Nanocarbon Composites Research Articles

Two-dimensional architecture of N,S-codoped nanocarbon composites embedding few-layer MoS2 for efficient lithium storage.

The exploration and advancement of highly efficient anode materials for lithium-ion batteries (LIBs) are critical to meet the growing demands of the energy storage market. In this study, we present an easily scalable synthesis method for the one-pot formation of few-layer MoS2 nanosheets on a N,S dual-doped carbon monolith with a two-dimensional (2D) architecture, termed MoS2/NSCS. Systematic electrochemical measurements demonstrate that MoS2/NSCS, when employed as the anode material in LIBs, exhibits a high capacity of 681 mA h g-1 at 0.2 A g-1 even after 110 cycles. The exceptional electrochemical performance of MoS2/NSCS can be attributed to its unique porous 2D architecture. The few-layer MoS2 sheets with a large interlayer distance reduce ion diffusion pathways and enhance ion mobility rates. Additionally, the N,S-doped porous carbon matrix not only preserves structural integrity but also facilitates electronic conductivity. These combined factors contribute to the reversible electrochemical activities observed in MoS2/NSCS, highlighting its potential as a promising anode material for high-performance LIBs.

Nitrogen and sulphur co-doped carbon-based composites as electrocatalysts for the anion-exchange membrane fuel cell cathode

Nitrogen and sulphur co-doped nanocarbon composites based on silicon carbide-derived carbon (SiCDC), carbon nanotubes (CNT) and/or mesoporous carbon (MPC) are prepared for oxygen reduction reaction (ORR) and anion-exchange membrane fuel cell (AEMFC) studies. Thiosemicarbazide is used as nitrogen and sulphur doping agent. The rotating ring-disc electrode (RRDE) measurements exhibit good electrocatalytic activity towards the ORR for all the prepared catalysts in alkaline solution. Obtained materials are rich in pyridinic-N and consist of thiophene-S, which could improve the ORR performance due to the synergistic effect of N and S. Textural properties, including specific surface area (SSA) and porosity parameters are different amongst the three studied N,S-doped nanocomposite materials, which also affect the outcome of AEMFC test results. In AEMFC testing using Aemion+ (AF2-HLE8-10-X, 10 μm) anion-exchange membrane, N,S-SiCDC/MPC (with SSAdft = 952 m2 g−1) shows the highest performance with the peak power density (Pmax) of 379 mW cm–2. This result is comparable with the performance of Pt/C catalyst in AEMFC (Pmax = 347 mW cm–2), making N,S-doped nanocomposite materials promising cathode catalyst for AEMFCs.

Core-Shell-Structured Electrorheological Fluid with a Polarizability-Tunable Nanocarbon Shell for Enhanced Stimuli-Responsive Activity.

The incorporation of nanocarbon-based materials into electrorheological fluids has been shown to be an effective means of improving the electrorheological (ER) response. However, the mechanism of the sp2/sp3-hybridized carbon structure and high ER response is still under investigation. Herein, barium titanate@nanocarbon shell (BTO@NCs) composites are proposed and prepared by introducing carbonized polydopamine (C-PDA) into a shell. When the polymerization time of dopamine is tuned, the shell thickness, surface polar functional groups, and sp2/sp3-hybridized carbon can be effectively controlled. The maximum yield stress of the BTO@NCs-24 h ER fluid reaches 2.5 kPa under an electric field of 4 kV mm-1, which is attributed to the increased content of sp3 C-OH and oxygenous functional groups within the shell, resulting in a rapidly achievable polarization. Furthermore, the SiO2@NCs and TiO2@NCs ER fluids are also prepared with enhanced ER behavior in these phenomena, confirming an approach to high-performance ER fluids based on nanocarbon composites.

Highly Ecofriendly Inorganic Pesticide Based on TiO2 Incorporated with Nano-Carbon Composites for Phytophthora palmivora Fungus Disinfection.

The online version contains supplementary material available at 10.1007/s12088-023-01076-7.

