DFT study on ORR catalyzed by bimetallic Pt-skin metals over substrates of Ir, Pd and Au

Qi, Xueqiang; Yang, Tingting; Li, Pingbo; Wei, Zidong

doi:10.1016/j.nanoms.2021.06.002

Cited by 19 publications

(11 citation statements)

References 22 publications

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“…The calculated partial density of states (PDOS) for the metal surface demonstrated that the d-band center of Pt was lowered for PtCo(111)–Pt skin than the pure Pt(111) surface (Figure c), and therefore, the affinity toward S and H was changed. Previously reported literature studies − have shown that there are usually two kinds of effects on the properties of near-surface alloys, that is, strain effect involving morphological change and the other is ligand effect involving electronic structure change . The compressive strain causes the d-band center to move away from the Fermi level, while the tensile strain moves toward the Fermi level.…”

Section: Resultsmentioning

confidence: 99%

“…Previously reported literature studies 50−52 have shown that there are usually two kinds of effects on the properties of nearsurface alloys, that is, strain effect involving morphological change and the other is ligand effect involving electronic structure change. 53 The compressive strain causes the d-band center to move away from the Fermi level, while the tensile strain moves toward the Fermi level. In this work, the Pt−Pt distance (the distance of Pt atoms) of PtCo(111)−Pt skin was calculated to be 2.720−2.773 Å, which is shorter than that of Pt(111) (d Pt−Pt = 2.803 Å).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Understanding of Correlation between Electronic Properties and Sulfur Tolerance of Pt-Based Catalysts for Hydrogen Oxidation

Qiu

Zhao

et al. 2022

ACS Appl. Mater. Interfaces

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Renewable power-derived green hydrogen distributed via natural gas networks is considered one of the viable routes to drive the decarbonization of transportation and distributed power generation, while a trace amount of sulfur impurities is one of the key factors that affect the durability and life cycle expense of proton-exchange membrane fuel cells (PEMFCs) for end users. Herein, we explore the underlying effect of sulfur resistance for Ptbased hydrogen oxidation reaction (HOR) electrocatalysts devoted to high-performance and durable PEMFCs. Two typical electrocatalysts, Pt/C with pure Pt nanoparticles (NPs) and PtCo/C with Pt 3 Co-alloy-core-Pt-skin NPs, were investigated to demonstrate the structure−property relation for Pt-based electrocatalysts. It was revealed that the PtCo/C demonstrated alleviated sulfur poisoning with the adsorption rate constant reduced by 21.7% compared with Pt/C, and the desorption of the adsorbed sulfur was also more favorable with Pt−S bond decomposition temperature lowered by approximately 25 °C. Characterization indicated that sulfur was predominantly adsorbed in the edge mode for PtCo/C, but in a comparable edge and bridge mode for Pt/C, which caused the strengthened Pt−S binding by the chelation effect for Pt/C. The lowered d-band center of surface Pt for PtCo/C, tuned by electron transfer from Co to Pt and Pt lattice strain, was also found responsible for the weakened Pt−S interaction. The recovery test based on electro-oxidation suggested that PtCo/C also outperformed Pt/C with faster and more thorough release of HOR active sites. The SO 42− species derived from electro-oxidation of S 2− was more apt to adsorb on Pt/C than PtCo/C because of its stronger affinity to SO 4 2− caused by the higher d-band center of Pt. Therefore, it is clarified that adequate modification of the Pt d-band center, for example, negatively tuned for the state-of-the-art Pt/C, is crucial to improve the sulfur resistance and recovery capability for Pt-based electrocatalysts while reserving comparable HOR activity. In particular, the investigated PtCo/C electrocatalyst is a better choice over Pt/C for more durable PEMFC anodes.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Understanding of Correlation between Electronic Properties and Sulfur Tolerance of Pt-Based Catalysts for Hydrogen Oxidation

Qiu

Zhao

et al. 2022

ACS Appl. Mater. Interfaces

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“…Previously reported studies have shown that the lower d-band center for the metal surface can lead to the weakened bonding of adsorbates by decreasing the density of states for the binding orbit. , Thus, the affinity of chloride on the Pt surface in PtCo/C was decreased compared with Pt/C, showing a weakened strength of the Pt–Cl bond. The downshifted d-band center of Pt in PtCo/C can be explained by the ligand effect (i.e., electronic structure change) and geometry effect (i.e., lattice strain) . When Co was alloyed with Pt to construct the core–shell structure with the PtCo alloy as the core and Pt as the shell, the electrons could transfer from the sublayer Co atoms to surface Pt atoms due to the lower electronegativity of Co(1.88) compared with Pt (2.28).…”

