Publications
364 results found
Xie F, Xu Z, Jensen ACS, et al., 2019, Hard–Soft Carbon Composite Anodes with Synergistic Sodium Storage Performance, Advanced Functional Materials, Vol: 0, Pages: 1901072-1901072
Abstract A series of hard–soft carbon composite materials is produced from biomass and oil waste and applied as low-cost anodes for sodium-ion batteries to study the fundamentals behind the dependence of Na storage on their structural features. A good reversible capacity of 282 mAh g−1 is obtained at a current density of 30 mA g−1 with a high initial Coulombic efficiency of 80% at a carbonization temperature of only 1000 °C by adjusting the ratio of hard to soft carbon. The performance is superior to the pure hard or soft carbon anodes produced at the same temperatures. This synergy between hard and soft carbon resulting in an excellent performance is due to the blockage of some open pores in hard carbon by the soft carbon, which suppresses the solid electrolyte interface formation and increases the reversible sodium storage capacity.
Schlee P, Hosseinaei O, Baker D, et al., 2019, From Waste to Wealth: From Kraft Lignin to Free-standing Supercapacitors, Carbon, Vol: 145, Pages: 470-480, ISSN: 0008-6223
© 2019 Elsevier Ltd Pure eucalyptus Kraft lignin derived carbon fiber mats were produced based on a model workflow. It covers the preparation and characterization of the lignin precursor and the carbon materials and its testing in the final application (supercapacitor). Sequential solvent extraction was employed to produce a eucalyptus Kraft lignin precursor which could be electrospun into lignin fibers without any additives. The fiber formation from low molecular weight lignin is assigned to strong intermolecular interactions via hydrogen bonding and π-π-stacking between individual lignin macromolecules which gives rise to association complexes in the electrospinning solution. By stabilization in air, carbonization in N 2 and an activation step in CO 2 , free-standing microporous carbon fiber mats could be produced. These fiber mats possess mainly basic oxygen functional groups which proved to be beneficial when tested as free-standing electrodes in symmetric supercapacitors. Consequently, the CO 2 -activated fiber mats showed a high specific gravimetric capacitance of 155 F/g at 0.1 A/g, excellent rate capability with 113 F/g at 250 A/g and good capacitance retention of 94% after 6000 cycles when tested in 6 M KOH electrolyte. Therefore, we conclude that lignin itself is a promising precursor to produce microporous, oxygen functionalized carbon fibers serving as free-standing electrodes in aqueous supercapacitors.
Wang T, Gao L, Hou J, et al., 2019, Rational approach to guest confinement inside MOF cavities for low-temperature catalysis, Nature Communications, Vol: 10, Pages: 1-9, ISSN: 2041-1723
Geometric or electronic confinement of guests inside nanoporous hosts promises to deliver unusual catalytic or opto-electronic functionality from existing materials but is challenging to obtain particularly using metastable hosts, such as metal–organic frameworks (MOFs). Reagents (e.g. precursor) may be too large for impregnation and synthesis conditions may also destroy the hosts. Here we use thermodynamic Pourbaix diagrams (favorable redox and pH conditions) to describe a general method for metal-compound guest synthesis by rationally selecting reaction agents and conditions. Specifically we demonstrate a MOF-confined RuO2 catalyst (RuO2@MOF-808-P) with exceptionally high catalytic CO oxidation below 150 °C as compared to the conventionally made SiO2-supported RuO2 (RuO2/SiO2). This can be caused by weaker interactions between CO/O and the MOF-encapsulated RuO2 surface thus avoiding adsorption-induced catalytic surface passivation. We further describe applications of the Pourbaix-enabled guest synthesis (PEGS) strategy with tutorial examples for the general synthesis of arbitrary guests (e.g. metals, oxides, hydroxides, sulfides).
