Sulfur Co-doped Reduced Graphene Oxide Research Articles

Nitrogen and sulfur co-doped reduced graphene oxide (rGO)/gold nanoparticles hybrids for SERS sensing platform

Nitrogen and sulfur co-doped reduced graphene oxide (rGO)/gold nanoparticles hybrids for SERS sensing platform

Comparative study on the structural and electrochemical properties of nitrogen-doped and nitrogen and sulfur co-doped reduced graphene oxide electrode prepared by hydrothermal technique

Nitrogen- and co-nitrogen- and sulfur-doped reduced graphene oxide (named N-rGO and N/S-rGO) was prepared by a simple hydrothermal technique using urea and thiourea as doping agents, respectively, to improve the properties of supercapacitor electrodes. Both were compared with rGO in electrochemical evaluations. The supercapacitor using N-rGO in 1 M H2SO4 provided the largest specific capacitance, 99 F g−1, while those using N/S-rGO and rGO exhibited 51 and 19 F g−1 at 0.25 A g−1, respectively. Furthermore, the supercapacitors using N-rGO and N/S-rGO electrodes showed a smaller charge transfer resistance (Rct) and a lower IR-drop than those using the rGO electrode, indicating a faster charge transfer at the interface between electrode and electrolyte and higher electronic conductivity due to N or N/S heteroatom doping in the graphene oxide structure. Furthermore, the N-rGO electrode has a higher sp2 hybridization ratio and a lower ID/IG ratio than the N/S-rGO electrode. Furthermore, the lowest contact angles of the N/S-rGO electrode were found, which was attributed to better aqueous electrolyte compatibility than the N-rGO and rGO electrodes. Therefore, the higher electrical conductivity of the N-rGO electrode reveals more relevant characteristics for high-performance supercapacitors than the good wettability of the N/S-rGO electrode.

Comparative Study on the Structural and Electrochemical Properties of Nitrogen Doped and Nitrogen and Sulfur Co-Doped Reduced Graphene Oxide Electrode Prepared by Hydrothermal Technique

Comparative Study on the Structural and Electrochemical Properties of Nitrogen Doped and Nitrogen and Sulfur Co-Doped Reduced Graphene Oxide Electrode Prepared by Hydrothermal Technique

Synthesis of nitrogen and sulfur co-doped reduced graphene oxide by hydrothermal method for fabrication of cathodes in dye-sensitized solar cells

Carbon-based materials have been known as non-metal electrocatalysts with both high performance and low cost for the reduction at the cathode of dye-sensitized solar cells (DSSCs). In this work, nitrogen and sulfur co-doped reduced graphene oxide (NSG) materials were synthesized via using graphene oxide (GO) as a precursor with reducing agent thiourea as the source of providing heteroatoms. Furthermore, NSG materials were extensively prepared via hydrothermal treatment with the investigation of different mass ratios of GO to thiourea. To study the impact of the quantity of reductant on the properties of NSG, reduced graphene oxide (rGO) was prepared by reducing GO with ascorbic acid as a reference sample. Moreover, NSG and rGO cathodes were both prepared by drop-casting method, while platinum (Pt) cathodes were fabricated using commercial Pt paste by screen-printing method. The DSSCs based on NSG cathodes with ratio of GO to thiourea of 1:10 exhibited an efficiency of 7.21 %, which was similar to commercial DSSCs Pt (7.44 %), proving that the judicious heteroatom doping of GO might introduce a potential candidate for increasing performance of DSSCs.

Ultrafine CuS anchored on nitrogen and sulfur Co-doped graphene for selective CO2 electroreduction to formate

Electrochemical conversion of CO2 into hydrocarbons can effectively alleviate the energy crisis and promote carbon cycle. Herein, we report that small-size CuS nanoparticles are confined in nitrogen and sulfur co-doped reduced graphene oxide (CuS/N,S-rGO) for electrochemically reducing CO2 to formate. Specifically, the CuS/N,S-rGO electrode achieves maximum Faradaic efficiency of 82% for formate formation at −0.63 V versus the reversible hydrogen electrode (RHE). Moreover, this catalyst exhibits a stable performance during 20 h-electrolysis. Experiments demonstrate that the doping of nitrogen and sulfur can create an abundance of active sites on the graphene nanosheets to accelerate the CO2 reduction reaction (CO2RR). The CuS/N,S-rGO electrode exhibits excellent performance for CO2RR is attributed to the synergistic effect between N,S-rGO and CuS, and graphene can improve stability of composite. This work provides an efficient electrocatalyst for CO2RR and offers a facile and environmental friendly approach to synthesize small-size Cu-based composites.

