial yield of 88 %. At the current density of 1.0 A g−1, the Go-QAS displayed 225.5 F g−1, and kept about 220.2 F g−1 after 500 cycles. The well-designed bottom-up peeling process leads to graphene nanosheets with reduced structural degradation, high purity, and excellent conductivity. This technique is expected to introduce innovative concepts for the field.

High-Efficiency Enzyme Assay and Screening of Enzyme-Inhibiting Nanomaterials Using Capillary Electrophoresis with Hierarchically Porous Metal-Organic Framework-Based Immobilized Enzyme Microreactor.

Enzyme-inhibiting nanomaterials have significant potential for regulating enzyme activity. However, a universal and efficient method for systematically screening and evaluating the inhibitory effects of various nanomaterials on drug target enzymes has not been established. While the integrated technique of immobilized enzyme microreactor (IMER) with capillary electrophoresis (CE) serves as an effective tool for enzyme analysis, it still faces challenges such as low enzyme loadability, unsatisfactory stability, and limited applicability. Herein, hierarchical porous metal-organic frameworks (HP-MOFs) were explored as high-performance enzyme immobilization carriers and stationary phases to develop a novel HP-MOFs-based IMER-CE microanalysis system for efficient online enzyme assay and systematic screening of enzyme-inhibiting nanomaterials. As a proof-of-concept demonstration, the model enzyme xanthine oxidase (XOD) was immobilized on a HP-UiO-66-NH2 coated capillary, serving as an efficient and durable IMER for screening potential XOD-inhibiting nanomaterials. The hierarchically micro- and mesoporous structure and superior enzyme loadability of as-prepared HP-UiO-66-NH2-IMER was intensively characterized, followed by systematic evaluation of the separation performance of HP-UiO-66-NH2 coated column and the enzyme kinetics of the immobilized XOD. Compared to the microporous UiO-66-NH2-IMER, the HP-UiO-66-NH2-IMER-CE system showed significant improvements in enzyme loading, maximum reaction rate, repeatability, and long-term stability. Furthermore, the established method was effectively employed to screen the XOD inhibitory activity of various nanomaterials, revealing that graphene oxide, single wall carbon nanotube and three other nanomaterials exhibited inhibitory potentials. The HP-MOFs-based microanalysis system can be easily expanded by modifying the types of immobilized enzymes and holds the potential to accelerate the identification and rational design of effective enzyme-inhibiting nanomaterials.

Metal and metal oxide nanomaterials for heavy metal remediation: novel approaches for selective, regenerative, and scalable water treatment

Heavy metal contamination in water sources poses a significant threat to environmental and public health, necessitating effective remediation strategies. Nanomaterial-based approaches have emerged as promising solutions for heavy metal removal, offering enhanced selectivity, efficiency, and sustainability compared to traditional methods. This comprehensive review explores novel nanomaterial-based approaches for heavy metal remediation, focusing on factors such as selectivity, regeneration, scalability, and practical considerations. A systematic literature search was conducted using multiple academic databases, including PubMed, Web of Science, and Scopus, to identify relevant articles published between 2013 and 2024. The review identifies several promising nanomaterials, such as graphene oxide, carbon nanotubes, and metal-organic frameworks, which exhibit high surface areas, tunable surface chemistries, and excellent adsorption capacities. Surface functionalization with specific functional groups (e.g., carboxyl, amino, thiol) significantly enhances the selectivity for target heavy metal ions. Advances in regeneration strategies, including chemical desorption, electrochemical regeneration, and photocatalytic regeneration, have improved the reusability and cost-effectiveness of these materials. Scalability remains a critical challenge, but recent developments in synthesis methods, such as green synthesis and continuous-flow synthesis, offer promising solutions for large-scale production. The stability and longevity of nanomaterials have been improved through surface modification and the development of hybrid nanocomposites. Integrating nanomaterials with existing water treatment infrastructure and combining them with other remediation techniques, such as membrane filtration and electrochemical methods, can enhance overall treatment efficiency and feasibility. In conclusion, nanomaterial-based approaches hold immense promise for revolutionizing heavy metal remediation and advancing sustainable water management practices. As future research is geared towards retrofitting existing treatment plants, it is equally critical to mitigate unintended environmental and public health consequences associated with the widespread production and use of nanomaterials, such as their leachability into water systems and environmental persistence.

