C | An Open Access Journal from MDPI

17 pages, 5669 KiB

Open AccessArticle

Stacking Fault Nucleation in Films of Vertically Oriented Multiwall Carbon Nanotubes by Pyrolysis of Ferrocene and Dimethyl Ferrocene at a Low Vapor Flow Rate

by Ayoub Taallah, Shanling Wang, Omololu Odunmbaku, Lin Zhang, Xilong Guo, Yixin Dai, Wenkang Li, Huanqing Ye, Hansong Wu, Jiaxin Song, Jian Guo, Jiqiu Wen, Yi He and Filippo S. Boi

C 2024, 10(4), 91; https://doi.org/10.3390/c10040091 - 12 Oct 2024

Abstract

Recent observations of superconductivity in low-dimensional systems composed of twisted, untwisted, or rhombohedral graphene have attracted significant attention. One-dimensional moiré superlattices and flat bands have interestingly been identified in collapsed chiral carbon nanotubes (CNTs), opening up new avenues for the tunability of the [...] Read more.

Recent observations of superconductivity in low-dimensional systems composed of twisted, untwisted, or rhombohedral graphene have attracted significant attention. One-dimensional moiré superlattices and flat bands have interestingly been identified in collapsed chiral carbon nanotubes (CNTs), opening up new avenues for the tunability of the electronic properties in these systems. The nucleation of hexagonal moiré superlattices and other types of stacking faults has also been demonstrated in partially collapsed and uncollapsed carbon nano-onions (CNOs). Here, we report a novel investigation on the dynamics of stacking fault nucleation within the multilayered lattices of micrometer-scale vertically oriented films of multiwall CNTs (MWCNTs), resulting from the pyrolysis of molecular precursors consisting of ferrocene or dimethyl ferrocene, at low vapor flow rates of ~5–20 mL/min. Interestingly, local nucleation of moiré-like superlattices (as stacking faults) was found when employing dimethyl ferrocene as the pyrolysis precursor. The morphological and structural properties of these systems were investigated with the aid of scanning and transmission electron microscopies, namely SEM, TEM, and HRTEM, as well as X-ray diffraction (XRD) and Raman point/mapping spectroscopy. Deconvolution analyses of the Raman spectra also demonstrated a local surface oxidation, possibly occurring on defect-rich interfaces, frequently identified within or in proximity of bamboo-like graphitic caps. By employing high-temperature Raman spectroscopy, we demonstrate a post-growth re-graphitization, which may also be visualized as an alternative way of depleting the oxygen content within the MWCNTs’ interfaces through recrystallization. Full article

(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))

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10 pages, 1212 KiB

Open AccessArticle

Optimizing Graphene Oxide Film Quality: The Role of Solvent and Deposition Technique

by Grazia Giuseppina Politano

C 2024, 10(4), 90; https://doi.org/10.3390/c10040090 - 10 Oct 2024

Abstract

Graphene oxide (GO) is a promising material due to its high mechanical strength, electrical conductivity, and optical transparency, making it suitable for applications like optoelectronics and energy storage. This study focuses on a simplified method of depositing and characterizing GO films via drop [...] Read more.

Graphene oxide (GO) is a promising material due to its high mechanical strength, electrical conductivity, and optical transparency, making it suitable for applications like optoelectronics and energy storage. This study focuses on a simplified method of depositing and characterizing GO films via drop casting, particularly using isopropanol and water as solvents, and compares the results with reference samples of graphene produced by chemical vapor deposition (CVD) and GO films deposited by electrophoretic deposition (EPD). The optical properties of these films were analyzed using Variable Angle Spectroscopic Ellipsometry (VASE). The study revealed that GO films prepared with isopropanol exhibited a lower refractive index compared to those using water. Therefore, the research highlighted the significance of solvent choice and deposition method on the overall film quality. This work provides insights into optimizing GO film properties through careful solvent selection, contributing to the broader understanding and application of GO in advanced technologies. Full article

(This article belongs to the Topic Application of Graphene-Based Materials, 2nd Volume)

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24 pages, 5981 KiB

Open AccessArticle

Impact of Dispersive Solvent and Temperature on Supercapacitor Performance of N-Doped Reduced Graphene Oxide

by Ankit Yadav, Rajeev Kumar, Deepu Joseph, Nygil Thomas, Fei Yan and Balaram Sahoo

C 2024, 10(4), 89; https://doi.org/10.3390/c10040089 - 10 Oct 2024

Abstract

This study evaluates the critical roles of the dispersion medium and temperature during the solvothermal synthesis of nitrogen-doped reduced graphene oxide (NG) for enhancing its performance as an active material in supercapacitor electrodes. Using a fixed volume of a solvent (THF, ethanol, acetonitrile, [...] Read more.

This study evaluates the critical roles of the dispersion medium and temperature during the solvothermal synthesis of nitrogen-doped reduced graphene oxide (NG) for enhancing its performance as an active material in supercapacitor electrodes. Using a fixed volume of a solvent (THF, ethanol, acetonitrile, water, N,N-Dimethylformamide, ethylene glycol, or N-Methyl-2-pyrrolidone) as the dispersive medium, a series of samples at different temperatures (60, 75, 95, 120, 150, 180, and 195 °C) are synthesized and investigated. A proper removal of the oxygen moieties from their surface and an optimum number of N-based defects are essential for a better reduction of graphene oxide and better stacking of the NG sheets. The origin of the supercapacitance of NG sheets can be correlated to the inherent properties such as the boiling point, viscosity, dipole moment, and dielectric constant of all the studied solvents, along with the synthesis temperature. Due to the achievement of a suitable synthesis environment, NG synthesized using N,N-Dimethylformamide at 150 °C displays an excellent supercapacitance value of 514 F/g at 0.5 A/g, which is the highest among all our samples and also competitive among several state-of-the-art lightweight carbon materials. Our work not only helps in understanding the origin of the supercapacitance exhibited by graphene-based materials but also tuning them through a suitable choice of synthesis conditions. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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SEM images of (a) NG-3-DMF-150 and (b) NG-3-H2O-150 samples. Full article ">Figure 2
The XRD pattern of the (a) GO and rGO, and (b–h) NG-3 samples synthesized in various dispersive media and at different temperatures, as indicated. Full article ">Figure 3
(a) Cyclic voltammograms of all the NG samples at different temperatures with various dispersive solvents, measured at a fixed scan rate of 5 mV/s. The solvents used for synthesis are (a) THF, (b) ethanol, (c) acetonitrile, (d) H2O, (e) DMF, (f) ethylene glycol, and (g) NMP. Full article ">Figure 4
(a) The galvanostatic charging–discharging (GCD) plots for all the NG samples synthesized at different temperatures with various dispersive solvents as indicated. (a) THF, (b) ethanol, (c) acetonitrile, (d) H2O, (e) DMF, (f) ethylene glycol, and (g) NMP. (h) The specific capacitance of all the NG samples is calculated from the discharging region of the GCD curves by using Equation (2). Full article ">Figure 5
EIS spectra of all our synthesized NG samples at different temperatures in various dispersive solvents. Full article ">Figure 6
XPS spectra of synthesized NG-3 sample (left panel) N 1s, (middle panel) C 1s, and (right panel) O 1s. Full article ">Figure 7
The wide XPS spectra of the synthesized samples in the full measured energy range. Full article ">