Section: Resultsmentioning

confidence: 99%

“…The downshifted dband center of Pt in PtCo/C can be explained by the ligand effect (i.e., electronic structure change) and geometry effect (i.e., lattice strain). 43 When Co was alloyed with Pt to construct the core−shell structure with the PtCo alloy as the core and Pt as the shell, the electrons could transfer from the sublayer Co atoms to surface Pt atoms due to the lower electronegativity of Co(1.88) compared with Pt (2.28). The electron transfer between Pt and Co can result in an increase of the 5d electron density of Pt atoms.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Improved Chloride Tolerance of PtCo/C with a Pt-Skin Structure toward the Oxygen Reduction Reaction Due to a Weakened Pt–Cl Interaction

Sun

Qiu

et al. 2022

ACS Appl. Energy Mater.

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The high durability of proton exchange membrane fuel cells (PEMFCs) is crucial for their large-scale application in hydrogen mobility, while a trace amount of chloride in air significantly affects the durability of PEMFCs. Herein, we demonstrate a type of chloride-tolerant PtCo/C catalyst with a Pt3Co-core@Pt-skin structure showing that the chloride adsorption rate decreased by 34% compared with Pt/C. The introduction of Co weakens chloride adsorption on Pt with a decrease of ≥13% in the adsorption energy due to the downshifted Pt d-band center. The durability of PtCo/C outperforms that of Pt/C, exhibiting a stronger resistance toward the coupling effect of dynamic high-potential/chloride poisoning by mitigating Pt dissolution and hindering the Ostwald ripening of Pt nanoparticles. The presence of chloride aggravates the decay of Pt-based catalysts under the simulated potential cycling operation, and the aggravated effect is less severe for PtCo/C with an ∼40% decrease in the decay percentage in comparison to Pt/C after a 10,000-cycle test. This work provides a valuable guide for the design of robust antipoisoning catalysts by adjusting the Pt d-band center for long-life PEMFC application.

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“…When the ratio of Pt:Pd is 1:1, the d band centers of PtPd d , PtPd O1 , and PtPd O2 are calculated to be −2.352, −2.532, and −2.238 eV, respectively. Specifically, the d band centers of PtPd d and PtPd O1 are neither too high nor too low, and may possess better activity than the other alloys; the PtPd with the ration of 1:1 may be the most potential candidate as the MOR catalyst [35].…”

Section: The Properties Of Ptmpdn Alloymentioning

confidence: 99%

DFT Study on Methanol Oxidation Reaction Catalyzed by PtmPdn Alloys

Yang

Xue

et al. 2022

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Pt is widely used as the catalyst for methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFC). However, the high cost and limited supply of pure Pt limit the commercialization of DMFC. Herein, MOR catalyzed by variously designed Pd-doped PtmPdn was studied with the density functional theory (DFT); the PtmPdn(111) surface was chosen since it is the most stable surface among various low-index surfaces. The hydrogens in methyl groups were priorly dehydrogenated on Pt(111), followed by hydrogen in the hydroxyl group. The effects of both the ratio of Pt:Pd and the type of the alloy on the activity of PtmPdn catalysts toward MOR were also studied; both ordered and disordered PtPd with the 1:1 ratio had better catalytic activity towards MOR than other catalysts. Specifically, the disordered Pt:Pdd with the Pt:Pd ratio of 1:1 had the best activity for the relatively stronger adsorption of COH, but the lowest binding with CO and a moderate d band center. The adsorptions of both COH and CO are key steps in the MOR, since the steps of CH3OH→CH2OH→CHOH→COH have downhill energy profiles, while COH→CO is an uphill reaction. In addition, the d band centers of the surface atoms move towards the Fermi level with the increase of the Pd content; the d band can also be tuned by changing the atom arrangement. These findings can be used as rules to design high-performance catalysts for MOR.

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DFT study on ORR catalyzed by bimetallic Pt-skin metals over substrates of Ir, Pd and Au

Cited by 19 publications

References 22 publications

Understanding of Correlation between Electronic Properties and Sulfur Tolerance of Pt-Based Catalysts for Hydrogen Oxidation

Understanding of Correlation between Electronic Properties and Sulfur Tolerance of Pt-Based Catalysts for Hydrogen Oxidation

Improved Chloride Tolerance of PtCo/C with a Pt-Skin Structure toward the Oxygen Reduction Reaction Due to a Weakened Pt–Cl Interaction

DFT Study on Methanol Oxidation Reaction Catalyzed by PtmPdn Alloys

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