Sulfonated Reduced Graphene Oxide Research Articles

The effect of sulfonated reduced graphene oxide on the properties of ionic strength sensitive PEC film comprising protein/polysaccharides combined system

In the current study, sulfonated reduced graphene oxide (SRGO) at different amounts (0.0 %, 0.015 %, 0.030 %, 0.050 % w/v) was incorporated into the polyelectrolyte complex (PEC) which was produced by using protein/polysaccharides combined system composed of gelatin (Gel)/carboxymethyl cellulose (CMC) and hyaluronic acid (HA) not only to enhance mechanical and conductive properties but also to investigate the effect of sulfonyl groups on the ionic strength response of the produced PEC films. While FT-IR, SEM and zeta potential analyses were confirmed the character of produced samples, their mechanical and conductivity tests showed that the introduction of SRGO enhanced both mechanical performance and conductive feature of PEC films. Swelling and 5- fluorouracil (5-FU), a chemotherapeutic agent, release tests carried out in the solution with a varying ionic strength at a pH: 1.2 to simulate acidic stomach environment demonstrated that while pure PEC film has anti-polyelectrolyte behavior, SRGO based PEC films exhibited polyelectrolyte character due to sulfonyl groups with an increasing ionic strength of medium. It could be emphasized from all these results that the produced SRGO based PEC films with enhanced mechanical and conductive properties could be utilized as an ionic strength sensitive drug carrier which ensures controlled and targeted release for cancer treatments.

Preparing a binder-free cathode composed of NMC811/sulfonated reduced graphene oxide sheets/carbon black via in-situ electrophoretic deposition to enhance cyclability of Li-ion batteries

Disruption in the restacking of the graphene present in the electrodes could hamper the reduction in the conductivity and also the surface area, which may be a good reason why graphene has not yet performed as predicted. In this research, we employed the scalable electrophoretic deposition (EPD) procedure to make instantly a binder-free Li-ion battery cathode, consisting of LiNi0.8Mn0.1Co0.1O2 (NMC811), sulfonated reduced graphene oxide (SRGO) sheets, and carbon black (CB) particles. The EPD process caused a squeezing force, which not only wrapped the SRGO sheets around the NMC811 nanoparticles, but also inserted the CB particles into the composite in an electrostatically stabilized combination. As evidenced by the electrochemical measurements, the binder-free NMC/SRGO/CB electrode manifested better cycling performance at the current density of 0.2 C, where this electrode delivered discharge capacities of 170.3 and 143.7 mAh g−1, respectively, at the 1st and 200th cycle compared to discharge capacities of 162.3 and 122.6 mAh g−1 acquired for the NMC/SRGO electrode. The excellent cycle stability and rate capability of the optimized binder-free NMC/SRGO/CB cathode can be attributed to withstanding the volume expansion of the active particles during cycling due to wrapping graphene sheets, inhibition of the restacking of graphene sheets by sulfonated groups and CB spacers, electrostatic interaction between sulfonated groups and lithium ions, and efficient electrolyte infiltration by ion and electron conductive channels in the binder-free cathode structure.

A highly-sensitive electrochemical sensor based on Ni nanoparticles modified carbon nanotubes/sulfonated reduced graphene oxide for the detection of capsaicinoids in leisure sauced meat products

Unclear labeling of spiciness degrees on leisure sauced meat products is prone to resulting in customer complaints and commercial disputes. The content of capsaicinoids is the basis for evaluating the spiciness of food. In this work, an electrochemical sensor based on nickel nanoparticles modified carbon nanotubes (Ni-CNTs) and sulfonated reduced graphene oxide (S-rGO) was developed for the rapid detection of capsaicinoids content in leisure sauced meat products. The linear ranges of capsaicins are 0.01–100 μmol/L with ultra-low detection limits of 1 nmol/L. The outstanding performances are primarily due to the synergistic effect between Ni-CNTs and S-rGO. This effect not only created a three-dimensional stacked structure that improved the electrochemically active surface area, but also generated an internal electric field that improved the charge transfer rate. This work provides a basis for standardized evaluation of spiciness.

