Abstract:Graphene nanosheets (GS) were formed by the thermal‐expansion method. Large micropores about 1–2 nm were produced, which might provide abundant anchor sites for fixing catalyst. Platinum nanoparticles (NPs) supported on exfoliated GS (Pt/GS) were synthesized through an improved impregnation approach and mixture gas (5% H2 in N2) reduction. SEM and TEM images indicated the simple and clean method can effectively synthesize Pt with uniform dispersion and small size (below 3 nm) on the 2D specific and stratiform … Show more
“…However, their low electrical conductivity seriously impedes their further development as suitable catalyst supports for DMFCs. Graphene is a monolayer of carbon atoms packed into a dense honeycomb crystal structure; this material has recently attracted increased attention due to its potential application as a catalyst support in fuel cells. − Pt NPs can be deposited on graphene sheets to achieve specific properties, such as a large surface area to provide high metal dispersion, a high electrical conductivity to facilitate electron transfer, a suitable porosity to promote gas flow, and a high stability to avoid corrosion in both acidic and alkaline media.…”
We report a simple and environmentally friendly route to prepare platinum/reduced graphene oxide (Pt/rGO) nanocomposites (NCs) with highly reactive MnOx colloids as reducing agents and sacrificial templates. The colloids are obtained by laser ablation of a metallic Mn target in graphene oxide (GO)-containing solution. Structural and morphological investigations of the as-prepared NCs revealed that ultrafine Pt nanoparticles (NPs) with an average size of 1.8 (±0.6) nm are uniformly dispersed on the surfaces of rGO nanosheets. Compared with commercial Pt/C catalysts, Pt/rGO NCs with highly electrochemically active surface areas show remarkably improved catalytic activity and durability toward methanol oxidation. All of these superior characteristics can be attributed to the small particle size and uniform distribution of the Pt NPs, as well as the excellent electrical conductivity and stability of the rGO catalyst support. These findings suggest that Pt/rGO electrocatalysts are promising candidate materials for practical use in fuel cells.
“…However, their low electrical conductivity seriously impedes their further development as suitable catalyst supports for DMFCs. Graphene is a monolayer of carbon atoms packed into a dense honeycomb crystal structure; this material has recently attracted increased attention due to its potential application as a catalyst support in fuel cells. − Pt NPs can be deposited on graphene sheets to achieve specific properties, such as a large surface area to provide high metal dispersion, a high electrical conductivity to facilitate electron transfer, a suitable porosity to promote gas flow, and a high stability to avoid corrosion in both acidic and alkaline media.…”
We report a simple and environmentally friendly route to prepare platinum/reduced graphene oxide (Pt/rGO) nanocomposites (NCs) with highly reactive MnOx colloids as reducing agents and sacrificial templates. The colloids are obtained by laser ablation of a metallic Mn target in graphene oxide (GO)-containing solution. Structural and morphological investigations of the as-prepared NCs revealed that ultrafine Pt nanoparticles (NPs) with an average size of 1.8 (±0.6) nm are uniformly dispersed on the surfaces of rGO nanosheets. Compared with commercial Pt/C catalysts, Pt/rGO NCs with highly electrochemically active surface areas show remarkably improved catalytic activity and durability toward methanol oxidation. All of these superior characteristics can be attributed to the small particle size and uniform distribution of the Pt NPs, as well as the excellent electrical conductivity and stability of the rGO catalyst support. These findings suggest that Pt/rGO electrocatalysts are promising candidate materials for practical use in fuel cells.
“…Platinum (Pt) catalysts are widely used as anode materials in fuel cells due to their high activity and selectivity. Experimental observations demonstrate that subnanometer Pt nanoparticles supported on graphene exhibit increased stability, uniform dispersion, tolerance to CO poisoning, and exceptionally high activity for oxidation reactions, making them attractive candidates as electrocatalysts in direct methanol fuel cells, proton exchange membrane fuel cells, and hydrogen fuel cells. − More specifically, experimental studies attribute the improved performance of Pt–graphene nanocatalysts to the synergetic effect between the Pt catalyst and the graphene support, mainly due to the presence of defects and functional groups in the graphene support that are formed during the fabrication process, leading to a strong interaction between the cluster and the support. − Computational studies also report a strong binding of Pt clusters at defect sites in graphene relative to pristine graphene, significantly modifying the morphology and the electronic structure of the clusters, thus having an immediate effect on their catalytic activity. − …”
We investigate support effects on the CO oxidation reaction on graphene−supported Pt 13 nanoclusters using first-principles density functional theory calculations. As CO adsorption on Pt 13 clusters is found to be substantially stronger than O adsorption, we focus on understanding CO oxidation kinetics on CO-saturated Pt nanoclusters. For this high CO coverage regime, the relevant kinetic mechanism is shown to proceed via a CO*-assisted activation of the O 2 molecule, resulting in the formation of an O*−O−C*−O transition state that eventually forms a CO 2 molecule and a chemisorbed O* species. By sampling this particular reaction pathway at various surface sites on unsupported Pt 13 nanoclusters as well as clusters bound at support point defects (vacancies/ divacancies) in graphene, we show that strong support−cluster interactions substantially reduce the CO oxidation reaction barrier, on average, by about 0.5 eV. Our results suggest that defect engineering of carbon supports could serve to enhance the catalytic activity of ultrasmall Pt nanoclusters, opening up another dimension for rational design of catalytic materials.
“…2 . Also, several researches based on graphene such as GO modified Pt nanoflower [ 35 ], Pt nanoparticle on defective graphene [ 36 ], and sandwich-structured graphene/Pt/graphene [ 7 ] have been researched to reduce Pt consumption. Fig.…”
Developments of high efficient materials for electrocatalyst are significant topics of numerous researches since a few decades. Recent global interests related with energy conversion and storage lead to the expansion of efforts to find cost-effective catalysts that can substitute conventional catalytic materials. Especially, in the field of fuel cell, novel materials for oxygen reduction reaction (ORR) have been noticed to overcome disadvantages of conventional platinum-based catalysts. Various approaching methods have been attempted to achieve low cost and high electrochemical activity comparable with Pt-based catalysts, including reducing Pt consumption by the formation of hybrid materials, Pt-based alloys, and not-Pt metal or carbon based materials. To enhance catalytic performance and stability, numerous methods such as structural modifications and complex formations with other functional materials are proposed, and they are basically based on well-defined and well-ordered catalytic active sites by exquisite control at nanoscale. In this review, we highlight the development of nano-structured catalytic materials for ORR based on recent findings, and discuss about an outlook for the direction of future researches.
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