A simple electrochemical sensor for quercetin detection based on cadmium telluride nanoparticle incorporated on boron, sulfur co-doped reduced graphene oxide composite

Quercetin (QR) is an essential component of the human diet, according to that low-cost, rapid, and portable sensors are required for the detection of QR in the diet supplements, fruits, vegetables, and pharmaceutical samples. A highly sensitive, low-cost, and facile hydrothermally synthesized cadmium telluride (CdTe) with (BS-RGO) boron- sulphur co-doped reduced graphene oxide nanocomposite based electrochemical sensor material for the detection of (QR) was established successfully. Here, prepared the CdTe/BS-RGO nanocomposite was confirmed by the morphological and structural examination such as FESEM, HRTEM, EDX, XRD, Raman, and XPS techniques. The electrical conductivity of the electrode material investigated by EIS and CV analysis, which confirmed the electrical conductivity of CdTe was boosted by the BS-RGO nanosheets. The electrochemical studies were established that the developed CdTe/BS-RGO sensor was highly selective and sensitive to QR. Furthermore, the CdTe/BS-RGO sensor exhibits good sensitivity, an excellent low detection limit (LOD) and a wide linear range was 2.3492 μA μM−1 cm−2, 18 nM, and 0.001–564 µM respectively for QR detection under optimized experimental conditions. In addition, we investigated the realistic performance of the proposed sensor for QR detection in grape juice and apple juice samples.

Ivermectin detection using Ag@ B, S co-doped reduced graphene oxide nanohybrid

Silver nanoparticles (AgNPs) modified boron and sulfur co-doped reduced graphene oxide (B, S@rGO) were prepared by one-pot hydrothermal method for the first time. The combination between AgNPs and B, S@rGO decreases stacking of B, S@rGO and decreases the particle size of AgNPs; in addition, it enhances the effective surface area and electro-catalytic activities of the nanocomposite. The morphology and structure of AgNPs/B, S@rGO were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron microscope (XPS), Raman spectroscopy, UV-Vis spectroscopy, thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET). The electro-catalytic activity of AgNPs/B, S@rGO was studied using cyclic voltammetry (CV), electron impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Because of the synergetic effects of AgNPs and B, S@rGO, the modified electrode displayed considerably enhanced sensitivity to ivermectin (IVM) determination. The voltammetric response is linear over the range of 0.3–60.0 nM with LOD (S/N = 3) of 0.1 nM. The proposed sensor exhibited good selectivity, reproducibility, and long-term stability. The modified electrode was used to analyze IVM in injections, urine, and tap-water with recoveries % of 99.6–105.8% and RSDs of 2.14–3.65%.

Nitrogen and sulfur co-doped reduced graphene oxide-gold nanoparticle composites for electrochemical sensing of rutin

The extraordinary biological and physiological properties of rutin have been used in the preparation of therapeutical drugs. So it is very significant to develop a simple and sensitive method for rutin determaination in pharmaceutical samples. Herein, nitrogen and sulfur co-doped reduced graphene oxide attached with gold nanoparticles (NS-rGO/AuNPs) was developed for electrochemical determination of rutin. The NS-rGO was first prepared by a simple one-step thermal annealing method, and AuNPs were embedded onto NS-rGO through the interaction force of Au with N and S atoms. Detailed characterizations showed that the AuNPs are well dispersed and the presence of nitrogen and sulfur are significant. The NS-rGO/AuNPs modified electrode exhibited a significantly enhanced electrocatalytic activity towards rutin compared with NS-rGO, N-rGO and S-rGO modified electrodes. The excellent performance was achieved by the synergistic effect of AuNPs and heteroatoms co-doping. As a consequence, the NS-rGO/AuNPs based sensor showed a wide linear range of 0.2–1400 nM with a nanomolar detection limit of 0.067 nM (S/N = 3). Also the sensor exhibited satisfying selectivity, reproducibility, and stability. Finally, the sensor was successfully used to determine rutin in pharmaceutical tablets.

