Electrocatalytic Activity of Ionic-Liquid-Derived Porous Carbon Materials for the Oxygen Reduction Reaction (original) (raw)
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We have successfully prepared nanoporous Carbon-L and -S materials by using ZIF-7 as a precursor and glucose as an additional carbon source. Results indicate that Carbon-L and -S show an appropriate nitrogen content, high surface area, robust pore structure and excellent graphitization degree. The addition of an environmentally friendly carbon sourceglucosenot only improves the graphitization degree of samples, but also plays a key role in removing residual Zn metal and zinc compound impurities, which makes the resulting materials metal-free in situ nitrogen-doped porous carbons. By further investigating the electrocatalytic performance of these nitrogen-doped porous carbons for oxygen reduction reaction (ORR), we find that Carbon-L, as a metal-free electrocatalyst, shows excellent electrocatalytic activity (the onset and half-wave potentials are 0.86 and 0.70 V vs. RHE, respectively) and nearly four electron selectivity (the electron transfer number is 3.68 at 0.3 V), which is close to commercial 20% Pt/C. Moreover, when methanol was added, the Pt/C catalyst would be poisoned while the Carbon-L and -S would be unaffected. By exploring the current-time chronoamperometric response in 25 000 s, we found that the duration stability of Carbon-L is much better than the commercial 20% Pt/C. Thus, both Carbon-L and -S exhibit excellent ability to avoid methanol crossover effects, and longterm operation stability superior to the Pt/C catalyst. This work provides a new strategy for in situ synthesis of N-doped porous carbons as metal-free electrocatalysts for ORR in fuel cells.
Carbon letters, 2016
Nitrogen (N)-doped ordered mesoporous carbons (OMCs) with a dual transition metal system were synthesized as non-Pt catalysts for the ORR. The highly nitrogen doped OMCs were prepared by the precursor of ionic liquid (3-methyl-1-butylpyridine dicyanamide) for N/C species and a mesoporous silica template for the physical structure. Mostly, N-doped carbons are promoted by a single transition metal to improve catalytic activity for ORR in PEMFCs. In this study, our N-doped mesoporous carbons were promoted by the dual transition metals of iron and cobalt (Fe, Co), which were incorporated into the N-doped carbons lattice by subsequently heat treatments. All the prepared carbons were characterized by via transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). To evaluate the activities of synthesized doped carbons, linear sweep was recorded in an acidic solution to compare the ORR catalytic activities values for the use in the PEMFC system. The dual transition metal promotion improved the ORR activity compared with the single transition metal promotion, due to the increase in the quaternary nitrogen species from the structural change by the dual metals. The effect of different ratio of the dual metals into the N doped carbon were examined to evaluate the activities of the oxygen reduction reaction.
It is highly essential to produce cost-effective and efficient multifunctional porous carbon materials for sustainable energy technologies. Here, we report a facile approach to synthesis biomass derived porous carbon having inherited heteroatoms by mechanochemical method and post pyrolyzing treatment. The optimized porous carbon exhibits superior oxygen reduction reaction performances in an alkaline electrolyte with a half-wave potential of 0.76 V (vs. reversible hydrogen electrode) with a small kinetic current density of 35.5 mV dec À1 and outsanding stability with great tolerance against methanol poisoning. It also shows the multifunctional capability of electrochemical energy storage as supercapacitor electrode material (coin cell), showing high gravimetric capacitance of 273 F g À1 in the aqueous electrolyte with superior cycling stability.
