Enhancement of oxygen reduction reaction activity by grain boundaries in platinum nanostructures

Zhu, Enbo; Wang, Xue; Wang, Shiyi; Yan, Xucheng; Zhou, Jingxuan; Liu, Yang; Jin, Chengyan; Liu, Ershuai; Jia, Qingying; Duan, Xiangfeng; Li, Yujing; Heinz, Hendrik; Huang, Yu

doi:10.1007/s12274-020-3007-2

Cited by 19 publications

(40 citation statements)

References 46 publications

(53 reference statements)

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“…1B and table S7). R-NWs without grain boundaries show lower coordination numbers and lower contact time than R-NWs with grain boundaries, also consistent with experiments ( 66 ). Jagged nanowires and nanoplates show the highest coordination numbers, percent of time adsorbed, and residence time of O 2 , consistent with the highest ORR activities seen in experiments ( 34 , 35 ).…”

Section: Resultssupporting

confidence: 90%

“…We will discuss additional evidence for irregular Pt nanostructures ( Fig. 1 ) ( 34 , 35 , 66 ) and the role of oxygen partial pressure ( 67 ) further below, after in-depth discussion of site-specific adsorption, time scale, applied potential, and initial chemical reactions following adsorption.…”

Section: Resultsmentioning

confidence: 99%

“…Pt nanocatalysts used in practice are structurally complex, consist of multiple Pt(hkl) facets and defects, and often reconstruct during reactions ( 34 , 35 , 66 , 78 ). The analysis of O 2 adsorption on Pt nanostructures, which are covered by multiple (hkl) surfaces, therefore provides further insights under more realistic reaction conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Models of R-NW without grain boundaries, R-NW with grain boundaries, J-NW, and Pt nanoplates were prepared using dimensions, grain boundary density, and surface corrugation as described and tested for ORR in previous experiments ( 34 , 35 , 66 ). Models of R-NW without grain boundaries were built starting with an elongated bulk Pt supercell of 157.5 Å in length with (111) surfaces at the ends, which was radially cut to yield a cylinder of 1.8 nm in diameter.…”

Section: Methodsmentioning

confidence: 99%

“…Subsequently, further core atoms were randomly removed, and the model equilibrated in the NVT ensemble until a J-NW of 2.2 nm in diameter was obtained, consistent with transmission electron microscopy (TEM) images ( 34 ). The model of the nanoplates was assembled from 36 individual cuboctahedral Pt nanoparticles with 3.5 nm in diameter, following the mechanism reported in experiments ( 66 ). The constituting nanoparticles were placed at close distance next to each other at about the same height in a simulation box with 188 Å by 200 Å cross-sectional area in vacuum, bringing the nanoparticles in a position to fuse into a nanoplate.…”

Section: Methodsmentioning

confidence: 99%

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Direct correlation of oxygen adsorption on platinum-electrolyte interfaces with the activity in the oxygen reduction reaction

et al. 2021

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The oxygen reduction reaction (ORR) on platinum catalysts is essential in fuel cells. Quantitative predictions of the relative ORR activity in experiments, in the range of 1 to 50 times, have remained challenging because of incomplete mechanistic understanding and lack of computational tools to account for the associated small differences in activation energies (<2.3 kilocalories per mole). Using highly accurate molecular dynamics (MD) simulation with the Interface force field (0.1 kilocalories per mole), we elucidated the mechanism of adsorption of molecular oxygen on regular and irregular platinum surfaces and nanostructures, followed by local density functional theory (DFT) calculations. The relative ORR activity is determined by oxygen access to platinum surfaces, which greatly depends on specific water adlayers, while electron transfer occurs at a similar slow rate. The MD methods facilitate quantitative predictions of relative ORR activities of any platinum nanostructures, are applicable to other catalysts, and enable effective MD/DFT approaches.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Direct correlation of oxygen adsorption on platinum-electrolyte interfaces with the activity in the oxygen reduction reaction

et al. 2021

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Stability of Platinum‐Group‐Metal‐Based Electrocatalysts in Proton Exchange Membrane Fuel Cells

Zhu

et al. 2022

Adv Funct Materials

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Proton exchange membrane fuel cells (PEMFCs) have attracted significant interest as a promising alternative technology to the combustion engine to power next-generation vehicles with zero emission. Among the various technological targets, system cost and durability are currently identified as the main obstacles toward large-scale implementation of PEMFCs. Platinumgroup-metal-based (PGM-based) catalysts are the most efficient catalyst for the rate-limiting cathodic oxygen reduction reaction in PEMFCs and take the highest share in the cost breakdown. Therefore, the stability of PGM-based electrocatalysts plays a significant role in the development of PEMFCs. This review will summarize the recent progress made on the understanding of both the fundamental chemical and structural stability of PGM-based catalysts, and their durability in operational PEMFC devices. It calls for systematic studies on the chemical, structural, and operational durability of the PGMbased catalyst and the need to coin practical descriptors for catalyst design with both superior activity and durability for cost-effective and high-performance PEMFCs.

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Revisit to Grain Boundary Effect in Pt Nanocrystals toward the Oxygen Electroreduction Reaction

Kabiraz

Choi

2023

ChemCatChem

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The effect of catalytic surface defects in the oxygen reduction reaction (ORR) has been extensively studied to enhance the performance of proton‐exchange‐membrane fuel cells. Platinum (Pt)‐based nanocatalysts have been used to overcome the poor performance of ORR, and Sabatier‐type activity plots have been used to identify the optimal adsorption properties for ORR intermediates on the catalytic surface. Grain boundaries (GBs) within the nanostructures have been identified as the optimal active sites for ORR due to their reasonable coordination number and high oxygen residence time. However, oxidation of Pt atoms exposed at GB sites and leaching of non‐noble metals from bimetallic Pt alloys have been identified as the “Achilles Heel” of GB‐containing nanocatalysts. In this concept, we revisit the effect of GBs on nanocatalysts, summarize the mechanism of GBs towards ORR, and suggest outlooks for improving ORR for future design of nanocatalysts.

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Enhancement of oxygen reduction reaction activity by grain boundaries in platinum nanostructures

Cited by 19 publications

References 46 publications

Direct correlation of oxygen adsorption on platinum-electrolyte interfaces with the activity in the oxygen reduction reaction

Direct correlation of oxygen adsorption on platinum-electrolyte interfaces with the activity in the oxygen reduction reaction

Stability of Platinum‐Group‐Metal‐Based Electrocatalysts in Proton Exchange Membrane Fuel Cells

Revisit to Grain Boundary Effect in Pt Nanocrystals toward the Oxygen Electroreduction Reaction

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