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Catalysts
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Graphene Nanocomposites: Environmentally Friendly Synthesis and Applications
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Graphene Nanocomposites: Environmentally Friendly Synthesis and Applications

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Catalytic Materials".

Deadline for manuscript submissions: closed (31 August 2020) | Viewed by 13741

Special Issue Editors

Prof. Dr. Ick Soo Kim

E-Mail Website
Guest Editor
Nano Fusion Technology Research Group, Division of Frontier Fibers, Institute for Fiber Engineering (IFES), Interdisciplinary Cluster for Cutting Edge Research (ICCER), Shinshu University, Tokida 3-15-1, Ueda, Nagano Prefecture 386-8567, Japan
Interests: nanofibers; polymers; carbon nanomaterials; catalysis; supercapacitor; biomedical
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Seoung Hun KIM

E-Mail Website
Guest Editor
Department of Organic and Nano Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea
Interests: polymer processing and materials; nanocomposites; conducting polymer; nanofibers; graphene materials

Special Issue Information

Dear Colleagues,

Graphene nanocomposites have gained vast attention due to their ultrafine size and shape-dependent physicochemical properties. The demand for graphene nanocomposites has been increasing rapidly due to their importance in various applications such as electronics, catalysis, sensing, and medicine. Indeed, novel synthesis of graphene nanocomposites deserves special attention. Several routes including chemical and physical synthetic methods are proposed for the preparation of such nanocomposites. However, to avoid environmental drawbacks and high production cost, environmentally friendly synthesis has been largely focused on. Since the microstructure and properties are extremely tunable via green synthetic methods, it is very interesting to investigate the graphene nanocomposites derived from such methods.

In this Special Issue, we invite authors to submit original research and review articles that focus on environmentally feasible synthesis and applications of graphene nanocomposites. Particularly, the preparation of graphene nanocomposites under environmentally feasible conditions (without using toxic reagents) is one of the main focuses of this Special Issue. Potential applications of graphene nanocomposites in energy storage, catalysis, sensors, and biomedical, are also of interest.

Prof. Dr. Ick Soo Kim
Prof. Dr. Seoung Hun KIM
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Feasible synthetic routes
  • Toxic reagents-free synthesis
  • Graphene nanocomposites
  • Microstructure
  • Catalysis
  • Energy
  • Biomedical
  • Sensors

Published Papers (5 papers)