Díez N, Qiao M, Gómez-Urbano JL, et al., 2019, High density graphene-carbon nanosphere films for capacitive energy storage, Journal of Materials Chemistry A, Vol: 7, Pages: 6126-6133, ISSN: 2050-7488
© 2019 The Royal Society of Chemistry. Highly packed films of reduced graphene oxide and sugar-based carbon nanospheres (CNSs) were prepared by a simple hydrothermal treatment. Under hydrothermal conditions, graphene oxide was partially reduced and self-assembled forming a monolith that effectively embedded the CNSs. The spheres were homogeneously distributed within the films, that had an apparent density of up to 1.40 g cm -3 . The films thus synthesized were directly assembled into a cell and tested as free-standing electrodes for supercapacitors without using any binder or conductive additive. Electrodes with a mass loading similar to that of commercial devices showed very high values of volumetric capacitance (252 F cm -3 ) and also an excellent rate capability (64% at 10 A g -1 ) despite their highly packed microstructure. The homogeneous dispersion of the nanospheres was responsible for the improved ion diffusion when compared to the CNS-free counterpart. The use of a small CNS/graphene wt ratio is essential for achieving such good rate capability without compromising its performance in volumetric terms.
Schlee P, Herou S, Jervis R, et al., 2019, Free-standing supercapacitors from Kraft lignin nanofibers with remarkable volumetric energy density, Chemical Science, Vol: 10, Pages: 2980-2988, ISSN: 2041-6520
© 2019 The Royal Society of Chemistry. We have discovered a very simple method to address the challenge associated with the low volumetric energy density of free-standing carbon nanofiber electrodes for supercapacitors by electrospinning Kraft lignin in the presence of an oxidizing salt (NaNO 3 ) and subsequent carbonization in a reducing atmosphere. The presence of the oxidative salt decreases the diameter of the resulting carbon nanofibers doubling their packing density from 0.51 to 1.03 mg cm -2 and hence doubling the volumetric energy density. At the same time, the oxidative NaNO 3 salt eletrospun and carbonized together with lignin dissolved in NaOH acts as a template to increase the microporosity, thus contributing to a good gravimetric energy density. By simply adjusting the process parameters (amount of oxidizing/reducing agent), the gravimetric and volumetric energy density of the resulting lignin free-standing carbon nanofiber electrodes can be carefully tailored to fit specific power to energy demands. The areal capacitance increased from 147 mF cm -2 in the absence of NaNO 3 to 350 mF cm -2 with NaNO 3 translating into a volumetric energy density increase from 949 μW h cm -3 without NaNO 3 to 2245 μW h cm -3 with NaNO 3 . Meanwhile, the gravimetric capacitance also increased from 151 F g -1 without to 192 F g -1 with NaNO 3 .
Qiao M, Ferrero GA, Fernández Velasco L, et al., 2019, Boosting the Oxygen Reduction Electrocatalytic Performance of Nonprecious Metal Nanocarbons via Triple Boundary Engineering Using Protic Ionic Liquids., ACS Appl Mater Interfaces
The oxygen reduction reaction (ORR) in aqueous media plays a critical role in sustainable and clean energy technologies such as polymer electrolyte membrane and alkaline fuel cells. In this work, we present a new concept to improve the ORR performance by engineering the interface reaction at the electrocatalyst/electrolyte/oxygen triple-phase boundary using a protic and hydrophobic ionic liquid and demonstrate the wide and general applicability of this concept to several Pt-free catalysts. Two catalysts, Fe-N codoped and metal-free N-doped carbon electrocatalysts, are used as a proof of concept. The ionic liquid layer grafted at the nanocarbon surface creates a water-equilibrated secondary reaction medium with a higher O2 affinity toward oxygen adsorption, promoting the diffusion toward the catalytic active site, while its protic character provides sufficient H+/H3O+ conductivity, and the hydrophobic nature prevents the resulting reaction product water from accumulating and blocking the interface. Our strategy brings obvious improvements in the ORR performance in both acid and alkaline electrolytes, while the catalytic activity of FeNC-nanocarbon outperforms commercial Pt-C in alkaline electrolytes. We believe that this research will pave new routes toward the development of high-performance ORR catalysts free of noble metals via careful interface engineering at the triple point.
Preuss K, Siwoniku AM, Bucur CI, et al., 2019, The Influence of Heteroatom Dopants Nitrogen, Boron, Sulfur, and Phosphorus on Carbon Electrocatalysts for the Oxygen Reduction Reaction, ChemPlusChem
© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim A hard templating method, using SBA-15 in combination with glucose solution and different heteroatom precursors, has been employed to investigate the influence of the different heteroatom dopants nitrogen, boron, sulfur, and phosphorus on carbon electrocatalysts for the oxygen reduction reaction. Samples were synthesized under the same conditions and resulted in a similar morphology and surface areas around 1000 m 2 /g. Incorporating nitrogen into the carbon matrix was found to be easier than for boron or phosphorus, while sulfur doping proved problematic and only yielded 2 at% of sulfur or less. Different dopant concentrations as well as a combination of dopants suggested that nitrogen was the only heteroatom exerting an actual influence on the catalytic activity, resulting in higher electron transfer numbers. The other dopants exhibited a similar performance regardless of the dopant content, though slightly improved when compared to an undoped control sample. These findings indicate that incorporated nitrogen can act as catalytic sites, while boron, sulfur and phosphorus can enhance the catalytic activity by possibly creating defects in the carbon matrix.
