Acid Functionalized Graphene Oxide Research Articles

Study on the Application Performance of Polymer Electrolyte Membrane Functionalized with Triethyl Phosphite-Modified Graphene Oxide in Fuel Cells.

In this paper, we successfully synthesize phosphoric acid functionalized graphene oxide (PGO) based on acid modification of graphene oxide. The composite membrane is further prepared by adding PGO into sulfonated poly(aryl ether ketone sulfone) containing carboxyl groups matrix (C-SPAEKS). The PGO as well as the composite membranes were characterized by a series of tests. The prepared composite proton exchange membranes (PEMs) have good mechanical and electrochemical properties. Compared to the C-SPAEKS membrane, the best composite membrane has a tensile strength of 40.7 MPa while exhibiting superior proton conductivity (110.17 mS cm-1 at 80 °C). In addition, the open-circuit voltage and power density of C-SPAEKS@1% PGO are 0.918 V and 792.17 mW cm-2, respectively. Compared with C-SPAEKS (0.867 V and 166 mW cm-2), it can be seen that our work has a certain effect on the improvement of the single cell performance. The above results demonstrate that the functionalized graphene oxide has greatly improved the electrochemical performance and even the overall performance of PEMs.

Stimuli-responsive Graphene-Polysaccharide Nanocomposites for Drug Delivery and Tissue Engineering

Abstract:: Natural polysaccharide-based nanoparticles are known for their non-toxic nature and diverse medical applications. Graphene oxide (GO) nanoparticles show potential in cancer treat-ment due to their ability to target medication delivery and influence ROS generation. These nanocomposites are versatile in gene transport, therapy, and photodynamic therapy, especially when surface-modified. Proper dispersion and functionalization of GO in polymer matrices are crucial, with examples like hyaluronic acid-functionalized GO offering versatile platforms for cancer drug administration. The potential of graphene oxide extends to cancer phototherapy, electronic nanowires, hydrogels, antibacterial nanocomposites, and environmental applications. When activated by polysaccharides, graphene-based nanocomposites exhibit anti-inflammatory and anticancer properties, making them valuable across various industries, including water treat-ment.

Photosensitive Hydrogel with Temperature-Controlled Reversible Nano-Apertures for Single-Cell Protein Analysis.

Single cell western blot (scWB) is one of the most important methods for cellular heterogeneity profiling. However, current scWB based on conventional photoactive polyacrylamide hydrogel material suffers from the tradeoff between in-gel probing and separation resolution. Here, a highly sensitive temperature-controlled single-cell western blotting (tc-scWB) method is introduced, which is based on a thermo/photo-dualistic-sensitive polyacrylamide hydrogel, namely acrylic acid-functionalized graphene oxide (AFGO) assisted, N-isopropylacrylamide modified polyacrylamide (ANP) hydrogel. The ANP hydrogel is contracted at high-temperature to constrain protein band diffusion during microchip electrophoretic separation, while the gel aperture is expanded under low-temperature for better antibody penetration into the hydrogel. The tc-scWB method enables the separation and profiling of small-molecule-weight proteins with highly crosslinked gel (12% T) in SDS-PAGE. The tc-scWB is demonstrated on three metabolic and ER stress-specific proteins (CHOP, MDH2 and FH) in four pancreatic cell subtypes, revealing the expression of key enzymes in the Krebs cycle is upregulated with enhanced ER stress. It is found that ER stress can regulate crucial enzyme (MDH2 and FH) activities of metabolic cascade in cancer cells, boosting aerobic respiration to attenuate the Warburg effect and promote cell apoptosis. The tc-scWB is a general toolbox for the analysis of low-abundance small-molecular functional proteins at the single-cell level.

Experimental and computational studies of crystal violet removal from aqueous solution using sulfonated graphene oxide

Positively charged contaminants can be strongly attracted by sulfanilic acid-functionalized graphene oxide. Here, sulfonated graphene oxide (GO-SO3H) was synthesized and characterized for cationic crystal violet (CV) adsorption. We further studied the effect of pH, initial concentration, and temperature on CV uptake. The highest CV uptake occurred at pH 8. A kinetic study was also carried out by applying the pseudo-first-order and pseudo-second-order models. The pseudo-second-order’s adsorption capacity (qe) value was much closer to the experimental qe (qeexp:0.13, qecal:0.12) than the pseudo-first-order model (qeexp:0.13, qecal:0.05). The adsorption performance was accomplished rapidly since the adsorption equilibrium was closely obtained within 30 min. Furthermore, the adsorption capacity was significantly increased from 42.85 to 79.23%. The maximum adsorption capacities of GO-SO3H where 97.65, 202.5, and 196.2 mg·g−1 for CV removal at 298, 308, and 328 K, respectively. The Langmuir and Freundlich adsorption isotherms were applied to the experimental data. The data fit well into Langmuir and Freundlich except at 298 K, where only Langmuir isotherm was most suitable. Thermodynamic studies established that the adsorption was spontaneous and endothermic. The adsorption mechanism was revealed by combining experimental and computational methods. These findings suggest that GO-SO3H is a highly adsorbent for removing harmful cationic dye from aqueous media.