High-Capacitance γ-rGO/MXene Cathode and Rapid Na+-Transfer Dynamics Sodium Titanate Anode for a Quasi-Solid-State Sodium-Ion Capacitor

Sodium-ion capacitors (SICs) bear the advantages of secondary batteries and supercapacitors and are regarded as promising energy-storage devices. However, the matching of the respective Na+-transfer kinetics of the anode and the cathode and the low energy density are still a challenge. Herein, to achieve a high-capacity cathode, 2D V2C MXene nanosheets were introduced into γ-ray-reduced graphene oxide (γ-rGO), and the γ-rGO/V2C MXene foam (GMF) was fabricated. The GMF provides a high specific capacitance of 391.4 mF cm–2 (130.5 F g–1) at a high current density of 60 mA cm–2 (20 A g–1). Meanwhile, the structure-directing strategy combining multiple nanocarbon composites accelerates the Na+-transfer kinetics of sodium titanate (NTO). The as-fabricated CNT film-supported sodium titanate nanowires encapsulated by the graphene (CNTF@NTO-G) anode deliver a specific capacity of 109 mA h g–1 at a high current density of 10 A g–1. As a result, the assembled quasi-solid-state SIC displays an energy density of 5.61 mW h cm–3 (56.1 W h kg–1) at a power density of 1 W cm–3 (10 kW kg–1) with excellent cycle stability (87.3% capacitance retention after 10,000 cycles).

A review article on application of ZnO-based nanocomposite materials in environmental remediation

ZnO is an intriguing material for photocatalysis applications because of its high rate of charge carrier recombination activity, ease of availability of raw materials, low manufacturing costs, and non-toxic nature. Depending on the preparation process and their conditions, a variety of Zinc Oxide (ZnO) nano and microstructures can be generated. As a result, the creation of ZnO–nanocarbon composites have proven to be a promising option for developing novel, more active as well as stable photocatalytic systems. Other metallic and carbon-based with well 2-D materials with good physical and chemical properties, could be attractive choices to hybridise with ZnO. This review examines recent developments in ZnO–based nanocomposites, focusing on synthesis methods as well as structural, morphological, etc. We also look at how photocatalytic degradation of organic and inorganic dye is affected by ZnO- based composites.

Probe-Integrated Label-Free Electrochemical Immunosensor Based on Binary Nanocarbon Composites for Detection of CA19-9.

Convenient and sensitive detection of tumor biomarkers is crucial for the early diagnosis and treatment of cancer. Herein, we present a probe-integrated and label-free electrochemical immunosensor based on binary nanocarbon composites and surface-immobilized methylene blue (MB) redox probes for detection of carbohydrate antigen 199 (CA19-9), which is closely associated with gastric malignancies. Nanocarbon composites consisting of electrochemically reduced graphene oxides and carbon nanotubes (ErGO-CNT) are electrodeposited onto an indium tin oxide (ITO) electrode surface to form a 3D nanocomposite film, which could provide high surface area to immobilize abundant MB probes, facilitate the electron transfer of MB, and therefore, improve sensitivity. Polydopamine (PDA) served as a bifunctional linker is able to immobilize anti-CA19-9 antibodies and stabilize the inner probe, conferring the sensing interface with specific recognition capacity. Electrochemical detection of CA19-9 is achieved based on the decrease of the redox signal of MB after specific binding of CA19-9 with a wide linear range of 0.1 mU/mL to 100 U/mL and a limit of detection (LOD) of 0.54 nU/mL (S/N = 3). The constructed electrochemical immunosensor has good selectivity, repeatability, reproducibility, and stability. Furthermore, determination of CA19-9 in human serum samples is also realized.

