Superfast Synthesis of Carbon Xerogels
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PROVIDER: S-EPMC10701873 | biostudies-literature | 2023 Nov
REPOSITORIES: biostudies-literature
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Project description:Carbon xerogels with different macropore sizes and degrees of graphitization were evaluated as electrodes in lithium-ion batteries. It was found that pore structure of the xerogels has a marked effect on the degree of graphitization of the final carbons. Moreover, the incorporation of graphene oxide to the polymeric structure of the carbon xerogels also leads to a change in their carbonaceous structure and to a remarkable increase in the graphitic phase of the samples studied. The sample with the highest degree of graphitization (i.e., hybrid graphene-carbon xerogel) displayed the highest capacity and stability over 100 cycles, with values even higher than those of the commercial graphite SLP50 used as reference.
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Project description:L-asparaginase (ASNase) is an aminohydrolase currently used in the pharmaceutical and food industries. Enzyme immobilization is an exciting option for both applications, allowing for a more straightforward recovery and increased stability. High surface area and customizable porosity make carbon xerogels (CXs) promising materials for ASNase immobilization. This work describes the influence of contact time, pH, and ASNase concentration on the immobilization yield (IY) and relative recovered activity (RRA) using the Central Composite Design methodology. The most promising results were obtained using CX with an average pore size of 4 nm (CX-4), reaching IY and RRA of 100%. At the optimal conditions (contact time 49 min, pH 6.73, and [ASNase] 0.26 mg·mL-1), the ASNase-CXs biocomposite was characterized and evaluated in terms of kinetic properties and operational, thermal, and pH stabilities. The immobilized ASNase onto CX-4 retained 71% of its original activity after six continuous reaction cycles, showed good thermal stability at 37 °C (RRA of 91% after 90 min), and was able to adapt to both acidic and alkaline environments. Finally, the results indicated a 3.9-fold increase in the immobilized ASNase affinity for the substrate, confirming the potential of CXs as a support for ASNase and as a cost-effective tool for subsequent use in the therapeutic and food sectors.
| S-EPMC9264400 | biostudies-literature
Project description:Monolithic carbon xerogels with hierarchical porosity were prepared from resorcinol (R) and formaldehyde (F) via a base-catalysed hydrothermal polycondensation reaction, without a template and supercritical drying. First, an aqueous solution of resorcinol, formaldehyde and sodium carbonate was prepared by varying R/W (25-45) and R/C (1-10k) ratios to produce monolithic RF gels. The reaction was carried out in a pressurized Teflon mould at 100 °C for 6 h to give a co-continuous pore structure via spinodal decomposition and a tenacious gel to avoid supercritical drying. Next, the RF gels were dried for 42 h at 60 °C and another 6 h at 100 °C to produce RF xerogels without cracks, followed by pyrolysis in a tube furnace at 900 °C for 2 h under N2 flow, and then activation at 1000 °C for 2, 4 or 6 h under CO2 flow. Finally, the carbon xerogels were characterized by SEM and N2 adsorption-desorption measurements. Monolithic RF gels were obtained from all combinations of R/W and R/C, but the gels from R/W = 45 exhibited a co-continuous large-pore structure, providing a specific surface area (SSA) of ∼650 m2 g-1, which increased to 3311 m2 g-1 (for R/C = 10k) at 6 h of CO2 activation without exhibiting cracks. N2 isotherms demonstrated that micro- and meso-pores were introduced via activation, forming hierarchical porosity in combination with large pores from spinodal decomposition without using a template.
| S-EPMC9080866 | biostudies-literature
Project description:A total of two carbon xerogels doped with cobalt and nickel were prepared by the sol-gel method. The obtained carbon xerogels underwent further surface modification with three binary metal oxides namely: nickel cobaltite, nickel ferrite, and cobalt ferrite through the hydrothermal method. The mesopore volumes of these materials ranged between 0.24 and 0.40 cm3/g. Moreover, there was a morphology transformation for the carbon xerogels doped with nickel cobaltite, which is in the form of nano-needles after the hydrothermal process. Whereas the carbon xerogels doped with nickel ferrite and cobalt ferrite maintained the normal carbon xerogel structure after the hydrothermal process. The prepared materials were tested as electrocatalysts for oxygen reduction reaction using 0.1 M KOH. Among the prepared carbon xerogels cobalt-doped carbon xerogel had better electrocatalytic performance than the nickel-doped ones. Moreover, the carbon xerogels doped with nickel cobaltite showed excellent activity for oxygen reduction reaction due to mesoporosity development. NiCo2O4/Co-CX showed to be the best electrocatalyst of all the prepared electrocatalysts for oxygen reduction reaction application, exhibiting the highest electrocatalytic activity, lowest onset potential Eonset of -0.06 V, and the lowest equivalent series resistance (ESR) of 2.74 Ω.