Structure of phytic acid functionalized graphene oxide prepared by hydrothermal method based on aqueous species distribution and the hard-soft acid-base theory

Phytic acid functionalized graphene oxide (PA-GO) has encouraging application in environmental treatment. Herein, structure of PA-GO fabricated by hydrothermal method was inspected. Firstly, the aqueous species distribution and ionization states of phytic acid (PA) and graphene oxide (GO) under varying pH was analyzed according to equilibrium thermodynamics to clarify the primary interacting species involved in PA-GO fabrication. Secondly, the hard-soft acid-base (HSAB) theory and spectroscopic characterizations (XPS, FTIR, Raman, UV–Vis and fluorescent spectra) were employed to elucidate the plausible interactions existing in PA-GO. Thermodynamic deduction indicates, C6H6O24P612- is the dominant species of PA, while –OH and –COO- are the dominant state of graphene oxide groups in PA-GO fabrication system. HSAB theory illuminates, the primary interactions occurs between deprotonated oxygen O(O-) and bridged oxygen O(-O-) of phytic acid with hydroxyl group O(Ar-OH) and π electron of graphene oxide. Moreover, electron flows from GO towards PA to induce energy lowering whereby PA-GO is stabilized. HSAB theory prediction was substantiated by spectroscopic analyses. Furthermore, PA-GO efficiently removes ionic dyes in five consecutive cycles with high adsorption capacity. This work may shed light on the fabrication chemistry of PA-GO framework serving as a potential adsorbent.

Synergistic contribution of sulfonated poly(ether sulfone) and iminodiacetic acid functionalized-graphene oxide nanosheets towards enhancing cationic dye wastewater purification using nanocomposite membranes

Water purification and wastewater treatment can be achieved using membrane technologies. However, conventional poly(ether sulfone) (PES) membranes suffer from hydrophobicity, fouling issues, and insufficient dye removal. In this study, hydrophilic sulfonated PES (sPES) and iminodiacetic acid-functionalized graphene oxide (IDA-GO) nanosheets were incorporated into the PES membranes to enhance cationic dye removal efficiency. PES/sPES membranes containing 0.05–0.2 wt% IDA-GO nanosheets were fabricated via phase inversion. PES/sPES@IDA-GO membrane and IDA-GO nanosheets were fully characterized using various analytical techniques. With a negative surface charge, the PES/sPES@IDA-GO membrane is a good candidate to remove cationic days. Compared with pristine PES membranes, hydrophilic nanosheets improve membrane porosity, hydrophilicity, and mechanical properties. Further altering the membrane structure by incorporating IDA-GO nanosheets into the PES/sPES-based casting solution increased the porosity and mean pore radius. Using PES/sPES@IDA-GO membrane containing IDA-GO nanosheets as low as 0.1 wt%, values of 99.9 % 19.4 L/m2.h were achieved for dye rejection and pure water flux, respectively. Tuning membrane properties using sPES and IDA-GO nanosheets enabled exceptional cationic dye removal. This offers a facile approach to engineering high-performance PES membranes for effective wastewater purification and environmental remediation applications.

Functionalized graphene oxide by 4-amino-3-hydroxy-1-naphthalenesulfonic acid as a heterogeneous nanocatalyst for the one-pot synthesis of tetraketone and tetrahydrobenzo[b]pyran derivatives under green conditions

4-Amino-3-hydroxy-1-naphthalenesulfonic acid-functionalized graphene oxide (GO-ANSA) was prepared and used as a highly efficient and reusable solid acid carbocatalyst for synthesis of tetraketone as well as tetrahydrobenzo[b]pyran derivatives.

A simple, efficient, and rapid method for dye removal from wastewater using an IDA-GO@Fe3O4 magnetic nanocomposite.