(Digital Presentation) Recovery of Copper from Wastewater By Electrodeposition Onto Nanocarbon Composites

The connection of carbon nanostructures such as graphene or carbon nanotubes with other materials like metals [1] or polymers [2] is often beneficial. For example, composites consisting of copper and nanocarbon materials have improved electrical [1] and mechanical [3] properties due to the synergy effect. Unfortunately, the integration between copper and nanocarbon is not an easy task because of the “cuprophobic” nature of nanocarbon [4]. Recently, many methods have been developed to accomplish this challenge. Out of all available techniques, physical (casting, spark plasma sintering or metal spinning) and electrochemical [5] gained a considerable share of attention. In particular, electrodeposition is a commonly employed strategy to deposit copper onto nanocarbon electrodes. In this method, nanocarbon surface plays the role of working electrode, onto which copper ions are reduced, thereby creating a Cu coating on the surface.This study demonstrates the recovery of copper from industrial wastewater by thin films based on carbon nanotubes (CNTs). Such a substrate was found as an ideal surface for the electrodeposition of metallic particles. Single/multi-walled CNTs, oxidized CNTs, nitrogen-doped CNTs and graphene were combined to obtain nanocarbon-nanocarbon composite electrodes, which were then used as substrates in Cu electrodeposition [6].To establish the coating process parameters, synthetic solution of CuSO4 was first used as a source of copper ions. Then, wastewater of complex composition was employed directly for the electrodeposition process. Besides the 40 ppm of Cu, the wastewater contained other elements like salts Fe, Mg, Al, Zn and As in much greater amounts. It was discovered that such nanocomposite materials may be an excellent substrate for electrochemical recovery of Cu also from such a problematic waste, while simultaneously giving a product of high added value. Interestingly, the product was free from other metals, and only copper was detected on the nanocarbon surface. After just 1-hour of electrodeposition at -0.1V vs. SCE, a nanocarbon-based composite evenly coated with Cu was manufactured. Thorough investigation of the microstructure, and chemical composition of the nanocomposites correlated with the properties of the Cu coated materials enabled us to deduce critical parameters needed to make the Cu coating process effective [7].[1] C. Arnaud, F. Lecouturier, D. Mesguich, N. Ferreira, G. Chevallier, C. Estournès, A. Weibel, C. Laurent, High strength - High conductivity double-walled carbon nanotube - Copper composite wires, Carbon N. Y. 96 (2016) 212–215. doi:10.1016/j.carbon.2015.09.061.[2] S.N. Beesabathuni, J.G. Stockham, J.H. Kim, H.B. Lee, J.H. Chung, A.Q. Shen, Fabrication of conducting polyaniline microspheres using droplet microfluidics, RSC Adv. 3 (2013) 24423–24429. doi:10.1039/c3ra44808h.[3] R. Jiang, X. Zhou, Q. Fang, Z. Liu, Copper-graphene bulk composites with homogeneous graphene dispersion and enhanced mechanical properties, Mater. Sci. Eng. A. 654 (2016) 124–130. doi:10.1016/j.msea.2015.12.039.[4] D. Janas, B. Liszka, Copper matrix nanocomposites based on carbon nanotubes or graphene, Mater. Chem. Front. 2 (2018) 22–35. doi:10.1039/c7qm00316a.[5] A. Singh, T. Ram Prabhu, A.R. Sanjay, V. Koti, An Overview of Processing and Properties of CU/CNT Nano Composites, Mater. Today Proc. 4 (2017) 3872–3881. doi:10.1016/J.MATPR.2017.02.286.[6] D. Janas, M. Rdest, K.K.K. Koziol, Free-standing films from chirality-controlled carbon nanotubes, Mater. Des. 121 (2017) 119–125. doi:10.1016/j.matdes.2017.02.062.[7] G. Stando, P.-M. Hannula, B. Kumanek, M. Lundström, D. Janas, Copper recovery from industrial wastewater - Synergistic electrodeposition onto nanocarbon materials, Water Resour. Ind. 26 (2021) 100156. doi:10.1016/J.WRI.2021.100156.G.S. and P.S. would like to thank the Ministry of Science and Higher Education of Poland for financial support of research (under Diamond Grant, grant agreement 0036/DIA/201948). G.S. also would like to thank European Union for thanks for financing the costs of the conference (European Social Fund, grant nr POWR.03.05.00-00-Z305) and National Agency for Academic Exchange of Poland (under the Iwanowska program, grant agreement PPN/IWA/2019/1/00017/UO/00001) for financial support during the stay at the University of Pittsburgh in the USA. G.S. and H.L. acknowledge NSF (CBET-2028826) for partial support of this work. G. S. and D.J. acknowledge the National Agency for Academic Exchange of Poland (under the Academic International Partnerships program, grant agreement PPI/APM/2018/1/00004) for supporting training in the Aalto University. G.S, B.K. and D.J. would like to thank the National Centre for Research and Development, Poland (under the Leader program, grant agreement LIDER/0001/L-8/16/NCBR/2017).