| S-EPMC6696479 | biostudies-literature
Project description: Not available
| S-EPMC10780504 | biostudies-literature
Project description:Organic-inorganic xerogel networks were synthesized from bacterial poly (3-hydroxybutyrate) (PHB) for potential biomedical applications. Since silane-based networks usually demonstrate increased biocompatibility and mechanical properties, siloxane groups have been added onto polyurethane (PU) architectures. In this work, a diol oligomer (oligoPHB-diol) was first prepared from bacterial poly(3-hydroxybutyrate) (PHB) with an environmentally friendly method. Then, hexamethylene diisocyanate or biobased dimeryl diisocyanate was used as diisocyanate to react with the short oligoPHB-diol for the synthesis of different NCO-terminated PU systems in a bulk process and without catalyst. Various PU systems containing increasing NCO/OH molar ratios were prepared. Siloxane precursors were then obtained after reaction of the NCO-terminated PUs with (3-aminopropyl)triethoxysilane, resulting in silane-terminated polymers. These structures were confirmed by different analytical techniques. Finally, four series of xerogels were prepared via a sol-gel process from the siloxane precursors, and their properties were evaluated depending on varying parameters such as the inorganic network crosslinking density. The final xerogels exhibited adequate properties in connection with biomedical applications such as a high in vitro degradation up to 15 wt% after 12 weeks.
| S-EPMC8659847 | biostudies-literature
Project description:The data presented in this article are related to the research article entitled "Novel controlled synthesis of nanoporous carbon nanorods from resorcinol-formaldehyde xerogels" (Awadallah-F and Al-Muhtaseb, 2017) [1]. This article describes the novel controlled approach of nanoporous carbon nanorods synthesis from resorcinol/formaldehyde xerogels. The field dataset is made publicly available to enable critical or extended analyzes.
| S-EPMC5996399 | biostudies-literature
Project description:We show that a perylene bisimide (PBI)-based gelator forms self-sorted mixtures with a stilbene-based gelator. To form the self-sorted gels, we use a slow pH change induced by the hydrolysis of glucono-δ-lactone (GdL) to gluconic acid. We prove that self-sorting occurs using NMR spectroscopy, UV-Vis spectroscopy, rheology, and viscometry. The corresponding xerogels are photoconductive. Importantly, the wavelength dependence of the photoconductive films is different to that of the films formed from the perylene bisimide alone. Transient absorption spectroscopy of the xerogels reveals changes in the spectrum of the PBI on the picosecond timescale in the presence of stilbene with a PBI radical anion being formed within 10 ps when the stilbene is present. The ability to form the PBI radical anion under visible light leads to the enhanced spectral response of the multicomponent gels. These systems therefore have potential as useful visible-active optoelectronics.
| S-EPMC5355952 | biostudies-literature
Project description:Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearly establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. This nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales.
| S-EPMC5357312 | biostudies-literature
Project description:The development of metal-free supercapacitor electrodes with a high energy density is a crucial requirement in the global shift towards sustainable energy sources and industrial pursuit of an optimal supercapacitor. Indeed, from an industrial perspective, time assumes a paramount role in the manufacturing process. A majority of synthesis methods employed for the fabrication of carbon xerogel-based supercapacitor electrodes are characterized by prolonged durations, and result in relatively poor energy and power density. These limitations hinder their practical applications and impede their widespread manufacturing capabilities. In this study, carbon xerogel-based supercapacitor electrodes were made in the shortest time ever reported by making the condition highly acidic with hydrochloric acid (HCl). Furthermore, the investigation of the effect of HCl concentrations (0.1 M, 0.05 M, and 0.01 M) on the morphology and electrochemical behavior of the prepared samples is reported herein. Interestingly, the highest concentration of HCl developed the highest BET surface area, 1032 m2 g-1, which enforced the capacitive behavior to deliver a specific capacitance of 402 F g-1 at 1 A g-1 and a capacitance retention of 80.8% at a current density of 2 A g-1 in an electrolyte containing 0.5 M H2SO4 + 0.5 M Na2SO4. Moreover, an impressive energy density of 45 W h kg-1 at a power density of 18.2 kW kg-1 was achieved. Interestingly, as the HCl concentration increased, the equivalent series resistance decreased to 3.9 W with carbon xerogel 0.1 M HCl (CX0.1). The superior performance of CX0.1 may be attributed to its enlarged BET surface area, pore volume, pore diameter, and smaller particle size. This work provides a facile approach for the large-scale production of metal-free carbon supercapacitor electrodes with improved performance and stability and opens novel horizons to explore the impacts of many types of catalysts during the carbon xerogel preparation.
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