With the rapid advancement of the dye and textile industry, there has been increasing concern regarding the contamination of wastewater with dyes and its potential influence on human health. Therefore, the removal of dye pollutants from wastewater has become a matter of significant importance. In this study, a magnetically responsive iminodiacetic acid-functionalized graphene oxide (IDA-GO@Fe3O4) nanocomposite was utilized for the adsorption of both cationic and anionic dyes. The IDA-GO@Fe3O4 nanocomposite was synthesized and thoroughly characterized using several analytical techniques such as XRD, SEM, FT-IR, TGA and BET analysis. The prepared magnetic nanocomposite had a much higher thermal stability than pure graphene oxide. The negatively charged surface of the IDA-GO@Fe3O4 magnetic nanocomposite made it an excellent candidate for removing cationic dyes. The effects of various factors, including pH, initial concentration (isotherms), amount of adsorbent, and contact time (kinetics), on adsorption efficiency were investigated. The optimal conditions for the removal of methylene blue were determined to be 0.005 g of adsorbent, a pH of 10, and a contact time of 160 minutes. In contrast, the optimal conditions for the removal of methylene orange were found to be 0.005 g of adsorbent, a pH of 2, and a contact time of 120 minutes. Experimental data shows that the adsorption capacity for MB is reported as 437.10 mg g-1 at pH 10, while for MO it is 165.65 mg g-1 at pH 2. Furthermore, the adsorption process followed a pseudo-second-order kinetic model and Langmuir isotherm model. The proposed adsorption mechanism of MB and MO dyes onto the IDA-GO@Fe3O4 nanocomposite involve various interactions, such as electrostatic interactions, H-bonding, n-π, and π-π interactions. Importantly, the IDA-GO@Fe3O4 nanocomposite exhibited outstanding recyclability, retaining its effectiveness even after five successive cycles for MB. This suggests a straightforward method for developing high-performance IDA-GO@Fe3O4 magnetic nanocomposites for efficient wastewater purification and environmental remediation applications.

Interaction mechanism of phytic acid functionalized graphene oxide with ionic dyes

Phytic acid functionalized graphene oxide (PA-GO) has fascinating application in environmental remediation. Herein, PA-GO was facilely prepared via hydrothermal method and utilized as adsorbent to remove aqueous Congo red (CR) and malachite green (MG). The adsorbent-adsorbate interaction mechanism was elaborately scrutinized based on the hard and soft acid base (HSAB) principle, spectroscopic analysis and adsorption fitting. Result shows, after five consecutive cycles, PA-GO maintains adsorption quantity 242.82 mg·g−1 and 117.53 mg·g−1 for CR and MG, respectively. The HSAB principle illuminates, primary interaction of PA-GO with both CR and MG is provided by phytic acid moiety (PA). For CR adsorption, electron of N atom in –NH2 group flows towards O atom in OH and O(-O-) of PA. While for MG adsorption, electron of N atom in (CH3)2N– group flows towards O atom in OH and O(-O-) of PA. FTIR, UV–Vis analyses supports the HSAB principle prediction. In brief, the hydroxyls and phosphoric groups introduced by PA functionalization enhance the adsorption affinity of GO. Adsorption of CR, MG by PA-GO under favorable pH is thermodynamically chemical but kinetically impelled by electrostatic interaction. This work may promote the development of efficient adsorbent based on PA-GO architecture for environmental remediation.

Functionalized graphene-based ultrafiltration and thin-film composite nanofiltration membranes for arsenic, chromium, and fluoride removal from simulated groundwater: Mechanism and effect of pH

Groundwater contaminant removal using ultrafiltration (UF) and nanofiltration (NF) membranes is complex due to limitations such as low selectivity-permeability and membrane fouling tendency. In this study, we fabricated a thin film composite (TFC) membrane over a highly permeable mixed matrix support UF membrane using sulfonic acid functionalized graphene oxide (SGO) and polyethersulfone (PES) for groundwater remediation application. The pure water permeability of the PES-SGO-TFC membrane was threefold (3.09 LMH bar−1) compared to the pristine PES-TFC membrane. The membrane showed excellent organic fouling resistance with more than 95% flux recovery. The salts and contaminant removal were checked in a cross-flow mode to understand a more practical approach to the applicability of the developed PES-SGO-TFC membrane. The membrane rejected Cr(VI), As(V), and fluoride to the extent of ∼89%, ⁓99%, and ∼77%, respectively, at pH ⁓7. The membrane separation performance varied as a function of pH, with more than 90% removal for monovalent fluoride at higher pH values. In a simulated groundwater matrix, the membrane demonstrated promising results for rejecting these ions. However, the simultaneous rejection of As(V) and fluoride may be impacted by interfering co-ions. This study offers a novel approach for developing highly permeable support UF-modified TFC membranes for better separation for groundwater remediation.