An ultra-sensitive kaempferol electrochemical sensor based on flower-like ZIF-8 pyrolysis-derived ZnWO4/porous nanocarbon composites

Kaempferol (KA), an important polyphenolic compound, is able to combat a variety of inflammatory diseases. Here, a ZnWO4 / porous nanocarbon based electrochemical sensor has been constructed to detect KA for the first time. Innovatively, ZnWO4 has been synthesized by pyrolysis using ZIF-8 as a zinc source, while porous nanocarbon was introduced. The nanocomposites have been characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy and demonstrated that Acidified ZnWO4/porous nanocarbon has been successfully prepared. Notably, the excellent catalytic properties of ZnWO4 and the great enrichment ability and conductivity of porous nanocarbon greatly enhanced the detection performance of the sensor for KA with a linear range of 0.009–0.7 μM and a LOD of 2.03 nM. In addition, the sensor has obtained satisfactory results for the detection of KA in actual natural samples (broccoli and kaempferia powder). The reaction sites and redox mechanism of KA were shown by density functional theory. Finally, the sensor is highly sensitive and stable, making it a novel detection method with extremely high potential applications.

Effect on kinetics and energy distribution of riboflavin adsorption from magnetic nano-carbon composites with adsorbed water layer

As a precursor of vitamin B2 (riboflavin), it supports cellular biochemistry activities in living organisms. This study aims to investigate an effect of adsorbed water layer on absorbance of riboflavin in water solution. A radio of 3:1 Fe3O4/MCNT was chosen as raw material, ball-milling method was used to prepare the adsorbents. According to XPS (X-ray photoelectron spectroscopy) results, the adsorbed water layer of the 5 wt% sample was significantly recognized; it can dramatically impact adsorption kinetic and average site energy of riboflavin. The results showed that the best absorbance behaviour of 5 wt% adsorbent is better than the sample of 30 wt% and dried absorbents; the thermodynamics and dynamics models fit well in the Langmuir-Fredrich model and Pseudo-second-order model. It indicated that the adsorbed water layer could change adsorption energy distribution and increase adsorption capacity. This is because oxygen has different chemical states in the adsorbents from different water contents. The main mechanisms are enhanced π-π interaction and hydrogen bond interaction, and it could be affected by the adsorption water molecular, so appropriate water molecular regulation increases adsorption capacity. It means a potential new separation approach with the help of a simple mechanical ball milling and moisture control could improve the adsorption behavior.

Porous Ultrahigh Molecular Weight Polyethylene/Functionalized Activated Nanocarbon Composites with Improved Biocompatibility.

Ultrahigh molecular weight polyethylene (UHMWPE) materials have been prevalent joint replacement materials for more than 45 years because of their excellent biocompatibility and wear resistance. In this study, functionalized activated nanocarbon (FANC) was prepared by grafting maleic anhydride polyethylene onto acid-treated activated nanocarbon. A novel porous UHMWPE composite was prepared by incorporating the appropriate amount of FANC and pore-forming agents during the hot-pressing process for medical UHMWPE powder. The experimental results showed that the best prepared porous UHMWPE/FANC exhibited appropriate tensile strength, porosity, and excellent hydrophilicity, with a contact angle of 65.9°. In vitro experiments showed that the porous UHMWPE/FANC had excellent biocompatibility, which is due to its porous structure and hydrophilicity caused by FANC. This study demonstrates the potential viability for our porous UHMWPE/FANC to be used as cartilage replacement material for biomedical applications.

