Co-doped Graphene Oxide Research Articles

One-step chronoamperometric synthesis of S, N co-doped graphene oxide electrodes for nonenzymatic electrochemical H2O2 sensor

One-step chronoamperometric synthesis of S, N co-doped graphene oxide electrodes for nonenzymatic electrochemical H2O2 sensor

Synergistic nanomaterial system for luminescence sensing of MnO4- anion and enhanced photocatalytic removal of antibiotic chloramphenicol (CAP) in aqueous environments using Dy3+/Tb3+ co-doped NaYF4 and graphene oxide hybrid

The presence of industrial pollutants in water bodies, particularly metal anions and organic pollutants, has put human health and the environment at risk worldwide, triggering the research and development of multifunctional nanoparticles that not only have excellent luminescence detection ability but also possess simultaneous photo-degradation activity against harmful pollutants. Herein, we have synthesized Dy3+/Tb3+ co-doped NaYF4 (Tb-NP) and (Tb-GO) NaYF4:Dy3+/Tb3+@GO(GO=Graphene oxide) nano hybrids via hydrothermal approach and tested their functional activity for the fluorescence selective detection of MnO4- anions and photocatalytic degradation of drug Chloramphenicol (CAP) in aqueous medium. The physicochemical characterization of prepared nanosamples was examined utilizing variety of analytical methods. The luminescent property of NaYF4:Dy3+/Tb3+(7 %) revealed that it is exceptionally sensitive and selective towards the detection ofMnO4- anion in aqueous medium. It was observed that, when varied amount of MnO4- anion was added to a suspension solution containing the synthesized NaYF4:Dy3+/Tb3+(7 %) chemosensor, the photoluminescence emission band at 545 nm was significantly quenched. Moreover, NaYF4:Dy3+/Tb3+(Tb-NP) exhibited the limit of detection (LOD)value of 0.65 ppm along with high Stern-Volmer (Ksv) quenching constant value of 4.75 ×105 M−1 for MnO4- anion, indicating great selectivity and sensitivity of the designed nanosensors towards MnO4- anion. Further, the Graphene oxide (GO) conjoined NaYF4:Dy3+/Tb3+(7 %) nanohybrid showed accelerating photocatalytic activity toward the degradation of CAP in aqueous medium under UV-irradiation. The obtained results of UV-Vis spectroscopy clearly indicate that NaYF4:Dy3+/Tb3+@GO (Tb/GO) nanohybrid can act as a superior nanocatalyst than that of NaYF4:Dy3+/Tb3+(Tb-NP) nanophosphors. The photocatalytic efficiency of NaYF4:Dy3+/Tb3+@GO (Tb/GO) nanohybrid toward degradation of CAP is around 95.6 % within 50 minutes under UV light and it maintains remarkable stability even after five repeated catalytic cycles. In conclusion, this study presents a feasible method for immediate detection of MnO4- anion and improved photo-catalytic degradation of CAP in an aqueous medium employing NaYF4:Dy3+/Tb3+(Tb-NP) and NaYF4:Dy3+/Tb3+@GO (Tb/GO) as dual functional nanomaterials.

Selective NO2 Gas Sensors Employing Nitrogen- and Boron-Doped and Codoped Reduced Graphene Oxide.

In this paper, we develop high-performance gas sensors based on heteroatom-doped and -codoped graphene oxide as a sensing material for the detection of NO2 at trace levels. Graphene oxide (GO) was doped with nitrogen and boron by a chemical method using urea and boric acid as precursors. The prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The obtained results proved the successful reduction of graphene oxide by doping effects, leading to the removal of some oxygen functional groups and restoration of an sp2 carbon structure. New bonds in honeycombs, such as pyridinic, pyrrolic, graphitic, B-C3, B-C2-O, and B-O, were created. Compared to the nondoped GO, the N/B-rGO materials exhibited enhanced responses toward low concentrations of NO2 (<1 ppm) at 100 °C. Particularly, the N-rGO-based device showed the highest sensitivity and lowest limit of detection.