Study on the Flame Retardancy of Rigid Polyurethane Foam with Phytic Acid-Functionalized Graphene Oxide.

A rigid polyurethane foam (RPUF) composite was prepared by compounding phytic acid (PA)-functionalized Graphite oxide (PA-GO) with flame-retardant poly (Ammonium phosphate) (APP) and expandable graphite (EG). The effects of PA-GO on the thermal, flame-retardant, and mechanical properties of RPUF were studied using a thermogravimetric analyzer, a limiting oxygen index (LOI) tester, a UL-94 vertical combustion tester, a cone calorimeter, scanning electron microscopy, and a universal tensile testing machine. The results indicated that there was a significant synergistic flame-retardant effect between PA-GO and the intumescent flame retardants (IFR) in the RPUF matrix. Compared with RPUF-1, the addition of 0.3 wt% PA-GO could increase LOI from 25.7% to 26.5%, increase UL-94 rating from V-2 to V-0, and reduce the peak heat release rate (PHRR) and total heat release rate (THR) by 28.5% and 22.2%, respectively. Moreover, the amount of residual char increased from 22.2 wt% to 24.6 wt%, and the char layer was continuous and dense, with almost no holes. Meanwhile, the loss of mechanical properties was apparently lightened.

Hyaluronic acid-graphene oxide quantum dots nanoconjugate as dual purpose drug delivery and therapeutic agent in meta-inflammation

Type 2 diabetes mellitus (T2DM) predominantly considered a metabolic disease is now being considered an inflammatory disease as well due to the involvement of meta-inflammation. Obesity-induced adipose tissue inflammation (ATI) is one of the earliest phenomena in the case of meta-inflammation, leading to the advent of insulin resistance (IR) and T2DM. The key events of ATI are orchestrated by macrophages, which aggravate the inflammatory state in the tissue upon activation, ultimately leading to systemic chronic low-grade inflammation and Non-Alcoholic Steatohepatitis (NASH) through the involvement of proinflammatory cytokines. The CD44 receptor on macrophages is overexpressed in ATI, NASH, and IR. Therefore, we developed a CD44 targeted Hyaluronic Acid functionalized Graphene Oxide Quantum Dots (GOQD-HA) nanocomposite for tissue-specific delivery of metformin. Metformin-loaded GOQD-HA (GOQD-HA-Met) successfully downregulated the expression of proinflammatory cytokines and restored antioxidant status at lower doses than free metformin in both palmitic acid-induced RAW264.7 cells and diet induced obese mice. Our study revealed that the GOQD-HA nanocarrier enhanced the efficacy of Metformin primarily by acting as a therapeutic agent apart from being a drug delivery platform. The therapeutic properties of GOQD-HA stem from both HA and GOQD having anti-inflammatory and antioxidant properties respectively. This study unravels the function of GOQD-HA as a targeted drug delivery option for metformin in meta-inflammation where the nanocarrier itself acts as a therapeutic agent.Graphical

An electrochemical sensor for the detection of arsenic using nanocomposite-modified electrode

The aim of this research is to develop an electrochemical sensor based on a conducting polymer, polyaniline, and a cationic polymer, poly(diallyldimethylammonium chloride), reinforced with graphene oxide nanosheets functionalized with acrylic acid. The two-dimensional nature of acrylic acid functionalized graphene oxide nanosheets and clusters made of conductive polymers and acrylic acid functionalized graphene oxide nanosheets were confirmed by microscopic tests. The prepared nanocomposite was deposited on the glassy carbon electrode in order to prepare an electrochemical sensor for the detection of arsenic by cyclic voltammetry and differential pulse voltammetry methods. It should be mentioned that the presence of acrylic acid functionalized graphene oxide nanosheets increases the surface area due to the nano size effect and better dispersion of this nanomaterial, poly(diallyldimethylammonium chloride), increases the adsorption capacity of the analyte due to electrostatic interaction between the negatively charged analyte and positively charged surface, and polyanilin increases the charge transfer rate due to the good conductivity. The results show that the prepared electrode has a sensitivity equal to 1.79 A/M with 0.12 μM as the detection limit. The proposed sensor could be used for the determination of total inorganic arsenic by first oxidative pretreatment for conversion of As(III) to As(V).

