Oxidation Of Carbon Materials Research Articles

Investigating the radical properties of oxidized carbon materials under photo-irradiation: behavior of carbon radicals and their application in catalytic reactions.

Oxidized carbon materials have abundant surface functional groups and customizable properties, making them an excellent platform for generating radicals. Unlike reactive oxygen species such as hydroxide or superoxide radicals that have been reported previously, oxidized carbon also produces stable carbon radicals under photo-irradiation. This has been confirmed through electron spin resonance. Among the various oxidized carbon materials synthesized, graphene oxide shows the largest number of carbon radicals when exposed to blue LED light. The light absorption capacity, high surface area, and unique structural characteristics of oxidized carbon materials offer a unique function for radical-mediated oxidative reactions.

A Flexible Ammonia Gas Sensor Based on a Grafted Polyaniline Grown on a Polyethylene Terephthalate Film.

A novel NH3 gas sensor is introduced, employing polyaniline (PANI) with a unique structure called a graft film. The preparation method was simple: polydopamine (PD) was coated on a flexible polyethylene terephthalate (PET) film and PANI graft chains were grown on its surface. This distinctive three-layer sensor showed a response value of 12 for 50 ppm NH3 in a dry atmosphere at 50 °C. This value surpasses those of previously reported sensors using structurally controlled PANI films. Additionally, it is on par with sensors that combine PANI with metal oxide semiconductors or carbon materials, the high sensitivity of which have been reported. To confirm our film's potential as a flexible sensor, the effect of bending on the its characteristics was investigated. This revealed that although bending decreased the response value, it had no effect on the response time or recovery. This indicated that the sensor film itself was not broken by bending and had sufficient mechanical strength.

Isomerization Engineering of Oxygen-Enriched Carbon Quantum Dots for Efficient Electrochemical Hydrogen Peroxide Production.

Hydrogen peroxide (H2O2) has emerged as a kind of multi-functional green oxidants with extensive industrial utility. Oxidized carbon materials exhibit promises as electrocatalysts in the two-electron (2e-) oxygen reduction reaction (ORR) for H2O2 production. However, the precise identification and fabrication of active sites that selectively yield H2O2 present a serious challenge. Herein, a structural engineering strategy is employed to synthesize oxygen-doped carbon quantum dots (o-CQD) for the 2e- ORR. The surface electronic structure of the o-CQDs is systematically modulated by varying isomerization precursors, thereby demonstrating excellent electrocatalyst performance. Notably, o-CQD-3 emerges as the most promising candidate, showcasing a remarkable H2O2 selectivity of 96.2% (n = 2.07) at 0.68V versus RHE, coupled with a low Tafel diagram of 66.95mV dec-1. In the flow cell configuration, o-CQD-3 achieves a H2O2 productivity of 338.7mmol gcatalyst -1 h-1, maintaining consistent production stability over an impressive 120-hour duration. Utilizing in situ technology and density functional theory calculations, it is unveil that edge sites of o-CQD-3 are facilely functionalized by C-O-C groups under alkaline ORR conditions. This isomerization engineering approach advances the forefront of sustainable catalysis and provides a profound insight into the carbon-based catalyst design for environmental-friendly chemical synthesis processes.

A novel approach for the facile synthesis of zinc oxide/carbon hybrid systems from corn distillers soluble: Surface modification and characterization for sustainable remediation

Sustainable, efficient, and environmentally friendly ways to tailor the carbonaceous materials from bio sources with desired functionalities remain a challenge around the world. In this study, we represent a novel approach to synthesize carbon hybrid material based on Zinc Oxide/carbon (ZnO/C) hybrid systems by catalytic hydrothermal process via crosslinking reaction through nucleation and growth of ZnO particles at the functional groups of oxidized carbon material. This research explored the volarization of Condensed Corn Distillers Soluble (CDS) as a carbon precursor to synthesize biobased carbon spheres. Surface modification of the produced carbon spheres took place using zinc chloride (ZnCl2) during hydrothermal carbonization (HTC). Zinc chloride (ZnCl2) was used to function as a catalyst during HTC and functioned as a ZnO source to synthesize (ZnO/C) hybrid systems. Design Expert software v13 was used to design the hydrothermal carbonization (HTC) experiments and response surface methodology was used to find the optimized conditions for the preparation of carbon hybrid systems. The hydrothermal synthesis process introduced 3D stone like zinc oxide particles onto the carbon matrix. These particles were self-assembled onto the carbon framework to produce carbon hybrid systems with unique physical, chemical, structural and functional properties. Herein, the obtained carbon hybrid systems (ZnO/C) were investigated and discussed in detail. ZnO/C hybrid systems were analyzed for surface morphology using scanning electron microscopy (SEM) that presented a 3D spherical interconnected phase and XRD analyses were used for phase crystallinity that showed new crystalline phases such as hopeite and zincite after the ZnCl2 incorporation. Surface functional groups were also analyzed by FTIR and results confirmed the presence of hydrophilic groups such as –OH, CC, and COOH on the surface of ZnO/C hybrid carbon systems. This study provided the insightful guidance for tailoring novel design of multifunctional carbon material as an adsorbent/catalyst for various applications of sustainable remediation.

