Chemically Reduced Graphene Oxide Research Articles

Boosting Zinc Hybrid Supercapacitor Performance via Thiol Functionalization of Graphene-Based Cathodes.

Zinc hybrid supercapacitors (Zn-HSCs) hold immense potential toward the next-generation energy storage systems, effectively spanning the divide between conventional lithium-ion batteries (LIBs) and supercapacitors. Unfortunately, the energy density of most of Zn-HSCs has not yet rivalled the levels observed in LIBs. The electrochemical performance of aqueous Zn-HSCs can be enhanced through the chemical functionalization of graphene-based cathode materials with thiol moieties as they will be highly suitable for favoring Zn2+ adsorption/desorption. Here, a single-step reaction is employed to synthesize thiol-functionalized reduced graphene oxide (rGOSH), incorporating both oxygen functional groups (OFGs) and thiol functionalities, as demonstrated by X-ray photoelectron spectroscopy (XPS) studies. Electrochemical analysis reveals that rGOSH cathodes exhibit a specific capacitance (540 Fg-1) and specific capacity (139 mAhg-1) at 0.1 Ag-1 as well as long-term stability, with over 92% capacitance retention after 10000 cycles, outperforming chemically reduced graphene oxide (CrGO). Notably, rGOSH electrodes displayed an exceptional maximum energy density of 187.6Whkg-1 and power density of 48.6kWkg-1. Overall, this study offers an unprecedented powerful strategy for the design and optimization of cathode materials, paving the way for efficient and sustainable energy storage solutions to meet the increasing demands of modern energy applications.

Analysis of contact creep behaviour of nanofilled composites

An effective modelling method for analysing the contact creep behaviour of composite materials with different nanofillers was proposed. Considering both the contact and creep material nonlinearities, an augmented Lagrangian algorithm was used to treat the unilateral contact constraints, and a time-hardening creep constitutive equation was adopted to describe the deformation characteristics of the nanocomposites. The constitutive parameters were extracted through a series of linear fittings based on the multiaxial creep theory and creep test curves, and the accuracy of the constitutive equation was validated. The applications of the proposed modelling method were demonstrated using a rope-wheel contact system (RWCS), in which the wheels were made of polystyrene (PS) with carbon black (CB), multi-walled carbon nanotubes (MWCNT), or chemically reduced graphene oxide (CRGO). The results indicated that the addition of nanofillers significantly reduced the creep deformation of the contact zone. The CRGO exhibited a better anti-creep performance than that of CB and MWCNT. Compared with pure PS, the maximum deformation on the contact path of the nanocomposite wheel with 5.0 wt% CRGO sheets at 1500 s and 104 s was reduced by approximately 22 % and 52 %, respectively. The coefficient of friction μ had a strong influence on the contact creep deformation when μ < 0.3. Additionally, the anti-creep capability of the added nanofillers became more evident as the loading time increased. The contact creep deformation of the CRGO composite was less than one-tenth that of the matrix material after 30 d.

Well-organized metal-free chemically reduced graphene oxide sheets as electrocatalysts for enhanced oxygen reduction reactions in alkaline media

Metal-free reduced graphene oxides have recently received attention as potential replacements for platinum-based electrocatalysts. In the present study, we investigated the electrochemical characteristics of chemically reduced graphene oxides (C-rGO) in oxygen reduction reactions (ORR). The C-rGO displays significantly enhanced catalytic activity towards the ORR in alkaline solutions compared to the starting graphene oxide (GO). The thermal properties of C-rGO show good thermal stability, and structural defects in C-rGO were confirmed by Raman analysis. Electrochemical impedance spectroscopy (ESI) analysis confirmed C-rGO superior electron transport capacity over GO. The onset potential (0.82 V), lower Tafel slope, and current density (-5.6 × 10-4 mA/cm2) of the C-rGO catalysts were increased compared to GO due to the majority of functional groups removed after chemical reductions. It's clear that catalysts work through four electron (e-) ORR processes bacause the C-rGO has higher electron transfer numbers (3.8 at a potential of −0.63 V).

Low-temperature selectivity study of chemically treated graphene oxide for detection of hydrogen gas

Chemically Reduced Graphene Oxide (CRGO) based resistive gas sensor exhibits exceptional hydrogen (H2) selectivity. The device sensitivity in the temperature range, room temperature (RT)-150 °C, was tested. A response of 1.83% towards hydrogen at RT, and nil cross-sensitivity to carbon monoxide (CO) and methane (CH4) gases was observed. The devices also showed hydrogen selectivity at elevated temperatures (≥75 °C). However, the nature of hydrogen sensing showed a typical transition upon increasing the temperature. A suitable sensing mechanism is used to explain the selective device characteristics at different temperatures.

