Editorial

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Open AccessEditorial

Synthesis, Functionalization and Applications of Nanocarbons

by Simona Bettini and Gabriele Giancane

Nanomaterials 2022, 12(16), 2738; https://doi.org/10.3390/nano12162738 - 10 Aug 2022

Cited by 2 | Viewed by 961

The Special Issue “Synthesis, Functionalization and Applications of Nanocarbons” starts from the growing interest of the scientific community in carbon-based materials and the various applications of these versatile compounds [...] Full article

(This article belongs to the Special Issue Synthesis, Functionalization and Applications of Nanocarbons)

Research

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13 pages, 6364 KiB

Open AccessEditor’s ChoiceArticle

Laser-Induced Modification of Hydrogenated Detonation Nanodiamonds in Ethanol

by Irena Bydzovska, Ekaterina Shagieva, Ivan Gordeev, Oleksandr Romanyuk, Zuzana Nemeckova, Jiri Henych, Lukas Ondic, Alexander Kromka and Stepan Stehlik

Nanomaterials 2021, 11(9), 2251; https://doi.org/10.3390/nano11092251 - 31 Aug 2021

Cited by 4 | Viewed by 2294

Abstract

Apart from the frequently used high-temperature annealing of detonation nanodiamonds (DNDs) in an inert environment, laser irradiation of DNDs in a liquid can be effectively used for onion-like carbon (OLC) formation. Here, we used fully de-aggregated hydrogenated DNDs (H-DNDs) dispersed in ethanol, which [...] Read more.

Apart from the frequently used high-temperature annealing of detonation nanodiamonds (DNDs) in an inert environment, laser irradiation of DNDs in a liquid can be effectively used for onion-like carbon (OLC) formation. Here, we used fully de-aggregated hydrogenated DNDs (H-DNDs) dispersed in ethanol, which were irradiated for up to 60 min using a 532 nm NdYAG laser with an energy of 150 mJ in a pulse (5 J/cm²) at a pulse duration of 10 ns and a repetition rate of 10 Hz. We investigated the DND surface chemistry, zeta potential, and structure as a function of laser irradiation time. Infrared spectroscopy revealed a monotonical decrease in the C–H_x band intensities and an increase of the C–O and C=O features. Transmission electron microscopy (TEM) revealed the formation of OLC, as well as a gradual loss of nanoparticle character, with increasing irradiation time. Surprisingly, for samples irradiated up to 40 min, the typical and unchanged DND Raman spectrum was recovered after their annealing in air at 450 °C for 300 min. This finding indicates the inhomogeneous sp³ to sp² carbon transformation during laser irradiation, as well as the insensitivity of DND Raman spectra to surface chemistry, size, and transient structural changes. Full article

(This article belongs to the Special Issue Synthesis, Functionalization and Applications of Nanocarbons)

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15 pages, 3865 KiB

Open AccessArticle

Stretchable Carbon and Silver Inks for Wearable Applications

by Andrew Claypole, James Claypole, Liam Kilduff, David Gethin and Tim Claypole

Nanomaterials 2021, 11(5), 1200; https://doi.org/10.3390/nano11051200 - 01 May 2021

Cited by 18 | Viewed by 3373

Abstract

For wearable electronic devices to be fully integrated into garments, without restricting or impeding movement, requires flexible and stretchable inks and coatings, which must have consistent performance and recover from mechanical strain. Combining Carbon Black (CB) and ammonia plasma functionalized Graphite Nanoplatelets (GNPs) [...] Read more.

For wearable electronic devices to be fully integrated into garments, without restricting or impeding movement, requires flexible and stretchable inks and coatings, which must have consistent performance and recover from mechanical strain. Combining Carbon Black (CB) and ammonia plasma functionalized Graphite Nanoplatelets (GNPs) in a Thermoplastic Polyurethane (TPU) resin created a conductive ink that could stretch to substrate failure (>300% nominal strain) and cyclic strains of up to 100% while maintaining an electrical network. This highly stretchable, conductive screen-printable ink was developed using relatively low-cost carbon materials and scalable processes making it a candidate for future wearable developments. The electromechanical performance of the carbon ink for wearable technology is compared to a screen-printable silver as a control. After initial plastic deformation and the alignment of the nano carbons in the matrix, the electrical performance was consistent under cycling to 100% nominal strain. Although the GNP flakes are pulled further apart a consistent, but less conductive path remains through the CB/TPU matrix. In contrast to the nano carbon ink, a more conductive ink made using silver flakes lost conductivity at 166% nominal strain falling short of the substrate failure strain. This was attributed to the failure of direct contact between the silver flakes. Full article

