Graphene Oxide Materials Research Articles

A novel screening on the specific peptides by molecular simulation and development of the highly-sensitive electrochemical sensor for saxitoxin

A simple and quick electrochemical sensor has been developed for the detection of saxitoxin (STX) based on the specific peptides, which were screened and identified by molecular simulation and electrochemical characterization, respectively. The library of saxitoxin peptides was obtained followed by structural analysis of the receptor and STX, molecular docking, amino acid mutation, and molecular dynamics. The specific peptide (named S4) was screened by the theoretical interaction energy (ΔE) and the fact electrochemical identification. Meanwhile, the reduced graphene oxide (rGO) and gold nanoparticles (AuNPs) materials were introduced to improve the electron mass transfer and increase the electrochemical signal. Under the optimal condition, one simple and quick electrochemical sensor was developed between the ΔI and the concentration of STX in the range of 10 ∼ 1000 ng/L with a limit of detection (LOD) of 6.9 × 10–4 μg/L (S/N = 3). In seawater, artificial seawater, and oyster powder samples, a good recovery rate was found in the range of 87.3 %–116.2 %. In addition, excellent selectivity, good reproducibility, and stability were obtained. It provides a novel idea for the screening of the specific peptides of toxins and the development of the electrochemical peptides sensor.

A graphene oxide based composite granule for methylene blue separation from aqueous solution: Adsorption, kinetics and thermodynamic studies

Graphene oxide and chitosan composite material using as a high-efficiency and low-cost granular adsorbent for methylene blue removal was fabricated via self-assembling method. The effects of pH value, contact time, initial concentration, adsorbent dose, temperature, and recyclic stability on the adsorption performance of methylene blue in aqueous solution were investigated in detail. Desorption process with the effects of solvents, contact time, and temperature were also conducted carefully in this study. The adsorption kinetics and adsorption isotherm of dye adsorption process showed that dye adsorption process was fitted to the pseudo-second-order kinetic model and the Freundlich adsorption isotherm, indicating a physical adsorption process with multilayer adsorption. The intra-particle diffusion model indicated that the dye adsorption by the granular adsorbent was strongly happened during the first 4 h. The thermodynamic study showed that the adsorption was a spontaneous and exothermic process and dye ions were condensed onto the surface of adsorbent. The maximum adsorption capacity of dye on the granular adsorbent was calculated as 951.35 mg/g and the adsorbent could maintain its adsorption performance after six cycles. In general, this study provided an efficient, cost-effective, and recyclable the granular adsorbent for dye separation from aqueous solution.

Sustainable selection of microwave absorbing materials: A green evaluation under interval-valued intuitionistic fuzzy environment

Environmentally friendly technology is being used by industries all over the world, and engineers in the manufacturing and materials industry are embracing sustainable business models. In this paradigm, materials are processed using economically and environmentally sound methods. The use of microwave-absorbing materials (MAMs) in low-altitude observatory aircraft and the rise in electromagnetic pollution have brought them to light. The main aim of this study is to select an ideal MAM with excellent physical, electromagnetic, chemical, and thermal properties, which also fulfills sustainability aspects based on expert judgments. In this regard, we have proposed a new hybrid framework consisting of Modified Digital Logic (MDL), a subjective weighting method in combination with the measurement of alternatives and ranking according to compromise solution (MARCOS) under an interval-valued intuitionistic fuzzy (IVIF) environment to select an optimum MAM. Furthermore, this research work contributes to streamlining the selection process by consolidating the plethora of work available in the literature on the synthesis and characterization of MAMs. A database is created for 160 potential candidate materials in C, S, X, and Ku bands for carbon-based materials, including carbon nanotubes (CNT), graphene, reduced graphene oxide (rGO), carbon fibers, and biomass-derived materials. These materials are then passed through successive screening stages to shortlist 14 materials, which are ranked subsequently over a set of 15 crisp and ambiguous criteria. This comprehensive study simultaneously caters to quantitative and qualitative information extracted from experimental work, material resource packs, or expert evaluations. The findings highlight CNT/Fe (20 wt%, E) (Al1) as the most suitable candidate for MAM application with outstanding electromagnetic properties. Finally, the results are compared with extant approaches to check the reliability of the proposed framework. In addition, sensitivity analysis is carried out to establish the feasibility and robustness of the obtained results.