Preparation and adsorption application of PLA/GO/PDA nanofiber membrane

Abstract In this study, PLA(polylactic acid)/GO(graphene oxide)/DA(Dopamine) porous nanofiber membrane was prepared by electrospinning. L16(43) orthogonal experiment was designed to investigate the effects of reaction temperature, reaction time, and DA concentration on the adsorption performance of DA oxidized and self-polymerized on the fiber. Based on the characterization of scanning electron microscopy and the determination of the adsorption performance of the fiber membrane to MB(methylene blue dye), data visualization analysis, variance analysis, and F-test were conducted to determine the optimal process parameters: reaction temperature of 45 ℃, reaction time of 30 h, and DA concentration of 2 mg/ml. PLA/GO/PDA(Polydopamine) nanofiber was prepared and characterized under the optimal process parameters. The results showed that the average diameter of the PDA-loaded nanofiber increased from 737 nm to 996 nm, and a layer of PDA with a thickness of about 129 nm was loaded on the outer surface of the fiber, making the contact angle of the fiber membrane with 0° and becoming a hydrophilic material. In adsorption performance testing of MB, the PLA/GO/PDA nanofiber membrane prepared based on the PLA/GO/DA fiber membrane with an adsorption rate of 98.81 % in 24 h was superior to the PLA/GO/PDA nanofiber membrane prepared based on the PLA/GO fiber membrane.

Nanocomposite Embedded Electric and Magnetic Material Enhancing Antenna Radiation by Linear Relation in Radiators

The main and auxiliary radiating elements are linked by linear mathematical relation and coated with nanocomposite (NC) materials to enhance radiation characteristics. Nanocomposite-based electric material (NE) and nanocomposite-based magnetic material (NM) coated on auxiliary radiating elements to enhance the electromagnetic radiation of the proposed antenna. The radiating elements coated with NE graphene oxide (GO) and NM barium ferrite (BF) have higher electric field and magnetic field distribution respectively. The linear relation of main and auxiliary elements is verified by two substrates FR4, Teflon with correlated results. This proposed NC-coated antenna produces a bandwidth of 4.15 GHz, 4.02 dBi average gain and radiation efficiency of 95.17%, being superior to the antenna without NC coating. Fabricated antenna has 1.56–5.71 GHz bandwidth that includes 2.4/5.2 GHz WLAN, 2.5/3.5 GHz WiMAX, 2.4 GHz ISM, 5G SUB-6 GHz, 5G NR 78 and 2.4/5 GHz Wi-Fi bands.

Bipolar Membranes Via Divergent Synthesis: On the Interplay between Ion Exchange Capacity and Water Dissociation Catalysis.

Bipolar membranes (BPMs) enable the operation of electrochemical reactors with electrode compartments in different chemical environments or pH. The transport properties at the microscopic scale are dictated by the composition and morphology of the interfacial junctions as well as the specific chemistry of the ion-exchange layers that support the current of protons and hydroxide ions. This work elucidates the relation between water-dissociation efficiency and the physicochemical properties of the individual ion-exchange membrane layers in the poly(styrene-b-poly(ethylene-ran-butylene)-b-polystyrene) (SEBS)-based BPM. The optimal water dissociation performance of three previously reported water-dissociation catalysts in the SEBS-based BPM was examined, with junction thickness of graphene oxide > TiO2 > SnO2, resulting in disparate junction morphologies at the BPM's interface. A hybrid junction system, which included both the effective water dissociation catalyst SnO2 and direct contacting of the ion-exchange membrane layer, exhibited high water dissociation efficiency. This was likely due to the immediate ion transport pathway provided by direct membrane contact around the catalyst, which also improved the interfacial adhesion. A higher ion exchange capacity (IEC) in BPMs substantially enhanced the water dissociation performance in BPMs without water-dissociation catalysts. However, the incorporation of the effective SnO2 catalyst into the BPMs with a lower IEC significantly improved performance, an effect attributed to the hybrid junction system. Additionally, the increase in water uptake and ion conductivity of the cation exchange layer with higher IEC suggested that the cation exchange layer and its interface to the water-dissociation catalyst layer may play a key role in water dissociation. This study identifies the key parameters of individual BPM components and their interactions to water dissociation performance, offering new insights to guide in the construction of future BPMs optimized for enhanced water dissociation efficiency at high current densities.

Simultaneous Structural and Electronic Engineering on Bi- and Rh-co-doped SrTiO3 for Promoting Photocatalytic Water Splitting.