(This article belongs to the Special Issue Synthesis, Functionalization and Applications of Nanocarbons)

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13 pages, 1830 KiB

Open AccessArticle

Coffee Grounds-Derived CNPs for Efficient Cr(VI) Water Remediation

by Simona Bettini, Michela Ottolini, Rosanna Pagano, Sudipto Pal, Antonio Licciulli, Ludovico Valli and Gabriele Giancane

Nanomaterials 2021, 11(5), 1064; https://doi.org/10.3390/nano11051064 - 21 Apr 2021

Cited by 5 | Viewed by 2202

Abstract

Carbon nanomaterials are a group of materials characterized by sp²/sp³ carbon backbone which, combined with surface atoms and/or chemical groups, ensures peculiar physical chemical features for a wide range of applications. Among these materials, carbon dots and carbon nanoparticles belong [...] Read more.

Carbon nanomaterials are a group of materials characterized by sp²/sp³ carbon backbone which, combined with surface atoms and/or chemical groups, ensures peculiar physical chemical features for a wide range of applications. Among these materials, carbon dots and carbon nanoparticles belong to carbon nanomaterials with a few nanometer dimensions. In this work, carbon nanoparticles were produced from spent coffee grounds as sustainable carbon source through a simple, cheap and eco-friendly procedure according to an oxidation process (at controlled temperature) driven by hydrogen peroxide. Atomic Force Microscope (AFM) and fluorescence, UV-Vis absorption, FT-IR and Raman spectroscopy were used to assess the formation of carbon nanomaterials of about 10 nm with the typical emission and absorption properties of carbon dots and peculiar surface features. In fact, the presence of heteroatoms, i.e., phosphorus, and the carbonyl/carboxyl surface groups on carbon nanoparticles, was proposed to confer peculiar properties allowing the fast Mn(VII) reduction to Mn(II) at neutral pH and the Cr(VI) reduction to Cr(III) in weak acid aqueous media. Full article

(This article belongs to the Special Issue Synthesis, Functionalization and Applications of Nanocarbons)

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8 pages, 1368 KiB

Open AccessArticle

Accelerated Synthesis of Graphene Oxide from Graphene

by Mariana C. F. Costa, Valeria S. Marangoni, Pei Rou Ng, Hang T. L. Nguyen, Alexandra Carvalho and A. H. Castro Neto

Nanomaterials 2021, 11(2), 551; https://doi.org/10.3390/nano11020551 - 22 Feb 2021

Cited by 47 | Viewed by 9386

Abstract

Graphene oxide (GO) is an oxygenated functionalized form of graphene that has received considerable attention because of its unique physical and chemical properties that are suitable for a large number of industrial applications. Herein, GO is rapidly obtained directly from the oxidation of [...] Read more.

Graphene oxide (GO) is an oxygenated functionalized form of graphene that has received considerable attention because of its unique physical and chemical properties that are suitable for a large number of industrial applications. Herein, GO is rapidly obtained directly from the oxidation of graphene using an environmentally friendly modified Hummers method. As the starting material consists of graphene flakes, intercalant agents are not needed and the oxidation reaction is enhanced, leading to orders of magnitude reduction in the reaction time compared to the conventional methods of graphite oxidation. With a superior surface area, the graphene flakes are quickly and more homogeneously oxidized since the flakes are exposed at the same extension to the chemical agents, excluding the necessity of sonication to separate the stacked layers of graphite. This strategy shows an alternative approach to quickly producing GO with different degrees of oxidation that can be potentially used in distinct areas ranging from biomedical to energy storage applications. Full article

(This article belongs to the Special Issue Synthesis, Functionalization and Applications of Nanocarbons)

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13 pages, 66914 KiB

Open AccessArticle

Evaluation of Warpage and Residual Stress of Precision Glass Micro-Optics Heated by Carbide-Bonded Graphene Coating in Hot Embossing Process

by Lihua Li and Jian Zhou

Nanomaterials 2021, 11(2), 363; https://doi.org/10.3390/nano11020363 - 01 Feb 2021

Cited by 6 | Viewed by 2538

Abstract

A newly developed hot embossing technique which uses the localized rapid heating of a thin carbide-bonded graphene (CBG) coating, greatly reduces the energy consumption and promotes the fabrication efficiency. However, because of the non-isothermal heat transfer process, significant geometric deviation and residual stress [...] Read more.