The effect of the degree of sulphenylation on the stability of reduced graphene oxide nanofluids

Dispersion stability of nanoparticles in nanofluids is a prerequisite for allowing the nanofluids to act as convection heat transfer working fluids. This research prepared multiple types of sulfophenylated graphene (PSG) nanoparticles. Two samples subjected to different degrees of sulfophenylation were chosen to formulate different nanofluids with varying sulfophenylated particle concentrations. The nanofluids’ measured Zeta potential, electric conductivity, and thermal conductivity coefficients were used to investigate the stability. The research indicates the increase in the degree of sulfophenylation can improve the stability of nanofluids while exerting little influence on thermal conductivity; on the premise of ensuring stability, the number of nanoparticles added in base fluids can increase thermal conductivity. After that, high-sulfophenylated particle concentration nanofluids (2 mg/mL) were formulated using sulfonated-reduced graphene oxide (s-rGO) nanoparticles prepared to demonstrate excellent stability, and their thermal conductivity reached 0.773 W/m. K (55 °C).

Sulfonated nano-diamonds composite sulfonated reduced graphene oxide: A efficient hydrophilic material for high performance supercapacitors

This paper reports a simple reaction for the synthesis of sulfonated reduced graphene oxide composite with sulfonated diamond nanoparticles, (rGO/ND)-SO3H. It is based on the reaction of a mixture of graphene oxide (GO) and hydroxylated nano-diamonds (ND-OH) with 1,3-propanesultone at 150 °C for 48 h. During this process, ND-OH were converted to sulfonated ND (ND-SO3H) and composite sulfonated rGO formed rGO-SO3H. The electrochemical performance of (rGO/ND)-SO3H in 1 M H2SO4 was compared with that of ND-SO3H, rGO-SO3H and rGO/ND. It could be shown that a maximum specific capacitance of 160.1 F g−1 can be achieved by (rGO/ND)-SO3H at 1 A g−1. 81.5% capacitance retention upon increasing the charge-discharge current density from 0.5 A g−1 to 15 A g−1 was observed, making the material a potent candidate for supercapacitor applications. The high electrochemical surface area and easy accessibility of electrolyte to the electrode material are believed to be the underlying reasons for the improved performance. Furthermore, as-fabricated (rGO/ND)-SO3H shows excellent cycling stability with more the 99.1% retention of the specific capacitance after 6000 galvanostatic charge-discharge cycles, making it a promising matrix for high performance electrochemical capacitors.

Micron-dimensional sulfonated graphene sheets co-stabilized emulsion polymerization to prepare acrylic latex used for reinforced anticorrosion coatings

Waterborne polyacrylic anticorrosion coatings prepared with regular organic molecular emulsifiers suffer from reduced water and corrosion resistance. Herein this work, micron-dimensional sulfonated reduced graphene oxide (SRGO) sheets were prepared and introduced in-situ to co-stabilized the emulsion polymerization for improving dispersibility, compatibility and anticorrosive properties of polyacrylic/graphene composite coatings. By simulating the industrial polyacrylic latex formulation, effects of sulfonation degree of SRGO, dosage of SRGO and weight ratio of oil/water phase on the emulsion polymerization behaviour were systematically studied. The anticorrosion properties of polyacrylic/graphene composite coatings were evaluated through polarization curve and electrochemical impedance spectroscopy. Corrosion phenomena, such as bubbling and rusting, appearing on the surface of coatings after exposure to water or aqueous salt solution, were systematically identified to compare the degree of corrosion. All results demonstrated that micron-sized SRGO sheets with good hydrophilic property could be dispersed well in-situ to facilitate the emulsion polymerization. The anticorrosive performance of the polyacrylic/graphene composite coatings have been dramatically improved by introducing SRGO at a low dosage as 0.2%, which suggests the application of micron-sized graphene sheets in the industrial polyacrylic-based anticorrosion coatings would be accelerated.