A novel approach to impart selective response in palladium decorated reduced graphene oxide gas sensors

The optimum temperature for selective gas sensing using reduced graphene oxide depends on the reducing method of graphene oxide (GO). This work reveals that chemically reduced graphene oxide (CRGO) manifests selectivity at high temperature, while thermally reduced graphene oxide (TRGO) indicates gas selectivity at room temperature (RT). Both CRGO and TRGO are synthesized from the same GO source. Palladium nanoparticles were used to increase the catalytic activity of both the sensing surfaces. Hydrogen, carbon monoxide and methane gases were used for the sensor studies. The materials have been characterized to correlate the difference in properties with the selective sensing performance.

A comparative investigation of the chemical reduction of graphene oxide for electrical engineering applications.

The presence of oxygen-containing functional groups on the basal plane and at the edges endows graphene oxide (GO) with an insulating nature, which makes it rather unsuitable for electronic applications. Fortunately, the reduction process makes it possible to restore the sp2 conjugation. Among various protocols, chemical reduction is appealing because of its compatibility with large-scale production. Nevertheless, despite the vast number of reported chemical protocols, their comparative assessment has not yet been the subject of an in-depth investigation, rendering the establishment of a structure-performance relationship impossible. We report a systematic study on the chemical reduction of GO by exploring different reducing agents (hydrazine hydrate, sodium borohydride, ascorbic acid (AA), and sodium dithionite) and reaction times (2 or 12 hours) in order to boost the performance of chemically reduced GO (CrGO) in electronics and in electrochemical applications. In this work, we provide evidence that the optimal reduction conditions should vary depending on the chosen application, whether it is for electrical or electrochemical purposes. CrGO exhibiting a good electrical conductivity (>1800 S m-1) can be obtained by using AA (12 hours of reaction), Na2S2O4 and N2H4 (independent of the reaction time). Conversely, CrGO displaying a superior electrochemical performance (specific capacitance of 211 F g-1, and capacitance retention >99.5% after 2000 cycles) can be obtained by using NaBH4 (12 hours of reaction). Finally, the compatibility of the different CrGOs with wearable and flexible electronics is also demonstrated using skin irritation tests. The strategy described represents a significant advancement towards the development of environmentally friendly CrGOs with ad hoc properties for advanced applications in electronics and energy storage.

Paper-based potentiometric sensing devices modified with chemically reduced graphene oxide (CRGO) for trace level determination of pholcodine (opiate derivative drug).

Robust, reliable and cost-effective paper-based analytical device for potentiometric pholcodine (opiate derivative drug) ion sensing has been prepared and characterized. A printed pholcodinium (PHL)2+/5-nitrobarbiturate (NB)− ion-association complex as a sensory material-based all-solid-state ion-selective electrode (ISE) on a chemically reduced graphene oxide (CRGO) solid-contact, and a printed all-solid-state Ag/AgCl reference electrode, has been combined on a hydrophobic paper substrate coated with fluorinated alkyl silane (CF3(CF2)7CH2CH2SiCl3, CF10). The sensors revealed a potentiometric slope of 28.7 ± 0.3 mV dec−1 (R2 = 0.9998) over a linear range starting from 2.0 × 10−7 M to 1.0 × 10−2 M and a detection limit of 0.04 μg mL−1. The repeatability and stability of the pholcodine paper-based sensor was found to be 2.32%. The RSD% (n = 6) was found to be 2.67% when using five different paper-based sensors. The sensor revealed an excellent selectivity towards PHL over dextromethorphan, codeine, ephedrine, carbinoxamine, caffeine, ketamine, and K+, Na+ and Ca2+ ions. It showed a good recovery (94–104%) for the determination of PHL in different artificial serum samples. The presented paper-based analytical device was successfully introduced for PHL determination in different pharmaceutical formulations (i.e. syrups and suspensions) containing pholcodine. The current work can be considered as a promising possible analytical tool to obtain cost-effective and disposable paper-based potentiometric sensing devices. These devices can be potentially manufacturable at large scales in pharmaceutical, clinical and forensic applications for opiate drug assessment.

