scholarly journals Eco-Friendly and Solvent-Less Mechanochemical Synthesis of ZrO2–MnCO3/N-Doped Graphene Nanocomposites: A Highly Efficacious Catalyst for Base-Free Aerobic Oxidation of Various Types of Alcohols

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1136 ◽  
Author(s):  
Mufsir Kuniyil ◽  
J. V. Shanmukha Kumar ◽  
Syed Farooq Adil ◽  
Mohamed E. Assal ◽  
Mohammed Rafi Shaik ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Specific Activity ◽  
Aerobic Oxidation ◽  
Oxidation Catalyst ◽  
Mixed Metal Oxide ◽  
Heterogeneous Oxidation ◽  
Graphene Nanocomposites ◽  
X Ray ◽  
Doped Graphene ◽  
Zro2 Catalyst

In recent years, the development of green mechanochemical processes for the synthesis of new catalysts with higher catalytic efficacy and selectivity has received manifest interest. In continuation of our previous study, in which graphene oxide (GRO) and highly reduced graphene oxide (HRG) based nanocomposites were prepared and assessed, herein, we have explored a facile and solvent-less mechanochemical approach for the synthesis of N-doped graphene (NDG)/mixed metal oxide (MnCO3–ZrO2) ((X%)NDG/MnCO3–ZrO2), as the (X%)NDG/MnCO3–ZrO2 nano-composite was synthesized using physical grinding of separately synthesized NDG and pre-calcined (300 °C) MnCO3–ZrO2 via green milling method. The structures of the prepared materials were characterized in detail using X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), Raman, Thermogravimetric analysis (TGA), and N2 adsorption-desorption isotherm analysis. Besides, the obtained nanocomposites were employed as heterogeneous oxidation catalyst for the alcohol oxidation using green oxidant O2 without involving any surfactants or bases. The reaction factors were systematically studied during the oxidation of benzyl alcohol (PhCH2OH) as the model reactant to benzaldehyde (PhCHO). The NDG/MnCO3–ZrO2 exhibits premium specific activity (66.7 mmol·g−1·h−1) with 100% conversion of PhCH2OH and > 99.9% selectivity to PhCHO after only 6 min. The mechanochemically prepared NDG based nanocomposite exhibited notable improvement in the catalytic efficacy as well as the surface area compared to the pristine MnCO3–ZrO2. Under the optimal circumstances, the NDG/MnCO3–ZrO2 catalyst could selectively catalyze the aerobic oxidation of a broad array of alcohols to carbonyls with full convertibility without over-oxidized side products like acids. The NDG/MnCO3–ZrO2 catalyst were efficiently reused for six subsequent recycling reactions with a marginal decline in performance and selectivity.

scholarly journals Solventless Mechanochemical Fabrication of ZnO–MnCO3/N-Doped Graphene Nanocomposite: Efficacious and Recoverable Catalyst for Selective Aerobic Dehydrogenation of Alcohols under Alkali-Free Conditions

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 760
Author(s):  
Mujeeb Khan ◽  
Syed Farooq Adil ◽  
Mohamed E. Assal ◽  
Abdulrahman I. Alharthi ◽  
Mohammed Rafi Shaik ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Metal Oxide ◽  
Surface Area ◽  
Specific Activity ◽  
Systematic Investigation ◽  
Mixed Metal Oxide ◽  
X Ray ◽  
Mixed Metal ◽  
Recoverable Catalyst ◽  
Doped Graphene

Catalytic efficacy of metal-based catalysts can be significantly enhanced by doping graphene or its derivatives in the catalytic protocol. In continuation of previous work regarding the catalytic properties of highly-reduced graphene oxide (HRG), graphene-oxide (GO) doped mixed metal oxide-based nanocomposites, herein we report a simple, straightforward and solventless mechanochemical preparation of N-doped graphene (NDG)/mixed metal oxide-based nanocomposites of ZnO–MnCO3 (i.e., ZnO–MnCO3/(X%-NDG)), wherein N-doped graphene (NDG) is employed as a dopant. The nanocomposites were prepared by physical milling of separately fabricated NDG and ZnO–MnCO3 calcined at 300 °C through eco-friendly ball mill procedure. The as-obtained samples were characterized via X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), Raman, Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and surface area analysis techniques. To explore the effectiveness of the obtained materials, liquid-phase dehydrogenation of benzyl alcohol (BOH) to benzaldehyde (BH) was chosen as a benchmark reaction using eco-friendly oxidant (O2) without adding any harmful surfactants or additives. During the systematic investigation of reaction, it was revealed that the ZnO–MnCO3/NDG catalyst exhibited very distinct specific-activity (80 mmol/h.g) with a 100% BOH conversion and <99% selectivity towards BH in a very short time. The mechanochemically synthesized NDG-based nanocomposite showed remarkable enhancement in the catalytic performance and increased surface area compared with the catalyst without graphene (i.e., ZnO–MnCO3). Under the optimum catalytic conditions, the catalyst successfully transformed various aromatic, heterocyclic, allylic, primary, secondary and aliphatic alcohols to their respective ketones and aldehydes with high selectively and convertibility without over-oxidation to acids. In addition, the ZnO–MnCO3/NDG was also recycled up to six times with no apparent loss in its efficacy.