17 pages, 3329 KiB

Open AccessArticle

Role of Graphene Oxide in Disentangling Amyloid Beta Fibrils

by Brianna Duswalt, Isabella Wolson and Isaac Macwan

C 2024, 10(4), 88; https://doi.org/10.3390/c10040088 - 3 Oct 2024

Abstract

Recently, the accumulation of Amyloid Beta (Aβ) in the brain has been linked to the development of Alzheimer’s disease (AD) through the formation of aggregated plaques and neurofibrillary tangles (NFTs). Although carbon nanoparticles were previously shown as having a potential to address AD, [...] Read more.

Recently, the accumulation of Amyloid Beta (Aβ) in the brain has been linked to the development of Alzheimer’s disease (AD) through the formation of aggregated plaques and neurofibrillary tangles (NFTs). Although carbon nanoparticles were previously shown as having a potential to address AD, the interactions of Aβ with such nanoparticles have not been studied extensively. In this work, molecular dynamic simulations are utilized to simulate the interactions between a single atomic layer of graphene oxide (GO) and a 12-monomer Aβ fibril. These interactions are further compared to those between GO and five individual monomers of Aβ to further understand the conformational changes in Aβ as an individual monomer and as a component of the Aβ fibril. It was found that out of the 42 residues of the Aβ monomers, residues 27–42 are the most affected by the presence of GO. Furthermore, stability analysis through RMSD, conformational energies and salt bridges, along with nonbonding energy, illustrate that Aβ–Aβ interactions were successfully interrupted and dismantled by GO. Overall, the differences in the interactions between monomeric Aβ consisting of five monomers with GO, an Aβ fibril with GO, and control Aβ monomers among themselves, helped elucidate the potential that GO has to disentangle the Aβ tangles, both in case of individual monomers forming a cluster and as part of the Aβ fibril. Full article

(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)

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Role of GO in disentangling the neurofibrillary tangles. (A) Progression from a single Aβ monomer as a protein tangle to the formation of neurofibrillary tangle clusters; (B) GO attracts the Aβ tangles and disintegrates the neurofibrillary tangles; and (C) adsorption of the 12-monomer Aβ fibril onto the surface of GO showing the adsorbed atoms of Aβ. Full article ">Figure 2
RMSD trajectories and COMs for individual Aβ monomers and 12-monomer Aβ fibril: (A) RMSD Trajectory of 12-Aβ-GO system; (B) average RMSD for the 5-Aβ system in the presence and absence of GO; (C) COM distance between GO and the Aβ fibril for the 12-Aβ-GO system; and (D) COM distance between the individual Aβ monomers in the presence and absence of GO for the 5-Aβ system. Full article ">Figure 3
Interaction energies for 12-monomer Aβ fibril and individual 5-Aβ monomers: (A) Van der Waals energy between the Aβ fibril and GO and electrostatic energy within the Aβ fibril in the presence of GO; (B) total conformational energy of the Aβ fibril in the presence of GO; (C) electrostatic energy with 5-Aβ in the presence and absence of GO, and the total Van der Waals energy between 5-Aβ and GO; and (D) total conformational energy of 5-Aβ monomers in the presence and absence of GO. Note: wGO—with GO. Full article ">Figure 4
Analysis of hydrogen bonds to quantify stability. (A) hydrogen bonds within the Aβ fibril in the presence of GO; (B) hydrogen bonds within the 5 Aβ monomers in the presence and absence of GO; (C) hydrogen bonds between the Aβ monomers forming clump 1 involving the segments AP1, 2AP1, and 3AP1 in the absence of GO; and (D) hydrogen bonds between the Aβ monomers forming clump 2 involving the segments 1AP1 and 4AP1 in the absence of GO. Note: wGO—With GO; noGO—without GO. Full article ">Figure 5
Optimal adsorption distance analysis based on the number of adsorbed atoms and interaction energy per adsorbed atom. (A) number of atoms with and without hydrogen as a function of the distance from the surface of GO for the Aβ fibril system; (B) number of atoms with and without hydrogen as a function of the distance from the surface of GO for the 5-Aβ system; (C) interaction energy of the adsorbed atoms as a function of the distance from the surface of GO for the Aβ fibril system; (D) interaction energy of the adsorbed atoms as a function of the distance from the surface of GO for the 5-Aβ system; (E) optimal adsorption distance as a function of the distance from the surface of GO for the Aβ fibril system; and (F) optimal adsorption distance as a function of the distance from the surface of GO for the 5-Aβ system. Full article ">Figure 6
Quantification of the number of interfacial water molecules and their hydrogen bonds. (A) interfacial water molecules within 5 Å of GO and Aβ fibril; (B) hydrogen bonds of the interfacial water molecules during the interactions between Aβ fibril and GO; (C) total interfacial water molecules within 5 Å of GO and the monomeric 5-Aβ system; and (D) total number of hydrogen bonds of the interfacial water molecules during the interactions between individual Aβ monomers and GO. Full article ">

13 pages, 5615 KiB

Open AccessArticle

Self-Assembled Synthesis of Graphene Tubes from Melamine Catalyzed by Calcium Carbonate

by Wenping Zeng, Jingxiang Meng, Xinbo Zheng, Tingting Mao, Jintao Huang and Yonggang Min

C 2024, 10(4), 87; https://doi.org/10.3390/c10040087 - 26 Sep 2024

Abstract

This study investigates the carbon products generated by melamine under various heat-treatment temperatures with the catalysis of calcium carbonate. We discovered that the cost-effective precursor melamine readily self-assembles and curls into graphene tubes when catalyzed by the alkaline earth salt CaCO₃ at [...] Read more.