Ru-CoO heterostructured nanoparticles supported on nitrogen and sulfur codoped graphene nanosheets as effective electrocatalysts for hydrogen evolution reaction in alkaline media

Production of clean hydrogen energy from water splitting is vital for the future fuel industry, and nanocomposites have emerged as effective catalysts for the hydrogen evolution reaction (HER). In this study, Ru-CoO@SNG nanocomposites are prepared by controlled pyrolysis where Ru-CoO heterostructured nanoparticles are supported on nitrogen and sulfur codoped graphene oxide nanosheets. With a large surface area, the obtained composites exhibit a remarkable electrocatalytic activity toward HER in 1.0 M KOH with an overpotential of only −90 mV to reach the current density of 10 mA cm−2, in comparison to −60 mV for commercial Pt/C benchmark, along with high stability. Mechanistically, codoping of sulfur and nitrogen facilitates the dispersion of the nanoparticles, and the formation of Ru-CoO heterostructures increases the active site density, reduces the electron-transfer kinetics and boosts the catalytic performance. Results from this study highlight the unique potential of structural engineering in enhancing the electrocatalytic performance of heterostructured nanocomposites.

Exploring the impact of doping and co-doping with B and N on the properties of graphene oxide and its photocatalytic generation of hydrogen

The photocatalytic production of hydrogen was studied in graphene oxide materials doped with nitrogen or/and boron by hydrothermal treatments. Characterization of the materials was carried out by XRD, FTIR, XPS, Raman, UV–Vis, and photoluminescence spectroscopies, FESEM and TEM. The study of hydrogen evolution in the water splitting reaction was done using UV light as source of irradiation and methanol as hole scavenger. Boron-doped graphene oxide with the highest bulk electrical resistance exhibited the highest photocatalytic hydrogen generation, due to interstitial positioning of boron in the graphene lattice, which improved the light absorption coefficient, formation of inter-gap states and reduced charge recombination. This phenomenon is hypothesized for the first time as “decentralized reaction clusters”, which spread across the graphene lattice and produce hydrogen independently. Nitrogen-doped graphene oxide showed high electrical conductivity due to a significant removal of oxygen functional groups, and improved carrier density. Partially reduced nitrogen and boron co-doped graphene oxide showed the highest electrical conductivity, due to the presence of more electron-donating nitrogen configurations, such as pyrrolic N and pyridinic N. Nitrogen and boron co-doping of graphene oxide allows to modify the conduction band and valence bands, thus improving the electrical conductivity.

High-performance flexible electrothermal Joule heaters from laser reduced F-N Co-doped graphene oxide with extended Sp2 networks

Phonons play an important role in heat generation and propagation across graphene lattice; however, this is hindered by graphene heteroatom doping which generates highly defected structures. Consequently, heteroatom doping has not been primarily explored in electrothermal materials despite presenting a cost-effective and metal-free method of improving electronic activity in flexible 2D materials. Herein, we present a facile and scalable technique for fabrication of fluorine-nitrogen co-doped laser reduced graphene oxide (FN-G) Joule heaters by ultrasonic wetchemical doping and maskless laser writing method. Films containing 6.14 at. % F and 3.22 at. % N, low sheet resistance of 24.49 O/sq. and uniquely high degree of atomic ordering indicated by an ID/IG of 0.16 were successfully fabricated. The heaters showed highly competitive transient electrothermal behaviour with a saturation temperature of 365 °C for only 9 V applied voltage, high heating rate of 385.33 °C/s, and average response time of 0.68 s. An excellent temperature distribution, low power requirement, and a net-zero degradation in the electrical and electrothermal properties even after 500 bending cycles was demonstrated. These high-performance features render the FN-G heater suitable for applications in wearable electronics powered by low voltage portable electrochemical cells.

O3-assisted low-temperature preparation of marginal S and graphitic N co-doped graphene oxide as high-performance electrocatalyst for bisphenol A degradation

In this research, a novel insight was provided for oriented low-temperature S and N doping into graphene oxide (GO).Given the gradual concern in the high-temperature dependence of traditional annealing method for the oriented design of heteroatom doping, utilizing O3 etching-assisted heteroatom doping can simultaneously resolve the problems of energy consumption and doping species design. In this research, with O3 etching, 100 at.% marginal S (C-SOX-C) and 92 at.% graphitic N co-doped O3-S/NGO were successfully synthesized at annealing temperature of 200 °C. Characterization results showed that S and N doping via O3 etching maintained the sheet-like structure of GO without much stacking (layer thickness of 4–5 nm). In addition, active defects were formed by O3 etching and S/N atom doping to provide active center for catalytic reaction. The electrocatalytic degradation behavior proved that 100 % bisphenol A degradation efficiency could be achieved by O3-S/NGO within 30 min and that the main active species generated during the reaction were O2•−, 1O2 and active chlorine. The possible pathways of bisphenol A degradation were also determined to complete the discussion. This project was based on the environmental demand of organic pollution control and suggested an optimal preparation strategy for high-performance catalyst preparation and utilization.