Liang Y, Zhao C-Z, Yuan H, et al., 2019, A review of rechargeable batteries for portable electronic devices, INFOMAT, Vol: 1, Pages: 6-32
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- Citations: 607
Herou S, Ribadeneyra MC, Madhu R, et al., 2019, Ordered mesoporous carbons from lignin: a new class of biobased electrodes for supercapacitors, GREEN CHEMISTRY, Vol: 21, Pages: 550-559, ISSN: 1463-9262
Rybarczyk MK, Li Y, Qiao M, et al., 2019, Hard carbon derived from rice husk as low cost negative electrodes in Na-ion batteries, JOURNAL OF ENERGY CHEMISTRY, Vol: 29, Pages: 17-22, ISSN: 2095-4956
Hu C, Lin Y, Connell JW, et al., 2019, Carbon-Based Metal-Free Catalysts for Energy Storage and Environmental Remediation, Advanced Materials, ISSN: 0935-9648
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Owing to their high earth-abundance, eco-friendliness, high electrical conductivity, large surface area, structure tunability at the atomic/morphological levels, and excellent stability in harsh conditions, carbon-based metal-free materials have become promising advanced electrode materials for high-performance pseudocapacitors and metal–air batteries. Furthermore, carbon-based nanomaterials with well-defined structures can function as green catalysts because of their efficiency in advanced oxidation processes to remove organics in air or from water, which reduces the cost for air/water purification and avoids cross-contamination by eliminating the release of heavy metals/metal ions. Here, the research and development of carbon-based catalysts in supercapacitors and batteries for clean energy storage as well as in air/water treatments for environmental remediation are reviewed. The related mechanistic understanding and design principles of carbon-based metal-free catalysts are illustrated, along with the challenges and perspectives in this emerging field.
Li A, 2019, Bridging the gap between Homogenous Heterogenous and Electro‐Catalysis: Iron‐nitrogen molecular complexes within carbon materials for catalytic applications, ChemCatChem, ISSN: 1867-3880
Qiao M, Titirici M-M, 2018, Engineering the Interface of Carbon Electrocatalysts at the Triple Point for Enhanced Oxygen Reduction Reaction, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 24, Pages: 18374-18384, ISSN: 0947-6539
Yuan H, Huang JQ, Peng HJ, et al., 2018, A Review of Functional Binders in Lithium–Sulfur Batteries, Advanced Energy Materials, Vol: 8, ISSN: 1614-6832
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Lithium–sulfur (Li–S) batteries have received tremendous attention due to their superior theoretical energy density of 2600 Wh kg −1 , as well as the abundance of sulfur resources and its environmental friendliness. Polymer binders as an indispensable component in cathodes play a critical role in maintaining the structural integrity and stability of electrodes. Additionally, multifunctional polymer binders have been involved in Li–S batteries to benefit electrochemical performance by mitigating the shuttle effect, facilitating the electron/ion transportation, and propelling the redox kinetics. In the context of the significant impact of binders on the performance of Li–S batteries, recent progress in research on polymer binders in sulfur cathodes is herein summarized. Focusing on the functions and effects of the polymer binders, the authors hope to shed light on the rational construction of robust and stable sulfur cathode for high-energy-density Li–S batteries. Perspectives regarding the future research opportunities in Li–S batteries are also discussed.