Activating metal ion-doped oxides as visible-light-responsive photocatalysts requires intricate structural and electronic engineering, a task with inherent challenges. In this study, we employed a solid (template)-molten (dopants) reaction to synthesize Bi- and Rh-codoped SrTiO3 (SrTiO3 : Bi,Rh) particles. Our investigation reveals that SrTiO3 : Bi,Rh manifests as single-crystalline particles in a core (undoped)/shell (doped) structure. Furthermore, it exhibits a well-stabilized Rh3+ energy state for visible-light response without introducing undesirable trapping states. This precisely engineered structure and electronic configuration promoted the generation of high-concentration and long-lived free electrons, as well as facilitated their transfer to cocatalysts for H2 evolution. Impressively, SrTiO3 : Bi,Rh achieved an exceptional apparent quantum yield (AQY) of 18.9 % at 420 nm, setting a new benchmark among Rh-doped-based SrTiO3 materials. Furthermore, when integrated into an all-solid-state Z-Scheme system with Mo-doped BiVO4 and reduced graphene oxide, SrTiO3 : Bi,Rh enabled water splitting with an AQY of 7.1 % at 420 nm. This work underscores the significance of simultaneous structural and electronic engineering and introduces the solid-molten reaction as a viable approach for this purpose.

Simultaneous Structural and Electronic Engineering on Bi‐ and Rh‐co‐doped SrTiO3 for Promoting Photocatalytic Water Splitting

AbstractActivating metal ion‐doped oxides as visible‐light‐responsive photocatalysts requires intricate structural and electronic engineering, a task with inherent challenges. In this study, we employed a solid (template)‐molten (dopants) reaction to synthesize Bi‐ and Rh‐codoped SrTiO3 (SrTiO3 : Bi,Rh) particles. Our investigation reveals that SrTiO3 : Bi,Rh manifests as single‐crystalline particles in a core (undoped)/shell (doped) structure. Furthermore, it exhibits a well‐stabilized Rh3+ energy state for visible‐light response without introducing undesirable trapping states. This precisely engineered structure and electronic configuration promoted the generation of high‐concentration and long‐lived free electrons, as well as facilitated their transfer to cocatalysts for H2 evolution. Impressively, SrTiO3 : Bi,Rh achieved an exceptional apparent quantum yield (AQY) of 18.9 % at 420 nm, setting a new benchmark among Rh‐doped‐based SrTiO3 materials. Furthermore, when integrated into an all‐solid‐state Z‐Scheme system with Mo‐doped BiVO4 and reduced graphene oxide, SrTiO3 : Bi,Rh enabled water splitting with an AQY of 7.1 % at 420 nm. This work underscores the significance of simultaneous structural and electronic engineering and introduces the solid‐molten reaction as a viable approach for this purpose.

Synergistic Effect of GO and MXene Enables Ultrasensitive, Reversible, and Self-Powered Fire Warning of a GO/MXene/Chitosan Aerogel.

Graphene oxide (GO)-based fire alarm materials have garnered extensive attention because the thermal reduction of GO to reduced GO (RGO) enables rapid fire warning. However, they suffer from poor flame retardancy, irreversible fire warning, and dependence on an external power supply. Herein, a GO/MXene/chitosan aerogel with a low density of 0.018 g cm-3 and good compressibility has been developed. The experimental results demonstrate that (i) MXene effectively reduces the peak and mean heat release rate of GO, while RGO nanosheets compensate for the structural instability of MXene in the flame due to thermal oxidation into TiO2; as such, long-lasting fire warning (>120 s) has been achieved; (ii) the reducibility and conductivity of MXene contribute to the ultrasensitive response of GO, with a fire response time of 1 s; and (iii) notably, the thermoelectric effect of MXene enables the reversible and self-powered fire warning of the GO/MXene/CS aerogel without an external power supply. Compared to pure MXene/CS aerogel, the presence of GO improves the sensitivity and stability of self-powered fire warning, owing to the formation of the highly conductive RGO nanosheets. The results of this work highlight the cooperation between GO and MXene in realizing ultrasensitive, long-lasting, reversible, and self-powered fire warning.