Alpha-MnO2 nanofibers/nitrogen and sulfur-co-doped reduced graphene oxide for 4.5 V quasi-solid state supercapacitors using ionic liquid-based polymer electrolyte

α-MnO2 nanofibers combined with nitrogen and sulfur co-doped reduced graphene oxide (α-MnO2/N&S-rGO) were prepared through simple hydrothermal and ball milling processes. Structural characterization results by X-ray diffraction, X-ray photoemission spectroscopy, electron microscopy and Raman spectroscopy demonstrated that α-MnO2 nanofibers with the average diameter of ~40 nm were well dispersed on N&S-rGO nanoflakes. The synthesized material was incorporated into supercapacitor (SC) electrodes and assembled with the quasi-solid-state electrolyte comprising N,N-Diethyl-N-methyl-N-(2-methoxy-ethyl)ammonium bis (trifluoromethyl-sulfonyl)amide [DEME][TFSA]/polyvinylidene fluoride-hexafluoropropylene (PVDF-co-HFP) to produce coin-cell SCs. Electrochemical performances of SCs were measured by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. From the electrochemical data, SC using α-MnO2/N&S-rGO exhibited a good specific capacitance of 165F g−1 at 0.25 A g−1 with a wide potential window of 0–4.5 V, corresponding to a high energy density of 110 Wh kg−1 and a power density of 550 W kg−1. In addition, it exhibited good electrochemical stability with a capacitance retention of 75% after 10,000 cycles at 1 A g−1 and a low self-discharge loss. The attained energy-storage performances indicated that the α-MnO2/N&S-rGO composite could be highly promising for high-performance ionic liquid-based quasi solid-state supercapacitors.

Nitrogen, Sulfur Co-Doped Reduced Graphene Oxide: Synthesis and Characterization

Objective and Method: In this present research, a simple hydrothermal implantation technique for synthesizing N,S co-doped reduced graphene oxide (NS-r-GO) has been presented in which thiourea was used as a single-source precursor of N and S atoms. Results: Maximum N and S atoms, with an atomic percentage of 3.50 and 7.50 (at.%), were achieved in the GO matrix at the reaction temperature of 250°C. Introduction of N and S atoms into the GO lattice was confirmed by X-ray photoelectron spectroscopy (XPS). Different chemical bonds such as –C– S–C, C=O, N–O, and C–N–C have been suggested from the corresponding C1s, N1s, O1s, and S2p high-resolution XPS spectral analyses. Conclusion: FT-IR measurement also confirmed the presence of different functional groups as well as the formation of different bonds such as –OH, –N–H, –C=O, –C–OH, and C-S. XRD and Raman spectroscopy analyses confirmed the defects structures that arose from the penetration of N and S atoms into the GO lattice.

Hexagonal-WO3 nanorods encapsulated in nitrogen and sulfur co-doped reduced graphene oxide as a high-performance anode material for lithium ion batteries

Nanocomposites consisting of hexagonal WO3 nanorods embedded into nitrogen, sulfur co-doped reduced graphene oxide nanosheets (h-WO3/NSG) have been synthesized through a combination of ultrasonic processing and hydrothermal reactions. The nanocomposite containing 54 ​wt% of (N, S)-doped reduced graphene oxide shows an excellent discharge capacity of 1030 mAh g-1 at the first cycle and high rate capacities ranging from 513 to 150 mAh g-1 at the current density ranging from 100 to 2000 ​mA ​g-1, respectively. In addition, the synthesized WO3/NSG nanocomposite also exhibits remarkable cycle stability with a high discharge capacity of 196 mAh g-1 at the current density of 1500 ​mA ​g-1 for 200 cycles. The excellent electrochemical performance of h-WO3/NSG nanocomposite can be attributed to synergistic contributions from (1) the small size of WO3 nanorods, which increases the contact surface area with the electrolyte, effectively shortening the diffusion length of Li+ ions leading to high Li+ incorporation within h-WO3; (2) the structural support provided by the NSG matrix, which alleviates the large volume change of WO3 nanorods during Li+ insertion/extraction; and (3) the large numbers of surface defects provided by nitrogen and sulfur co-dopants, which serve as channels to improve the Li+ diffusion. Furthermore, electrochemical impedance spectroscopy (EIS) measurement demonstrates that nitrogen, sulfur co-doped reduced graphene oxide can reduce the electrochemical impedance of the electrode, further improving the electrochemical performance of the anode. This study provides important strategies for the design of future high performance anode materials for lithium ion battery.