This study investigates the carbon products generated by melamine under various heat-treatment temperatures with the catalysis of calcium carbonate. We discovered that the cost-effective precursor melamine readily self-assembles and curls into graphene tubes when catalyzed by the alkaline earth salt CaCO₃ at elevated temperatures. Under heat-treatment conditions of 1100 °C and 1200 °C, the growth morphology of graphene tubes with open structures and exceptionally large diameters was observed, and the diameters reached the micron level. These products exhibit a high degree of carbonization and an extremely low nitrogen content, as low as 1.7%. Further, the intensity ratio (ID/IG) of the D band and the G band is as low as 0.79 in Raman characterization. The results show that the products have a certain graphite structure, which proves the catalytic activity of CaCO₃. This is attributed to the incorporation of CaCO₃ into the raw material system, which impedes the complete thermal decomposition of melamine. On the other hand, the resulting CaO particles are evenly distributed along the tubular products, providing certain support for their self-assembly and growth, thereby achieving the efficient growth of graphene tubes. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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27 pages, 8205 KiB

Open AccessReview

Recent Advances in Carbon-Based Interfacial Photothermal Converters for Seawater Desalination: A Review

by Xiaoyu Jia, Yuke Niu, Shufang Zhu, Hongwei He and Xu Yan

C 2024, 10(3), 86; https://doi.org/10.3390/c10030086 - 22 Sep 2024

Abstract

Along with the rapid development of society, freshwater shortages have become a global concern. Although existing desalination technologies have alleviated this pressure to some extent, their long-term environmental impact and energy consumption are still questionable. Therefore, it is necessary to find a new [...] Read more.

Along with the rapid development of society, freshwater shortages have become a global concern. Although existing desalination technologies have alleviated this pressure to some extent, their long-term environmental impact and energy consumption are still questionable. Therefore, it is necessary to find a new effective way for seawater desalination with cleaner energy. Solar-driven interfacial water evaporation technology has the advantages of environmental protection, energy saving, high evaporation efficiency, low cost, and strong sustainability, and is considered one of the most effective technologies to relieve water resource stress. This review summarized the recent advances in carbon-based interfacial photothermal converters focused on the preparation methods of 2D and 3D photothermal absorbers, the potential ways to enhance the efficiency of photothermal conversion. Finally, this paper proposed the challenges and future trends of interfacial photothermal converters. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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18 pages, 10499 KiB

Open AccessArticle

Numerical Assessment of Effective Elastic Properties of Needled Carbon/Carbon Composites Based on a Multiscale Method

by Jian Ge, Xujiang Chao, Haoteng Hu, Wenlong Tian, Weiqi Li and Lehua Qi

C 2024, 10(3), 85; https://doi.org/10.3390/c10030085 - 16 Sep 2024

Abstract

Needled carbon/carbon composites contain complex microstructures such as irregular pores, anisotropic pyrolytic carbon, and interphases between fibers and pyrolytic carbon matrices. Additionally, these composites have hierarchical structures including weftless plies, short-cut fiber plies, and needled regions. To predict the effective elastic properties of [...] Read more.

Needled carbon/carbon composites contain complex microstructures such as irregular pores, anisotropic pyrolytic carbon, and interphases between fibers and pyrolytic carbon matrices. Additionally, these composites have hierarchical structures including weftless plies, short-cut fiber plies, and needled regions. To predict the effective elastic properties of needled carbon/carbon composites, this paper proposes a novel sequential multiscale method. At the microscale, representative volume element (RVE) models are established based on the microstructures of the weftless ply, short-cut fiber ply, and needled region, respectively. In the microscale RVE model, a modified Voronoi tessellation method is developed to characterize anisotropic pyrolytic carbon matrices. At the macroscale, an RVE model containing hierarchical structures is developed to predict the effective elastic properties of needled carbon/carbon composites. For the data interaction between scales, the homogenization results of microscale models are used as inputs for the macroscale model. By comparing these against the experimental results, the proposed multiscale model is validated. Furthermore, the effect of porosity on the effective elastic properties of needled carbon/carbon composites is investigated based on the multiscale model. The results show that the effective elastic properties of needled carbon/carbon composites decrease with the increase in porosity, but the extent of decrease is different in different directions. Full article

(This article belongs to the Special Issue Micro/Nanofabrication of Carbon-Based Devices and Their Applications)

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16 pages, 5753 KiB

Open AccessArticle

Enhanced Antibacterial Activity of Carbon Dots: A Hybrid Approach with Levofloxacin, Curcumin, and Tea Polyphenols

by Khurram Abbas, Haimei Zhu, Weixia Qin, Meiyan Wang, Zijian Li and Hong Bi

C 2024, 10(3), 84; https://doi.org/10.3390/c10030084 - 15 Sep 2024

Abstract

Bacterial infections and their increasing resistance to antibiotics pose a significant challenge in medical treatment. This study presents the synthesis and characterization of novel carbon dots (CDs) using levofloxacin (Lf), curcumin (Cur), and tea polyphenols (TP) through a facile hydrothermal method. The synthesized [...] Read more.

Bacterial infections and their increasing resistance to antibiotics pose a significant challenge in medical treatment. This study presents the synthesis and characterization of novel carbon dots (CDs) using levofloxacin (Lf), curcumin (Cur), and tea polyphenols (TP) through a facile hydrothermal method. The synthesized curcumin-tea polyphenol@carbon dots (Cur-TP@CDs) and levofloxacin-tea polyphenol@carbon dots (Lf-TP@CDs) were characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy, confirming their unique structural and chemical properties. Cur-TP@CDs exhibited an average particle size of 1.32 nanometers (nm), while Lf-TP@CDs averaged 1.58 nm. Both types demonstrated significant antibacterial activity, with Lf-TP@CDs showing superior effectiveness against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in broth dilution and disc diffusion assays. Biofilm inhibition assays revealed a significant reduction in biofilm formation at higher concentrations. The ultraviolet-visible (UV-vis) and photoluminescence (PL) spectral analyses indicated efficient photon emission, and electron paramagnetic resonance (EPR) analysis showed increased singlet oxygen generation, enhancing bactericidal effects. Live and dead bacterial staining followed by scanning electron microscopy (SEM) analysis confirmed dose-dependent bacterial cell damage and morphological deformities. These findings suggest that Cur-TP@CDs and Lf-TP@CDs are promising antibacterial agents, potentially offering a novel approach to combat antibiotic-resistant bacterial infections. Full article