Bimetallic Mixed Metal Oxide (CuO/NiO) In Fusion with Nitrogen-doped Graphene Oxide: An Alternate Approach for Developing Potential Biocarrier

2021 ◽  
pp. 105781
Author(s):  
Periasamy Anbu ◽  
Subash C.B. Gopinath ◽  
Kandasamy Saravanakumar ◽  
Sekar Vijayakumar ◽  
Santheraleka Ramanathan ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Metal Oxide ◽  
Mixed Metal Oxide ◽  
Mixed Metal ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

scholarly journals A Facile Synthesis of ZrOx-MnCO3/Graphene Oxide (GRO) Nanocomposites for the Oxidation of Alcohols using Molecular Oxygen under Base Free Conditions

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 759 ◽  
Author(s):  
Syed Farooq Adil ◽  
Mohamed E. Assal ◽  
Mohammed Rafi Shaik ◽  
Mufsir Kuniyil ◽  
Nawaf M. AlOtaibi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Specific Activity ◽  
Oxidation Catalyst ◽  
Facile Synthesis ◽  
Reduced Graphene ◽  
Short Period ◽  
Oxidation Of Alcohols ◽  
Lower Temperature ◽  
Optimized Conditions

Graphene and its nanocomposites are showing excellent potential in improving the catalytic performances of different materials. However, the synthetic protocol and its form, such as graphene oxide (GRO) or highly reduced graphene oxide (HRG), influence the catalytic efficiencies. Here, we present, a facile synthesis of graphene oxide (GRO) and ZrOx-MnCO3-based nanocomposites [(1%)ZrOx–MnCO3/(x%)GRO] and their outcome as an oxidation catalyst for alcohol oxidation under mild conditions using O2 as a clean oxidant. The ZrOx–MnCO3/GRO catalyst prepared by incorporating GRO to pre-calcined ZrOx-MnCO3 using ball milling showed remarkable enhancement in the catalytic activities as compared to pristine ZrOx–MnCO3, ZrOx–MnCO3 supported on HRG or ZrOx–MnCO3/GRO prepared by in-situ growth of ZrOx–MnCO3 onto GRO followed by calcination. The catalyst with composition (1%)ZrOx–MnCO3/(1%)GRO exhibited superior specific activity (57.1 mmol/g·h) with complete conversion and >99% selectivity of the product within a short period of time (7 min) and at a relatively lower temperature (100 °C). The catalyst could be recycled at least five times with a negligible decrease in efficiency and selectivity. The catalytic study was extended to different aromatic as well as aliphatic alcohols under optimized conditions, which confirmed the efficiency and selectivity of the catalyst.

Fabrication of Nickel Sulfide/Nitrogen-Doped Reduced Graphene Oxide Nanocomposite as Anode Material for Lithium-Ion Batteries and Its Electrochemical Performance

2020 ◽  
Vol 20 (11) ◽  
pp. 6782-6787
Author(s):  
Yeon-Ju Lee ◽  
Tae-Hyun Ha ◽  
Gyu-Bong Cho ◽  
Ki-Won Kim ◽  
Jou-Hyeon Ahn ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Lithium Ion ◽  
Treatment Method ◽  
Retention Capacity ◽  
Graphene Nanocomposites ◽  
X Ray ◽  
Nitrogen Doped ◽  
Reduced Graphene

In this study, NiS/graphene nanocomposites were synthesized by simple heat treatment method of three graphene materials (graphene oxide (GO), reduced graphene oxide (rGO) and nitrogen-doped graphene oxide (N-rGO)) and NiS precursor. The morphology and crystal structure of NiS/graphene nanocomposites were characterized using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Electrochemical properties were also investigated. NiS/graphene nanocomposites homogeneously wrapped by graphene materials have been successfully manufactured. Among the three nanocomposites, NiS/N-rGO nanocomposite exhibited the highest initial and retention capacity in discharge, respectively, of 1240 mAh/g and 467 mAh/g up to 100 cycles at 0.5 C.