Applied Catalysis B: Environmental, 2009
N-doped ordered porous carbon (CN x) was synthesized via a nano-casting process using polyacrylonitrile (PAN) as the carbon and nitrogen precursor and mesoporous silica as a hard template. Nitrogen adsorption/desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the synthesized CN x and the derived nonprecious metal oxygen-reduction catalysts. The CN x exhibited a highly ordered porosity and high graphitization with a surface area of 1132 m 2 g À1 and a nitrogen content of 6.88 at.%. The non-precious metal oxygen-reduction catalysts were prepared by pyrolyzing iron acetate-impregnated CN x in argon, followed by post-treatments. Optimizations of the iron loading and the pyrolyzing temperature were also explored. The catalytic activities of the CN x products for the oxygen reduction reaction (ORR) were examined by rotating disc electrode (RDE) measurements and single-cell tests. The onset potential for oxygen reduction in 0.5 M H 2 SO 4 of the best catalyst was as high as 0.88 V vs. normal hydrogen electrode (NHE). The current density obtained in an H 2 /O 2 proton exchange membrane fuel cell (PEMFC) was as high as 0.6 A cm À2 at 0.5 V with a cathode catalyst loading of 2 mg cm À2 .
ChemElectroChem, 2023
Due to their low cost, accessibility of resources, and improved stability and durability, carbon-based nanomaterials have attracted significant attention as cathode materials for oxygen reduction reactions. These materials also exhibit intrinsic physical and electrochemical features. However, their potential for use in fuel cells is constrained by low ORR activity and slow kinetics. Carbon nanomaterials can be functionalized and doped with heteroatoms to change their morphologies and generate a large number of oxygen reduction active sites to lessen the problems. Doping the carbon lattice with heteroatoms like N, S, and P and functionalizing the carbon structure with À OCH 3 , À F, À COO À , À O À are two of these modifications that can change specific properties of the carbon nanomaterials like expanding interlayer distance, producing a large number of active sites, and enhancing oxygen reduction activity. When compared to pristine carbon-based nanomaterials, these doped and functionalized carbon nanomaterials, including their composites, exhibit accelerated rate performance, outstanding stability, and higher methanol tolerance. This article summarizes the most recent developments in heteroatom-doped and functionalized carbonbased nanomaterials, covering different synthesis approaches, characterization methods, electrochemical performance, and oxygen reduction reaction mechanisms. As cathode materials for fuel cell technologies, the significance of heteroatom codoping and transition metal heteroatom co-doping is also underlined.
Catalysts
The development of non-precious metal electrocatalysts towards oxygen reduction reaction (ORR) is crucial for the commercialisation of polymer electrolyte fuel cells. In this work, cobalt-containing nitrogen-doped porous carbon materials were prepared by a pyrolysis of mixtures of saccharides, cobalt nitrate and dicyandiamide, which acts as a precursor for reactive carbon nitride template and a nitrogen source. The rotating disk electrode (RDE) experiments in 0.1 M KOH solution showed that the glucose-derived material with optimised cobalt content had excellent ORR activity, which was comparable to that of 20 wt% Pt/C catalyst. In addition, the catalyst exhibited high tolerance to methanol, good stability in short-time potential cycling test and low peroxide yield. The materials derived from xylan, xylose and cyclodextrin displayed similar activities, indicating that various saccharides can be used as inexpensive and sustainable precursors to synthesise active catalyst materials for...
2009
Nitrogen-modified carbon-based catalysts for oxygen reduction were synthesized by modifying carbon black with nitrogen-containing organic precursors. The electrocatalytic properties of catalysts were studied as a function of surface pre-treatments, nitrogen and oxygen concentrations, and heat-treatment temperatures. On the optimum catalyst, the onset potential for oxygen reduction is approximately 0.76 V ccepted 24 November 2008 vailable online 28 November 2008
Modified porous carbon materials as catalytic support for cathodic reduction of dioxygen
Fuel Processing Technology, 2002
Activated carbon materials were modified by generating several functional groups containing oxygen and/or nitrogen atoms on their surfaces. Surface properties of obtained carbon samples were investigated. The point of zero charge was determined by different methods. The catalytic properties of these materials in the decomposition of hydrogen peroxide and in the electrochemical reduction of dioxygen in aqueous electrolytes have been studied. The catalytic activity for O 2 reduction correlates with that for HO 2 À decomposition. A linear relationship was derived for the dioxygen reduction peak potential and the decomposition rate constant. Thus, the selection of active catalysts for the heterogeneous decomposition of HO 2 À is a good starting point for the design of a carbon-based oxygen cathode. D