Synthesis, Characterization, and Photocatalytic Performance of ZnO–Graphene Nanocomposites: A Review

ZnO is an exciting material for photocatalysis applications due to its high activity, easy accessibility of raw materials, low production costs, and nontoxic. Several ZnO nano and microstructures can be obtained, such as nanoparticles, nanorods, micro flowers, microspheres, among others, depending on the preparation method and conditions. ZnO is a wide bandgap semiconductor presenting massive recombination of the generated charge carriers, limiting its photocatalytic efficiency and stability. It is common to mix it with metal, metal oxide, sulfides, polymers, and nanocarbon-based materials to improve its photocatalytic behavior. Therefore, ZnO–nanocarbon composites formation has been a viable alternative that leads to new, more active, and stable photocatalytic systems. Mainly, graphene is a well-known two-dimensional material, which could be an excellent candidate to hybridize with ZnO due to its excellent physical and chemical properties (e.g., high specific surface area, optical transmittance, and thermal conductivity, among others). This review analyses ZnO–graphene nanocomposites’ recent advances, addressing the synthesis methods and the resulting structural, morphological, optical, and electronic properties. Moreover, we examine the ZnO–graphene composites’ role in the photocatalytic degradation of organic/inorganic pollutants.

Anionic oxygen vacancies in Nb2O5-/carbon hybrid host endow rapid catalytic behaviors for high-performance high areal loading lithium sulfur pouch cell

Oxygen-vacant niobium oxide electrocatalyst on a high-conductive hierarchical porous nanocarbon (AOV-Nb 2 O 5- x @HHPC) composites is developed as the sulfur species catalyzer and lithium ion accelerator by forming the Nb-S bonds. The as-prepared sulfur cathode shows excellent rate and cycling capability. Even under 4.2 mg cm −2 and lean electrolyte/sulfur ratio, the pouch cell delivers a high areal capacity retention and stabilizes for several tens of cycles. • Oxygen-vacant niobium oxide electrocatalyst is developed as the sulfur species catalyzer and lithium ion accelerator. • Theoretical simulations and electrochemical results reveal the catalytic effect is realized by forming the Nb-S bonds. • The as-prepared sulfur cathode shows excellent rate and cycling capability. • With lean electrolyte, the high-mass-loading pouch cell delivers a high areal capacity retention. The development of lithium/sulfur batteries has been hindered by notorious shuttling effect and sluggish electrochemical conversion kinetics owing to high barrier of lithium ion transport behaviors. In this work, anionic oxygen vacancies in niobium oxide nanoparticle is fabricated on a high-conductive hierarchical porous nanocarbon as a sulfur anchor and lithium ion accelerator. As evidenced by optical coloration and electrochemical measurements, the oxygen-deficient electrocatalyst shows much stronger interaction ability to polysulfides and endows superior catalytic ability of propelling ion kinetics and facilitating the precipitation of Li 2 S. Theoretical simulations have also revealed that Nb-S bonds are formed when polysulfides interacts with AOV-Nb 2 O 5- x catalyst. Consequently, the as-prepared sulfur cathode exhibits a high initial capacity of 1489 mA h g −1 , corresponding to the theoretical utilization of 89%, and a long life for 600 cycles at 1 C. Enhancing current rate to 5 C, a rate capacity of 899 mA h g −1 is obtained, demonstrating rapid conversion kinetics. Impressively, even increasing the areal loading to 4.2 mg cm −2 with the lean electrolyte, the pouch cell can still exhibit the initial areal capacity of 3.54 mA h cm −2 at 0.343 mA cm −2 and stabilize for several tens of cycles, providing the promise for fast-charge batteries.