High Reversible Capacity of Nitrogen-Doped Graphene as an Anode Material for Lithium-Ion Batteries

2014 ◽  
Vol 1070-1072 ◽  
pp. 459-464
Author(s):  
Chang Jing Fu ◽  
Shuang Li ◽  
Qian Wang
Keyword(s):  
Graphene Oxide ◽  
Electron Microscope ◽  
Lithium Ion Batteries ◽  
Current Density ◽  
Lithium Ion ◽  
X Ray ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene ◽  
A Current

Nitrogen-doped graphene (N-rGO) was synthesized in the process of preparation of reduced graphene oxide from the expanded graphite through the improved Hummers’ method. The morphology, structure and composition of nitrogen-doped graphene oxide (GO) and N-rGO were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The nitrogen content of N-rGO was approximately 5 at.%. The electrochemical performances of N-rGO as anode materials for lithium-ion batteries were evaluated in coin-type cells versus metallic lithium. Results showed that the obtained N-rGO exhibited a higher reversible specific capacity of 519 mAh g-1 at a current density of 100 mA⋅g-1 and 207.5 mAh⋅g-1 at a current density of 2000 mA⋅g-1. The excellent cycling stability and high-rate capability of N-rGO as anodes of lithium-ion battery were attributed to the large number of surface defects caused by the nitrogen doping, which facilitates the fast transport of Li-ion and electron on the interface of electrolyte/electrode.

Aerobic selective oxidation of 5-hydroxymethyl-furfural over nitrogen-doped graphene materials with 2,2,6,6-tetramethylpiperidin-oxyl as co-catalyst

2016 ◽  
Vol 6 (7) ◽  
pp. 2377-2386 ◽  
Author(s):  
Guangqiang Lv ◽  
Hongliang Wang ◽  
Yongxing Yang ◽  
Xiao Li ◽  
Tiansheng Deng ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Thermal Treatment ◽  
Selective Oxidation ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Co Catalyst ◽  
Nitrogen Doped ◽  
Hydroxymethyl Furfural ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

N-doped graphene materials were prepared via thermal treatment of graphene oxide in flowing NH3, and their catalytic performance was tested in aerobic oxidation of 5-hydroxymethy-furfural.

Fabrication and Electrochemical Performance of Nitrogen-Doped Graphene Synthesized by Hydrothermal Method

2014 ◽  
Vol 804 ◽  
pp. 35-38
Author(s):  
Sen Liang ◽  
Min Luo ◽  
Yuan Yun Dou ◽  
Lei Guo ◽  
Bin Liang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Electrical Measurements ◽  
X Ray ◽  
Nitrogen Doped ◽  
Reduced Graphene ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene ◽  
Nitrogen Substitution ◽  
Pyridinic N

In this study, nitrogen doped graphene (NG) was prepared by using hydrothermal treatment of graphene oxide (GO) and ethylene diamine (EDA). The surface chemistry of the reduced graphene oxide (rGO) and the NG was investigated by the X-ray photoelectron spectroscopy (XPS). The results revealed that there were four kinds of nitrogen substitution: pyrollic N, pyridinic N, graphitic N and C-NH2. Further, the electrical measurements illustrated that the NG had superior capacitive performance than that of the rGO. Specifically, the maximum specific capacitance of NG was 200.6 F/g due to the double-layer capacitive and pseudocapacitive effect from the nitrogen-doped graphene. In addition, the present studies showed that the EDA was not only choose as nitrogen doping source but also played a key role in reduction.