Bismuth and nitrogen co-doped graphene oxide for efficient electrochemical sensing of Pb(II) by synergistic dual-site interaction

Bismuth and nitrogen co-doped graphene oxide for efficient electrochemical sensing of Pb(II) by synergistic dual-site interaction

Hierarchical Nanoflowers of MgFe2O4, Bentonite and B-,P- Co-Doped Graphene Oxide as Adsorbent and Photocatalyst: Optimization of Parameters by Box-Behnken Methodology.

In the present study, nanocomposites having hierarchical nanoflowers (HNFs) -like morphology were synthesized by ultra-sonication approach. HNFs were ternary composite of MgFe2O4 and bentonite with boron-, phosphorous- co-doped graphene oxide (BPGO). The HNFs were fully characterized using different analytical tools viz. X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersion spectroscopy, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry and Mössbauer analysis. Transmission electron micrographs showed that chiffon-like BPGO nanosheets were wrapped on the MgFe2O4-bentonite surface, resulting in a porous flower-like morphology. The red-shift in XPS binding energies of HNFs as compared to MgFe2O4-bentoniteand BPGO revealed the presence of strong interactions between the two materials. Box–Behnken statistical methodology was employed to optimize adsorptive and photocatalytic parameters using Pb(II) and malathion as model pollutants, respectively. HNFs exhibited excellent adsorption ability for Pb(II) ions, with the Langmuir adsorption capacity of 654 mg g−1 at optimized pH 6.0 and 96% photocatalytic degradation of malathion at pH 9.0 as compared to MgFe2O4-bentonite and BPGO. Results obtained in this study clearly indicate that HNFs are promising nanocomposite for the removal of inorganic and organic contaminants from the aqueous solutions.

Anodic corrosion of heteroatom doped graphene oxide supports and its influence on the electrocatalytic oxygen evolution reaction

Transition metal-based electrocatalysts supported on carbon substrates face the challenges of anodic corrosion of carbon during oxygen evolution reaction at high oxidation potential. The role of electrophilic functional groups (carbonyl, pyridinic, thiol, etc.) incorporated in graphene oxide has been studied towards the anodic corrosion resistance. Heteroatom functionalized carbon supports possess modified electronic properties, surface oxygen content, and hydrophilicity, which are crucial in governing electrochemical corrosion in the alkaline oxidative environment. Evidently, electron-withdrawing groups in NGO support (pyridinic, cyano, nitro, etc) and its lower oxygen content impart maximum corrosion resistance and anodic stability in comparison to the other sulfur-doped and co-doped graphene oxide support. In this report, we establish the baseline evaluation of carbon-supported OER electrocatalysts by a systematic analysis of activity and substrate corrosion resistance. The result of this study establishes the role of surface composition of the doped supports while for designing a stable, corrosion-resistant OER electrocatalyst.

Cover Feature: Creating Hybrid Coordination Environment in Fe‐Based Single Atom Catalyst for Efficient Oxygen Reduction (ChemSusChem 12/2022)

The Cover Feature shows that metal phthalocyanine is selectively anchored on the N and S sites of N,S co-doped graphene oxide. The hybrid coordination environment of the metal center contributes to higher activity in the oxygen reduction reaction. More information can be found in the Research Article by W. Zhang, L. Wang, et al.

Electronic field effect detection of SARS-CoV-2 N-protein before the onset of symptoms

As part of the efforts to contain the pandemic, researchers around the world have raced to develop testing platforms to detect the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes the Coronavirus disease 2019 (COVID-19). Within the different detection platforms studied, the field effect transistor (FET) is a promising device due to its high sensitivity and fast detection capabilities. In this work, a graphene-based FET which uses a boron and nitrogen co-doped graphene oxide gel (BN-GO gel) transducer functionalized with nucleoprotein antibodies, has been investigated for the detection of SARS-CoV-2 nucleocapsid (N)-protein in buffer. This biosensor was able to detect the viral protein in less than 4 min, with a limit of detection (LOD) as low as 10 ag/mL and a wide linear detection range stretching over 11 orders of magnitude from 10 ag/mL–1 μg/mL. This represents the lowest LOD and widest detection range of any COVID-19 sensor and thus can potentially enable the detection of infected individuals before they become contagious. In addition to its potential use in the COVID-19 pandemic, our device serves as a proof-of-concept of the ability of functionalized BN-GO gel FETs to be used for ultrasensitive yet robust biosensors.