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Research

21 pages, 15082 KiB  
Article
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
by Mufsir Kuniyil, J. V. Shanmukha Kumar, Syed Farooq Adil, Mohamed E. Assal, Mohammed Rafi Shaik, Mujeeb Khan, Abdulrahman Al-Warthan, Mohammed Rafiq H. Siddiqui, Aslam Khan, Muhammad Bilal, Hafiz M. N. Iqbal and Waheed A. Al-Masry
Catalysts 2020, 10(10), 1136; https://doi.org/10.3390/catal10101136 - 01 Oct 2020
Cited by 5 | Viewed by 2037
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Graphene Nanocomposites: Environmentally Friendly Synthesis and Applications)
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17 pages, 4841 KiB  
Article
Synthesis of Graphene-Based Biopolymer TiO2 Electrodes Using Pyrolytic Direct Deposition Method and its Catalytic Performance
by Parminder Kaur, Sana Frindy, Yuri Park, Mika Sillanpää and Monzur A. Imteaz
Catalysts 2020, 10(9), 1050; https://doi.org/10.3390/catal10091050 - 11 Sep 2020
Cited by 3 | Viewed by 2268
Abstract
The traditional methods used to synthesize graphene layers over semiconductors are chemical-based methods. In the present investigation, a novel photoelectroactive electrode was synthesized using a chitosan biopolymer without the usage of chemicals. A chitosan-biopolymer layer over the surface of TiO2 was generated [...] Read more.
The traditional methods used to synthesize graphene layers over semiconductors are chemical-based methods. In the present investigation, a novel photoelectroactive electrode was synthesized using a chitosan biopolymer without the usage of chemicals. A chitosan-biopolymer layer over the surface of TiO2 was generated by electrodeposition. Furthermore, the pyrolysis method was used for the conversion of a biopolymer into graphene layers. The catalytic activity of the fabricated electrodes was investigated by the photo-electro-Fenton (PEF) process to oxidize chloramphenicol and nadolol pharmaceutical drugs in wastewater, remove metals (scandium, neodymium, and arsenic) and degrade real municipal wastewater. The PEF operational parameters (pH, voltage, reaction time, and Fenton catalytic dose) were optimized for the overall degradation of chloramphenicol and nadolol pharmaceutical drugs in wastewater. It was observed that at the optimum process operational parameters it took 40 min to degrade chloramphenicol and nadolol pharmaceutical drugs in wastewater. It was proved that biopolymer-based photoelectroactive novel electrodes render good catalytic activity. Furthermore, the reusability study of fabricated electrodes showed excellent storage and self-healing properties. Full article
(This article belongs to the Special Issue Graphene Nanocomposites: Environmentally Friendly Synthesis and Applications)
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17 pages, 4729 KiB  
Article
Eco-Friendly Mechanochemical Preparation of Ag2O–MnO2/Graphene Oxide Nanocomposite: An Efficient and Reusable Catalyst for the Base-Free, Aerial Oxidation of Alcohols
by Syed Farooq Adil, Mohamed E. Assal, Mujeeb Khan, Mohammed Rafi Shaik, Mufsir Kuniyil, Doumbia Sekou, Ahmed Z. Dewidar, Abdulrahman Al-Warthan and Mohammed Rafiq H. Siddiqui
Catalysts 2020, 10(3), 281; https://doi.org/10.3390/catal10030281 - 01 Mar 2020
Cited by 24 | Viewed by 3149
Abstract
Recently, the development of eco-friendly mechanochemical approaches for the preparation of novel catalysts with enhanced activity and selectivity has gained considerable attention. Herein, we developed a rapid and solvent-less mechanochemical method for the preparation of mixed metal oxide (Ag2O–MnO2) [...] Read more.
Recently, the development of eco-friendly mechanochemical approaches for the preparation of novel catalysts with enhanced activity and selectivity has gained considerable attention. Herein, we developed a rapid and solvent-less mechanochemical method for the preparation of mixed metal oxide (Ag2O–MnO2) decorated graphene oxide (GRO)-based nanocomposites (Ag2O–MnO2/(X wt.%)GRO), as the Ag2O–MnO2/(X wt.%)GRO nanocomposite was fabricated by the physical grinding of freshly prepared GRO and pre-annealed (300 °C) mixed metal oxide nanoparticles (NPs) (Ag2O–MnO2) using an eco-friendly milling procedure. The as-prepared nanocatalysts were characterized by using various techniques. Furthermore, the nanocomposites were applied as a heterogeneous catalyst for the oxidation of alcohol by employing gaseous O2 as an eco-friendly oxidant under base-free conditions. The mechanochemically obtained GRO-based composite exhibited noticeable enhancement in the surface area and catalytic performance compared to the pristine Ag2O–MnO2. The results revealed that (1%)Ag2O–MnO2/(5 wt.%)GRO catalyst exhibited higher specific performance (13.3 mmol·g−1·h−1) with a 100% conversion of benzyl alcohol (BnOH) and >99% selectivity towards benzaldehyde (BnH) within 30 min. The enhancement of the activity and selectivity of GRO-based nanocatalyst was attributed to the presence of various oxygen-containing functional groups, a large number of defects, and a high specific surface area of GRO. In addition, the as-prepared nanocatalyst also demonstrated excellent catalytic activity towards the conversion of a variety of other alcohols to respective carbonyls under optimal conditions. Besides, the catalyst ((1%)Ag2O–MnO2/(5 wt.%)GRO) could be efficiently recycled six times with no noticeable loss in its performance and selectivity. Full article