(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)

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(a) Schematic illustration of antibacterial CD synthesis from levofloxacin, curcumin, and tea polyphenols through hydrothermal method. Typical TEM images (inset: HRTEM image) and the corresponding particle size distribution histogram of (b) Cur-TP@CDs and (c) Lf-TP@CDs. Full article ">Figure 2
(a) FT–IR spectra of Cur-TP@CDs and Lf-TP@CDs. (b) XRD patterns of Cur-TP@CDs and Lf-TP@CDs. (c) XPS full-survey spectrum of Cur-TP@CDs, indicating the presence and proportion of carbon (C) nitrogen (N), and oxygen (O) with peaks corresponding to C1s, N1s, and O1s, reflecting the surface chemical composition and states. (d) XPS survey spectrum of LF-TP@CDs, showing the elemental composition with peaks corresponding to carbon (C1s), oxygen (O1s), nitrogen (N1s), and fluorine (F1s). The F1s peak is present but at a very low intensity, indicating that fluorine is at the detection limit. Full article ">Figure 3
(a) UV-vis absorption spectrum of Cur-TP@CDs. (b) Photoluminescence (PL) emission spectra of Cur-TP@CDs at different excitation wavelengths. (c) Time-resolved fluorescence decay profile of Cur-TP@CDs. (d) UV-vis absorption spectrum of Lf-TP@CDs. (e) PL emission spectra of Lf-TP@CDs at different excitation wavelengths. (f) Time-resolved fluorescence decay profile of Lf-TP@CDs. Full article ">Figure 4
EPR analysis of 1O2 generation of (a) Cur-TP@CDs at concentrations of 0 mg/mL, 0.125 mg/mL, 0.25 mg/mL, and 0.5 mg/mL and (b) Lf-TP@CDs at concentrations of 0 mg/mL, 0.125 mg/mL, 0.25 mg/mL, and 0.5 mg/mL by using TEMP as a 1O2 trapper. Full article ">Figure 5
(a) Survival rates of S. aureus treated with different concentrations of Lf-TP@CDs and Cur-TP@CDs. (b) Survival rates of E. coli treated with different concentrations of Lf-TP@CDs and Cur-TP@CDs. Full article ">Figure 6
Biofilm inhibition of Lf-TP@CDs and Cur-TP@CDs by (a) S. aureus and (b) E. coli. Full article ">Figure 7
(a) SEM images of S. aureus treated with different concentrations of Lf-TP@CDs and Cur-TP@CDs. (b) SEM images of E. coli treated with different concentrations of Lf-TP@CDs and Cur-TP@CDs. Full article ">

18 pages, 4255 KiB

Open AccessArticle

Emission Ellipsometry Study in Polymeric Interfaces Based on Poly(3-Hexylthiophene), [6,6]-Phenyl-C₆₁-Butyric Acid Methyl Ester, and Reduced Graphene Oxide

by Ana Clarissa Henrique Kolbow, Everton Crestani Rambo, Maria Ruth Neponucena dos Santos, Paulo Ernesto Marchezi, Ana Flávia Nogueira, Alexandre Marletta, Romildo Jerônimo Ramos and Eralci Moreira Therézio

C 2024, 10(3), 83; https://doi.org/10.3390/c10030083 - 11 Sep 2024

Abstract

We analyzed the interaction of three materials, reduced graphene oxide (RGO), [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM), and poly(3-hexylthiphene) (P3HT), as well as the dependence of its photophysical properties within the temperature range of 90 to 300 K. The nanocomposite of the [...] Read more.

We analyzed the interaction of three materials, reduced graphene oxide (RGO), [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM), and poly(3-hexylthiphene) (P3HT), as well as the dependence of its photophysical properties within the temperature range of 90 to 300 K. The nanocomposite of the films was analyzed by optical absorption ultraviolet–visible (UV-Vis) and photoluminescence (PL) and emission ellipsometry (EE) as a function of sample temperature. The surface morphology was studied by atomic force microscopy (AFM). We noted that onset levels (E_onset) of the nanocomposite of P3HT and RGO are smaller than the others. The PL spectra showed the presence of anomalies in the emission intensities in the nanocomposite of P3HT and PCBM. It was also possible to determine the electron–phonon coupling by calculating the Huang–Rhys parameters and the temperature dependence of samples. Through EE, it was possible to analyze the degree of polarization and the anisotropy. We observed a high degree of polarized emission of the P3HT films, which varies subtly according to the temperature. For nanocomposites with RGO, the polarization degree in the emission decreases, and the roughness on the surface increases. As a result, the RGO improves the energy transfer between adjacent polymer chains at the cost of greater surface roughness. Then, the greater energy transfer may favor applications of this type of nanocomposite in organic photovoltaic cells (OPVCs) with enhancement in energy conversion efficiency. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Composites: Synthesis, Processing, Characterization and Applications)

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14 pages, 5675 KiB

Open AccessArticle

A Novel Non-Enzymatic Efficient H₂O₂ Sensor Utilizing δ-FeOOH and Prussian Blue Anchoring on Carbon Felt Electrode

by Karoline S. Nantes, Ana L. H. K. Ferreira, Marcio C. Pereira, Francisco G. E. Nogueira and André S. Afonso

C 2024, 10(3), 82; https://doi.org/10.3390/c10030082 - 9 Sep 2024

Abstract

In this study, an efficient H₂O₂ sensor was developed based on electrochemical Prussian blue (PB) synthesized from the acid suspension of δ-FeOOH and K₃[Fe(CN)₆] using cyclic voltammetry (CV) and anchored on carbon felt (CF), yielding an [...] Read more.