Electrochemical reduction of NAD+ on graphene oxide and chemically reduced graphene oxide nanosheets

In this work, the electrochemical reduction of nicotinamide adenine dinucleotide (NAD+) was studied on graphene oxide (GO) and chemically reduced graphene oxide (CRGO) nanosheets. GO was prepared by modified Hummer’s method and reduced using hydrazine hydrate to obtain CRGO. The material was characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The TEM studies reveal the presence of nanosheets and the XRD exhibited the characteristic pattern of GO and CRGO respectively. The Raman spectrum showed a slight red shift for CRGO compared to GO. The electrochemical reduction of NAD+ was investigated on bare and modified glassy carbon electrode (GCE) using various electrochemical techniques such as linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The reduction of NAD+ to NADH occurs at a relatively lower potential of −1.04 V on GO/GCE compared to CRGO/GCE (−1.08 V) and bare GCE (−1.12 V). GO/GCE showed enhanced catalytic activity due to the presence of defect structures and oxygen functional groups on the carbon framework. The kinetic studies further revealed that reduction is an adsorption controlled process. From LSV obtained at different scan rates the number of electrons transferred was deduced as 1.7 and 1.2 for GO/GCE and CRGO/GCE respectively and the values are correlated with other electrochemical techniques such as hydrodynamic voltammetry and DPV. The heterogeneous rate constant determined from hydrodynamic voltammetry showed that GO/GCE (8.5 × 10−5 cm s−1) exhibited higher rate constant than CRGO/GCE (7.4 × 10−7 cm s−1). EIS was carried out at different cathodic potentials to analyze the kinetics at the electrode-electrolyte interface. The detection of NAD+ was performed on GO/GCE using DPV which showed a linear range of 100–1100 µM with a LOD of 19.36 µM. It was found that GO/GCE showed good catalytic activity compared to CRGO/GCE with better electron transfer kinetics.

An improved drop casting electrochemical strategy for furosemide quantification in natural waters exploiting chemically reduced graphene oxide on glassy carbon electrodes.

This work exploits the applicability of a chemically reduced graphene oxide (CRGO) modification on the electrochemical response of a glassy carbon electrode (GCE) for the first-time sensitive determination of furosemide in natural waters. The batch injection analysis (BIA) is proposed as an analytical method, where CRGO-GCE is coupled to a BIA cell for amperometric measurements. Acetate buffer (0.1μmolL-1, pH5.2) was used as the background electrolyte. The modification provided an increase in sensitivity (0.024μA/μmolL-1), low limit of detection (0.7μmolL-1), RSD (< 4%), and broad linear range (1-600μmolL-1). Recovery tests performed in two different concentration ranges resulted in values between 89 and 99%. Recovery tests were performed and compared with high-performance liquid chromatography (HPLC) with UV-Vis detection using Student's t test at a 95% significance level, and no significant differences were found, confirming the accuracy of the method. The developed method is proven faster (169h-1) compared with the HPLC analysis (5h-1), also comparable with other flow procedures hereby described, offering a low-cost strategy suitable to quantify an emerging pharmaceutical pollutant. Graphical abstract.

Comparison of thermally and chemically reduced graphene oxides by thermal analysis and Raman spectroscopy

Graphene oxide (GO) is not only an intermediate in top-down graphene preparation, but it is also acknowledged for its convenient application when the hydrophobicity of graphene is a drawback. Its preparation through the wet exfoliation of graphite inevitably leads to a product lacking several of the outstanding features of graphene. The destroyed graphene structure can be at least partially reconstructed by thermal and/or wet chemical reduction. Thermally reduced graphene oxide (TRGO) was obtained by mild heat treatment (300 °C) in argon, while chemically reduced graphene oxide (CRGO) was prepared by using a green reagent, ascorbic acid (AA). The parent GO and the two GO derivatives were compared by thermogravimetric analysis coupled with mass spectroscopy and Raman spectroscopy. Both reductive treatments resulted in enhanced thermal stability and higher C/O ratio. Although the chemical reduction with AA was more efficient in the elimination of the O functionalities, it also resulted in significant fragmentation of the graphene-like platelets.

