A strategy to reduce critical raw metals in nanocatalysts is to synthesize nanocomposites based on defective or bimetallic nanoparticles deposition on carbon nanomaterials. Conventional solution-based methods suffer from the extensive use of solvents and difficult scalability. In this study, defective Pt-Ni nanoparticles are formed on graphene nanoplatelets thanks to an original approach based on simultaneous or sequential low-temperature oxygen plasma treatments of nickel and platinum acetylacetonates. The two processing conditions produce aggregated Pt-Ni nanoparticles with variable morphologies, size crystallinities, and oxidation states.The materials analytical characterizations show that the sequential treatment promotes small Pt-Ni particle aggregates nucleation, while the simultaneous treatment leads to complex interconnected Pt-Ni-based phases. Such defective nanoparticles are promising for multiple applications in catalysis and energy. K E Y W O R D S graphene, low-pressure plasma treatment, prganometallic, Pt-Ni nanocomposites
Abstract:The design of efficient catalytic layers of proton exchange membrane fuel cells (PEMFCs) requires the preparation of highly-loaded and highly-dispersed Pt/C catalysts. During the last few years, our work focused on the preparation of Pt/carbon xerogel electrocatalysts, starting from simple impregnation techniques that were further optimized via the strong electrostatic adsorption (SEA) method to reach high dispersion and a high metal weight fraction. The SEA method, which consists of the optimization of the precursor/support electrostatic impregnation through an adequate choice of the impregnation pH with regard to the support surface chemistry, leads to very well-dispersed Pt/C samples with a maximum 8 wt.% Pt after drying and reduction under H2. To increase the metal loading, the impregnation-drying-reduction cycle of the SEA method can be repeated several times, either with fresh Pt precursor solution or with the solution recycled from the previous cycle. In each case, a high dispersion (Pt particle size ~3 nm) is obtained. Finally, the procedure can be simplified by combination of the SEA technique with dry impregnation, leading to no Pt loss during the procedure.
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