Advanced Graphene-Based Technologies for Antibiotic Removal from Wastewater: A Review (2016–2024)

The increasing presence of antibiotics in wastewater poses significant environmental risks, including the promotion of antibiotic resistance and harm to aquatic ecosystems. This study reviews advancements in graphene-based technologies for removing antibiotics from wastewater between 2020 and 2024. Graphene-based platforms, such as graphene oxide (GO), reduced graphene oxide (rGO), and graphene composites, have shown great promise in this field because of their exceptional adsorption capacities and rapid photocatalytic degradation capabilities. Functionalized graphene materials and graphene integrated with other substances, such as metal oxides and polymers, have enhanced performance in terms of antibiotic removal through mechanisms such as adsorption and photocatalysis. These technologies have been evaluated under various conditions, such as pH and temperature, demonstrating their practical applicability. Despite challenges related to scalability, cost-effectiveness, and environmental impact, the advancements in graphene-based technologies during this period highlight their significant potential for effective antibiotic removal, paving the way for safer and more sustainable environmental management practices.

Magneto-electrochemical water splitting performance of graphene oxide/nickel aluminum-layered double hydroxide nanocomposites

Designing efficient, cheap catalysts for oxygen production is very important for water electrolysis and green hydrogen production. Here, synthesis and electrocatalytic performance of graphene oxide (GO)/nickel-aluminum layered double hydroxide (NiAl-LDH) composites were investigated for water-splitting applications. The composition, microstructure, and morphology of the nanocomposites were confirmed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FE-SEM), and their water oxidation performance was examined in 0.1 M potassium hydroxide solution in the presence and absence of magnetic field. The results show that optimized GO/NiAl-LDH nanocomposite (GO-1 %/NiAl-LDH) exhibits the lowest overpotential compared with other prepared nanocomposites. This performance demonstrates comparable electroactivity to well-developed electrocatalysts like the perovskite-based electrodes, it also shows an improved electrocatalytic activity compared to NiAl-LDHs due to the presence of graphene oxide in the composite. We interpreted this significant performance to improve electron transform and high active site at the synthesized GO/NiAl-LDH composites. The best electrocatalytic activity with an overpotential of 443 and 473 mV at the current density 10 mA.cm−2 were evidenced for GO-1 %/NiAl-LDH nanocomposite in the presence and absence of external magnetic field, respectively. Furthermore, the tafel slope were reported about 54 and 162 mV.dec−1 in the presence and absence of magnetic field, respectively. This improved water oxidation can be attributed to the magneto-hydrodynamic effect and the increased number of metal sites on LDHs under the magnetic field.

Enhanced selectivity of SPEEK membrane incorporated covalent organic nanosheet crosslinked graphene oxide for vanadium redox flow battery

It is difficult for sulfonated poly(ether ether ketone) (SPEEK) to possess both high proton conduction and vanadium resistance owing to the degree of sulfonation. Herein, the composite membranes (S/GO-TpTG) with cationic covalent organic nanosheet (TpTG) crosslinked graphene oxide (GO-TpTG) are prepared to enhance selectivity by optimizing the ion transport channels. The GO-TpTG can efficiently transport protons utilizing its cationic porous structure and acid-base pairs' interaction with SPEEK. Meanwhile, it can block vanadium ions through the Donnan exclusion and physical blocking effects. The S/GO-TpTG membrane with 3 wt% GO-TpTG exhibits excellent proton conductivity (82.7 mS cm−1) and selectivity (77.9 × 10−7 cm2 min−1). The VRFB with this membrane exhibits excellent energy efficiency (88.6–81.0 % at 100–200 mA cm−2), cycle durability, and self-discharge time (209.8 h). This study confirms the great potential of GO-COF to balance proton conductivity and vanadium resistance, and provides an effective strategy to optimize proton channels.

Aptamer-guided graphene oxide quantum dots for targeted suicide gene therapy in an organoid model of luminal breast cancer

Breast cancer is one of the most common cancers in women. One of the best therapeutic methods against breast cancer is gene therapy, while having an appropriate gene carrier is the biggest challenge of gene therapy. Hence, developing carriers with low cytotoxicity and high gene transfection efficiency, and preferentially with the selective function of gene delivery is a critical demand for this method. In the present study, we introduce a novel targeted carrier to deliver the inducible caspase-9 suicide gene (pLVSIN-iC9) into breast cancer cells. The carrier is composed of graphene oxide quantum dots decorated with polyethyleneimine, and S2.2; an aptamer with high affinity to MUC1 (GOQD-PEI/S2.2). Due to the overexpression of MUC1 in breast cancer cells, the designed GOQD-PEI/S2.2/pLVSIN-iC9 can selectively target cancer cells. Moreover, to better mimic solid tumor conditions, and to evaluate the selective effect of the GOQD-PEI/S2.2/pLVSIN-iC9, an organoid model derived from human dermal fibroblasts (HDF) and MCF-7 cells (coculture organoid) was generated and characterized. The results demonstrate that the coculture organoid model adapts the tissue structure of luminal breast cancer, as well. Therefore, the organoids were subjected to treatment with targeted gene therapy using GOQD-PEI/S2.2/pLVSIN-iC9. Our evidence supports the targeted killing effect of iC9 on the breast cancer cells of the organoids and suggests the good potential of the newly introduced carriers in targeted gene delivery.