Zeolitic-imidazolate-framework-derived Co@Co3O4 embedded into iron, nitrogen, sulfur Co-doped reduced graphene oxide as efficient electrocatalysts for overall water splitting and zinc-air batteries

Rational design and fabrication of nonprecious metallic multifunctional catalysts with superior performance are crucial for energy-related electrochemical devices. Herein, we report the synthesis and electrochemical properties of a sandwich-like Co@Co3O4 embedded into Fe, N, S co-doped reduced graphene oxide (Co@Co3O4/FeNS-RGO) nanocomposite catalyst. The designed Co@Co3O4/FeNS-RGO catalyst is synthesized by pyrolysis of one-pot solvothermal method-induced nano-zeolitic imidazolate framework (ZIF)/graphene oxide nanocomposite using dimethylsulfoxide as both the solvent and sulfur source. The synthesized catalyst exhibits the outstanding electrocatalytic activity in basic media for oxygen reduction reaction and oxygen evolution reactions, which outperforms the commercial Pt/C and IrO2 catalysts, respectively. In addition, the synthesized catalyst also shows a promising electrocatalytic activity towards hydrogen evolution reaction. The performance of the thus-assembled zinc-battery and the overall water-splitting device reveals that the synthesized Co@Co3O4/FeNS-RGO can be practically applied in energy-related electrochemical devices with great activity and stability.

An electrochemical sandwich immunosensor for cardiac troponin I by using nitrogen/sulfur co-doped graphene oxide modified with Au@Ag nanocubes as amplifiers.

A voltammetric sandwich immunoassay is described for the biomarker cardiac troponin I (cTnI). The gold nanocube-functionalized graphene oxide (AuNC/GO) is employed as a substrate to accelerate the electron transfer and to immobilize more primary antibodies. It also employs composite materials prepared from bimetallic gold/silver core-shell nanocubes and nitrogen and sulfur co-doped reduced graphene oxide as the signal amplifier. The introduction of N and S into GO enlarges the active surface and accelerates the electron transfer rate. Such unique characteristics render the material an effective support substrate to load more Au@AgNC and to immobilize an increasing number of second antibodies via Ag-N bonds. After specific binding with cTnI, the immunosensor was incubated in a labeled cTnI secondary antibody solution. The amperometric signal change is then measured at 0.34V (vs. SCE) using o-phenylenediamine and hydrogen peroxide as an electrochemical probe. Response is linear in theconcentration range from 100fg∙mL-1 to 250ng∙mL-1, and the detection limit is 33fg∙mL-1. Graphical abstract Schematic presentation of cardiac troponin I (cTnI) electrochemical immunosensor based on gold nanocube-functionalized graphene oxide (AuNC/GO) as substrate material, bimetallic gold/silver core-shell nanocubes and nitrogen and sulfur co-doped reduced graphene oxide (Au@AgNC/N, S-rGO) as signal amplifier, and hydrogen peroxide (H2O2) and o-phenylenediamine (o-PD) as redox probe.

Plasma-Assisted Simultaneous Reduction and Nitrogen/Sulfur Codoping of Graphene Oxide for High-Performance Supercapacitors

Nitrogen and sulfur-codoped reduced graphene oxide (RGO) was prepared with the assistance of an environmentally benign and facile route using an inductive coupled plasma (ICP) source. This novel ga...

Porous interconnected NiCo2O4 nanosheets and nitrogen- and sulfur-codoped reduced graphene oxides for high-performance hybrid supercapacitors

We demonstrate a facile hydrothermal synthesis of the interconnected porous NiCo2O4 nanosheets for hybrid supercapacitor applications. The as-synthesized NiCo2O4 nanosheets show a high specific capacitance of 3137 F g−1 at a current density of 2 A g−1, which is much greater than 1916 and 1251 F g−1 of Co3O4 and NiO, respectively. Interestingly, the total specific capacitance of the NiCo2O4 is almost close to the sum of the specific capacitance of the NiO and Co3O4. Furthermore, a hybrid supercapacitor is configured with the NiCo2O4 nanosheets and the nitrogen- and sulfur-codoped reduced graphene oxide as the positive and negative electrodes, respectively. This hybrid supercapacitor delivers a maximum energy density of 33.64 W h kg−1 at a power density of 1196 W kg−1 and excellent long-term cyclic stability over 12,000 charge/discharge cycles at the enlarged voltage window of 1.5 V. The remarkable supercapacitive performances of the hybrid device are attributed to the interconnected porous structure of NiCo2O4 nanosheets and three-dimensional continuous macropores of codoped reduced graphene oxides.