Effective Chemical Vapor Deposition and Characterization of N-Doped Graphene for High Electrochemical Performance

2021 ◽  
Vol 21 (6) ◽  
pp. 3183-3191
Author(s):  
Shanmugam Mahalingam ◽  
Mani Durai ◽  
Chinnasamy Sengottaiyan ◽  
Young-Ho Ahn
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Active Material ◽  
Chemical Vapor ◽  
Diffraction Field ◽  
X Ray ◽  
Transmission Electron ◽  
Doped Graphene ◽  
Charge Discharge

Here we reports an effective synthetic method for the preparation of N-graphene upon thermal annealing of prepared graphene oxide in the existence of ammonia. N-doped graphene oxide was analysed using different characterization techniques like X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The nitrogen atom showed good binding with the graphene sheets, that are analysed by the X-ray photoelectron spectroscopy. The synthesized N-graphene have shown higher thermal stability compared with GO and graphene. The elcerochemnical performance like Cyclic voltammetry as well chronopotentiometry charge–discharge calculations revealed that the N-doped graphene exhibits remarkable behaviour favors a specific capacitance value about 209 F g−1 at 5 mV s−1 and 270 F g−1 for 1 A g−1 applied current density including outsanding charge–discharge stability about 98% of the initial capacitance subsequent 1000 cycles at 5 A g−1. The N-content in the graphene material with the optimized reaction parameters potentially improved electrode active material for energy storage applications.

scholarly journals One-Pot Synthesized Pd@N-Doped Graphene: An Efficient Catalyst for Suzuki–Miyaura Couplings

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 469 ◽  
Author(s):  
Mufsir Kuniyil ◽  
J. V. Shanmukha Kumar ◽  
Syed Farooq Adil ◽  
Mohammed Rafi Shaik ◽  
Mujeeb Khan ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Coupling Reaction ◽  
Ammonium Hydroxide ◽  
Coupling Reactions ◽  
One Pot ◽  
Efficient Catalyst ◽  
X Ray ◽  
Doped Graphene

Nitrogen-doped graphene (NDG)-palladium (Pd)-based nanocatalysts (NDG@Pd) can be potentially applied as an efficient catalyst for the preparation of biaryls in a Suzuki–Miyaura coupling reaction. Herein, we report the one-pot facile synthesis of an NDG@Pd nanocatalyst, wherein the nanocatalyst was prepared by the simultaneous reduction of graphene oxide (GRO) and PdCl2 in the presence of hydrazine hydrate as a reducing agent, while ammonium hydroxide was used as a source of “N’’ on the surface of graphene. The as-synthesized NDG@Pd nanocatalyst, consisting of smaller-sized, spherical-shaped palladium nanoparticles (Pd-NPs) on the surface of NDG, was characterized by several spectroscopic and microscopic techniques, including high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET). The nanocatalyst displayed outstanding catalytic activity in the Suzuki–Miyaura cross-coupling reactions of phenyl halides with phenyl boronic acids under facile conditions in water. The catalytic activity of NDG@Pd was found to be a more efficient catalyst when compared to pristine highly reduced graphene oxide (HRG) based Pd nanocatalyst (HRG@Pd). Furthermore, the reusability of the catalyst was also tested by repeatedly performing the same reaction using the recovered catalyst. The N-doped catalyst displayed excellent reusability even after several reactions.

Effect of Various Amounts of Hydrazine and Graphene Oxide on the Photocatalytic Performances of the ZnSe/Graphene Nanocomposites

2016 ◽  
Vol 863 ◽  
pp. 127-131
Author(s):  
Shu Huei Hsieh ◽  
Yu En Lee ◽  
Wen Jauh Chen
Keyword(s):  
Graphene Oxide ◽  
Visible Light ◽  
Dye Degradation ◽  
Degradation Efficiency ◽  
X Ray Diffraction ◽  
Graphene Nanocomposites ◽  
X Ray ◽  
Transmission Electron ◽  
Degradation Reaction ◽  
Graphene Nanocomposite

In this study, the hydrothermal method was used for synthesizing ZnSe/graphene nanocomposites with the amount of graphene oxide (GO) and hydrazine. Obtained ZnSe/graphene photocatalysts were characterized by X-ray diffraction analysis (XRD) and transmission electron microscope (TEM). Photocatalytic activity under visible light is evaluated in methylene blue (MB) dye degradation reaction in aqueous phase. The results show that the amount of graphene oxide (GO) and hydrazine have an effect on the degradation efficiency of the ZnSe/graphene nanocomposite. When GO/ZnSe ratio was 1. The optimum degradation efficiency of the ZnSe/graphene nanocomposites prepared with 5 mL of N2H4 was 99.6% after 5h of visible light irradiation.

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