In this study, an efficient H₂O₂ sensor was developed based on electrochemical Prussian blue (PB) synthesized from the acid suspension of δ-FeOOH and K₃[Fe(CN)₆] using cyclic voltammetry (CV) and anchored on carbon felt (CF), yielding an enhanced CF/PB-FeOOH electrode for sensing of H₂O₂ in pH-neutral solution. CF/PB-FeOOH electrode construction was proved by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD), and electrochemical properties were verified by impedance electrochemical and CV. The synergy of δ-FeOOH and PB coupled to CF increases electrocatalytic activity toward H₂O_2, with the sensor showing a linear range of 1.2 to 300 μM and a limit of detection of 0.36 μM. Notably, the CF/PB-FeOOH electrode exhibited excellent selectivity for H₂O₂ detection in the presence of dopamine (DA), uric acid (UA), and ascorbic acid (AA). The calculated H₂O₂ recovery rates varied between 93% and 101% in fetal bovine serum diluted in PBS. This work underscores the potential of CF/PB-FeOOH electrodes in progressing electrochemical sensing technologies for various biological and environmental applications. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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(A) Potentiodynamic growth of PB nanoparticles on CF electrode in N2-saturated 0.1 M KCl solution at pH 2.0 with 5 mM K3Fe(CN)6 and 22 mg of δ-FeOOH. The potential window was set from −0.2 V to 0.7 V at a scan rate of 50 mV s−1, applying 30 scans. The arrows indicate scans increase. (B) CV of FC/PB-FeOOH electrode in N2-saturated 0.1 M KCl at pH 2.0 at a scan rate of 50 mV s−1. The CF was subjected to the following treatments: (a) i, (b) ii, and (c) iii. Full article ">Figure 2
(A) Evaluation by the CV of PB synthesized in different pH levels of the precursor solution. (B) PB synthesized with (a) 44 mg, (b) 22 mg, or (c) 11 mg of δ-FeOOH. (C) Effect of the number of scans on the synthesis of PB: (a) background, (b) 15 scans, (c) 30 scans, (d) 50 scans, (e) 100 scans, and (f) 150 scans. N2-saturated 0.1 M KCl solution at pH 2.0 was the medium in which CVs were performed. The potential range was from −0.2 V to 0.7 V, and the scan rate was 50 mV s−1. Full article ">Figure 3
The XRD pattern for the PB-FeOOH film was deposited on FTO. Full article ">Figure 4
SEM micrographs of (A,B) CF electrode and (C,D) CF/PB-FeOOH electrode. (E) EDS spectrum of CF/PB-FeOOH electrode and (F) the weight % of EDS analysis. Full article ">Figure 5
(A) CV curves at 100 mV·s−1 and (B) EIS plots at open-circuit potential using N2-saturated 0.1 M KCl solution at pH 2.0 containing 1 mM K3Fe(CN)6 and 1 mM K4Fe(CN)6, (a) CF, and (b) CF/PB-FeOOH. Full article ">Figure 6
CV curves at a potential range from −0.2 V to 0.7 V at a scan rate of 100 mV·s−1 in 0.1 M of PBS without or with 1.0 mM of H2O2. (A) CF/PB-FeOOH electrode and (B) CF/PB electrode. Full article ">Figure 7
(A) Amperometric response of the CF/PB–δ-FeOOH electrode in 0.1 M PBS at −0.2 V versus Ag|AgCl with successive additions of H2O2 under stirring. (B) Corresponding calibration curve. The error bars show the standard deviation for n = 3. The arrow indicates the increase in concentration of H2O2. Full article ">Figure 8
Amperometric response of CF/PB-FeOOH electrode in 0.1 M PBS at −0.2 V using 80 μM of H2O2 (initial and final additions), 400 µM of uric acid, 100 µM of ascorbic acid, and 40 µM of dopamine. Full article ">

20 pages, 4937 KiB

Open AccessArticle

Miscanthus-Derived Biochar as a Platform for the Production of Fillers for the Improvement of Mechanical and Electromagnetic Properties of Epoxy Composites

by Salvatore Scavuzzo, Silvia Zecchi, Giovanni Cristoforo, Carlo Rosso, Daniele Torsello, Gianluca Ghigo, Luca Lavagna, Mauro Giorcelli, Alberto Tagliaferro, Marco Etzi and Mattia Bartoli

C 2024, 10(3), 81; https://doi.org/10.3390/c10030081 - 5 Sep 2024

Abstract

The production of multipurpose sustainable fillers is a matter of great interest, and biochar can play a pivotal role. Biochar is a biomass-derived carbon source that can act as a versatile platform for the engineering of fillers as neat or functionalized materials. In [...] Read more.

The production of multipurpose sustainable fillers is a matter of great interest, and biochar can play a pivotal role. Biochar is a biomass-derived carbon source that can act as a versatile platform for the engineering of fillers as neat or functionalized materials. In this work, we investigate the utilization of 800 °C annealed Miscanthus-derived biochar as a filler for the production of epoxy composites with promising mechanical and electrical properties. We also used it in the production of an iron-rich hybrid filler in order to fine-tune the surface and bulk properties. Our main findings reveal that hybrid composites containing 20 wt.% biochar exhibit a 27% increase in Young’s modulus (YM), reaching 1.4 ± 0.1 GPa, while the ultimate tensile strength (UTS) peaks at 30.3 ± 1.8 Mpa with 10 wt.% filler, a 27% improvement over pure epoxy. However, higher filler loadings (20 wt.%) result in decreased UTS and maximum elongation. The optimal toughness of 0.58 ± 0.14 MJ/m³ is observed at 5 wt.% filler content. For organic composites, YM sees a notable increase of 90%, reaching 2.1 ± 0.1 Gpa at 20 wt.%, and UTS improves by 32% with the same filler content. Flexural tests indicate an enhanced elastic modulus but reduced maximum elongation as filler content rises. Electromagnetic evaluations show that hybrid fillers maintain a primarily dielectric behavior with a negligible impact on permittivity, while biochar–epoxy composites exhibit increased conductivity at higher filler loadings, suitable for high-frequency applications. In light of these results, biochar-based fillers demonstrate significant potential for enhancing the mechanical and electrical properties of epoxy composites. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Composites: Synthesis, Processing, Characterization and Applications)

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14 pages, 9087 KiB

Open AccessArticle

The Influence of Annealing Temperature on the Interfacial Heat Transfer in Pulsed Laser Deposition-Grown Ga₂O₃ on Diamond Composite Substrates

by Lin Gu, Yi Shen, Wenjie Chen, Yuanhui Zuo, Hongping Ma and Qingchun Zhang

C 2024, 10(3), 80; https://doi.org/10.3390/c10030080 - 4 Sep 2024

Abstract

As devices become more miniaturized and integrated, the heat flux density has increased, highlighting the issue of heat concentration, especially for low thermal conductivity gallium oxide (Ga₂O₃). This study utilizes diamond composite substrates with an AlN transition layer to [...] Read more.

