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Cu assisted loading of Pt on CeO₂ as a carbon-free catalyst for methanol and oxygen reduction reaction.

ABSTRACT: The widely studied Pt/C catalyst for direct methanol fuel cells (DMFCs) suffers severe carbon corrosion under operation, which undermines the catalytic activity and durability. It is of great importance to develop a carbon-free support with co-catalytic functionality for improving both the activity and durability of Pt-based catalysts. The direct loading of Pt on the smooth surface of oxides may be difficult. Herein, the Cu assisted loading of Pt on CeO₂ is developed. Cu pre-coated CeO₂ was facilely synthesized and Pt was electrochemically deposited to fabricate the carbon-free PtCu/CeO₂ catalyst. The PtCu/CeO₂ catalyst has a mass activity up to 1.84 and 1.57 times higher than Pt/C towards methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR), respectively. Better durability is also confirmed by chronoamperometry and accelerated degradation tests. The strategy in this work would be greatly helpful for developing an efficient carbon-free support of Pt-based catalysts for applications in DMFCs.

SUBMITTER: Zou L

PROVIDER: S-EPMC9043534 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Lattice oxygen self-spillover on reducible oxide supported metal cluster: the water-gas shift reaction on Cu/CeO2 catalyst.

Project description:In this work we have tackled one of the most challenging problems in nanocatalysis namely understanding the role of reducible oxide supports in metal catalyzed reactions. As a prototypical example, the very well-studied water gas shift reaction catalyzed by CeO2 supported Cu nanoclusters is chosen to probe how the reducible oxide support modifies the catalyst structures, catalytically active sites and even the reaction mechanisms. By employing density functional theory calculations in conjunction with a genetic algorithm and ab initio molecular dynamics simulations, we have identified an unprecedented spillover of the surface lattice oxygen from the ceria support to the Cu cluster, which is rarely considered previously but may widely exist in oxide supported metal catalysts under realistic conditions. The oxygen spillover causes a highly energetic preference of the monolayered configuration of the supported Cu nanocluster, compared to multilayered configurations. Due to the strong metal-oxide interaction, after the O spillover the monolayered cluster is highly oxidized by transferring electrons to the Ce 4f orbitals. The water-gas-shift reaction is further found to more favorably take place on the supported copper monolayer than the copper-ceria periphery, where the on-site oxygen and the adjacent oxidized Cu sites account for the catalytically active sites, synergistically facilitating the water dissociation and the carboxyl formation. The present work provides mechanistic insights into the strong metal-support interaction and its role in catalytic reactions, which may pave a way towards the rational design of metal-oxide catalysts with promising stability, dispersion and catalytic activity.

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Project description:In the present study, methods to enhance the oxygen reduction reaction (ORR) activity of sub-nanosized Pt clusters were investigated in a theoretical manner. Using ab initio molecular dynamics and Monte Carlo simulations based on density functional theory, we have succeeded in determining the origin of the superior ORR activity of Pt12 compared to that of Pt13. That is, it was clarified that the electronic structure of Pt12 fluctuates to a greater extent compared to that of Pt13, which leads to stronger resistance against catalyst poisoning by O/OH. Based on this conclusion, a set of sub-nanosized Pt-alloy clusters was also explored to find catalysts with better ORR activities and lower financial costs. It was suggested that Ga4Pt8, Ge4Pt8, and Sn4Pt8 would be good candidates for ORR catalysts.

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