A Greener Approach for the Chemoselective Boc Protection of Amines Using Sulfonated Reduced Graphene Oxide as a Catalyst in Metal- and Solvent-Free Conditions

Sulfonated reduced graphene oxide (SrGO) has displayed great potential as a solid acid catalyst due to its efficiency, cost-effectiveness, and reliability. In this study, SrGO was synthesized by the introduction of sulfonic acid-containing aryl radicals onto chemically reduced graphene oxide using ultrasonication. The SrGO catalyst was characterized by Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Further, SrGO was effectively utilized as a metal-free and reusable solid acid catalyst for the chemoselective N-t-Boc protection of various aromatic and aliphatic amines under solvent-free conditions. The N-t-Boc protection of amines was easily achieved under ambient conditions affording high yields (84–95%) in very short reaction times (5 min–2 h). The authenticity of the approach was confirmed by a crystal structure. The catalyst could be easily recovered and was reused up to seven consecutive catalytic cycles without any substantial loss in its activity.

A durable and antifouling monovalent selective anion exchange membrane modified by polydopamine and sulfonated reduced graphene oxide

Abstract Developing a durable and antifouling monovalent selective anion exchange membrane is critical in practical electrodialysis (ED) process. Herein, a commercial anion exchange membrane was modified by sulfonated reduced graphene oxide (S-rGO) and polydopamine (PDA). Inspired by biological adhesion from mussels, the PDA coating on the surface of S-rGO-PDA membrane enhanced the stability of S-rGO nanosheets due to strong adhesion. The monovalent anion selectivity was evaluated by means of the Cl - / SO 4 2 - permeselectivity, and stability property was measured by the ion concentration changes of Cl - and SO 4 2 - for a long time application of ED. Moreover, antifouling property was measured by recording the time course of the potential difference in the presence of sodium dodecyl benzene sulfonate (SDBS). The results show that permselectivity of S-rGO-PDA membrane is 2.50, which is higher than pristine membrane (1.08). In addition, S-rGO-PDA membrane is stable, the permselectivity did not change significantly during 70 h ED process. Besides antifouling property of S-rGO-PDA membranes is improved compared with S-rGO membranes.

Simultaneous reduction and sulfonation of graphene oxide for efficient hole selectivity in polymer solar cells

We developed sulfonated, reduced graphene oxide (S-RGO) through fuming/concentrated sulfuric acid treatment of graphene oxide (GO) in ambient conditions. It was demonstrated that the optical band gap and electrical conductivity of S-RGO are easily tunable, and depend on the level of reduction and sulfonation of GO. Whereas, reduction and sulfonation were found dependent on SO3 content, acid strength, and gas tightness of the reaction mixture. It's actually the water content of oleum that determines the nature of the final product. The easily adjustable band gap and electrical conductivity suggest that S-RGO can be employed as a potential hole extraction layer (HEL) material for several donor-acceptor systems. For P3HT:PC61BM based inverted polymer solar cells, it was observed that the shape of the J–V curve is tailorable with the choice of HEL. Compared to a 2.75% power conversion efficiency (PCE) attained with PEDOT:PSS, a PCE of 2.80% was achieved with tuned S-RGO. Our results imply that an S-RGO of sufficiently high band gap and conductivity can replace some of the state of the art HEL materials for a host of device applications.

Sulfonated reduced graphene oxide modification layers to improve monovalent anions selectivity and controllable resistance of anion exchange membrane

Graphene oxide with lamellar structure has attracted research interest in various fields. In this study, sulfonated reduced graphene oxide (S-rGO) nanosheets with negatively charged sulfonic acid groups were synthesized via a facile distillation-precipitation polymerization, followed by hydrazine reduction. The sulfanilic acid was grafted on the graphene oxide sheets to separate GO nanosheets each other and provide anion channels for anions selectivity. These nanosheets were used to modify anion exchange membranes (AEMs), and to enhance the membrane monovalent anions selectivity and the modification layer conductivity, in order to meet industrial requirements. The permselectivity and separation efficiency were used to evaluate selectivities of the modified membranes. The results show that the unmodified AEM has no monovalent selectivity, while the permselectivity and separation efficiency of S-rGO modified AEMs (reduced by hydrazine hydrate steam in 10min) increases from 0.65 to 1.80 and from −0.13 to 0.31 (in 40min), respectively; and from 0.72 to 2.30 and from −0.07 to 0.28 (in 80min), respectively.