Autoclave-mediated reduction of graphene oxide for enhanced conductive films

A highly efficient and environmentally friendly method for producing high-quality reduced graphene oxide (rGO) films is explored. It consists of a scalable autoclave process devoid of hazardous reductants. In detail, the reduction of four distinct graphene oxide materials, whose O/C ratio varied from 0.28 to 0.58, through an autoclave-mediated hydrothermal process at 200 °C and 12 bars pressure is carried out. This employs overheated steam as a heat carrier, without any additional solvents or reducing agents. Upon mild annealing (80 °C), the final rGO films result being robust, self-supporting, and electrically conductive. This study investigates the impact of both the initial GO’s oxidation degree and the volume distribution on the efficacy of the hydrothermal process in synthesizing rGO systems. Furthermore, a comparison between films, created through both hydrothermal autoclave-mediated and thermal oven-mediated methods, is conducted, by assessing their electrical, morphological, chemical, and structural properties. Films produced via the autoclave method display notably improved electrical surface resistivity (3.34·102 Ω/sq) compared to the traditional thermal treatments (6.71·105 Ω/sq). These promising results emphasize the potential of this eco-friendly route as a foundation for scalable and sustainable fabrication of valuable graphene-based conductive materials.

Facile, cost-effective NO2 gas sensors based on polymer intercalated graphene/ reduced graphene oxide materials

BackgroundThe increasing severity of air pollution has driven the demand for efficient and cost-effective NO2 gas sensors. This report aims to develop a miniaturized NO2 gas sensor based on polymer intercalated graphene and reduced graphene oxide and investigate their adsorption mechanisms. MethodsThe fabrication of sensors is realized by depositing the graphene materials via a surfactant assisted two-step dipping onto laser-patterned interdigitated electrodes. The characterization of the graphene materials is carried out using various microscopic/spectroscopic techniques and the sensing performance is evaluated using a potentiostat. Significant findingsThe study reveals that the sensor based on reduced graphene oxide outperforms the graphene sensor, exhibiting a doubled response. Moreover, Langmuir adsorption isotherm also suggests the enhanced performance is attributable to the additional adsorption sites created by oxygen defects.

Simultaneous Immobilization of Cadmium and Arsenic in Paddy Soils with Novel Fe-Mn Combined Graphene Oxide

Novel Fe-Mn combined graphene oxide （GO-FM） material was produced and tested for its efficacy in remediating agricultural soil co-contaminated by Cd and As. In a 60-day soil incubation experiment， the remediation mechanism and immobilization effects of GO and GO-FM at different addition ratios （0.1%， 0.2%， and 0.3%） were investigated in Shangyu and Foshan soils， which had varying physicochemical properties and contamination degrees. The dynamic changes in pH， DOC concentration， bioavailable Cd and As content， and morphology of Cd and As were explored to determine the remediation efficacy of the materials. The results demonstrated that compared with that in the blank control， GO-FM increased the pH in Shangyu soil but decreased the pH in Foshan soil. After culture， both GO and GO-FM increased the soil DOC content. GO-FM decreased the soluble Cd concentration by 5.08%-19.19% and the bioavailability of Cd by 36.57%-42.8% in Foshan soil， and the main immobilization mechanism was electrostatic adsorption， complexation， and hydroxylated metal ion formation. The immobilization ability of GO-FM on Cd was lower than that of Foshan soil due to the influence of electrostatic repulsion in Shangyu acidic soil. However， with the increase in the amount of GO-FM， the trend of increasing the bioavailability of Cd by graphene oxide was inhibited. The addition of 0.2% and 0.3% GO-FM decreased the bioavailability of Cd by 6.45%-13.56% in Shangyu soil. Additionally， GO-FM decreased the bioavailability of As in Shangyu soil and Foshan soil by 4.34%-9.15% and 0.87%-5.71%， respectively. This was due to the immobilization mechanism of oxidation of As by manganese oxides and inner surface chelate between As and the surface hydroxyl group of iron oxides. In summary， the immobilization effect of GO-FM on Cd in Foshan soil was better than that in Shangyu soil， and the immobilization effect of GO-FM on As in Shangyu soil was better than that in Foshan soil， which can provide a theoretical basis and reference for the prevention and control of Cd and As co-contamination in different types of soil.

Preparation of GO/Diatomite/Polyacrylonitrile Functional Separator and Its Application in Li-S Batteries.

