Improved catalytic activity of mixed platinum catalysts supported on various carbon nanomaterials (original) (raw)
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Fuel cell performance of Pt electrocatalysts supported on carbon nanocoils
International Journal of Hydrogen Energy, 2014
Polymer electrolyte membrane fuel cell Carbon nanocoils Electrocatalyst a b s t r a c t Carbon nanocoils (CNCs) synthesized via the catalytic graphitization of resorcinolformaldehyde gel were investigated as an electrocatalyst support in PEMFC anodes. Their textural and physical properties make them a highly efficient catalyst support for anodic hydrogen oxidation in low temperature PEMFC.
International Journal of Hydrogen Energy, 2014
Commercially available graphitized carbon nanofibers and multi-walled carbon nanotubes, two carbon materials with very different structure, have been functionalized in a nitric esulfuric acid mixture. Further on, the materials have been platinized by a microwave assisted polyol method. The relative degree of graphitization has been estimated by means of Raman spectroscopy and X-ray diffraction while the relative concentration of oxygen containing groups has been estimated by X-ray photoelectron spectroscopy, which resulted in a graphitic character trend: Pt/GNF > Pt/F-GNF \ Pt/MWCNT > Pt/F-MWCNT. Transmission electron microscopy showed that the Pt particle size is around 3 nm for all samples, which was similar to the crystallite size obtained by X-ray diffraction. The activity towards electrochemical reduction of oxygen has been quantified using the thin-film rotating disk electrode, which has shown that all the samples have a better activity than the commercially available electrocatalysts. The trend obtained for the graphitic character maintained for the electrochemical activity, while the reverse trend has been obtained for the accelerated ageing test. Long-term potential cycling has demonstrated that the functionalization improves the stability for multi-walled carbon nanotubes, at the cost of decreased activity.
Catalysts, 2013
Different advanced nanostructured carbon materials, such as carbon nanocoils, carbon nanofibers, graphitized ordered mesoporous carbons and carbon xerogels, presenting interesting features such as high electrical conductivity and extensively developed porous structure were synthesized and used as supports in the preparation of electrocatalysts for direct methanol fuel cells (DMFCs). The main advantage of these supports is that their physical properties and surface chemistry can be tailored to adapt the carbonaceous material to the catalytic requirements. Moreover, all of them present a highly mesoporous structure, diminishing diffusion problems, and both graphitic character and surface area can be conveniently modified. In the present work, the influence of the particular features of each material on the catalytic activity and stability was analyzed. Results have been compared with those obtained for commercial catalysts supported on Vulcan XC-72R, Pt/C and PtRu/C (ETEK). Both a highly ordered graphitic and mesopore-enriched structure of these advanced nanostructured materials resulted in an improved electrochemical performance in comparison to the commercial catalysts assayed, both towards CO and alcohol oxidation. OPEN ACCESS Catalysts 2013, 3 672
Electrocatalytic performances of nanostructured platinum–carbon materials
Catalysis Today, 2005
The performances of platinum supported on carbon nanofibers (Pt/CNFs) and Pt nanoclusters on carbon Cloth (Pt nano /CC) as alternative electrodes for PEM fuel cells are compared with those of a commercial Pt-carbon black on carbon Cloth electrode in a 1 cm 2 fuel cell working at room temperature. Carbon nanofibers were grown by chemical vapour deposition on two different types of microshaped carbon supports (Felt and Cloth) and then Pt was deposited on these nano/micro composite carbon supports. The analysis of the results and in particular of the polarization curves indicate that (i) both Pt nano /CC and Pt/CNFs materials are better electrocatalysts than commercial one and (ii) Pt nano /CC gives the lowest ohmic losses while Pt/CNFs materials give the lowest mass transfer losses. Further studies and a better membrane and electrodes assembly (MEA) engineering are necessary to further validate the results, but these preliminary analysis pointed out that new electrode materials based both on Pt nanoclusters and carbon nanostructures (nanofibers/nanotubes) could be very interesting for fuel cells applications. #
ACS Catalysis, 2018
The influence of the texture, structure and chemistry of different carbon supports on the morphological properties, oxygen reduction reaction (ORR) activity and stability of porous hollow PtNi nanoparticles (NPs) was investigated. The carbon nanomaterials included carbon blacks, carbon nanotubes, graphene nanosheets and carbon xerogel, and featured different specific surface areas, degrees of graphitization and extent of surface functionalization. The external and inner diameters of the supported porous hollow PtNi/C NPs were found to decrease with the increase of the carbon mesopore surface area. Despite these differences, similar morphological properties and electrocatalytic activities for the ORR were reported. The stability of the synthesized electrocatalysts was assessed by simulating electrochemical potential variations occurring at a proton exchange membrane fuel cell (PEMFC) cathode during start-up/shutdown events. Identical location transmission electron microscopy (IL-TEM) and electrochemical methods revealed the occurrence of carbon-specific degradation mechanism: carbon corrosion into CO 2 and particle detachment were noticed on carbon xerogels and graphene nanosheets while, on carbon blacks, surface oxidation prevailed (C → CO surf) and did not result in modified electrical resistance of the catalytic layers, rendering these carbon supports better suited to prepare highly active and stable ORR electrocatalyst.