Sulfonic Groups Originated Dual-Functional Interlayer for High Performance Lithium-Sulfur Battery.

The lithium-sulfur battery is one of the most prospective chemistries in secondary energy storage field due to its high energy density and high theoretical capacity. However, the dissolution of polysulfides in liquid electrolytes causes the shuttle effect, and the rapid decay of lithium sulfur battery has greatly hindered its practical application. Herein, combination of sulfonated reduced graphene oxide (SRGO) interlayer on the separator is adopted to suppress the shuttle effect. We speculate that this SRGO layer plays two roles: physically blocking the migration of polysulfide as ion selective layer and anchoring lithium polysulfide by the electronegative sulfonic group. Lewis acid-base theory and density functional theory (DFT) calculations indicate that sulfonic groups have a strong tendency to interact with lithium ions in the lithium polysulfide. Hence, the synergic effect involved by the sulfonic group contributes to the enhancement of the battery performance. Furthermore, the uniformly distributed sulfonic groups working as active sites which could induce the uniform distribution of sulfur, alleviating the excessive growth of sulfur and enhancing the utilization of active sulfur. With this interlayer, the prototype battery exhibits a high reversible discharge capacity of more than 1300 mAh g-1 and good capacity retention of 802 mAh g-1 after 250 cycles at 0.5 C rate. After 60 cycles at different rates from 0.2 to 4 C, the cell with this functional separator still recovered a high specific capacity of 1100 mAh g-1 at 0.2 C. The results demonstrate a promising interlayer design toward high performance lithium-sulfur battery with longer cycling life, high specific capacity, and rate capability.

Highly sensitive, reproducible and stable SERS substrate based on reduced graphene oxide/silver nanoparticles coated weighing paper

Paper-based surface-enhanced Raman scattering (SERS) substrates receive a great deal of attention due to low cost and high flexibility. Herein, we developed an efficient SERS substrate by gravure printing of sulfonated reduced graphene-oxide (S-RGO) thin film and inkjet printing of silver nanoparticles (AgNPs) on weighing paper successively. Malachite green (MG) and rhodamine 6G (R6G) were chosen as probe molecules to evaluate the enhanced performance of the fabricated SERS-active substrates. It was found that the S-RGO/AgNPs composite structure possessed higher enhancement ability than the pure AgNPs. The Raman enhancement factor of S-RGO/AgNPs was calculated to be as large as 109. The minimum detection limit for MG and R6G was down to 10−7M with good linear responses (R2=0.9996, 0.9983) range from 10−4M to 10−7M. In addition, the S-RGO/AgNPs exhibited good uniformity with a relative standard deviation (RSD) of 7.90% measured by 572 points, excellent reproducibility with RSD smaller than 3.36%, and long-term stability with RSD less than 7.19%.

Sulfonated reduced graphene oxide as a conductive layer in sulfonated poly(ether ether ketone) nanocomposite membranes

In this work, sulfonated reduced graphene oxide (SRGO) has been synthesized and incorporated into conventional random sulfonated poly(ether ether ketone) (SPEEK) in order to decrease the proton conduction barrier between isolated sulfonic acid groups in SPEEK and improve its conduction properties. SRGO was prepared by a facile arylation of reduced graphene oxide (RGO) with diazonium salt, which allowed the benzene sulfonate groups to be covalently bonded to the RGO layer. By a physical blending approach, the SRGO/SPEEK composite membranes were obtained in a homogenous state, and exhibited considerably improved thermal stability, mechanical strength and dimensional stability. Since the sulfonic acid groups presented in SRGO promote ion conduction through both Vehicle and Grotthuss mechanisms, the composite membranes exhibited better proton conductivities (σ), particularly at low relative humidity (RH) conditions. Taking SPEEK/SRGO-1.0 membrane as an example, its σ was as high as 8.6mScm-1 at 80°C/50% RH, which is three times greater than that of the blank. Moreover, the H2/air single cell test further confirmed the superior performance of the SPEEK/SRGO-1.0 membrane. A higher power output of 705mWcm-2 was generated with this composite membrane under the testing conditions, whereas only 636mWcm-2 for the pristine SPEEK membrane.