Essential L-Amino Acid-Functionalized Graphene Oxide for Liquid Crystalline Phase Formation

The colloidal 2D materials based on graphene and its modifications are of great interest when it comes to forming LC phases. These LC phases allow controlling the orientational order of colloidal particles, paving the way for the efficient processing of modified graphene with anisotropic properties. Here, we present the peculiarities of AA functionalization of GO, along with the formation of its LC phase and orientational behavior in an external magnetic field. We discuss the influence of pH on the GOLC, ultimately showing its pH-dependent behavior for GO-AA complexes. In addition, we observe different GO morphology changes due to the presence of AA functional groups, namely L-cysteine dimerization on the GO platform. The pH dependency of AA-functionalized LC phase of GO is examined for the first time. We believe that our studies will open new possibilities for applications in bionanotechnologies due to self‐assembling properties of LCs and magnificent properties of GO.

Green synthesis and characterizations of citric acid-functionalized graphene oxide via electrochemical method: In situ surface modification using citric acid

Surface modification by using citric acid (CA) in the graphene is a process to modify the physicochemical properties of graphene oxide. The strategy that has been proposed depends upon the electrochemical exfoliation of reduced graphene oxide (rGO), and simultaneously, the surface modification of rGO with CA carried out in accordance with the green technique. The synthesis of graphene oxide that has been doped with CA was accomplished via an electrochemical process in an aqueous medium containing fresh lime juice and sulphuric acid (electrolyte heating aided method at [Formula: see text]C) as an electrolyte. The electrolyte has been prepared using CA & H2SO4 (sulphuric acid), and both were mixed in a proportion of 1:2. In order to dilute the H2SO4 and perform the sonication, the water that has been pasteurized (according to the USP standards for irrigation) was used. The crystallite size, structural disorder, structure and surface morphology of the CA-doped graphene oxide were identified through X-ray diffraction (XRD) analysis, Raman spectroscopy, Field emission scanning electron microscope (FE-SEM). The presence of oxygen-containing functional group and adsorption has been analyzed using Fourier transform infrared (FTIR), and UV–Vis spectroscopy. The thermal stability of the CA-doped, and without CA-doped thermally reduced graphene oxide (TRGO) has been analyzed via thermogravimetric analysis (TGA). A green, simple, and environmentally friendly method has been demonstrated for the synthesis of CA-doped TRGO by electrochemical synthesis method by using natural dopant.

One-Step Synthesis of Aminobenzoic Acid Functionalized Graphene Oxide by Electrochemical Exfoliation of Graphite for Oxygen Reduction to Hydrogen Peroxide and Supercapacitors.

Graphene-based materials have attracted considerable attention as promising electrocatalysts for the oxygen reduction reaction (ORR) and as electrode materials for supercapacitors. In this work, electrochemical exfoliation of graphite in the presence of 4-aminebenzoic acid (4-ABA) is used as a one-step method to prepare graphene oxide materials (EGO) functionalized with aminobenzoic acid (EGO-ABA). The EGO and EGO-ABAs materials were characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction and scanning electron microscopy. It was found that the EGO-ABA materials have smaller flake size and higher density of oxygenated functional groups compared to bare EGO. The electrochemical studies showed that the EGO-ABA catalysts have higher activity for the ORR to H2O2 in alkaline medium compared to EGO due to their higher density of oxygenated functional groups. However, bare EGO has a higher selectivity for the 2-electron process (81%) compared to the EGO-ABA (between 64 and 72%) which was related to a lower content of carbonyl groups. The specific capacitance of the EGO-ABA materials was higher than that of EGO, with an increase by a factor of 3 for the materials prepared from exfoliation in 5 mM 4-ABA/0.1 M H2SO4. This electrode material also showed a remarkable cycling capability with a loss of only 19.4% after 5000 cycles at 50 mVs-1.