Rechargeable Manganese Dioxide||Hard Carbon Lithium Batteries in an Ether Electrolyte

Earth-abundant, cost-effective electrode materials are essential for sustainable rechargeable batteries and global decarbonization. Manganese dioxide (MnO2) and hard carbon both exhibit high structural and chemical tunability, making them excellent electrode candidates for batteries. Herein, we elucidate the impact of electrolytes on the cycling performance of commercial electrolytic manganese dioxide in Li chemistry. We leverage synchrotron X-ray analysis to discern the chemical state and local structural characteristics of Mn during cycling, as well as to quantify the Mn deposition on the counter electrode. By using an ether-based electrolyte instead of conventional carbonate electrolytes, we circumvent the formation of a surface Mn(II)-layer and Mn dissolution from LixMnO2. Consequently, we achieved an impressive ∼100% capacity retention for MnO2 after 300 cycles at C/3. To create a lithium metal-lean full cell, we introduce hard carbon as the anode which is compatible with ether-based electrolytes. Commercial hard carbon delivers a specific capacity of ∼230 mAh g−1 at 0.1 A g−1 without plateau, indicating a surface-adsorption mechanism. The resulting manganese dioxide||hard carbon full cell exhibits stable cycling and high Coulombic efficiency. Our research provides a promising solution to develop cost-effective, scalable, and safe energy storage solutions using widely available manganese oxide and hard carbon materials.

Boosted carbon electrocatalytic effect towards sensing and green energy applications by tailoring the catalyst-support interface on a nature-inspired solution

Carbon electrodes are widely accepted as very versatile platforms, with applications ranging from electrocatalysis to sensors and other devices, like fuel cells and water electrolyzers. However, there are still difficulties given that over time, at high potentials, the oxidation of carbon materials (as a catalyst and/or catalyst support) can play a detrimental role, undermining the efficiency and stability of the electrochemical processes and devices performance. In this paper, it is reported the research work followed by resourcing to electrochemical analytical techniques, like cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), along with complementary atomic force microscopy (AFM) and water contact angle (WCA) measurements. These techniques were used to characterise glass-type and paper-based carbon electrodes. On a nature-inspired solution, we took advantage of the different interfacial carbon-support hierarchical porous structures to boost the carbon electrocatalytic effect towards sensing the ferri/ferrocyanide redox couple ([Fe(CN)6]3-/4−) in aqueous solution. It is shown that the best results were achieved with carbon paper electrodes without wet proofing, given its hierarchical porous structure and absence of the insulating binder. This research endeavors to contribute to the ongoing advancements in the field of electrochemical green energy conversion by exploring innovative approaches and materials, with the ultimate aim of developing carbon substrates that not only enhance performance but also promote environmental sustainability.

Reductive Fractionation of Flax Shives in Ethanol Medium over RuNi Bimetallic Catalysts.

The reductive catalytic fractionation of flax shives in the presence of bimetallic NiRu catalysts supported on oxidized carbon materials (CM) such as mesoporous Sibunit and carbon mesostructured by KAIST (CMK-3) was studied. The catalysts based on CMK-3 were characterized by a higher surface area (1216 m2/g) compared to the ones based on Sibunit (315 m2/g). The catalyst supported on CMK-3 (10Ni3RuC400) was characterized by a more uniform distribution of Ni particles, in contrast to the Sibunit-based catalyst (10Ni3RuS450), on the surface of which large agglomerated particles (300-400 nm) were presented. The bimetallic catalysts were found to be more selective towards propanol-substituted methoxyphenols compared to monometallic Ru/C and Ni/C catalysts. A high yield of monomers (up to 26 wt%, including 17% 4-propanol guaiacol) was obtained in the presence of a 10Ni3RuC400 catalyst based on CMK-3.

Oxidized Carbon Materials as Hole Transport Layers for High‐Performance Organic Photovoltaics

Flexible Organic Photovoltaics In article number 2200908, Dong-Yu Kim and co-workers introduced an oxidized carbon soot (OCS)-based hole-transporting layer to improve charge transport without charge recombination, finally enhancing the device performance up to 15.04%. Due to the functionalization of OCS with octadecylamine, the largesized and flexible organic photovoltaics prepared by blade coating exhibited high storage stability (71% retention) and mechanical stability (78% retention).