Electrochemical studies of NADH oxidation on chemically reduced graphene oxide nanosheets modified glassy carbon electrode

In this study, the electrochemical oxidation of NADH was investigated on chemically reduced graphene oxide (CRGO) modified glassy carbon electrode (GCE) using various electrochemical techniques. CRGO was prepared by modified Hummer's method and characterized using transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) and UV–vis spectroscopy respectively. The TEM studies revealed the presence of nanosheets and the incorporation of residual functional group was confirmed through FTIR spectroscopy. Raman analysis showed the corresponding D and G band with a blue shift for CRGO nanosheets. Also the CRGO showed high defect compared to GO as elucidated from ID/IG ratio. The initial electrochemical studies were carried out using cyclic voltammetry wherein the CRGO/GCE exhibited low overpotential and high oxidation current compared to GO/GCE and bare GCE. Kinetic studies revealed that the oxidation is an adsorption controlled reaction and the number of electron transfer was determined using hydrodynamic voltammetry. Further, the EIS analysis was carried out at various potentials to study the charge transfer kinetics at the electrode/electrolyte interface. As the applied potential is varied from the double layer to Faradaic region, the charge transfer resistance decreases which indicates the NADH oxidation at the corresponding potential. Also, the decrease in the double layer capacitance confirms the adsorption of reaction products leading to fouling of the electrode surface. The detection of NADH on CRGO/GCE was performed using differential pulse voltammetry (DPV). The limit of detection was found to be 21.85 μM with a linear range of 50 μM–650 μM. It is found that CRGO showed better activity compared to GO but their electron transfer kinetics is very poor and suffered from electrode fouling.

Chemically reduced graphene oxide (CRGO) from waste batteries and morphological assessment of CRGO/methyl cellulose transdermal film

Disposed battery is a huge source of graphite in our environment. This graphite can be recycled by carrying out electrolysis at fixed voltage and the obtained product can be easily converted into graphene by the generation of graphene oxide (GO) as an intermediate using Hummer’s method. GO is converted into chemically reduced graphite oxide (CRGO) by sodium carbonate treatment and the material obtained is used as a filler in a drug (Ketorolac Tromethamine) loaded Hydroxypropyl methylcellulose (MC) matrix. The KT loaded CRGO\\MC nanocomposite films is used to develop transdermal film for drug delivery where CRGO acts as a carrier. The recycled graphite (RGF), GO and CRGO materials has been characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), Ultra-violet (UV) spectroscopy, Transmission Electron Microscopy (TEM), Thermo-Gravimetric Analysis (TGA) and Dynamic Light Scattering (DLS). KT loaded CRGO\\MC nanocomposite films are characterized by TGA, XRD and moisture absorption properties analysis. The experimental result reveals the formation of successful exfoliated and stable KT loaded CRGO\\MC transdermal film. XRD study reveals the crystalline nature of nanocomposite films. In vitro drug release studies showed that CRGO\\MC based films can be used for controlled transdermal drug delivery applications.

Chemically Reduced Graphene Oxide on Gold Electrodes from Recordable CDs: Characterization and Potential Sensing Applications

This work presents the development and characterization of a new chemically modified electrode exploiting recordable Au-rewritable compact discs (AuCDs) as substrate for drop casting of a chemically-reduced graphene-oxide slurry focusing on simple and low-cost electrochemical sensors. Increase in electrochemical responses in cyclic voltammetric and amperometric measurements were achieved using the proposed sensor. Both scanning electron microscopy and atomic force microscopy data showed increase in rugosity (about 46% higher) for the chemically reduced graphene oxide (CRGO) AuCD surface while Raman spectroscopy confirmed the presence of structural defects of graphene. The calculated charge transfer resistances (Rct) and heterogeneous electron transfer rate constants (k0) were 1638 Ω and 0.0022 cm s-1 for the bare substrate, and 91 Ω and 0.0027 cm s-1 for the modified electrode, evidencing the facilitated electron transfer of the CRGO-AuCD surface. The dopamine (DP) amperometric detection using CRGO-AuCD provided low detection limit (0.12 µg L-1) compared with other modified electrodes already reported, high precision (relative standard deviation (RSD) < 5%) and analytical frequency (370 h-1). As a proof-of-concept, DP determination in synthetic saliva samples was performed and a satisfactory recovery value (98.6 ± 0.9%) was obtained.