Ethylenediaminetetraacetic acid-functionalized graphene oxide for fabrication of a strong laminated film by ionic cross-linking

Graphene oxide is functionalized with ethylenediaminetetraacetic acid groups to investigate the effect of ethylenediaminetetraacetic acid groups on its colloidal, assembly, and ionic cross-linking behaviors. Ethylenediaminetetraacetic acid-functionalized graphene oxide exhibits a high aqueous dispersibility for presenting a nematic liquid-crystalline phase which is an important factor for fabrication of the well-ordered laminated films. Ethylenediaminetetraacetic acid-graphene oxide films show a distinct internal structure from graphene oxide films owing to the heterogeneous surface of ethylenediaminetetraacetic acid-graphene oxide sheets composed of partially reduced and ethylenediaminetetraacetic acid decorated regions. In addition, the mechanical properties of ethylenediaminetetraacetic acid-graphene oxide films are more enhanced by ionic cross-linking with divalent cations, and their degree of mechanical enhancement is also more dependent on the type of cations than graphene oxide films. The interesting behaviors of ethylenediaminetetraacetic acid-graphene oxide suggest the ethylenediaminetetraacetic acid functionalization can greatly improve the potential of graphene oxide derivatives to develop a high-performance structural material.

A novel strategy toward the advancement of proton exchange membranes through the incorporation of propylsulfonic acid-functionalized graphene oxide in crosslinked acid-base polymer blends

Propylsulfonic acid-functionalized graphene oxide (PrSGO) was introduced into the sulfonated poly(ether ether ketone) (SPEEK)-sulfonated poly(benzimidazole) (SPBI) blend in this study to understand the impact on glass transition temperature (Tg), structural properties, increase mechanical properties, proton conductivity, and single-cell performance. At different loadings of PrSGO, atomistic molecular dynamics (MD) simulations of SPEEK/SPBI, cross-linked SPEEK/SPBI (XSPEEK/SPBI), and XSPEEK/SPBI/PrSGO composite systems were performed. Tg was increased after cross-linking the polymer systems and increasing the loading percent of PrSGO filler and SPBI in the polymer systems. The mechanical properties, chemical and thermal stability of the XSPEEK/SPBI/PrSGO nanocomposite membranes significantly increased PrSGO loading because of the strong interfacial interaction between PrSGO and the XSPEEK/SPBI matrix. XSPEEK/SPBI/PrSGO nanocomposite membrane at 4 wt % PrSGO loading demonstrated a considerable improvement in proton conductivity up to 0.17 S/cm at 100% relative humidity (RH) at 90 °C. Furthermore, the XSPEEK/SPBI/PrSGO nanocomposite membrane at 4 wt% PrSGO loading demonstrated good fuel cell (FC) performance with a maximum power density of ∼0.82 W/cm2 at 100% RH, 80 °C. Incorporating PrSGO nanofillers in the polymer matrix considerably improved proton conductivity of the membranes, other significant properties, and overall FC performance due to their hygroscopic nature, a higher number of sulfonic acid groups, and excellent interaction of the acid functionalized fillers with the cross-linked SPEEK/SPBI-based matrix.

Surface functionalization of graphene oxide with tannic acid: Covalent vs non-covalent approaches

Graphene oxide (GO) is gaining a lot of interest in material science, biomedicine and biotechnology due to its outstanding physical properties, combined with its surface functionalization capacity, processability in aqueous media and biocompatibility. However, van der Waals forces among GO layers result in aggregation, yet its dispersion, large-scale production, and reinforcing efficiency remain challenging. Herein, simple and environmentally friendly methods via covalent and non-covalent routes have been developed to exfoliate and prepare surface-functionalized GO nanosheets with tannic acid (TA), a biological macromolecule with antioxidant activity. Four esterification strategies were tested: direct, carbodiimide activated, oxalyl chloride acylation and via an acid-functionalized GO intermediate. The resulting samples have been extensively characterized to get knowledge on the GO-TA interactions and the degree of grafting, as well as their surface topography, level of hydrophilicity, solubility/dispersibility, thermal and antibacterial properties. The covalent grafting of TA renders the GO surface more hydrophobic, resulting in improved dispersion in organic solvents. Besides, TA acts as a crosslinker between the GO nanosheets, leading to higher thermal resistance. A synergistic effect of both GO and TA on inhibiting bacterial growth has also been found. The esterification via carbodiimide leads to the highest grafting degree, the best thermal stability and the most effective antibacterial activity. This work not only highlights the great potential of TA for both exfoliation and surface functionalization of GO, but also extends its applications in biomedicine and for the development of green nanocomposites.

Fabrication of a Strong Artificial Nacre Based on Tannic Acid-Functionalized Graphene Oxide and Poly(vinyl alcohol) Through Their Multidentate Hydrogen Bonding

Fabrication of a Strong Artificial Nacre Based on Tannic Acid-Functionalized Graphene Oxide and Poly(vinyl alcohol) Through Their Multidentate Hydrogen Bonding