As devices become more miniaturized and integrated, the heat flux density has increased, highlighting the issue of heat concentration, especially for low thermal conductivity gallium oxide (Ga₂O₃). This study utilizes diamond composite substrates with an AlN transition layer to assist Ga₂O₃ in rapid thermal dissipation. All samples were prepared using pulsed laser deposition (PLD) and annealed at 600–1000 °C. The microstructure, surface morphology, vacancy defects, and thermal characteristics of post-annealed Ga₂O₃ were then thoroughly investigated to determine the mechanism by which annealing temperature influences the heat transfer of heterostructures. The results demonstrate that increasing the annealing temperature can improve the crystallinity of Ga₂O₃ while also reducing oxygen vacancy defects from 20.6% to 9.9%. As the temperature rises to 1000 °C, the thermal conductivity of Ga₂O₃ reaches a maximum of 12.25 W/(m·K). However, the interface microstructure has no direct correlation with annealing temperature. At 700 °C, Ga₂O₃/diamond exhibits a maximum thermal boundary conductance of 127.06 MW/(m²·K). Higher temperatures (>800 °C) cause irregular mixtures to form near the heterointerface, intensifying phonon interface scattering and sharply deteriorating interfacial heat transfer. These findings contribute to a better understanding of the heterointerface thermal transfer influence mechanism and provide theoretical guidance for the thermal management design and physical analysis of Ga₂O₃-based power devices. Full article

(This article belongs to the Special Issue Micro/Nanofabrication of Carbon-Based Devices and Their Applications)

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XRD patterns of Ga2O3 on diamond composite substrates at different (a) ambients and (b) annealing temperatures. Full article ">Figure 2
AFM images of Ga2O3 films on diamond composite substrates at different annealing temperatures: (a) as-grown; (b) 600 °C; (c) 700 °C; (d) 800 °C; (e) 900 °C; (f) 1000 °C. Full article ">Figure 3
HRTEM patterns of interface microstructure of Ga2O3 on diamond composite substrates at different annealing temperatures: (a–c) deposited state; (d–f) 700 °C; (g–i) 900 °C. Inserts in (b): FFT results of Ga2O3, Ga2O3/AlN, and AlN. Full article ">Figure 4
TEM images of interface microstructure of Ga2O3 on diamond composite substrates at different annealing temperatures: (a) as-grown; (b) 700 °C; (c–e) 900 °C. (e) Distribution of Ga, O, Al, and N elements within the yellow dashed line. Full article ">Figure 5
(a) XPS survey, (b) O 1s, and (c) Ga 3d of Ga2O3 films on diamond composite substrates at different annealing temperatures. (d–i) O 1s peak fitting. Full article ">Figure 6
Schematic of the typical TDTR setup. The acronyms EOM and PBS stand for electro-optic modulator and polarizing beam splitter, respectively. Full article ">Figure 7
TDTR signal intensity versus delay time at different annealing temperatures: (a) as-grown; (b) 600 °C; (c) 700 °C; (d) 800 °C; (e) 900 °C; (f) 1000 °C. (g) The variation in thermal characteristics parameters of Ga2O3 on diamond composite substrates versus annealing temperature. (h) Summary of κGaO versus (κGaO × TBCGaO-dia) reported in the literature [<a href="#B16-carbon-10-00080" class="html-bibr">16</a>,<a href="#B35-carbon-10-00080" class="html-bibr">35</a>,<a href="#B52-carbon-10-00080" class="html-bibr">52</a>,<a href="#B53-carbon-10-00080" class="html-bibr">53</a>,<a href="#B54-carbon-10-00080" class="html-bibr">54</a>]. Full article ">

18 pages, 8468 KiB

Open AccessArticle

One-Stage Synthesis of Microporous Carbon Adsorbents from Walnut Shells—Evolution of Porosity and Structure

by Ilya E. Men’shchikov, Andrey A. Shiryaev, Andrey V. Shkolin, Alexander E. Grinchenko, Elena V. Khozina, Alexey A. Averin and Anatolii A. Fomkin

C 2024, 10(3), 79; https://doi.org/10.3390/c10030079 - 2 Sep 2024

Abstract

One-stage synthesis technology for preparing carbon adsorbents with tailored porosity from agricultural waste is worthwhile due to their extensive application value. Thermal gravimetric analysis, low-temperature N₂ adsorption, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and Raman spectroscopy were used to record the [...] Read more.

One-stage synthesis technology for preparing carbon adsorbents with tailored porosity from agricultural waste is worthwhile due to their extensive application value. Thermal gravimetric analysis, low-temperature N₂ adsorption, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and Raman spectroscopy were used to record the structure transformations of carbon materials, namely pore development, proceeding in the course of the step-wise pyrolysis of renewable and low-cost raw materials such as walnut shells (WNSs), which was carried out within a temperature range of 240–950 °C in a CO₂ flow. The minimum threshold carbonization temperature for preparing nanoporous carbon materials from WNSs, determined by the examination of the N₂ adsorption data, was 500 °C. The maximum specific micropore volume and BET surface achieved in the process without holding a material at a specified temperature were only 0.19 cm³/g and 440 m²/g, respectively. The pyrolysis at 400–600 °C produced amorphous sp² carbon. At a temperature as high as 750 °C, an increase in the X-ray reflection intensity indicated the ordering of graphite-like crystallites. At high burn-off degrees, the size of coherently scattering domains becomes smaller, and an increased background in X-ray patterns indicates the destruction of cellulose nanofibrils, the disordering of graphene stacks, and an increase in the amount of disordered carbon. At this stage, pores develop in the crystallites. They are tentatively assigned to crystallites with sizes of 15–20 nm and to micropores. According to the Raman spectra combined with the XRD and SAXS data, the structure of all the pyrolysis products is influenced by the complex structure of the walnut shell precursor, which comprises cellulose nanofibrils embedded in lignin. This structure was preserved in the initial stage of pyrolysis, and the graphitization of cellulose fibrils and lignin proceeds at different rates. Most of the pores accessible for gas molecules in the resulting carbon materials are associated with former cellulose fibrils. Full article

(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))

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45 pages, 12156 KiB

Open AccessReview

Research Progress in Graphene-Based Adsorbents for Wastewater Treatment: Preparation, Adsorption Properties and Mechanisms for Inorganic and Organic Pollutants

by Guangqian Li, Ruiling Du, Zhanfang Cao, Changxin Li, Jianrong Xue, Xin Ma and Shuai Wang

C 2024, 10(3), 78; https://doi.org/10.3390/c10030078 - 29 Aug 2024

Abstract

Graphene-based adsorbents show great potential for application in the field of environmental pollution treatment due to their unique two-dimensional structure, high specific surface area, and tunable surface chemistry. This paper reviews the research on the application of graphene and its derivatives as novel [...] Read more.