Synthesis of nitrogen and sulfur co-doped reduced graphene oxide as efficient metal-free cocatalyst for the photo-activity enhancement of CdS

Nitrogen and sulfur co-doped reduced graphene oxide (NS-rGO) was synthesized using a facile low temperature calcination method, which was then used as support and cocatalyst for the anchor of CdS. The obtained CdS/NS-rGO nanocomposites exhibit ultra-high photocatalytic activity for hydrogen evolution and 4-nitrophenol (4-NP) reduction under visible light (λ ≥ 420 nm). Their activity could also be adjusted by changing the doping amount of S and N, or by changing the ratios between CdS and NS-rGO. The optimum percentage of NS-rGO is 5 wt%, at which CdS/NS-rGO photocatalyst could achieve the highest H2 evolution rate of 1701 μmol h–1 g–1. Moreover, the reduction from 4-NP to 4-aminophenol (4-AP) could be completed within only 6 min over this optimized composite. NS-rGO here could provide more active sites as well as tune the band gap structure to increase the photo-activity. The density functional theory (DFT) calculations reveal that NS-rGO has a small Gibbs free energy for H* adsorption (ΔGH), which could increase the utilization efficency of photo-generated electrons for H2 generation. NS-rGO is therefore an idea alternate cocatalyst of noble metals for new photocatalysts development.

Nanoscale α-MnS crystallites grown on N-S co-doped rGO as a long-life and high-capacity anode material of Li-ion batteries

The rock-salt structural manganous sulfide (α-MnS) is of higher lithium storage capacity. To improve the cyclability of α-MnS anode in lithium-ion batteries, we prepared a composite of α-MnS nanocrystallites grown on nitrogen and sulfur co-doped reduced graphene oxide (rGO) honeycomb framework. N and S atoms have been co-doped into rGO along with the growth of the α-MnS nanocystallites by a one-pot hydrothermal synthesis using thiourea as dopant and reactant. The typical α-MnS/NS co-doped rGO (NSG) composite electrode exhibits a reversible capacity as high as 763.5mAhg−1 after 100 cycles at 100mAg−1, and a reversible capacity of 576.7mAhg−1 even after 2000 cycles at 1000mAg−1. More importantly, the α-MnS/NSG composite electrodes show superior cycle performance at asymmetric discharge/charge current densities. The excellent electrochemical performance can be attributed to that the α-MnS nanocrystallites shorten lithium ion transmission distance, N-S co-doping improves the electronic conductivity of rGO, and the formation of chemical bonds combination between α-MnS and NSG enhances the electrode structural stability and the electron transport. In addition, more stable architecture of NSG-supported ultrafine α-MnS particles is formed upon cycling, which greatly enhances the electrical contact and further improves the electrochemical performance.

Preparation of Cobalt Sulfide Nanoparticle-Decorated Nitrogen and Sulfur Co-Doped Reduced Graphene Oxide Aerogel Used as a Highly Efficient Electrocatalyst for Oxygen Reduction Reaction.

A novel 3D cobalt sulfide (CoS) nanoparticle-decorated nitrogen and sulfur co-doped reduced graphene oxide aerogel (NSGA), referred to as CoS/NSGA, is prepared via three sequential processes, i.e., freeze-drying, annealing, and sulfidization. The obtained CoS/NSGA exhibits excellent electrocatalytic performance in the alkaline solution.

Nitrogen and Sulfur Codoped Reduced Graphene Oxide as a General Platform for Rapid and Sensitive Fluorescent Detection of Biological Species.

Nitrogen (N) and sulfur (S) codoped reduced graphene oxide (N,S-rGO) was synthesized through a facile solvothermal process. The introduction of N and S heteroatoms into GO effectively activated the sp(2)-hybridized carbon lattice and made the material an ideal electron/energy acceptor. Such unique properties enable this material to perform as a general platform for rapid and sensitive detection of various biological species through simple fluorescence quenching and recovering. When quantum dot (QD)-labeled HBV (human being disease-related gene hepatitis B virus DNA) and HIV (human being disease-related gene human immunodeficiency virus DNA) molecular beacon probes were mixed with N,S-rGO, QD fluorescence was quenched; when target HBV and HIV DNA were added, QD fluorescence was recovered. By the recovered fluorescence intensity, the target virus DNA detection limits were reduced to 2.4 nM for HBV and 3.0 nM for HIV with detection time of less than 5 min. It must be stressed out that different viruses in the same homogeneous aqueous media could be discriminated and quantified simultaneously through choosing diverse QD probes with different colors. Moreover, even one mismatched target DNA could be distinguished using this method. When altering the molecular beacon loop domain to protein aptamers, this sensing strategy was also able to detect thrombin and IgE in 5 min with detection limits of 0.17 ng mL(-1) and 0.19 ng mL(-1), respectively, which was far more rapid and sensitive than bare GO-based fluorescence detection strategy.

Microwave-assisted solvothermal preparation of nitrogen and sulfur co-doped reduced graphene oxide and graphene quantum dots hybrids for highly efficient oxygen reduction

Microwave-assisted solvothermal preparation of nitrogen and sulfur co-doped reduced graphene oxide/graphene quantum dot hybrids for highly efficient oxygen reduction.