A newly developed hot embossing technique which uses the localized rapid heating of a thin carbide-bonded graphene (CBG) coating, greatly reduces the energy consumption and promotes the fabrication efficiency. However, because of the non-isothermal heat transfer process, significant geometric deviation and residual stress could be introduced. In this paper, we successfully facilitate the CBG-heating-based hot embossing into the fabrication of microlens array on inorganic glass N-BK7 substrate, where the forming temperature is as high as 800 °C. The embossed microlens array has high replication fidelity, but an obvious geometric warpage along the glass substrate also arises. Thermo-mechanical coupled finite element modelling of the embossing process is conducted and verified by the experimental results. Based on trial and error simulations, an appropriate compensation curvature is determined and adopted to modify the geometrical design of the silicon wafer mold. The warpage of the re-embossed microlens array is significantly decreased using the compensated mold, which demonstrates the feasibility of the simulation-oriented compensation scheme. Our work would contribute to improving the quality of optics embossed by this innovative CBG-heating-based hot embossing technique. Full article

(This article belongs to the Special Issue Synthesis, Functionalization and Applications of Nanocarbons)

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13 pages, 2448 KiB

Open AccessArticle

Mechanochemically Synthetized PAN-Based Co-N-Doped Carbon Materials as Electrocatalyst for Oxygen Evolution Reaction

by Paulette Gómez-López, José Ángel Salatti-Dorado, Daily Rodríguez-Padrón, Manuel Cano, Clemente G. Alvarado-Beltrán, Alain R. Puente-Santiago, Juan J. Giner-Casares and Rafael Luque

Nanomaterials 2021, 11(2), 290; https://doi.org/10.3390/nano11020290 - 22 Jan 2021

Cited by 12 | Viewed by 2478

Abstract

We report a new class of polyacrylonitrile (PAN)-based Co-N-doped carbon materials that can act as suitable catalyst for oxygen evolution reactions (OER). Different Co loadings were mechanochemically added into post-consumed PAN fibers. Subsequently, the samples were treated at 300 °C under air (PAN-A) [...] Read more.

We report a new class of polyacrylonitrile (PAN)-based Co-N-doped carbon materials that can act as suitable catalyst for oxygen evolution reactions (OER). Different Co loadings were mechanochemically added into post-consumed PAN fibers. Subsequently, the samples were treated at 300 °C under air (PAN-A) or nitrogen (PAN-N) atmosphere to promote simultaneously the Co₃O₄ species and PAN cyclization. The resulting electrocatalysts were fully characterized and analyzed by X-ray diffraction (XRD) and photoelectron spectroscopy (XPS), transmission (TEM) and scanning electron (SEM) microscopies, as well as nitrogen porosimetry. The catalytic performance of the Co-N-doped carbon nanomaterials were tested for OER in alkaline environments. Cobalt-doped PAN-A samples showed worse OER electrocatalytic performance than their homologous PAN-N ones. The PAN-N/3% Co catalyst exhibited the lowest OER overpotential (460 mV) among all the Co-N-doped carbon nanocomposites, reaching 10 mA/cm². This work provides in-depth insights on the electrocatalytic performance of metal-doped carbon nanomaterials for OER. Full article

(This article belongs to the Special Issue Synthesis, Functionalization and Applications of Nanocarbons)

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Review

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71 pages, 6692 KiB

Open AccessReview

You Don’t Learn That in School: An Updated Practical Guide to Carbon Quantum Dots

by Helena B. A. Sousa, Catarina S. M. Martins and João A. V. Prior

Nanomaterials 2021, 11(3), 611; https://doi.org/10.3390/nano11030611 - 01 Mar 2021

Cited by 17 | Viewed by 4578

Abstract

Carbon quantum dots (CQDs) have started to emerge as candidates for application in cell imaging, biosensing, and targeted drug delivery, amongst other research fields, due to their unique properties. Those applications are possible as the CQDs exhibit tunable fluorescence, biocompatibility, and a versatile [...] Read more.

Carbon quantum dots (CQDs) have started to emerge as candidates for application in cell imaging, biosensing, and targeted drug delivery, amongst other research fields, due to their unique properties. Those applications are possible as the CQDs exhibit tunable fluorescence, biocompatibility, and a versatile surface. This review aims to summarize the recent development in the field of CQDs research, namely the latest synthesis progress concerning materials/methods, surface modifications, characterization methods, and purification techniques. Furthermore, this work will systematically explore the several applications CQDs have been subjected to, such as bioimaging, fluorescence sensing, and cancer/gene therapy. Finally, we will briefly discuss in the concluding section the present and future challenges, as well as future perspectives and views regarding the emerging paradigm that is the CQDs research field. Full article

(This article belongs to the Special Issue Synthesis, Functionalization and Applications of Nanocarbons)

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