Tailored Electron Transfer Pathways in Aucore/Ptshell–Graphene Nanocatalysts for Fuel Cells |
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| Authors: | Nedjeljko Seselj Christian Engelbrekt Yi Ding Hans Aage Hjuler Jens Ulstrup Jingdong Zhang |
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| Affiliation: | 1. Department of Chemistry, Technical University of Denmark (DTU), Kgs. Lyngby, Denmark;2. Tianjin Key Laboratory of Advanced Functional Porous Materials, Institute for New Energy Materials and Low‐Carbon Technologies, Tianjin University of Technology, Tianjin, P. R. China;3. Danish Power Systems Ltd., Kvistg?rd, Denmark |
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| Abstract: | Aucore/Ptshell–graphene catalysts (G‐Cys‐Au@Pt) are prepared through chemical and surface chemical reactions. Au–Pt core–shell nanoparticles (Au@Pt NPs) covalently immobilized on graphene (G) are efficient electrocatalysts in low‐temperature polymer electrolyte membrane fuel cells. The 9.5 ± 2 nm Au@Pt NPs with atomically thin Pt shells are attached on graphene via l ‐cysteine (Cys), which serves as linkers controlling NP loading and dispersion, enhancing the Au@Pt NP stability, and facilitating interfacial electron transfer. The increased activity of G‐Cys‐Au@Pt, compared to non‐chemically immobilized G‐Au@Pt and commercial platinum NPs catalyst (C‐Pt), is a result of (1) the tailored electron transfer pathways of covalent bonds integrating Au@Pt NPs into the graphene framework, and (2) synergetic electronic effects of atomically thin Pt shells on Au cores. Enhanced electrocatalytic oxidation of formic acid, methanol, and ethanol is observed as higher specific currents and increased stability of G‐Cys‐Au@Pt compared to G‐Au@Pt and C–Pt. Oxygen reduction on G‐Cys‐Au@Pt occurs at 25 mV lower potential and 43 A gPt?1 higher current (at 0.9 V vs reversible hydrogen electrode) than for C–Pt. Functional tests in direct fomic acid, methanol and ethanol fuel cells exhibit 95%, 53%, and 107% increased power densities for G‐Cys‐Au@Pt over C–Pt, respectively. |
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| Keywords: | Au– Pt core– shell electron pathway fuel cells graphene |
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