Adsorption chemistry of co-doped graphene nanoribbon and its derivatives towards carbon based gases for gas sensing applications: Quantum DFT investigation

Sensing of the toxic gases plays a vital role in the human life to improve their health aspects and the quality of life. Using the first-principles calculations combined with density functional theory (DFT), the authors in this research work have explored the adsorption energy and electronic features of co-doped armchair graphene nanoribbon (ArGNR) and its derivatives, such as the co-doped armchair graphene oxide nanoribbon (ArGONR) and co-doped armchair reduced graphene oxide nanoribbon (ArRGONR) with boron and phosphorus (BP) atoms. A comparative study of detection of toxic carbon based gases (CO, CO2, CH4) on co-doped graphene nanoribbon (BP-ArGNR), and its derivatives such as BP-ArGONR (addition of more oxygen atoms in pristine ArGNR) and BP-ArRGONR (addition of less oxygen atoms in pristine ArGNR) has been performed. To evaluate the sensing of carbon based gases, their adsorption energies, binding distances, charge transfer, band structures and density of states have been studied for different variants. Before modification, adsorption energies for BP-ArGNR have been found to be smaller than the BP-ArGONR for CO, CO2 and CH4 molecules, thereby showing physisorption mechanism. Our computational results also revealed that after modification with oxygen atoms, BP-ArGONR shows relatively more negative value of adsorption energy in comparison to the pristine ArGNR (PR-ArGNR) for CO, CO2 and CH4 molecules, thereby showing chemisorption phenomenon. Band structure analysis predicts large band gap variations for BP-ArGONR as compared to PR-ArGNR. Thus, the authors concluded that after modification of graphene surface, enormous changes are observed in adsorption energies and band gap for BP-ArGONR towards all carbon based gases under study and hence significantly enhance the sensing performance of pristine graphene.

Creating Hybrid Coordination Environment in Fe-Based Single Atom Catalyst for Efficient Oxygen Reduction.

Tailoring the local chemistry environment to optimize the geometric and electronic properties of single atom catalysts has received much attention recently. Yet, most efforts have been devoted to establishing the preferable binding between the solid support and the single metal atom. In this work, a hybrid coordination environment was created for Fe‐based single atom catalysts, comprising inorganic anchoring site from the support and organic ligands from the precursor. Using N,S co‐doped graphene oxide as the support, Fe phthalocyanine was selectively anchored by the N/S sites, creating the unique N/S−Fe−N4 active sites as evidenced by extended X‐ray absorption fine structure and Mössbauer spectrometry. Compared with other analogues with different metal centers or support, N/S−Fe−N4 showed much improved activity in oxygen reduction reaction, delivering onset and half‐wave potentials of 1.02 and 0.94 V. This was superior over the state‐of‐the‐art 20 wt % Pt/C and the classic Fe−N4 carbon catalysts. Density functional theory calculations revealed that the interaction between phthalocyanine ligands and heteroatom dopant from the support pushed electrons of Fe site to para‐position, facilitating O2 adsorption and activation. This work shows the exciting opportunities of creating a hybrid coordination environment in single atom catalysts and paves a new avenue of improving their catalytic performance.

Electroluminescence and photocatalytic hydrogen evolution of S,N co-doped graphene oxide quantum dots

S,N-GOQDs with stable electroluminescence, photoluminescence, and photocatalytic properties have been developed. They can be used as emitters for LED devices and as photocatalysts for hydrogen evolution in photo-electro-chemical energy conversion.

Simultaneous microwave-assisted reduction and B/N co-doping of graphene oxide for selective recognition of VOCs

The influence of heteroatom domains on the volatile organic compound (VOC) detection properties of B/N co-doped graphene oxide nanostructures is investigated by using different boron (B) and nitrogen (N) sources.