Physical Chemistry Chemical Physics, 2012
We report on new insights into the relationships between structure and activity of glassy carbon (GC), as a model material for electrocatalyst support, during its anodization in acid solution. Our investigation strongly confirms the role of CFGs in promotion of Pt activity by the ''spill-over'' effect related to CO ads for methanol electrooxidation (MEO) on a carbon-supported Pt catalyst. Combined analysis of voltammetric and impedance behaviour as well as changes in GC surface morphology induced by intensification of anodizing conditions reveal an intrinsic influence of the carbon functionalization and the structure of a graphene oxide (GO) layer on the electrical and electrocatalytic properties of activated GC. Although GO continuously grows during anodization, it structurally changes from being a graphite inter-layer within graphite ribbons toward a continuous GO surface layer that deteriorates the native structure of GC. As a consequence of the increased distance between GO-spaced graphite layers, the GC conductivity decreases until the case of profound GO exfoliation under drastic anodizing conditions. This exposes the native, yet abundantly functionalized, GC texture. While GC capacitance continuously increases with intensification of anodizing conditions, the surface nano-roughness and GO resistance reach the highest values at modest anodizing conditions, and then decrease upon drastic anodization due to the onset of GO exfoliation. We found for the first time that the activity of a GC-supported Pt catalyst in MEO, as one of the promising half-reactions in polymer electrolyte fuel cells, strictly follows the changes in GC nano-roughness and GO-induced GC resistance. The highest GC/Pt MEO activity is reached when optimal distance between graphite layers and optimal degree of GC functionalization bring the highest amount of CFGs into intimate contact with the Pt surface. This confirms the promoting role of CFGs in MEO catalysis. GC I -polished and cycled in the potential range À0.3 to 0.8 V vs. SCE; GC II -polished and cycled in the potential range À0.3 to 1.2 V vs. SCE until stable voltammetric response; GC ox III -polished and oxidized at 1.2 V vs. SCE; GC ox IV -polished and oxidized at 1.5 V vs. SCE; GC ox V -polished and oxidized 1.7 V vs. SCE; GC ox VI -polished and oxidized at 2.0 V vs. SCE; GC ox VII -polished and oxidized at 2.2 V vs. SCE; GC and GC ox electrodes were investigated by CV on a VoltaLab 80 PGZ402 instrument in 0.5 M H 2 SO 4 at a sweep rate of 50 mV s À1 in the potential range between hydrogen and
Materials Chemistry and Physics, 2011
Pt nanoparticles have been supported on different carbon materials for their use as electrocatalysts in polymeric electrolyte fuel cells. Carbon nanofibers (CNF) and ordered mesoporous carbon (CMK-3) have been studied as supports that could replace carbon black in the preparation of commercial electrocatalysts. The use of these non-conventional carbon materials allowed the determination of the influence of the support on the physicochemical properties of catalysts. Additionally, Pt catalyst supported on Vulcan XC-72R (commercial electrocatalyst support) has been prepared in order to establish a comparison. Catalysts were prepared by the incipient wetness impregnation method, and subsequently, they were reduced in a H 2 flow. Supports and catalysts were characterized by different analytical techniques in order to determine the effect of the support. Results proved that the support has a strong influence on the physicochemical properties of catalysts. These properties depended on the nature of the support and are associated with the metal-support interaction.
Performance and application of carbon-based electrocatalysts in direct methanol fuel cell
Materials advances, 2021
The growing energy demand with rapid consumption of fossil fuels and continuous rise in environmental issues have led to the development of an alternative energy conversion system, direct methanol fuel cell (DMFC). The high energy density, easy transportability of methanol and compact design, lightweight are some of the advantages of DMFC over other types of fuel cells. However, the high cost of platinum (Pt) catalyst and the poisoning of Pt electrode, sluggish reaction kinetics as well as methanol crossover are the major limitations of DMFC. Currently, carbon materials have drawn tremendous attention from researchers as catalyst support in DMFC due to remarkable properties, such as good electronic conductivity, better stability and environment friendliness that have an immense influence on fuel cell performance. In this regard, recently, advancements in carbon-based materials, including mesoporous carbon, carbon black, carbon quantum dots, carbon nanotubes, carbon nanofibre, graphene and other carbon forms such as carbon nanosheet, nanohorns, nanosphere as electrocatalyst support have been reported. The influence of doping with heteroatoms, functionalization, presence of defects and porous structure of carbon on the electrocatalytic performance has also been discussed in this report. Finally, challenges related to new generation carbon material-based electrocatalysts and future perspectives are discussed.
World Journal of Nano Science and Engineering, 2013
Highly-dispersed platinum and platinum-based catalysts on a conductive support are commonly used as electrode materials in low-temperature fuel cells, particularly the hydrogen PEMFC and the direct methanol PEMFC. The performance and durability/stability of these catalysts strongly depend on the characteristics of the support. Catalysts supported on high surface area carbon black are widely used in low-temperature fuel cells. However, the corrosion of carbon black has been recognized as one of major causes of performance degradation and durability issues of low-temperature fuel cells under high-potential conditions. So the need for alternative supports with outstanding physical and mechanical properties to carry out the successful reaction in catalyst layer and give a longer lifetime for the electrocatalysts is inevitable. The emergence of nanotechnology and development of nanostructure materials in recent years has opened up new avenues of materials development for low-temperature fuel cells. This paper presents the performance with a variety of carbon-based nanostructured materials such as carbon nanotubes (CNT), carbon nanofibers (CNF), carbon aerogels, nanoplates of graphene, etc. So the present paper provides an overview of these nanostructured materials as low-temperature fuel cell catalyst supports. The improved characteristics of the nanostructured supports with respect to commercially used carbon black (Vulcan XC-72) and their effect on the electrochemical activity are highlighted. Additionally, it reviews the literature on the synthesis of nanostructured-supported Pt electrocatalysts for proton exchange membrane (PEM) fuel cell catalyst loading reducing through the improvement of catalyst utilization and activity. The features of each synthetic method were also discussed based on the morphology of the synthesized catalysts.