Pt nanoparticle (NP)-supported SWCNTs and Vulcan® XC-72 produced using a Pt NP-dispersed IL prepared by sputtering show an unexpected high durability as electrode catalysts for the oxygen reduction reaction due to the existence of an IL thin layer.
Pt and PtNi alloy nanoparticle-supported multiwalled carbon nanotubes (Pt/MWCNTs and PtNi/MWCNTs) are prepared by a one-pot pyrolysis method with the N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)amide ionic liquid (IL) containing platinum and nickel precursors, Pt(acac)2, Ni[Tf2N]2, and Ni(acac)2, with suspended MWCNTs. The composite materials can be prepared by simply heating the IL solution at 573 K. The resulting materials show favorable catalytic activity toward the oxygen reduction reaction and durability superior to those of typical commercially available electrocatalysts. The catalytic activity of the PtNi/MWCNTs depends on the Ni content of the PtNi alloy nanoparticles. One of the PtNi/MWCNTs shows 1.4 times higher mass activity than a typical commercial electrocatalyst. A plot of the mass activity as a function of the Ni content gives a mountain-shaped curve with a vertex at ca. 25 atomic percent Ni. This one-pot process can readily control the catalytic properties of the PtNi/MWCNTs by changing the molar fraction of Pt and Ni precursors.
this corrosion, including the use of sp 2carbon materials without functional groups, i.e., carbon nanotubes [11] and graphene, [12] and noncarbon materials [13] as nanoparticle supports and the decoration of the Pt nanoparticles on carbon. [14] Although these approaches have been effective in reducing the degradation to varying degrees, unfortunately, further developments are required due to the high costs, complex preparation procedures, and insufficient electrode performances resulting from these approaches. Hence, developing an effective approach to provide high electrocatalytic activity and catalyst stability is a great challenge.An ionic liquid (IL) is a liquid salt consisting of a cation and anion at room temperature and is a subset of a molten salt. The unique features of an IL, such as a negligible vapor pressure, wide electrochemical window, good thermal stability, antistatic properties, have led to many proposed applications thus far. Recently, we reported Pt-nanoparticle-supported carbon electrocatalysts easily produced by agitating Pt-nanoparticle-monodispersed ILs, which were prepared by magnetron sputtering onto the ILs, [15,16] with various carbon supports, e.g., carbon nanotubes and carbon black, under heating conditions. [17][18][19][20][21][22] The resulting electrocatalysts showed favorable catalytic activities for ORR and high durabilities. [23] The latter feature was attributed to the thin IL layer between the Pt nanoparticles and carbon support, which suppressed carbon corrosion. [23] ILs should play key roles in the further improvement of electrocatalysts. Here, we focused on a protic organic salt (POS) and protic ionic liquid (PIL) that are easily synthesized, a cost-effective option and often show desirable physicochemical properties over commonly used ILs. [24][25][26][27] To reveal the effects of the ILs on the catalytic activities of the resulting Pt-nanoparticle-supported carbon materials, diphenylammonium hydrogen sulfate ([DPA][HSO 4 ]) and N,N-diethyl-N-methylammonium hydrogen sulfate ([DEMA] [HSO 4 ]) were exploited in this investigation as a POS and a PIL, respectively. The aim of this study is to disclose approaches to improve the performances of electrocatalysts for PEFCs.[DPA] [HSO 4 ] and [DEMA] [HSO 4 ] were prepared by procedures described in previous articles. [26,27] [DEMA] [HSO 4 ] was used in a sputtering process to produce a Pt-nanoparticlemonodispersed IL.[DPA] [HSO 4 ], which is a solid salt at room temperature, was used as an additive to provide functionality to the Pt-nanoparticle-supported carbon materials. In this article, electrocatalysts prepared with and without [DPA][HSO 4 ] Pt-nanoparticle-supported carbon catalysts for the electrochemical oxygen reduction reaction produced using a Pt-nanoparticle-monodispersed ionic liquid (IL) show better durability than a commercially available catalyst due to the small amount of IL between the Pt nanoparticles and the carbon support. In this study, to add further functionality to the catalysts prepared with the Pt-na...
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