Yu M, Picot OT, Saunders TG, et al., 2018, Graphene-reinforced silicon oxycarbide composites prepared by phase transfer, CARBON, Vol: 139, Pages: 813-823, ISSN: 0008-6223
Ibrahim Abouelamaiem D, Mostazo-López MJ, He G, et al., 2018, New insights into the electrochemical behaviour of porous carbon electrodes for supercapacitors, Journal of Energy Storage, Vol: 19, Pages: 337-347
© 2018 The Authors Activated carbons, with different surface chemistry and porous textures, were used to study the mechanism of electrochemical hydrogen and oxygen evolution in supercapacitor devices. Cellulose precursor materials were activated with different potassium hydroxide (KOH) ratios, and the electrochemical behaviour was studied in 6 M KOH electrolyte. In situ Raman spectra were collected to obtain the structural changes of the activated carbons under severe electrochemical oxidation and reduction conditions, and the obtained data were correlated to the cyclic voltammograms obtained at high anodic and cathodic potentials. Carbon-hydrogen bonds were detected for the materials activated at high KOH ratios, which form reversibly under cathodic conditions. The influence of the specific surface area, narrow microporosity and functional groups in the carbon electrodes on their chemical stability and hydrogen capture mechanism in supercapacitor applications has been revealed.
Abouelamaiem DI, Rasha L, He G, et al., 2018, Integration of supercapacitors into printed circuit boards, JOURNAL OF ENERGY STORAGE, Vol: 19, Pages: 28-34, ISSN: 2352-152X
Ren M, Jia Z, Tian Z, et al., 2018, High Performance N-Doped Carbon Electrodes Obtained via Hydrothermal Carbonization of Macroalgae for Supercapacitor Applications, CHEMELECTROCHEM, Vol: 5, Pages: 2686-2693, ISSN: 2196-0216
Abouelamaiem DI, He G, Neville TP, et al., 2018, Correlating electrochemical impedance with hierarchical structure for porous carbon-based supercapacitors using a truncated transmission line model, Electrochimica Acta, Vol: 284, Pages: 597-608, ISSN: 0013-4686
© 2018 Elsevier Ltd This work considers the relationship between the morphology of porous carbon materials used for supercapacitors and the electrochemical impedance spectroscopy (EIS) response. EIS is a powerful tool that can be used to study the porous 3-dimensional electrode behavior in different electrochemical systems. Porous carbons prepared by treatment of cellulose with different compositions of potassium hydroxide (KOH) were used as model systems to investigate the form vs. electrochemical function relationship. A simple equivalent circuit that represents the electrochemical impedance behavior over a wide range of frequencies was designed. The associated impedances with the bulk electrolyte, Faradaic electrode processes and different pore size ranges were investigated using a truncated version of the standard transmission line model. The analysis considers the requirements of porous materials as electrodes in supercapacitor applications, reasons for their non-ideal performance and the concept of ‘best capacitance’ behavior in different frequency ranges.
Kong L, Yan C, Huang J-Q, et al., 2018, A Review of Advanced Energy Materials for Magnesium-Sulfur Batteries, ENERGY & ENVIRONMENTAL MATERIALS, Vol: 1, Pages: 100-112
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- Citations: 105
Volpe R, Menendes JB, Reina TR, et al., 2018, Chemical pathways in thermal decomposition of citrus waste via slow pyrolysis, 256th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nanoscience, Nanotechnology and Beyond, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Titirici M, 2018, Sustainable carbon materials from biopolymers for renewable energy, 256th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nanoscience, Nanotechnology and Beyond, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Yu M, Bernardo E, Colombo P, et al., 2018, Preparation and properties of biomorphic potassium-based geopolymer (KGP)-biocarbon (C<inf>B</inf>) composite, Ceramics International, Vol: 44, Pages: 12957-12964, ISSN: 0272-8842
© 2018 Anisotropic, biomorphic (wood-derived) potassium-based geopolymer (KGP) - biocarbon (CB) composites with net shape were manufactured by infiltrating KGP slurry into monolithic porous biocarbon (CB) structures (~77 vol% porosity) derived from pyrolyzing beech wood. About 70% of the pores in the three-dimensional (3D) CB structures were infiltrated by the KGP slurry. Compared to pure KGP, the energy absorption per unit volume in compression loading of the KGP-CB composites was increased by ten-fold. After heat treatment at 1000 °C for 1 h in N2, the compressive strength of the KGP-CB composites increased from ~7–24 MPa, accompanied by the formation of crystalline leucite (K2O·Al2O3·4SiO2) phase in the KGP. The KGP-CB composite also exhibited three orders higher electrical conductivity than pure KGP. The effect of temperature on the formation of crystalline phases in KGP and KGP-CB composites was investigated. FTIR, TGA and SEM analyses were used to investigate the changes in microstructures and phase formation during thermal treatment.