Oxidized Carbon Materials as Hole Transport Layers for High‐Performance Organic Photovoltaics

Organic photovoltaics (OPVs) have recently advanced as promising solar cells owing to their many advantages, including the possibility of a low‐temperature solution process, lightweight, and flexibility. In OPVs, the role of the interlayer is important for efficient charge transport from the photoactive layer to electrodes. However, as a hole‐transporting layer (HTL), molybdenum oxide and poly(3,4‐ethylenedioxythiophene)–poly(styrenesulfonate) are still used for commercialization despite their drawbacks. The development of novel materials with suitable energy levels and solvent orthogonality is required to enhance hole extraction and optimize the film morphology. Herein, oxidized carbon soot (OCS) and OCS‐functionalized octadecylamine (OCS‐ODA) nanoparticles as HTL materials are synthesized. As a large number of oxygen functional groups are produced via Hummer's method, the devices with the OCS‐ODA exhibit high hole extraction ability. The ODA long alkyl chains functionalized by facile process also improve film morphology to minimize contact resistance and charge recombination. The small‐area (SA), large‐area, and flexible (F) OPVs with OCS‐ODA show power conversion efficiencies of 15.04%, 14.57%, and 12.73%, respectively. In particular, OPVs with OCS‐ODA are further demonstrated to possess storage stability in SA‐OPVs (71% retention after 450 h) and mechanical stability in F‐OPVs (78% retention after 1000 bendings).

Nanozymes – A route to overcome microbial resistance: A viewpoint

Abstract The bactericide is one of the major objective consequences related to healthcare in the world. Natural enzymes have been broadly utilized in various applications such as biomedical areas due to their broad catalytic activities and substrate particularity. While anticipating, it has drawbacks like higher cost, low stability, and troubles in reprocessing. Additionally, artificial enzymes (nanozymes) have favors above natural enzymes, for example, the effortless yield on a big scale, low costs, and high stability in coarse surrounds. The amount of antibiotic repellent microorganisms has activated big concern in the growth of stuff with essential bactericide potentials such as metal or metal oxide nanoparticles, cationic polymeric compounds, graphene oxide, and other carbon materials that can be used as antibacterial agents by altering cell morphology. In this report, we have summarized catalytic antibacterial strategies by natural enzymes, artificial enzymes, or photocatalytic activity. Furthermore, the demands and hereafter contents about catalytic antibacterial strategies are supposed in this report.

High Surface Area “3D Graphene Oxide” for Enhanced Sorption of Radionuclides

AbstractHere preparation of high surface area activated reduced graphene oxide (arGO) oxidized into a 3D analogue of defect‐rich GO (dGO) is reported. Surface oxidation of arGO results in carbon to oxygen ratio C/O = 3.3, similar to the oxidation state of graphene oxide while preserving high BET surface area of about 880 m2 g−1. Analysis of surface oxidized arGO shows high abundance of oxygen functional groups which converts hydrophobic precursor into hydrophilic material. High surface area carbons provide the whole surface for oxidation without the need of intercalation and lattice expansion. Therefore, surface oxidation methods are sufficient to convert the materials into 3D architectures with chemical properties similar to graphene oxide. The “3D graphene oxide” shows high sorption capacity for U(VI) removal in an extraordinary broad interval of pH. Notably, the surface oxidized carbon material has a rigid 3D structure with micropores accessible for penetration of radionuclide ions. Therefore, the bulk “3D GO” can be used as a sorbent directly without dispersing, the step required for GO to make its surface area accessible for pollutants.

The High‐Temperature Acidity Paradox of Oxidized Carbon: An in situ DRIFTS Study

AbstractUntil now, oxygen functionalized carbon materials were not considered to exhibit significant acidity at high temperatures, since carboxylic acids, the most prominent acidic functionality, are prone to decarboxylation at temperatures exceeding 250 °C. Paradoxically, we could show that oxidized carbon materials can act as highly active high‐temperature solid acid catalysts in the dehydration of methanol at 300 °C, showing an attractive selectivity to dimethyl ether (DME) of up to 92 % at a conversion of 47 %. Building on a tailor‐made carbon model material, we developed a strategy to utilize in situ DRIFT spectroscopy for the analysis of carbon surface species under process conditions, which until now proofed to be highly challenging due to the high intrinsic absorbance of carbon. By correlating the catalytic behavior with a comprehensive in situ DRIFTS study and extensive post mortem analysis we could attribute the high‐temperature acidity of oxidized carbons to the interaction of thermally stable carboxylic anhydrides and lactones with nucleophilic constituents of the reaction atmosphere e. g. methanol and H2O. Dynamic equilibria of surface oxides depending on reaction atmosphere and temperature were observed, and a methyl ester, formed by methanolysis of anhydrides and lactones, was identified as key intermediate for DME generation on oxidized carbon catalysts.