Lithium-sulfur (Li-S) batteries have received extensive attention due to their numerous advantages, including a high theoretical specific capacity, high energy density, abundant reserves of sulfur in cathode materials, and low cost. Li-S batteries also face several challenges, such as the insulating properties of sulfur, volume expansion during charging and discharging processes, polysulfide shuttling, and lithium dendritic crystal growth. In this study, a composite of a porous multi-site diatomite-loaded graphene oxide material and a PAN fiber membrane is developed to obtain a porous and high-temperature-resistant GO/diatomite/polyacrylonitrile functional separator (GO/DE/PAN) to improve the electrochemical performance of Li-S batteries. The results show that the use of GO/DE/PAN helps to inhibit lithium phosphorus sulfide (LPS) shuttling and improve the electrolyte wetting of the separator as well as the thermal stability of the battery. The initial discharge capacity of the battery using GO/DE/PAN is up to 964.7 mAh g-1 at 0.2 C, and after 100 cycles, the reversible capacity is 683 mAh g-1 with a coulombic efficiency of 98.8%. The improved electrochemical performance may be attributed to the porous structure of diatomite and the layered composite of graphene oxide, which can combine physical adsorption and spatial site resistance as well as chemical repulsion to inhibit the shuttle effect of LPS. The results show that GO/DE/PAN has great potential for application in Li-S batteries to improve their electrochemical performance.

Physical and Chemical Characterization of Collagen/Alginate/Poly(Vinyl Alcohol) Scaffold with the Addition of Multi-Walled Carbon Nanotube, Reduced Graphene Oxide, Titanium Dioxide, and Zinc Oxide Materials

Physical and Chemical Characterization of Collagen/Alginate/Poly(Vinyl Alcohol) Scaffold with the Addition of Multi-Walled Carbon Nanotube, Reduced Graphene Oxide, Titanium Dioxide, and Zinc Oxide Materials

Enhanced ionic conductivity of Li1.3Al0.3Ti1.7(PO4)3 under the influence of graphene oxide

As a new type of clean and efficient energy storage device, lithium-ion batteries have been widely used in electronic products, electric vehicles, and other fields, and the accompanying safety issues are of increasing concern. Therefore, solid-state lithium-ion conductors have become a current research hotspot. This paper used graphene oxide material to design and prepare Li1.3Al0.3Ti1.7(PO4)3 solid electrolytes by the co-precipitation method and performed some relevant characterizations. The results showed that the addition of graphene oxide optimized the electrolyte structure improved the density of the powder, promoted grain growth, improved the transport path of lithium ions, and thus increased the total ionic conductivity. The optimal doping ratio was 0.5 wt%, and the total ionic conductivity reached the maximum of 2.42 × 10−4 S/cm. Compared to pure Li1.3Al0.3Ti1.7(PO4)3, the ionic conductivity increased by 154% after using the graphene oxide. It is believed that larger grains, fewer grain boundaries, and denser microstructure resulted in a less distorted migration pathway for lithium ions. Under the influence of graphene oxide, Li1.3Al0.3Ti1.7(PO4)3 exhibited better air stability than pure Li1.3Al0.3Ti1.7(PO4)3 electrolyte. The electrolyte prepared in this study showed great application potential in all-solid-state batteries.

Graphene oxide and bacteria interactions: what is known and what should we expect?

Graphene oxide (GO) and graphene-based materials (GBMs) have gained over the last two decades considerable attention due to their intrinsic physicochemical properties and their applications. Besides, a lot of concern regarding the potential toxicity of GBMs has emerged. One of the aspects of concern is the interactions between GBMs and different environmental compartments, especially indigenous microbial and, in particular, bacterial communities. Recent research showed that GO and GBMs impacted bacterial pure culture or bacterial communities; therefore, these interactions have to be further studied to better understand and assess the fate of these materials in the environment. Here, we present our opinion and hypotheses related to possible degradation mechanisms of GO that can be used by environmental bacteria. This work is the first attempt to deduce and summarize plausible degradation pathways of GO, from structurally similar recalcitrant and toxic compounds, such as polyaromatic hydrocarbons.

