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Exploration of Long-Life Pt/Heteroatom-Doped Graphene Catalysts in Hydrogen Atmosphere.

ABSTRACT: We investigated the H and H₂ adsorption effects on the stability of a Pt atom on various heteroatom-doped graphene supports using first-principles calculations based on density functional theory. We show that H and H₂ adsorptions on the Pt atom weaken the interaction between the Pt atom and graphene support and decrease the adsorption energy of Pt atoms. H₂ adsorption on Pt atoms decreases the adsorption energy of Pt atoms on all graphene supports by more than 30%, whereas H adsorption only affects pristine, O-, and S-doped graphene. These results indicate that the hydrogen atmosphere enhances the detachment of Pt catalysts. However, the B-, O-, Si-, P-doped, and monovacant graphene still maintained large adsorption energies of PtH and PtH₂ of more than 1.5 eV. In addition, the diffusion barriers of PtH and PtH₂ on pristine graphene were calculated to be less than 0.07 eV, which further demonstrated that H and H₂ enhance the degradation of Pt catalysts. Even after H and H₂ adsorptions on a Pt atom, O-, Si-, P-doped, and monovacant graphene still maintained large diffusion barriers of more than 1 eV. Therefore, we concluded that O-, Si-, and P-doped graphene are suitable supports for Pt catalysts in a hydrogen atmosphere.

SUBMITTER: Hasegawa S

PROVIDER: S-EPMC6648745 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Exploration of Long-Life Pt/Heteroatom-Doped Graphene Catalysts in Hydrogen Atmosphere.

Hasegawa Shun S Kunisada Yuji Y Sakaguchi Norihito N

ACS omega 20190410 4

We investigated the H and H2 adsorption effects on the stability of a Pt atom on various heteroatom-doped graphene supports using first-principles calculations based on density functional theory. We show that H and H2 adsorptions on the Pt atom weaken the interaction between the Pt atom and graphene support and decrease the adsorption energy of Pt atoms. H2 adsorption on Pt atoms decreases the adsorption energy of Pt atoms on all graphene supports by more than 30 ...[more]

PMID: 31459787

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Project description:Pt/C catalysts have been considered the ideal cathodic catalyst for proton exchange membrane fuel cells (PEMFCs) due to their superior oxygen reduction reaction (ORR) catalytic activity at low temperatures. However, oxidation and corrosion of the carbon black support at the cathode result in the agglomeration of Pt particles, which reduces the active sites in the Pt/C catalyst. Graphene supports have shown great promise to address this issue, and therefore, finding out the main structural features of the graphene support is of great significance for guiding the rational construction of graphene-based Pt (Pt/graphene) catalysts for optimized ORR catalysts. In order to systematically study the influence of the structural features of the graphene support on the electro-catalytic properties of Pt/graphene catalysts, we prepared porous nitrogen-doped reduced graphene oxide (P-NRGO), nitrogen-doped reduced graphene oxide (NRGO), treated P-NRGO (TP-NRGO) and reduced graphene oxide (RGO) with different nitrogen species contents (7.76, 7.54, 3.24, and 0.14 at%), oxygen species contents (18.68, 18.12, 6.34 and 21.12 at%), specific surface areas (370.4, 70.6, 347.7 and 276.2 m2 g-1) and pore volumes (1.366, 0.1424, 1.3299 and 1.0414 cm3 g-1). The ORR activity of the four Pt/graphene catalysts when listed in the order of their half-wave potentials (E 1/2) and peak power densities was found to be as Pt/P-NRGO > Pt/NRGO > Pt/TP-NRGO > Pt/RGO. The long-term durability of Pt/P-NRGO for the operation of H2-air PEMFCs is better than that of commercial Pt/C catalysts. The excellent ORR catalytic performance of Pt/P-NRGO compared to that of the other three Pt/graphene catalysts is ascribed to the high nitrogen species content of P-NRGO that can facilitate the uniform dispersion of Pt particles and provide accessible active sites for ORR. The results indicate that the specific surface area (SSA) and heteroatom dopants have strong influence on the Pt particle size, and that the nitrogen species of graphene supports play a more important role than the oxygen species, specific surface area and pore volume for the Pt/graphene catalysts in providing accessible active sites.

Dataset Information

Exploration of Long-Life Pt/Heteroatom-Doped Graphene Catalysts in Hydrogen Atmosphere.

Publications

Exploration of Long-Life Pt/Heteroatom-Doped Graphene Catalysts in Hydrogen Atmosphere.

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