Graphene-based adsorbents show great potential for application in the field of environmental pollution treatment due to their unique two-dimensional structure, high specific surface area, and tunable surface chemistry. This paper reviews the research on the application of graphene and its derivatives as novel adsorbents in the field of wastewater treatment in recent years, focusing on the preparation and functionalization of graphene-based adsorbents, as well as their adsorption performance and mechanism of action in the removal of inorganic and organic pollutants, and provides an outlook on the future directions of the research on graphene-based adsorbents. The analysis in this paper focuses on the functionalization of graphene-based adsorbents by introducing magnetic particles, hybridization with other materials, and grafting with polymers. The modified graphene-based adsorbents showed significant adsorption and removal of pollutants and were easy to recycle and regenerate. The adsorption of pollutants on graphene-based adsorbents is mainly carried out through π–π interaction, hydrogen bonding, and electrostatic interaction, which is related to the structure of the pollutants. Future research directions on graphene-based adsorbents should focus on in-depth adsorption mechanism studies and the development of cost-effective graphene-based adsorbents for wastewater treatment. Full article

(This article belongs to the Special Issue Carbon-Based Materials Applied in Water and Wastewater Treatment)

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19 pages, 7653 KiB

Open AccessArticle

Charcoal in Anaerobic Digestion: Part 1—Characterisation of Charcoal

by Hans Korte, Jan Sprafke, Pooja Girdharbhai Parmar, Thomas Steiner, Ruth Freitag and Volker Haag

C 2024, 10(3), 77; https://doi.org/10.3390/c10030077 - 26 Aug 2024

Abstract

Biochar (BC) is often used as an additive in anaerobic digestion (AD) to increase yield and/or to stabilise the process when the manure content is increased. Unfortunately, BC is rarely described in detail in terms of its raw material sources, production processes, and [...] Read more.

Biochar (BC) is often used as an additive in anaerobic digestion (AD) to increase yield and/or to stabilise the process when the manure content is increased. Unfortunately, BC is rarely described in detail in terms of its raw material sources, production processes, and structural, physical and chemical properties to allow correlation with its effects on AD. It is an open question whether microorganisms from AD can penetrate into different biochar pore types, depending on their wood origin. In this paper, we describe the preparation (temperatures, treatment times, yields) and characterisation shrinkage, density, pore sizes, pore size distribution, specific surface area, ash, volatiles, fixed carbon, elemental composition, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), benzene, toluene, ethyl-toluene, xylene (BTEX) and volatile halogenated hydrocarbons (VHH) of BC cubes of Scots pine (Pinus sylvestris) and common beech (Fagus sylvatica) powder made from this BC in addition to commercial charcoal powder. The pore size distribution determined by mercury porosimetry differs from that determined by 3D-reflected light microscopy. After incubating BC cubes in AD, the cubes were mechanically cleaned and cut into two pieces. Microorganisms were detected inside the cubes by fluorescence microscopy. Particle size and wood source determine the influence of BC on AD. Full article

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10 pages, 2545 KiB

Open AccessArticle

Low-Temperature Annealing of Nanoscale Defects in Polycrystalline Graphite

by Gongyuan Liu, Hajin Oh, Md Hafijur Rahman, Jing Du, William Windes and Aman Haque

C 2024, 10(3), 76; https://doi.org/10.3390/c10030076 - 26 Aug 2024

Abstract

Polycrystalline graphite contains multi-scale defects, which are difficult to anneal thermally because of the extremely high temperatures involved in the manufacturing process. In this study, we demonstrate annealing of nuclear graphite NBG-18 at temperatures below 28 °C, exploiting the electron wind force, a [...] Read more.

Polycrystalline graphite contains multi-scale defects, which are difficult to anneal thermally because of the extremely high temperatures involved in the manufacturing process. In this study, we demonstrate annealing of nuclear graphite NBG-18 at temperatures below 28 °C, exploiting the electron wind force, a non-thermal stimulus. High current density pulses were passed through the specimens with a very low-duty cycle so that the electron momentum could mobilize the defects without heating the specimen. The effectiveness of this technique is presented with a significant decrease in electrical resistivity, defect counts from X-ray computed tomography, Raman spectroscopy, and nanoindentation-based mechanical characterization. Such multi-modal evidence highlights the feasibility of nanoscale defect control at temperatures about two orders of magnitude below the graphitization temperature. Full article

(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))

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15 pages, 4153 KiB

Open AccessArticle

Enhanced Tetracycline Removal from Water through Synergistic Adsorption and Photodegradation Using Lignocellulose-Derived Hydrothermal Carbonation Carbon

by Yanchi Zhou, Xingdi Ma, Zhonglin Chen, Ruihang Chen, Yingxu Gong, Lei Cui, Jing Kang, Jimin Shen, Shengxin Zhao and Chen Li

C 2024, 10(3), 75; https://doi.org/10.3390/c10030075 - 20 Aug 2024

Abstract

Hydrothermal carbonation carbon (HTCC) is emerging as a promising material for the adsorption and photodegradation of environmental contaminants. However, the chemical and structural properties of HTCC derived from different lignocellulose biomass have obvious impacts on adsorption and photodegradation. This work employed three different [...] Read more.

Hydrothermal carbonation carbon (HTCC) is emerging as a promising material for the adsorption and photodegradation of environmental contaminants. However, the chemical and structural properties of HTCC derived from different lignocellulose biomass have obvious impacts on adsorption and photodegradation. This work employed three different lignocellulose components, including cellulose, hemicellulose, and lignin to synthesize HTCC within a hydrothermal temperature range of 210~290 °C. In comparison to HTCC derived from cellulose and hemicellulose, HTCC derived from lignin (HTCC-L) demonstrated the optimal synergistic adsorption and photodegradation ability for TC degradation, achieving a 63.5% removal efficiency within 120 min. Characterization highlighted the crucial involvement of oxygenated functional groups, especially carboxyl groups, presented on the surface of HTCC-L in TC adsorption. Moreover, the photodegradation of HTCC-L was found to follow a non-radical mechanism, characterized by the charge transformation occurring between the excited unpaired electrons of HTCC-L and TC adsorbed on its surface. This work clarified the differences in HTCC derived from different lignocellulose components on the adsorption and photodegradation of organic pollutants, and provided a novel perspective on the application of HTCC in water treatment. Full article