Electrocatalysts Based on Cobalt- and Nitrogen-Doped Nanocarbon Composites for Oxygen Reduction Reaction and Anion Exchange Membrane Fuel Cells

With an increasing energy demand, there is a need for renewable energy conversion devices. Among the possible options are low temperature polymer electrolyte fuel cells, in which electrocatalysts play vital roles, especially on the cathode, where the oxygen reduction reaction (ORR) occurs. The most efficient electrocatalysts for the ORR are based on noble metals, mainly platinum, which however have various disadvantages including their high price and scarcity. As a replacement, different transition metal-nitrogen-carbon (M−N−C) catalyst materials have shown great promise.1,2 Herein, a composite of nanocarbons, namely carbide-derived carbon/carbon nanotube (CDC/CNT), is employed as a support to produce the M−N−C type of catalysts. This composite offers a novel catalyst structure in which both micro- and mesopores are present that can be beneficial for the anion exchange membrane fuel cell (AEMFC) application. The doping was done via pyrolysis at 800 °C in the presence of a cobalt salt and a nitrogen precursor (either dicyandiamide, urea or melamine).3 The catalysts were characterized using different physico-chemical methods (e.g. SEM, TEM, XPS, XRD, Raman spectroscopy, and N2 adsorption), which proved the success of doping as well as the feasible micro- and mesoporous structure with defects present. Both the RDE and RRDE methods were employed for the electrochemical testing and in alkaline medium all three catalyst materials exhibited similar and good electrocatalytic activity for the ORR. The half-wave potential for ORR of Co-N-CDC/CNT catalysts was close to that of a Pt/C catalyst (Figure 1, left). The possible application of the Co-N-CDC/CNT material was tested out by employing it as a cathode catalyst in AEMFC. The Co-N-CDC/CNT catalyst together with a novel HMT-PMBI4 membrane exhibited excellent performance with peak power density of 577 mW cm–2, which was significantly higher than that obtained with a Pt/C cathode (Figure 1, right). This shows that the Co-N-CDC/CNT materials are promising cathode catalysts for the AEMFC application.3 References A. Sarapuu, E. Kibena-Põldsepp, M. Borghei, and K. Tammeveski, J. Mater. Chem. A, 6, 776-804 (2018).G. Wu, A. Santandreu, W. Kellogg, S. Gupta, O. Ogoke, H. Zhang, H. L. Wang, and L. Dai, Nano Energy, 29, 83−110 (2016).J. Lilloja, E. Kibena-Põldsepp, A. Sarapuu, M. Kodali, Y. Chen, T. Asset, M. Käärik, M. Merisalu, P. Paiste, J. Aruväli, A. Treshchalov, M. Rähn, J. Leis, V. Sammelselg, S. Holdcroft, P. Atanassov, and K. Tammeveski, ACS Appl. Energy Mater., 2020, (DOI: 10.1021/acsaem.0c00381)A. G. Wright, J. T. Fan, B. Britton, T. Weissbach, H. F. Lee, E. A. Kitching, T. J. Peckham, and S. Holdcroft, Energy Environ. Sci., 9, 2130-2142 (2016). Figure 1

Electrical and structural characterization of nano-carbon–aluminum composites fabricated by electro-charging-assisted process

Incorporating nano-carbon phases into metal-matrix composites is a promising strategy for simultaneously enhancing electrical conductivity and mechanical properties of metals. Here, we describe the manufacture of novel nano-carbon-aluminum composites by an electro-charging-assisted process (EAP) that show 5.6% ± 1.7% increase in electrical conductivity compared to the base metal alloy. The source of nano-carbon that was used in this study is activated carbon with particle size less than 100 nm. The enhancement is attributed to nano-graphitic structures that extend through the lattice of the metal. Through electron transfer from the metal to the nano-structures the electron density at the interface of nano-crystalline graphite and the metal lattice increases thereby enhancing the bulk electrical conductivity. We identify the important fabrication parameters of the EAP for a reaction system employing a tapered graphite cathode. A high current density of 100 A/cm2 causes ionization and crystallization of the carbon in the liquid metal. The increase in electrical conductivity of the composite is directly related to the incorporation of the nanocrystalline carbon in the metal lattice. The superior performance of these nano-carbon aluminum composites makes them promising candidates for power transmission lines and other applications.