Development of A Resistive Sensor Array Based on Graphene and Conducting Polymer Composites for Coffee Aroma Classification

This work aims to create a resistive sensor array for categorizing coffee from various plantations. A mixture of graphene oxide and a conductive polymer is used to create the sensor array. Eight types of sensors were made by dripping various mixtures of graphene oxide, polypyrrole, polyaniline, and poly acetate materials on the interdigitated electrode. Coffee fragrance gas was used for the sensor array test. The surface of the sensor array receives the scent gas created by the brewing of coffee grinds. Each sensor’s response profile is recorded. Each coffee sample has a distinct sensor response profile for simple separation with a distinct pattern. PCA analysis was used to examine sensor responses in order to find classification patterns of coffee samples from diverse plantations that were separated by brewing category. Sensor response data underwent PCA analysis, yielding scores of 54.74% PC1 and 26.17% PC2. These findings suggest that graphene-based and conducting polymer sensor array have a good potential for quick differentiation of different coffee varieties.

Graphene oxide stimulated low-temperature denitrification activity of microbial communities in lake sediments by enhancing anabolism and inhibiting cellular respiration

Nitrate pollution in fresh water is becoming increasingly serious. In this study, the effects of temperature and graphene oxide materials on the potential functions of denitrification communities in lake sediments were investigated by metagenome. The addition of graphene oxide significantly affected the abundance of denitrification genes such as Nap, Nos, and enhanced the contribution of Pseudomonas, making low temperature and material addition conducive to the denitrification process. Module network implied that low temperature increased the centrality of denitrification in community functions. At low temperatures, graphene oxide enhanced community anabolism by stimulation organic carbon consumption and regulating the gene abundance in the citric acid cycle and the semi-phosphorylation Entner-Doudoroff, thus possibly stimulating extracellular polymeric substances (EPS) synthesis and secretion. In addition, graphene oxide may also regulate the transfer of reducing electrons from NADH to denitrifying enzymes by affecting the gene abundances of complex I and complex IV.

Lanthanide-modified graphene oxide and nanodiamond materials and their cytotoxicity

Integrating lanthanide elements with carbon-based nanomaterials results in the creation of hybrid materials and nanocomposites with unique properties. We report a functionalization approach free of organic solvents for modifying graphene oxide (GO) and nanodiamond (ND) with various lanthanides (La(III), Ce(III), Eu(III), Gd(III), Tb(III) and Ho(III)). The aqueous-phase impregnation with their acetates was followed first by drying at 80 °C and then by heating at 300 °C for 2 h in air conditions. Scanning electron microscopy revealed that after the initial drying, the samples exhibited the presence of larger lanthanide-containing particles, whereas after the heating at 300 °C they became indistinguishable, and thus the lanthanide species became more homogeneously distributed throughout GO and ND. The toxicity, which is commonly associated with the presence of lanthanides, was evaluated in terms of the ability to inhibit the proliferation of COS-7 monkey kidney cell cultures. Most composites demonstrated a dose-dependent toxicity, with significantly lower cytotoxic effects compared to both the thermally treated GO and ND, as well as the pristine GO. The composites functionalized with gadolinium were among the least toxic at the maximum tested concentration (100 µg/ml). The ND-based composites were not cytotoxic at 50 µg/ml, the lowest tested concentration.

Concurrent Thermal Reduction and Boron-Doped Graphene Oxide by Metal–Organic Chemical Vapor Deposition for Ultraviolet Sensing Application

We synthesized a boron-doped reduced graphene oxide (BrGO) material characterized by various electrical properties, through simultaneous thermal reduction and doping procedures, using a metal–organic chemical vapor deposition technique. X-ray photoelectron spectroscopy (XPS) was used to study the impact of the doping level on the B bonding in the reduced graphene oxide (rGO) layer that is influenced by the annealing temperature. The synthesized BrGO layer demonstrated a high B concentration with a considerable number of O-B bonds, that were altered by annealing temperatures. This resulted in a decreased work function and the formation of a Schottky contact between the BrGO and n-type Si substrate. Due to the higher proportion of B-C and B-C3 bonding in the BrGO/Si device than that in the rGO/Si, the decreased Schottky barrier height of the BrGO/n-Si vertical junction photodetector resulted in a higher responsivity. This study showcases a promise of a simple B-doping method in use to alter the electrical characteristics of graphene materials.

