Reduced Graphene Oxide as a Metal‐Free Catalyst for the Light‐Assisted Fenton‐Like Reaction

Espinosa, Juan Carlos; Navalón, Sergio; Álvaro, Mercedes; Garcı́a, Hermenegildo

doi:10.1002/cctc.201600364

Cited by 47 publications

(37 citation statements)

References 62 publications

(54 reference statements)

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“…Thed econvolution of the C1sp eak for all three catalysts shows as imilart ypeo fo xygen functional groups.F our main carbon bondingt ypes:C ÀC ( % 284.7 eV), CÀO( % 286.9 eV), C=O( % 288.4 eV), and COOH ( % 288.9 eV)c an be ascribed. [21] The C/O atomicr atio obtained from XPS is 1.2 for O-CQDs, less than that of 1.7 for the GO catalysto r2 .2 for HO-CQDs. Further analysis shows that 35.8 % of the total oxygen is in the form of CÀOa nd 5.3% in the form of COOH for O-CQDs, both higher than the case in GO (30.9 % of CÀOa nd 2.7 %o fC OOH).…”

Section: Resultsmentioning

confidence: 83%

Oxygen‐Rich Carbon Quantum Dots as Catalysts for Selective Oxidation of Amines and Alcohols

Liu

et al. 2017

ChemCatChem

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Metal‐free carbocatalysis has been widely utilized for aerobic oxidative reactions. Here, we report that oxygen‐rich carbon quantum dots (O‐CQDs) demonstrate a catalytic performance superior to graphene oxide, if used as a metal‐free nanocatalyst for the direct transformation of amines and alcohols, under mild and solvent‐free conditions. O‐CQDs show a yield of 75 % for the oxidative coupling of amine to imine (with 5 wt % catalyst loading) and a conversion of 3.8 % for benzyl alcohol (with 2 wt % catalyst loading). The catalytic activities of thermally treated O‐CQDs are further improved for benzylamine, for example, indicated by a yield of up to 98 % with 4 wt % catalyst loading. In addition, O‐CQDs show a photoenhanced catalytic ability of amine (98 % yield with 5 wt % catalyst loading for 6 h reaction). Characterizations and simulations show that numerous carboxyl oxygen functional groups and unpaired electrons at the edge sites of O‐CQDs are likely involved in the aerobic oxidation of amines.

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Section: Resultsmentioning

confidence: 83%

Oxygen‐Rich Carbon Quantum Dots as Catalysts for Selective Oxidation of Amines and Alcohols

Liu

et al. 2017

ChemCatChem

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“…Since reactions involving reactive oxygen species are typically radical chain mechanisms, the presence of quencher in this proportion should be reflected in a significant change in the temporal conversion profile after its addition. As selective quenchers, p‐ benzoquinone to inhibit superoxide (O 2 ·− ) and dimethylsulfoxide (DMSO) to intercept hydroxyl radicals (·OH) were used. The results are presented in Figure b.…”

Section: Resultsmentioning

confidence: 99%

Templateless Synthesis of Ultra‐Microporous 3D Graphitic Carbon from Cyclodextrins and Their Use as Selective Catalyst for Oxygen Activation

et al. 2020

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Pyrolysis of α‐, β‐, and γ‐cyclodextrins at 900 °C gives rise to the formation of crystalline graphitic porous nanoparticles (GCD), where the dimensions of the pores are uniform in the range from 0.63 to 0.97 nm, from Gα‐CD to Gγ‐CD, as determined by transmission electron microscopy. It is found that, while for Gβ‐CD and Gγ‐CD, the surface area measured by N2 adsorption is about 330–550 m2 g−1, respectively, no area can be measured for Gα‐CD with N2 or Ar due to its small pore dimensions. However, CO2 adsorption reveals for Gα‐CD the presence of ultra‐microporosity and a surface area of 727 m2 g−1. GCD exhibits activity as metal‐free catalysts for the aerobic oxidation of alcohols and the activity increases as the pore dimension decreases. Density functional theory calculations indicate that this high catalytic activity for O2 activation derives from confinement effects that favor charge transfer from the graphitic walls to O2. Studies on the formation mechanism shows that the key step leading to the formation of the channels is the melting of cyclodextrin precursors that makes possible the assembly of these capsules before their transformation into microporous graphitic particles.

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“…According to the deconvolution of 58,59 and is in line with the ability of hydroquinones to promote Fenton-like chemistry as organocatalysts. 54,60 Importantly, the catalytic activity of the 10-times-used HSAG− OH can be restored to the value of the fresh sample by performing a reduction process either with hydrazine as reducing agent or by thermal reduction at 300°C (Figures 3c and 4e,f). XPS of the 10-times-used HSAG sample treated by thermal treatment or hydrazine confirms the success of the reduction process to restore the used HSAG−OH material by observing the coincidence of the C 1s and O 1s peaks of the treated samples with those of the fresh HSAG [ Figures 4 and S8 (SI)].…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Catalytic Ozonation Using Edge-Hydroxylated Graphite-Based Materials

Bernat-Quesada

Espinosa

Barbera

et al. 2019

ACS Sustainable Chem. Eng.

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This work reports the catalytic ozonation activity of high surface area graphite materials selectively functionalized at the edges with hydroxyl groups. The graphite-based catalyst shows higher activity than the parent graphite, commercial activated carbon, commercial multiwall carbon nanotubes, commercial diamond nanoparticles, graphene oxide, or reduced graphene oxide. Importantly, the catalytic activity of the graphite-based material is also higher than those of benchmark ozonation catalysts such as Co 3 O 4 or Fe 2 O 3. The graphite catalyst was reused up to 10 times with only a minor decrease in the catalytic activity. Catalytic activation of O 3 leads to the generation of hydroperoxide radicals and 1 O 2. These results have been interpreted as derived from the combination of a suitable work function and the presence of phenolic/semiquinone-like redox pairs, as well as high dispersibility in water due to the presence of −OH groups. This work highlights the possibility of engineering active and stable carbocatalysts for reactions typically promoted by transition metals.

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Reduced Graphene Oxide as a Metal‐Free Catalyst for the Light‐Assisted Fenton‐Like Reaction

Abstract: Natural Sunlight irradiation increases the catalytic activity of reduced graphene oxide (rGO) as metal-free Fenton-like catalyst for phenol degradation. Intermediacy of hydroxyl radicals was proved by electron paramagnetic resonance spectroscopy using a spin trapping agent.

Cited by 47 publications

References 62 publications

Oxygen‐Rich Carbon Quantum Dots as Catalysts for Selective Oxidation of Amines and Alcohols

Oxygen‐Rich Carbon Quantum Dots as Catalysts for Selective Oxidation of Amines and Alcohols

Templateless Synthesis of Ultra‐Microporous 3D Graphitic Carbon from Cyclodextrins and Their Use as Selective Catalyst for Oxygen Activation

Catalytic Ozonation Using Edge-Hydroxylated Graphite-Based Materials

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