Tailored and highly efficient oxidation of various-sized graphite by kneading for high-quality graphene nanosheets

Abstract Graphene oxide (GO) exfoliated from graphite oxide is a precursor of graphene, which is a highly promising two-dimensional material for energy storage, printing electronics, composites, conducting fibers, etc. However, during the fabrication of GO by chemical oxidation, large amounts of oxidants and acid are used, which lead to many concerns, such as severe environmental pollution and high processing cost. In this study, we propose a highly efficient and rational oxidation of various-sized graphite powder by minimizing the amount of acid used (reducing 1/10 times) through kneading, inspired by the concept of kneading dough. First, NaClO3 and graphite were mixed together. Then, a small amount of fuming nitric acid was added, and the mixture was kneaded for several minutes. The ratio of oxidant to graphite and the reaction time, with and without kneading, were investigated based on the lateral size of graphite, because large-sized graphite requires more diffusion time for oxidizing the species through the graphitic layers. The chemically-reduced GO nanosheets exhibit highly crystalline structures based on the Raman spectroscopy and transmission electron microscopy studies, and their films exhibit a high electrical conductivity of over 45,000 S/m from large graphite, which is promising for electrical and electrochemical applications.

Chemically‐reduced Graphene Oxide Sensor for Dipyrone Quantification in Pharmaceutical Samples Using Amperometric Detection

AbstractDipyrone (metamizole sodium) is one of the most consumed drugs in the world. In this work a novel analytical method was developed for dipyrone sensing. This method involves the amperometric detection on a chemically‐reduced graphene‐oxide (CRGO)‐modified glassy carbon electrode. Raman spectroscopy and scanning electron microscopy revealed the presence of multilayer graphene layers that contributed to the electrocatalytic oxidation of dipyrone and increase in the electroactive area. Advantages of this sensor include elimination of previous separations, solvent extraction, or sample filtration, low detection limit (0.13 μmol L−1) with a linear range from 48 to 246 μmol L−1 and adequate recovery values (97–103 %). Applied to commercial pharmaceutical samples, this method showed results ranging from 451 to 541 mg of dipyrone per tablet, which agreed with the expected values. The results obtained by amperometry were compared statistically with the official method recommended by the Brazilian Pharmacopoeia (iodometric method), with no significant differences between them at 95 % confidence level. The proposed method is accurate for the monitoring of sodium dipyrone in pharmaceutical formulations, highlighting the lower reagent consumption and interferences in the analytical process.

Square-Wave Voltammetry Determination of Ciprofloxacin in Pharmaceutical Formulations and Milk Using a Reduced Graphene Oxide Sensor

In this paper, a simple, sensitive and precise electroanalytical method was developed using a chemically-reduced graphene-oxide (CRGO)-modified glassy carbon electrode and square wave voltammetry (SWV) for determination of ciprofloxacin in pharmaceutical formulations (tablets) and milk samples. Advantages of this sensor include a potential displacement of 100 mV and a 5-fold current increase for the electrochemical oxidation of ciprofloxacin, which resulted in a highly sensitive sensor, when compared to unmodified electrode. The improved properties of the modified electrode are likely due to the formation of a porous surface evidenced by the change in electrode kinetics (thin-layer diffusion process). The proposed sensor is free from interference of sample matrix (pharmaceutical formulations and low/high-fat milk) avoiding cumbersome processes such as previous separations, solvent extraction, or sample filtration (samples were only diluted in Britton-Robinson buffer solution). The results by SWV showed a limit of detection of 0.21 µmol L-1 (correspondent to 0.069 mg L-1), which is lower than the ones obtained using other carbon-based electrodes, relative standard deviations lower than 12%, and satisfactory recoveries in the range from 84 to 109%. The results obtained were statistically similar (95% confidence level) with those performed through high-performance liquid chromatography (HPLC).

Quantifying Graphene Oxide Reduction Using Spectroscopic Techniques: A Chemometric Analysis.

The surface chemistry of graphene oxide (GO) can be modified by the chemical reduction of oxygen-containing groups using L-ascorbic acid (L-AA). Being able to "tune" the surface hydrophobicity of GO in a controlled manner, with a well-defined level of reduction, provides a valuable tool for understanding and controlling interactions with hydrophobic surfaces. Numerous analytical and chemical methods have been used to determine the extent of reduction in chemically reduced graphene oxide (CRGO) samples. However, many of these methods are limited by their laborious nature, cost, or lack of sensitivity in resolving oxygen content in samples that have only been reduced for short periods of time, making them inappropriate for rapid use with multiple samples. Here, we have used ultraviolet (UV), Raman, and attenuated total reflection infrared (ATR-IR) spectroscopy to monitor the chemical reduction of GO. These three techniques are simple, rapid, nondestructive, accurate, and widely available. The data set from each technique has been correlated and modeled against a reference data set (carbon to oxygen ratio obtained from elemental analysis) using partial least squares regression (PSLR). Using this approach, the chemical reduction of GO was quantified from UV (r2 = 0.983, RMSECV = 0.049), Raman (r2 = 0.961, RMSECV = 0.073) and ATR-IR (r2 = 0.993, RMSECV = 0.032) data. ATR-IR enabled identification of the different oxygen-containing groups on GO, and coupled with chemometric modeling, provides an excellent approach for the routine quantitative analysis of the chemical reduction of GO.