Structurally Optimized Fluorinated Small‐Sized Graphene Oxide for Enhanced Magnetic Resonance Imaging during Pregnancy

AbstractGadolinium‐based complex contrast agents (GBCAs), frequently applied in magnetic resonance imaging (MRI), are associated with severe acute anaphylactic shock and incurable nephrogenic systemic fibrosis. Besides, the repeated use of GBCAs may result in the accumulation in various tissues. Given these potential adverse effects, GBCAs have not been well used during pregnancy. Herein, a novel metal‐free T2‐weighted MRI nanoprobe, designated fluorinated small‐sized graphene oxide with optimized fluorine content (LF‐sGO), is developed via graphene oxide materials. By introducing specific polar C─F bonds onto the small‐sized graphene oxide (sGO) skeleton, the prepared nanoprobe exhibits excellent water solubility, as well as superior MRI capabilities, thereby furnishing high‐resolution MRI anatomical information. Furthermore, the free radicals on LF‐sGO stabilized by C─F bonds confer LF‐sGO enrichment in the tumor region, enabling comprehensive imaging capability. The cytotoxicity study in vitro indicates that LF‐sGO has the potential to serve as a biocompatible imaging probe. Moreover, detailed in vivo studies on pregnant mice and zebrafish adequately demonstrate that microinjection of LF‐sGO does not induce dysontogensis and teratogenesis. This study successfully showcases a metal‐free nanoprobe that exhibits exceptional MRI capabilities for the purpose of tumor diagnosis. Notably, this nanoprobe holds promise for safe and effective tumor diagnosis during pregnancy.

Preparation of CO2‐activated Porous Graphene for Enhancing the Electrochemical Hydrogen Storage Properties of Co9S8 Material

AbstractIn this work, Co9S8 hydrogen storage material was synthesized by mechanical alloying. To improve the electrocatalytic activity and conductivity of Co9S8, a series of porous reduced graphene oxide (PRGO) materials were fabricated via a facile CO2 activation treatment of RGO at different processing times. The composites of Co9S8 doping with different amount of PRGO were manufactured through ball milling. During the electrochemical hydrogen storage test, the porous Co9S8+PRGO exhibited higher discharge capacity than Co9S8+NRGO and conventional Co9S8. Moreover, the CO2 activation time and additive amount of PRGO had significant impact on the electrochemical properties of Co9S8. Ultimately, the electrode of 6 wt.% PRGO‐2 modified Co9S8 attained the optimum discharge capacity of 653 mAh/g. The special porous structure and high specific surface area of porous graphene could provide more electrochemical active sites and facilitate the hydrogen diffusion. After PRGO modification, the cycling stability, high‐rate dischargeability (HRD) and kinetic properties of Co9S8 were also enhanced. It can be concluded that porous graphene possesses better effect than conventional graphene in improving the performance of hydrogen storage alloy.

Synthesis and electrochemical properties of porous carbon materials from sludge sources

Anaerobic digestion sludge technology is a green and efficient method of treating sludge. However, the presence of humic acid (HA) in sludge can inhibit methanogenic efficiency, and it is necessary to reduce its impact on biogas production by removal or pretreatment. HA, a graphene oxide material can be used to produce high-performance energy-storage materials. Thus, this study examined the sludge source of HA as a precursor, and different electrode materials were prepared by varying the reaction conditions. The structure and electrochemical properties of the electrode materials were analyzed. The results showed that the electrode material prepared using KOH as an activator at 700 °C exhibited optimal performance, with a high specific surface area (1480.53 m2·g−1), pore volume (0.943 cm3·g−1), specific capacitance (185.9 F·g−1), and equivalent series resistance (0.73 Ω). The material maintained 97.8% of its specific capacitance after 1000 cycles at a current density of 1 A·g−1 with benign cycle stability. This study confirmed that the production of HA as an electrode material at a low cost with good performance presents significant prospects.

Synthesis, characterization and insights into the supercapacitive and electrocatalytic (OER) bi-functional properties of nitrogen-doped reduced graphene oxide using dicyandiamide precursor