Fabrication of Pt–CeO2 nanoparticles supported sulfonated reduced graphene oxide as an efficient electrocatalyst for ethanol oxidation

We synthesized graphene oxide (GO) using the electrochemical exfoliation of graphite rod and then fabricated sulfonated reduced graphene oxide (SRGO) using lyophilization-assisted technique from a liquid mixture of GO and (NH4)2SO4 with a subsequent thermal treatment in N2 saturated. Pt and CeO2 nanoparticles can be anchored on the oxygenated functional groups of SRGO sheets. The as-prepared SRGO, CeO2/SRGO, Pt/SRGO, and PtCeO2/SRGO nanocomposites have been carefully characterized by spectroscopic and electrochemical techniques. FTIR spectrum confirms the presence of a sulfonic acid group. X-ray diffractometer and tunneling electron microscopy techniques are employed to study the crystallite size. The ionic resistance of Pt/SRGO without Nafion solution in catalyst layer was equal to the Pt/RGO and Nafion solution but the catalytic activities of the PtCeO2/SRGO are higher than Pt/RGO with Nafion and Pt/SRGO electrodes for ethanol oxidation. Furthermore, the activation energy of the Pt–CeO2/SRGO anode was much lower than that of the Pt/RGO with Nafion and Pt/SRGO, which can reveal the particular properties of the exfoliated SRGO supports and PtCeO2.

Sulfonated graphene anchored with tin oxide nanoparticles for detection of nitrogen dioxide at room temperature with enhanced sensing performances

The development of graphene-based room temperature gas sensors has drawn massive attention due to their unique advantage of gas sensing at room temperature. In this paper, in pursuit of developing high-performance graphene-based gas sensors, a NO2 gas sensor has been successfully fabricated using sulfonated reduced graphene oxide (S-rGO) anchoring with SnO2 nanoparticles as sensing materials. The SnO2 nanoparticles modified S-rGO (SnO2/S-rGO) hybrids were prepared by deposition of SnO2 nanoparticles on the surface of S-rGO through hydrothermal synthesis method. The combined characterizations of X-ray diffraction, UV–vis spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, energy-dispersive spectroscopy, as well as N2 sorption isotherm indicate the successful preparation of SnO2/S-rGO hybrids with porous structure. Most importantly, SnO2/S-rGO hybrids exhibit good sensing performances for detection of NO2 at room temperature, such as high response, fast response and recovery rate, and good selectivity. The sensor based on SnO2/S-rGO hybrids exhibits better sensing performances than the previously reported rGO-based gas sensors. Furthermore, the excellent sensing performances of sensor based on SnO2/S-rGO also render it suitable for development of high performance gas sensors operated at room temperature.

Gravure printing of hybrid MoS2@S-rGO interdigitated electrodes for flexible microsupercapacitors

In this letter, we demonstrated gravure printing of hybrid MoS2@S-rGO consisting of sulfonated reduced graphene oxide (S-rGO) and MoS2 nanoflowers to obtain a highly porous pattern of interdigitated electrodes, leading to a microsupercapacitor on a flexible polyimide substrate. The in-plane interdigital design of the printed microelectrodes is effective in increasing accessibility of electrolyte ions into the large active surface area. The optimized MoS2@S-rGO microsupercapacitor achieved a high specific capacitance (6.56 mF/cm2), energy density (0.58 mWh/cm3), and power density (13.4 mW/cm3), respectively. In addition, the printed microsupercapacitor lost only 9% of the maximum capacity after 1000 cycles, indicating that the printed hybrid MoS2@S-rGO microsupercapacitors are quite stable for potential flexible device applications.

Sulfonated Reduced Graphene Oxide: A High Performance Anode Material for Lithium Ion Battery

In this work, the sulfonated reduced graphene oxide (SRGO) was synthesized and proposed as an enhanced anode material for lithium ion battery (LIB). The result shows that the SRGO has an improved battery performance (i.e., ∼341.7 mAh/g and ∼190.6 mAh/g corresponds to SRGO and RGO at the 100th cycle with a current density of 200 mA/g) and superior cycling stability compared with pristine reduced graphene oxide (RGO). These are attributed to the improved specific surface area (448.35 m2/g) and conductivity (2.5 × 10-4 S/m). Further, the SRGO exhibits good rate capability and excellent energy density at various current densities ranging from 50 mAh/g to 2000 mAh/g, suggesting that SRGO could be a promising anode material for high capacity LIB.