Strong Dependence of Surface Enhanced Raman Scattering on Structure of Graphene Oxide Film.

Graphene and its derivatives have been demonstrated to be good surface-enhanced Raman scattering (SERS) substrates. However, the literature offers some contrasting views on the SERS effect of graphene-based materials. Thus, understanding the mechanism of the SERS enhancement of graphene is essential for exploring its application as a SERS substrate. In this study, graphene oxide (GO) and chemically reduced graphene oxide (CRGO) films with different morphologies and structures were prepared and applied as SERS substrates to detect Raman dye molecules. The observed enhancement factors can be as large as 10~103. The mechanism of SERS enhancement is discussed. It is shown that the SERS effect was independent of the adsorption of dye molecules and the surface morphologies of graphene-based films. Raman shifts are observed and are almost the same on different graphene-based films, indicating the existence of charge transfer between dye molecules and substrates. The Raman enhancement factors and sensitivities of dye molecules on different films are consistently within the IG/ID ratios of graphene-based substrates, indicating that the dramatically enhanced Raman spectra on graphene-based films are strongly dependent on the average size of sp2 carbon domain.

Graphene Oxide/ZnS:Mn Nanocomposite Functionalized with Folic Acid as a Nontoxic and Effective Theranostic Platform for Breast Cancer Treatment.

Nanoparticle-based cancer theranostic agents generally suffer of poor dispersability in biological media, re-agglomeration over time, and toxicity concerns. To address these challenges, we developed a nanocomposite consisting of chemically-reduced graphene oxide combined with manganese-doped zinc sulfide quantum dots and functionalized with folic acid (FA-rGO/ZnS:Mn). We studied the dispersion stability, Doxorubicin (DOX) loading and release efficiency, target specificity, internalization, and biocompatibility of FA-rGO/ZnS:Mn against folate-rich breast cancer cells, and compared to its uncoated counterpart (rGO/ZnS:Mn). The results indicate that DOX is adsorbed on the graphene surface via π–π stacking and hydrophobic interaction, with enhanced loading (~35%) and entrapment (~60%) efficiency that are associated to the chelation of DOX and surface Zn2+ ions. DOX release is favored under acidic conditions reaching a release of up to 95% after 70 h. Membrane integrity of the cells assessed by Lactate dehydrogenase (LDH) release indicate that the surface passivation caused by folic acid (FA) functionalization decreases the strong hydrophobic interaction between the cell membrane wall and the edges/corners of graphene flakes. Chemotherapeutic effect assays reveal that the cancer cell viability was reduced up to ~50% at 3 µg/mL of DOX-FA-rGO/ZnS:Mn exposure, which is more pronounced than those obtained for free DOX at the same doses. Moreover, DOX-rGO/ZnS:Mn did not show any signs of toxicity. An opposite trend was observed for cells that do not overexpress the folate receptors, indicating that FA functionalization endows rGO/ZnS:Mn with an effective ability to discriminate positive folate receptor cancerous cells, enhancing its drug loading/release efficiency as a compact drug delivery system (DDS). This study paves the way for the potential use of functionalized rGO/ZnS:Mn nanocomposite as a platform for targeted cancer treatment.

Simultaneously ‘pushing’ and ‘pulling’ graphene oxide into low-polar solvents through a designed interface

Dispersing graphene oxide (GO) in low-polar solvents can realize a perfect self-assembly with functional molecules and application in removal of organic impurities that only dissolve in low-polar solvents. The surface chemistry of GO plays an important role in its dispersity in these solvents. The direct transfer of hydrophilic GO into low-polar solvents, however, has remained an experimental challenge. In this study, we design an interface to transfer GO by simultaneously ‘pushing and pulling’ the nanosheets into low-polar solvents. Our approach is outstanding due to the ability to obtain monolayers of chemically reduced GO (CRGO) with designed surface properties in the organic phase. Using the transferred GO or CRGO dispersions, we have fabricated GO/fullerene nanocomposites and assessed the ability of CRGOs for dye adsorption. We hope our work can provide a universal approach for the phase transfer of other nanomaterials.