Long-term corrosion protection of styrene acrylic coatings enhanced by fluorine and nitrogen co-doped graphene oxide

Graphene materials are widely used as a physical barrier when applying anticorrosion polymer coatings due to their large surface area and layered structure. However, the electrical conductivity of intrinsic graphene can accelerate galvanic corrosion and shorten the protection period. In this work, fluorine and nitrogen co-doped graphene oxide (FNGO) was synthesized by a hydrothermal process and acted as an anticorrosion filler in waterborne styrene acrylic coatings. Styrene acrylic coatings with 0.4 wt% FNGO showed a corrosion current density that was two orders of magnitude lower than the other samples in the potential polarization test and the largest impedance modulus in the electrochemical impedance spectroscopy results. The outstanding corrosion protection was attributed to the graphene acting as a physical barrier and the synergistic effect of the doped fluorine and nitrogen. In addition to the ‘labyrinth effect’ of the graphene matrix, the nitrogen atoms inserted in the graphene plane and fluorine atoms grafted on the graphene simultaneously adjusted the electrical properties of graphene, prohibiting electron transport between it and the styrene acrylic resin matrix. This result indicates that doped graphene oxide has great potential to increase the corrosion resistance of waterborne coatings.

MnO 2 / Co 3 O 4 with N and S co‐doped graphene oxide bimetallic nanocomposite for hybrid supercapacitor and photosensor applications

This report presents the synthesis of MnO2/Co3O4 with N and S co-doped graphene oxide (GO) hybrid composite by hydrothermal route for supercapacitor and photosensor applications. MnO2/Co3O4 nanoflakes and nanoparticles were directly grown on dual N and S doped GO sheets, where doping was achieved using a single reagent thiourea in one-pot synthesis. Individual Co3O4 and MnO2 electrodes have poor reversibility and cycling properties due to electrolytic instability and low electrical conductivities. However, the hybrid provides good catalytic properties, and combined with highly conducting two-dimensional GO it can reduce mismatching properties due to high conductivity and layered structure. The incorporated composite sheet-like structure provides good mechanical strength with high conductivity, permitting easy ion penetration into the electrode, and providing considerably more active surfaces. Thus, the proposed hybrid material delivers significantly improved performance for supercapacitor and/or photosensor applications, achieving 614 F.g−1 specific capacitance at 1 Ag−1, and exceeding 95% retention up to 10 000 cycles. This composite material also shows good photosensing with 1 order of increased current under visible light.

Three-dimensional N/S Co-doped holey graphene oxide based hydrogel electrodes for high performance supercapacitors

Large specific surface area, conductivity and doping are necessary to design high performance supercapacitor electrode materials. Nevertheless, the traditional graphene as electrode materials is unable to achieve superior electrochemical performance. Here we prepared a three-dimensional N-and S co-doped holey graphene hydrogel (N/S-HGH) to achieve an optimized pore structure with a high conductivity, effective electron and ion transfer pathways. The binder-free N/S-HGH electrode delivers a gravimetric capacitance of 346 F g−1 with a volumetric capacitance of 242 F cm−3 and retains 93.8% of the original capacitance after 10000 cycles at 10 A g−1. Moreover, the supercapacitor fabricated from N/S-HGH deliver gravimetric and volumetric energy density of 24.6Wh kg−1 and 17.2 Wh L−1 respectively, at a power density of 415.4W kg−1 (290.8 W L−1), displaying enormous prospect for practical applications.

Preparation of nitrogen and sulfur co‐doped graphene/Fe3O4/C nanocomposite and study on the absorbing properties

Nitrogen and sulfur co-doped graphene oxide (NS-GO) is obtained using a simple hydrothermal method using thiourea as nitrogen source and sulfur source, and then nitrogen and sulfur co-doped graphene/Fe3O4 (NS-rGO/Fe3O4) composite is synthesized by a solvent method. On this basis, nitrogen and sulfur co-doped graphene/Fe3O4/C nanocomposite (NS-rGO/Fe3O4/C) is obtained using a solvent method combined with a high temperature calcination process using pitch as carbon source. When the matching thickness is 2.7 mm, the NS-rGO/Fe3O4/C has a reflection loss peak at 10.56 GHz, the value of which is − 46.33 dB, and the effective absorption (RL ≤ − 10 dB) bandwidth of the nanocomposite is 5.04 GHz. Compared with NS-rGO/Fe3O4, the NS-rGO/Fe3O4/C shows higher reflection loss (RL) value, thinner matching thickness and wider effective absorption (RL ≤ − 10 dB) bandwidth. The presence of amorphous carbon regulates the dielectric parameters of the material and increases the interface of the material. Sulfur and nitrogen diatoms regulate the band gap of graphene, and the composite material has good impedance matching characteristics and multiple interface effects.