A facile methodology to synthesize the nitrogen-doped reduced graphene oxide (NG) via a solvothermal process exhibiting a substantial content of either pyrrolic-N or pyridinic N, is demonstrated. In the synthesis of NG, different amounts of dicyandiamide (DCDA) with a constant (1 g) amount of graphene oxide have been taken in DMF (solvent). This approach produced the nanosheets of N-doped graphene (NG-2) which possess optimum defect density and 10.58 % total nitrogen. Nitrogen within this NG material predominantly manifests in four distinct bonding configurations, with the most prevalent being pyrrolic-N. The solvothermally synthesized N-doped reduced graphene oxide exhibited good charge storage characteristics. Three electrode testing of NG-2 shows high specific capacitance (865.82 F/g at a particular current density of 0.5 A/g) and a high energy density (76.96 Wh/kg) in acidic conditions. This sample showed poor electrocatalytic activity for oxygen evolution reaction (OER). However, the material prepared with very high amount of DCDA (NG-4) showed a total N-content of 29 % with high contribution of pyridinic N, demonstrated good electrocatalytic activity for OER following the four-electron path. The Tafel slope of NG-4 sample is around 140 mV/dec which implies the facile conversion of OH− into O2, at relatively low overpotential within an alkaline system. Consequently, the synthesized dual-functional N-doped reduced graphene oxide material holds characteristics for the advancement of carbon-based energy storage materials, and simultaneously be utilized as catalyst for OER.

Enhancement electrochemical properties of supercapacitors using hybrid CuO/Ag/rGO based nanoporous composite as electrode materials

Utilizing clean and renewable energy sources requires the development of effective, reliable, and reasonably priced electrodes for supercapacitors. Herein, a simple, cheap, and fast synthesis method was developed to synthesize CuO/Ag/RGO(S1) as electrode material for Supercapacitors. Also, the effect of adding different proportions of silica nanoparticles S2A (1CuO/1Ag/1RGO/0.5SiNp), S2B (1CuO/1Ag/1RGO/1SiNp), and S4 (1CuO/1Ag/1RGO/1.5 SiNp) on the electrochemical properties of the composite was also investigated. Among the four synthesized composites, composite S1, due to its porous structure, has better electrochemical parameters than the other three composites. Also, the correct combination of a metal base (CuO, Ag) and carbon base (Reduced graphene oxide) materials with the accurate synthesis method and the use of proper precursors (F127, Ag(NO3), Cu(NO3)2) made the S1 composite have an ideal electrochemical result(Specific capacitance: 936 F g−1, energy density: 130 Wh kg−1, power density: 500 W kg−1, cycle stability: 90% rate capability: 88%) Compared to the pure state of each of these materials and other similar hybrid compounds. The reason for such ideal electrochemical results, which distinguishes this project from other similar projects, is the synergistic effect of the combination of CuO, Ag, and RGO, along with the hierarchical porosity obtained in the correct synthesis method. In our opinion, CuO/Ag/RGO maybe a viable choice for electrocatalytic and energy storage applications that require distinct electrochemical performances.

Variation in the bandgap by gradual reduction of GOs with different oxidation degrees: A DFT analysis

The bandgap of two-dimensional graphene (G), graphene oxide (GO), and reduced graphene oxide (rGO) materials is modified by the gradual incorporation and removal of functional groups on the surface of the material. In this work, using Density Functional Theory (DFT) with BIOVIA Materials Studio software, the variation of the bandgap of GO and rGO as a function of the O/C ratio has been studied. The direct relationship between the bandgap and the number of epoxide functional groups in the GO is demonstrated. A gradual increase in the bandgap from 0.211 to 3.58 eV was observed by varying the O/C ratio from 0.06 to 0.50. In the range of O/C ratios from 0.17 to 0.28, the bandgap decreased, estimating the lowest value of 0.0211 eV at O/C = 0.22 despite the increased functional groups in the material. This phenomenon is explained by the balance between the number of sp2 conducting states and the loss of linearity of the sheets due to the incorporation of functional groups. On the other hand, the GOs were reduced by gradually removing their functional groups at different O/C ratios, ranging from 0.50 to the total elimination of the epoxide functional groups. This study showed that the bandgap of the now-called rGOs varies according to two parameters: (i) the number of functional groups to be eliminated in a GO (reduction process) and (ii) the number of functional groups present in the GO to be reduced. This theoretical study has calculated the existence of multiple bandgaps in these materials, finding the most significant difference in the O/C ratio=0.33, estimating bandgaps of 0.50 eV and 1.82 eV, for rGO and GO, respectively, thus raising the need to be more specific in their denomination. Finally, the use of a nomenclature based on subscripts a, b, c, and d, describing the number of layers, the type of functional group, the number of functional groups added (in GO), and the number of functional groups removed in rGO, respectively, has been proposed.