Electrospinning of Polyaniline/Poly Acrylonitrile/Reduced Graphene Oxide Doped with Aluminium Oxide Nanoparticles for Supercapacitors Application

Electrospinning of Polyaniline/Poly Acrylonitrile/Reduced Graphene Oxide Doped with Aluminium Oxide Nanoparticles for Supercapacitors Application

Fabrication of Co/Zn Doped Manganese Ferrite Magnetic Nanoparticles: Improving Electrochemical Detection of Antibiotic Through Modification of Reduced Graphene Oxide

Fabrication of Co/Zn Doped Manganese Ferrite Magnetic Nanoparticles: Improving Electrochemical Detection of Antibiotic Through Modification of Reduced Graphene Oxide

Controlled Growth of ZIF-8 Membranes on GO-Coated α-Alumina Supports via ZnO Atomic Layer Deposition for Improved Gas Separation.

This study presents a novel approach for fabricating ZIF-8 membranes supported on α-alumina hollow fibers through the introduction of a graphene oxide (GO) gutter layer and the application of zinc oxide (ZnO) Atomic Layer Deposition (ALD). The method successfully addressed key challenges, including excessive precursor penetration and membrane thickness. The introduction of the GO layer and subsequent ZnO ALD treatment significantly reduced membrane thickness to approximately 300 nm and eliminated delamination issues between the GO layer and the alumina support. The optimized membranes demonstrated enhanced propylene permeance, with values approximately three times higher than those of membranes without GO, and achieved higher separation factors, indicating minimal inter-crystalline defects. Notably, the GO layer influenced the microstructure, leading to an increase in permeance with rising temperatures. These findings highlight the potential of this strategy for developing high-performance ZIF-8 membranes for gas separation applications.

Two-Dimensional Hydration and Triple-Interlayer Lattice Structures in Sulfate-Intercalated Graphene Oxide Nanosheets

Sulfate anions (SO42−) are pivotal in various scientific and industrial domains, including mineralogy, biology, and materials science. While extensive research has elucidated sulfate hydration in bulk solids, liquids, and gaseous clusters, a significant gap persists in understanding sulfate interactions within two-dimensional materials, particularly graphene oxide (GO) nanosheets. This study investigates the intricate hydration phenomena and novel triple-interlayer lattice configurations that emerge from sulfate intercalation in GO nanosheets. Utilizing a straightforward methodology for obtaining precise X-ray measurements of confined nanospaces, we analyzed the temperature-dependent behavior and structural characteristics of these systems. Our findings reveal how sulfate ions modulate interlayer spacing, the dynamics of GO layers, and phase transitions. This research offers an atomic-scale understanding of hybrid hydration behaviors within confined SO4-H2O nano-environments, advancing our knowledge of sulfate interactions in two-dimensional materials.

How is graphene influencing the electronic properties of NiO–TiO2 heterojunction?

Abstract We synthesized a new nanocomposite bearing nitrogen-doped graphene as a carbon additive to the nickel oxide nanoparticles-titanium dioxide nanotubes heterojunction. The main purpose was the comparison of its structural and electronic properties, hence potential applications, with its undoped, reduced graphene oxide (GO) homolog. The beneficial effect of graphene on TiO2 heterojunctions is an accepted fact in the materials science field, mainly in favor of the nitrogen-doped one. Our data show that both graphenes have little influence on the band offset values of the NiO–TiO2 heterojunction. Still, the presence of reduced, undoped GO allows an improved electron transfer process from titania, causing a better charge carriers’ separation. This correlates well with their observed photocatalytic activity under visible light exposure, for the degradation of four emerging contaminant pollutants (amoxicillin, acetaminophen, ibuprofen, and β-estradiol). In addition, the band alignment of the NiO–TiO2 heterojunction with graphenes, and the corrected thermodynamic potentials of the organic pollutants explain well the observed photocatalytic behavior.