Tunable mechanical behavior of graphene nanoribbon-metal composites fabricated through an electrocharge-assisted process

This work investigates the role of a carbon nanophase on the local mechanical behavior of nano-carbon metal composites (NCMCs) produced through an electrocharge-assisted process. Nanoindentation experiments on single crystal Al, Al 1350 parent alloys, and Al 1350 NCMCs revealed variable mechanical properties, caused by an interplay between microstructure and graphitic reinforcements. TEM and AFM studies also reveal nanoscale structural changes based on the incorporation of a carbon nanophase. In order to decouple the effects of the aforementioned mechanical behaviors, molecular dynamics nanoindentation simulations were performed on the (111) surface of Al and Al NCMC samples containing semi-infinite graphene nanoribbons to examine the evolution of plasticity over time. Findings indicate that the arrangement of a finite graphene nanophase within a host matrix can alter plasticity mechanisms and therefore yield strength in near-surface mechanical behaviors with little effect on elastic properties. This understanding should enable further study into tunable bulk properties of Al-based NCMCs while isolating microstructural effects and reinforcement effects of the carbon phase. Such an understanding could lead to application-specific material geometries ranging from high-performing vehicle structures to next-generation electrical devices.

Ascorbic Acid Fuel Cells Using Nano Carbon and Conducting Polymer Composites for Anode and Paper for Separator

Performances of direct ascorbic acid fuel cells using anodes of nano carbons (SWCNT, graphene, C60) and their composites with conducting polymers were studied. The output power using polyaniline@SW...

Cathode Catalysts Based on Cobalt- and Nitrogen-Doped Nanocarbon Composites for Anion Exchange Membrane Fuel Cells

Cobalt- and nitrogen-doped carbide-derived carbon/carbon nanotube (CDC/CNT) composites are prepared and used as oxygen reduction reaction (ORR) electrocatalysts for an anion exchange membrane fuel ...

Revealing the structure of composite nanodiamond–graphene oxide aqueous dispersions by small-angle scattering

The work presents the results of studying the structure of binary liquid nanocarbon systems obtained by mixing hydrosol of detonation nanodiamond and aqueous dispersions of single layer graphene oxide flakes. We studied size and space distribution of nanocarbon clusters formed upon interaction of the components in aqueous media by mutually complement methods of small-angle X-ray and neutron scattering. The formation of small secondary agglomerates of nanodiamond particles on the surface of graphene oxide flakes was concluded and supported by the data of transmission electron microscopy from dried samples. The observed effect can significantly modify the structure of nanocarbon composites formed of nanodiamond and graphene oxide. The structural features of binary dispersions detonation nanodiamond–graphene oxide should be taken into account at the preparation of the conductive composites of reduced graphene oxide for energy storage systems.

Insights into the active sites and catalytic mechanism of oxidative esterification of 5-hydroxymethylfurfural by metal-organic frameworks-derived N-doped carbon

Directly oxidative esterification of Biomass-derived 5-hydroxymethylfurfural (HMF) into dimethyl furan dicarboxylate (DMFDCA) is a promising route for the replacement of petroleum-derived commodity chemical terephthalic acid (TPA) extensively employed in polyester synthesis. Co-based N-doped carbon materials are one of the most promising applied catalysts for oxidative esterification reaction, however, the active sites and reaction pathway of these catalysts have not been clearly clarified, which is crucial to the practical application. Herein, we report that ZIF-67 (a zeolitic imidazolate framework (ZIF)-type cobalt-containing MOF) derived Co@C-N material is a highly effective catalyst for the selective conversion of HMF into DMFDCA in 95% yield. The high activity of the ZIF-67 derived nanocarbon composites Co@C-N can be attributed to the electron transfer between nitrogen-doped carbon shells and Co nanoparticles. The appropriate graphitic N and pyridinic N doping increases the electronic mobility and active sites. Density functional theory (DFT) simulations indicated that oxygen, HMF and methanol molecules are adsorbed and activated on C-N materials. Furthermore, no 2, 5-diformylfuran (DFF) was captured as an intermediate because the oxidative esterification of aldehyde preferentially occurred than the oxidation of hydroxyl group in HMF. We anticipate that these results can drive progress in the bio-based polymers sector and oxidative esterification reaction.