(This article belongs to the Special Issue Graphene Nanocomposites: Environmentally Friendly Synthesis and Applications)
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21 pages, 7706 KiB  
Article
Stepwise Construction of Ru(II)Center Containing Chiral Thiourea Ligand on Graphene Oxide: First Efficient, Reusable, and Stable Catalyst for Asymmetric Transfer Hydrogenation of Ketones
by Gopiraman Mayakrishnan, Kim Ick Soo and Chung Ill Min
Catalysts 2020, 10(2), 175; https://doi.org/10.3390/catal10020175 - 02 Feb 2020
Cited by 5 | Viewed by 3005
Abstract
Heterogenization of homogenous catalysts on solid support has attracted tremendous attention in organic synthesis due to the key benefits of heterogenized catalysts such as easy recovery and reusability. Although a considerable number of heterogenized catalysts are available, to the best of our knowledge, [...] Read more.
Heterogenization of homogenous catalysts on solid support has attracted tremendous attention in organic synthesis due to the key benefits of heterogenized catalysts such as easy recovery and reusability. Although a considerable number of heterogenized catalysts are available, to the best of our knowledge, there is no efficient and reusable heterogenized catalyst reported for asymmetric reactions to date. Herein, we prepared a [RuCl2(η6-p-cymene)]/chiralthiourea ligand covalently bonded to graphene nanosheets (G-CLRu(II), where G represents graphene oxide (GO), CL denotes chiral N-((1-phenylethyl)carbamothioyl)acetamide and Ru(II) symbolizes [RuCl2(η6-p-cymene)]), for the asymmetric transfer hydrogenation of ketones. Five simple steps were involved in the preparation of the G-CLRu(II) catalyst. The structure of G-CLRu(II) was investigated by means of various spectroscopic and microscopic techniques. Coordination mode and covalent bonding involved in the G-CLRu(II) structure we reconfirmed. G-CLRu(II) demonstrated good catalytic performance towards the asymmetric transfer hydrogenation of ketones (conversion of up to 95%, enantiomeric excesses (ee) of up to 99%, and turnover number (TON) and turnover frequency (TOF) values of 535.9 and 22.3 h−1, respectively). A possible mechanism is proposed for the G-CLRu(II)-catalyzed asymmetric transfer hydrogenation of ketones. Recovery (~95%), reusability (fifth cycle, yield of 89% and ee of 81%), and stability of G-CLRu(II) were found to be good. We believe that the present stepwise preparation of G-CLRu(II) opens a new door for designing various metal-centered heterogenized chiral catalysts for asymmetric synthesis. Full article
(This article belongs to the Special Issue Graphene Nanocomposites: Environmentally Friendly Synthesis and Applications)
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18 pages, 5666 KiB  
Article
Facile Green Preparation of Rhodium Nanoclusters Supported Nano-Scaled Graphene Platelets for Sonogashira Coupling Reaction and Reduction of p-Nitrophenol
by Gopiraman Mayakrishnan, Saravanamoorthy Somasundaram, Sana Ullah, Ilangovan Andivelu, Kim Ick Soo and Chung Ill Min
Catalysts 2019, 9(11), 908; https://doi.org/10.3390/catal9110908 - 30 Oct 2019
Cited by 8 | Viewed by 2728
Abstract
Rhodium nanoclusters were uniformly dispersed on nano-scaled graphene platelets by a simple ‘mix and heat’ method without using any toxic reagents. Distilled water was used to obtain the homogenous dispersion of Rh-nanoclusters on graphene platelets. The morphology of the resultant catalyst (Rh(0)NCs/GNPs) was [...] Read more.
Rhodium nanoclusters were uniformly dispersed on nano-scaled graphene platelets by a simple ‘mix and heat’ method without using any toxic reagents. Distilled water was used to obtain the homogenous dispersion of Rh-nanoclusters on graphene platelets. The morphology of the resultant catalyst (Rh(0)NCs/GNPs) was studied by means of transmission electron microscope (TEM) and atomic force microscope (AFM) analyses. The X-ray photoemission spectroscope (XPS) result confirmed the metallic form of Rh-nanoclusters in Rh(0)NCs/GNPs. The crystalline property and the interaction between Rh-nanoclusters and graphene platelets (GNPs) were studied by means of XRD and Raman analysis. The Rh-loading in Rh(0)NCs/GNPs was confirmed by scanning electron microscope and energy dispersive spectroscope (SEM-EDS) and inductively coupled plasma-mass spectroscope (ICP-MS) analysis. After being optimized, the Rh(0)NCs/GNPs used as catalyst for the reduction of 4-nitrophenol with NaBH4 and the Sonogashira coupling reaction between iodobenzene with phenylacetylene. To our delight, the Rh(0)NCs/GNPs showed excellent catalytic activity towards the reduction of 4-nitrophenol with an excellent turnover frequency (TOF) value of 112.5 min−1. The kapp and k’ values were calculated to be 62.07 × 10−3 min−1(0.002 mg of Rh(0)NCs/GNPs) and 31035 × 10−3 mg−1 min−1,respectively. Alike, under the optimal conditions, the Rh(0)NCs/GNPs gave the desired product, diphenylacetylene, in a good yield of 87% with 91% selectivity. The Rh(0)NCs/GNPs can be reused without significant loss in its catalytic activity. Full article
(This article belongs to the Special Issue Graphene Nanocomposites: Environmentally Friendly Synthesis and Applications)
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