Enhanced H2O2 electrosynthesis on kneading oxidized carbon nanotubes

Electrochemical oxygen reduction reaction (ORR) via two-electron pathway is a viable method to produce hydrogen peroxide (H2O2). Here, oxidized carbon nanotubes (O-CNTs) rich in oxidized functional groups are obtained by rapid kneading oxidation within two hours. The optimal sample, O-CNTs-7, exhibits remarkable electrocatalytic performance for the H2O2 production under alkaline environment. The O-CNTs-7 shows a high onset potential of 0.74 V (vs. RHE), and could delivers up to 90% selectivity for H2O2 production over a wide voltage window (0.3 V to 0.7 V). In situ attenuated total reflection infrared (ATR-IR) spectroscopy show the certain relationship between potential and the adsorption behavior of *HOOH and *OOH, which confirm the associative two-electron pathway for O-CNTs-7. This study provides a general method to obtain highly oxidized carbon materials with abundant oxygen-containing groups towards highly efficient H2O2 electrosynthesis.

Long-Term Cycling Stability of Ni-Rich Li-Ion Batteries Cells Using the Encapsulation of Multifunctional Materials

Ni-rich cathode materials have been considered as a next-generation of the lithium-ion batteries, used for advanced applications such as electric vehicles. Although they have high specific capacities, the major drawbacks of these materials result in the obstacle of commercialization. In this work, the composite materials of high ionic-conductivity metal oxide and conductive carbon materials were coated on the surface of the Ni-rich cathode materials by mechano-fusion technique, forming the core@shell structure to protect the morphological instability, as well as the electrolyte decomposition. Also, the multi-functional shell elevates the Li-ion diffusion and ionic conductivity. Moreover, we firstly reported the novel formation protocol of cylindrical cell type lithium-ion battery (18650). As a result, the optimized 18650 Li-ion batteries show higher overall charge-storage performances.

Influence of different alumina powders on thermal decomposition of CNTs during debinding of CNT/Al2O3-composite ceramics

The influence of 12 different alumina powders on carbon nanotube (CNT) and polymer oxidation was investigated by means of thermogravimetric analysis of alumina based composites containing 3 wt% CNTs or other organic additives. The presented research shows that alumina powders, even if they have a purity of more than 99.75%, have a significant influence on the oxidation of carbon materials. The alumina affected temperature shift of the CNT-oxidation is up to 65 K. Particle size, pH-value, sodium-content and other impurities were characterized as important alumina properties influencing the carbon-oxidation. The findings from this investigation could help to determine optimal debinding temperatures for CNT/Al2O3-ceramics.The investigated catalytic effect of alumina powders on carbon-oxidation is fundamental for all types of alumina composites containing carbon materials like CNTs or organic additives.

Highly dispersed and stabilized Co3O4/C anchored on porous biochar for bisphenol A degradation by sulfate radical advanced oxidation process.

Cobalt oxide and porous carbon materials are desirable catalysts for peroxymonosulfate (PMS) advanced oxidation reaction in the degradation of organic pollutants. Herein, carbon-coated Co3O4 (Co3O4/C) mounted biochar (BC) composites (Co3O4/C-BC) with a three-dimensional spongy-like network were constructed by driving a dual-precursors of zeolitic imidazolate framework (ZIF-67) and Eichhornia crassipes. Considering the unique structures and compositions, the Co3O4/C-BC composites enhanced the dispersion of Co3O4/C nanoparticles, minimized the Co leaching, mediated the size of Co3O4/C nanoparticles, and enhanced the overall catalytic activity. Co3O4/C-BC effectively activated PMS for bisphenol A (BPA) degradation along with satisfactory reusability in advanced oxidation reaction. Electron paramagnetic resonance and radical quenching tests revealed that the generation and effect of sulfate and hydroxyl radicals in reaction process. This work not only provided a promising catalyst for the degradation of organic pollutants but also expanded BPA degradation pathway and PMS activation mechanism.