Preuss K, Qiao M, Titirici MM, 2018, Hydrothermal carbon materials for the oxygen reduction reaction, Carbon-Based Metal-Free Catalysts: Design and Applications, Pages: 369-401, ISBN: 9783527343416
As renewable energy resources become more popular, cost reduction and improved performance and stability play a decisive role in their widespread commercialization. One example is fuel cells, which can convert chemical energy into electricity with a high efficiency, but their cost due to the usage of platinum as a catalyst is still a limiting factor. Thus, the development of novel materials, ideally metal-free, as alternatives to platinum is a crucial factor. Hydrothermal carbonization presents a promising and inexpensive approach to convert any kind of biomass or biowaste into useful carbon materials for various applications. This approach provides materials with tunable surface areas, pore properties, and dopants via an easy one-pot synthesis. Based on this process, new metal-free materials are presented from different starting materials as well as in combination with graphene and carbon nanotubes.
Wang H-F, Chen R, Feng J, et al., 2018, Freestanding Non-Precious Metal Electrocatalysts for Oxygen Evolution and Reduction Reactions, CHEMELECTROCHEM, Vol: 5, Pages: 1786-1804, ISSN: 2196-0216
Butt MTZ, Preuss K, Titirici MM, et al., 2018, Biomass-derived nitrogen-doped carbon aerogel counter electrodes for dye sensitized solar cells, Materials, Vol: 11
© 2018 by the authors. Dye sensitized solar cells have emerged as an attractive alternative to conventional solar cells due to their easy processing and the abundance and low cost of their materials. However, the counter electrode in these cells employs platinum which significantly impacts their cost. Here, we report biomass-derived, nitrogen-doped carbon aerogel as an effective alternative to conventional platinum-based counter electrodes for dye sensitized solar cells. A stable suspension of biomass-derived, nitrogen-doped carbon aerogel was prepared in DMF by using oleylamine as a binder. The nitrogen-doped carbon aerogel electrode was annealed at different temperatures, and its impact on photovoltaic performance is investigated. I-V measurements confirm that the annealing temperature substantially enhances the photovoltaic parameters of these devices; these enhancements are linked to the removal of the organic binders. Electrochemical impedance spectra of the counter electrodes confirm that removal of oleylamine in nitrogen-doped carbon aerogels reduces the series resistance of the resulting electrodes. The power conversion efficiency of the solar cells from optimized nitrogen-doped carbon aerogel exhibited comparable efficiency to that of a cell fabricated using a platinum-based counter electrode. This study demonstrates the potential of biomass-derived carbon aerogels as a cheap and sustainable replacement of platinum in DSSCs.
Zhang DW, Papaioannou N, David NM, et al., 2018, Photoelectrochemical response of carbon dots (CDs) derived from chitosan and their use in electrochemical imaging, Materials Horizons, Vol: 5, Pages: 423-428, ISSN: 2051-6347
©The Royal Society of Chemistry 2018. We report a direct photoelectrochemical response from low cost carbon dots (CDs) prepared from chitosan via a solvothermal method. The carbon dots were covalently linked to an indium tin oxide (ITO) surface through a self-assembled silane monolayer. We attribute the photocurrent of the ITO-silane-CD surface to a photogenerated electron-transfer process by CDs under illumination with a wavelength of 420 nm to 450 nm. The self-assembled monolayer of CDs was used for ac-photocurrent imaging of the surface with micron scale lateral resolution. This discovery opens up new applications for CDs as biocompatible, light-addressable electrochemical sensors in bioanalytical and bioimaging applications.
Papaioannou N, Marinovic A, Yoshizawa N, et al., 2018, Structure and solvents effects on the optical properties of sugar-derived carbon nanodots, SCIENTIFIC REPORTS, Vol: 8, ISSN: 2045-2322
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- Citations: 99
Qiao M, Meysami SS, Alvarez Ferrero G, et al., 2018, Low-Cost Chitosan-Derived N-Doped Carbons Boost Electrocatalytic Activity of Multiwall Carbon Nanotubes, ADVANCED FUNCTIONAL MATERIALS, Vol: 28, ISSN: 1616-301X
Rybarczyk MK, Gontarek E, Lieder M, et al., 2018, Salt melt synthesis of curved nitrogen-doped carbon nanostructures: ORR kinetics boost, APPLIED SURFACE SCIENCE, Vol: 435, Pages: 543-551, ISSN: 0169-4332
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