Preparation of sulfonated reduced graphene oxide by radiation-induced chemical reduction of sulfonated graphene oxide

We report the preparation of sulfonated reduced graphene oxide (SRGO) by the sulfonation of graphene oxide followed by radiation-induced chemical reduction. Graphene oxide prepared by the well-known modified Hummer's method was sulfonated with the aryl diazonium salt of sulfanilic acid. Sulfonated graphene oxide (SGO) dispersed in ethanol was subsequently reduced by γ-ray irradiation at various absorbed doses to produce SRGO. The results of optical, chemical, and thermal analyses revealed that SRGO was successfully prepared by γ-ray irradiation-induced chemical reduction of the SGO suspension. Moreover, the electrical conductivity of SRGO was increased up to 2.94 S/cm with an increase of the absorbed dose.

Fully printed, rapid-response sensors based on chemically modified graphene for detecting NO2 at room temperature.

Reduced graphene oxide (RGO) has proven to be effective in trace gas detection at room temperature ambient conditions. However, the slow response-recovery characteristic is a major hurdle for the RGO-based gas sensors. Herein, we report a gravure-printed chemoresistor-type NO2 sensor based on sulfonated RGO (S-RGO) decorated with Ag nanoparticles (Ag-S-RGO). Large amounts of silver nanoparticles with an average particle size of 10-20 nm were uniformly assembled on flat S-RGO surfaces. The printed Ag-S-RGO sensor possesses a high sensitivity and fast response-recovery characteristic over NO2 concentrations ranging from 0.5 to 50 ppm. Upon exposure to 50 ppm NO2 at room temperature, the Ag-S-RGO sensor shows a sensitivity of 74.6%, a response time of 12 s and a recovery time of 20 s. In addition, the Ag-S-RGO sensors exhibit satisfactory flexibility with an almost constant resistance after 1000 bending cycles. The printed and high-performance Ag-S-RGO sensors described here will be a good prospect in environmental monitoring of NO2.

Self-Assembled Multilayer Films of Sulfonated Graphene and Polystyrene-Based Diazonium Salt as Photo-Cross-Linkable Supercapacitor Electrodes

Photo-cross-linkable multilayer films composed of sulfonated reduced graphene oxide (SRGO) and polystyrene-based diazonium salt (PSDAS) were fabricated by electrostatic layer-by-layer (LbL) self-assembly. Polystyrene with narrow molecular weight distribution was synthesized by atom transfer radical polymerization (ATRP), and cationic PSDAS was prepared through nitration, reduction, and diazotization reactions. Negatively charged SRGO nanosheets were prepared through prereduced by NaBH4, modified by diazonium salt of sulfanilic acid, and then further reduced by hydrazine. The multilayer films were obtained by alternately dipping substrates in the PSDAS solution and SRGO dispersion in acidic conditions. The cross-linking between the components occurred during the multilayer formation process and was further achieved by the UV light irradiation after the film preparation. The assembling process and surface morphology of LbL multilayer films were monitored by UV-vis spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The cross-linking between SRGO and PSDAS was verified by attenuated total reflectance FTIR (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angle measurement. The graphene nanosheets were found to be homogeneously distributed in the cross-linked network of the films. The large accessible surface area of graphene nanosheets and the cross-linking structure afforded the LbL films with high specific capacitance and excellent cyclic stability when used as supercapacitor electrodes. At a sweeping rate of 10 mV/s, the film with nine bilayers exhibited a specific capacitance of 150.4 F/g with ideal rectangular cyclic voltammogram. Large capacitance retention of 97% was observed after 10 000 charge-discharge cycles under the scanning rate of 1000 mV/s. This new approach for preparing graphene-containing multilayer films can be used to develop supercapacitor electrodes and other functional devices.