Recyclable catalysts for the synthesis of heterocyclic compounds using carbon materials

AbstractHeterogeneous catalytic reactions play a major role in the industry to produce a number of compounds that are essential in our daily life. Synthesis of heterocyclic compounds using heterogeneous catalysis is one of the rapidly growing research areas. Inherent ability to produce high selectivity and potentiality to recycle, the catalyst makes the heterogeneous systems more attractive, especially on the industrial scale. Various recyclable catalytic systems have been extensively developed for the synthesis of heterocyclic compounds via dehydration, partial oxidations, three‐component couplings, dehydrogenations, and others. Different supports like polymers, metal oxides, and quite recently carbon supports like carbon nanotubes (CNTs), graphene oxide (GO), graphitic nitride (GCN), and nitrogenous carbon materials (NGr) have been widely used to synthesize diverse heterocycles. The use of GO in the synthesis of heterocyclic compounds has been reviewed recently, hence we did not focus on GO in this review. The aim of this review article is to explore the emerging areas of carbon‐based heterogeneous materials such as CNTs, GCN, and NGr in the synthesis of heterocycles. This review also focused on the most recent examples, their preparation, and recycling studies of highly excited catalytic systems used for the heterocycles.

Fabrication of MOF-derivated CuOx-C electrode for electrochemical degradation of ceftazidime from aqueous solution

Antibiotic contamination has already been one of hazards to aquatic environment due to the abuse of antibiotics. Metal-organic frameworks (MOFs) are known as a kind of promising porous material for solving the environmental deterioration. In this article, the physicochemical and electrochemical properties of a series of porous copper oxide carbon materials (CuOx-C) synthesized by carbonizing Cu-BTC were compared. Due to the suitable carbonization temperature, CuOx-C-550 N, whose geometric structure was similar to Cu-BTC, possessed a multiscale pore structure containing many mesopores and partial macropores in accordance with the pore size distribution curves. More copper/copper oxides were introduced toimproving the electrochemical ability, evidence by XRD, XPS, CV and EIS characterization. Moreover, the degradation of ceftazidime (CAZ) through anodic oxidation was discussed. In AO/CuOx-C-550 N system, the effects of current, solution pH, initial CAZ concentration and Na2SO4 concentration were analyzed. CAZ removal rate reached 100% within 20 min under the optimal condition and a good electrocatalytic ability with 90% CAZ removal after 20 runs indicated a good electrochemical stability of CuOx-C-550 N. Furthermore, the degradation mechanism and pathway of CAZ were proposed. The Cu(II)/Cu(I) oxidation-reduction couples on the anodic surface contribute to the efficiently selective degradation of cephalosporins for CuOx-C-550 N. Overall, this study shows a good method to design and prepare a new MOF derivative for the remediation of aquatic contamination.

Synthesis strategies towards amorphous porous carbons with selective oxygen functionalization for the application as reference material

Manipulation of carbon surface functionalization and especially of oxygen surface groups has been demonstrated to be key for obtaining high performance materials in a multitude of applications. Although control of carbon surface chemistry offers large potential in many technical relevant applications, qualitative and quantitative analysis of surface oxides for amorphous and porous carbons remains challenging. In this study, we attempt selective, organic chemistry-based functionalization of a polymer-derived porous model carbon featuring high oxygen loadings, with the aim to establish analytical standards for temperature programmed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In this context, quantitative chemical reduction of an oxidized carbon material with lithium aluminum hydride (LiAlH4) is utilized as the key for the synthesis of carbon materials with defined ensembles of oxygen surface groups (hydroxyl groups and ethers). Based on this reduction strategy, selective LiAlH4 reduction based on protection group chemistry leads to aldehydes, ketones and quinones as surface functional groups and chemical grafting is studied for the selective introduction of phenyl esters, methyl ethers and carboxylic acids. All materials are evaluated with respect to the applicability as analytical standard by DRIFT spectroscopy, TPD, X-ray photoelectron spectroscopy and titration methods.

Building and identifying highly active oxygenated groups in carbon materials for oxygen reduction to H2O2

The one-step electrochemical synthesis of H2O2 is an on-site method that reduces dependence on the energy-intensive anthraquinone process. Oxidized carbon materials have proven to be promising catalysts due to their low cost and facile synthetic procedures. However, the nature of the active sites is still controversial, and direct experimental evidence is presently lacking. Here, we activate a carbon material with dangling edge sites and then decorate them with targeted functional groups. We show that quinone-enriched samples exhibit high selectivity and activity with a H2O2 yield ratio of up to 97.8 % at 0.75 V vs. RHE. Using density functional theory calculations, we identify the activity trends of different possible quinone functional groups in the edge and basal plane of the carbon nanostructure and determine the most active motif. Our findings provide guidelines for designing carbon-based catalysts, which have simultaneous high selectivity and activity for H2O2 synthesis.