(This article belongs to the Special Issue High-Performance Carbon Materials and Their Composites)

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Full article ">Figure 1
(a) Schematic illustration of synthesizing hydrothermal carbonation carbon (HTCC) derived from cellulose, hemicellulose, and lignin. (b) Tetracycline (TC) removal by HTCC derived from cellulose (HTCC-C), hemicellulose (HTCC-HC), and lignin (HTCC-L) with and without visible light. (c) Synergistic adsorption and photodegradation of TC by as-prepared HTCC samples under different hydrothermal temperatures. Conditions: [TC]0 = 1.0 mg/L, [HTCC] 0 = 100 mg/L, pH = 6.0, T = 25 °C. Full article ">Figure 2
(a) Ionization equilibrium of TC. (b) Zeta potential of HTCC-L synthesized at 230 °C (HTCC-L-230). (c) Synergistic adsorption and photodegradation of TC in the HTCC-L-230/visible light system under different pH values. Conditions: [TC]0 = 1.0 mg/L, [HTCC-L-230]0 = 100 mg/L, pH = 6.0, T = 25 °C. Full article ">Figure 3
Scanning electron microscope images of as-prepared (a) HTCC-L synthesized at 210 °C (HTCC-L-210), (b) HTCC-L-230, (c) HTCC-L synthesized at 250 °C (HTCC-L-250), (d) HTCC-L synthesized at 270 °C (HTCC-L-270), and (e) HTCC-L synthesized at 290 °C (HTCC-L-290). (f) Corresponding element mapping for C, O of HTCC-L-230. Full article ">Figure 4
(a) N2 adsorption–desorption isotherms, (b) porosity distributions, and (c) Fourier transform-infrared (FT-IR) spectra of as-prepared HTCC-L samples. Full article ">Figure 5
(a) The adsorption kinetics and (b) intra-particle diffusion model of TC onto as-prepared HTCC-L samples. (c) Correlation between the specific surface areas, pore volumes, and adsorption capacities of as-prepared HTCC-L samples. (d) Electrostatic potential distributions of TC. Full article ">Figure 6
(a) FT-IR spectra of HTCC-L and HTCC-L after oxidation treatment (HTCC-Lox). (b) High-resolution C 1s XPS spectra of HTCC-L and HTCC-Lox. (c) Adsorption and photodegradation of TC by HTCC-L and HTCC-Lox with and without visible light. (d) Electron paramagnetic resonance signals of HTCC-L and HTCC-L-used. Full article ">Figure 7
(a) Molecule structure, (b) the highest occupied molecular orbitals, (c) the lowest unoccupied molecular orbitals, and (d) Fukui functions of TC. The isosurface value is 0.02 e/Å3. (e) Schematic illustration of the proposed pathways for TC degradation in the HTCC-L-230/visible light system. Full article ">

16 pages, 9803 KiB

Open AccessArticle

The Flower-Shaped Co (II) and Cu (II) Phthalocyanine Polymers as Highly Efficient and Stable Catalysts for Chemical Fixation of CO₂ to Cyclic Carbonate

by Yuyang Zhou, Shengyu Shao, Xiang Han, Baocheng Zhou, Yifeng Han, Xiaoping Dong and Sanchuan Yu

C 2024, 10(3), 74; https://doi.org/10.3390/c10030074 - 19 Aug 2024

Abstract

New flower-shaped metallophthalocyanine polymers (THB-4-M, M = Co, Cu) have been synthesized by using 1,3,5-Tri(4-hydroxyphenhyl) benzene (THB) as rigid and contorted units to control the morphology under the solvothermal method. The polymers were characterized using FT-IR, UV-vis, SEM, TGA, and XPS. These polymers [...] Read more.

New flower-shaped metallophthalocyanine polymers (THB-4-M, M = Co, Cu) have been synthesized by using 1,3,5-Tri(4-hydroxyphenhyl) benzene (THB) as rigid and contorted units to control the morphology under the solvothermal method. The polymers were characterized using FT-IR, UV-vis, SEM, TGA, and XPS. These polymers were applied as heterogeneous catalysts for the chemical fixation of carbon dioxide (CO₂) to cyclic carbonates without solvent. The influence of reaction parameters and different metal centers on the catalytic performance were studied in detail. Under optimal conditions, the catalysts showed high conversion (49.9–99.0%), selectivity (over 85%), and reusability at ambient conditions (at 1 bar CO₂). Full article

(This article belongs to the Section Carbon Cycle, Capture and Storage)

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8 pages, 1729 KiB

Open AccessCommunication

H₂ Adsorption on Small Pd-Ni Clusters Deposited on N-Doped Graphene: A Theoretical Study

by Brenda García-Hilerio, Lidia Santiago-Silva, Adriana Vásquez-García, Alejandro Gomez-Sanchez, Víctor A. Franco-Luján and Heriberto Cruz-Martínez

C 2024, 10(3), 73; https://doi.org/10.3390/c10030073 - 13 Aug 2024

Abstract

The study of novel materials for H₂ storage is essential to consolidate the hydrogen as a clean energy source. In this sense, the H₂ adsorption on Pd_4-nNi_n (n = 0–3) clusters embedded on pyridinic-type N-doped graphene (PNG) was [...] Read more.

The study of novel materials for H₂ storage is essential to consolidate the hydrogen as a clean energy source. In this sense, the H₂ adsorption on Pd_4-nNi_n (n = 0–3) clusters embedded on pyridinic-type N-doped graphene (PNG) was investigated using density functional theory calculations. First, the properties of Pd_4-nNi_n (n = 0–3) clusters embedded on PNG were analyzed in detail. Then, the H₂ adsorption on these composites was computed. The E_int between the Pd_4-nNi_n (n = 0–3) clusters and the PNG was greater than that computed in the literature for Pd-based systems embedded on pristine graphene. Consequently, it was deduced that PNG can more significantly stabilize the Pd_4-nNi_n (n = 0–3) clusters. The analyzed composites exhibited a HOMO–LUMO gap less than 1 eV, indicating good reactivity. Based on the E_ads of H₂ on Pd_4-nNi_n (n = 0–3) clusters embedded on PNG, it was observed that the analyzed systems meet the standards set by the DOE. Therefore, these composites can be viable alternatives for hydrogen storage. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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