Electrochemical Strain Dynamics in Noble Metal Nanocatalysts

Chattot, Raphaël; Martens, Isaac; Mirolo, Marta; Ronovský, Michal; Russello, Florian; Isérn, H.; Braesch, Guillaume; Hornberger, Elisabeth; Strasser, Peter; Sibert, Éric; Chatenet, Marian; Honkimäki, V.; Drnec, Jakub

doi:10.1021/jacs.1c06780

Cited by 25 publications

(50 citation statements)

References 46 publications

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“…Previous studies on Pt nanoparticle strain dynamics revealed that lattice parameter contraction is associated with desorption of various charged species from the surface. 38,39 HISPEC3000 showed no such contraction.…”

Section: ■ Results and Discussionmentioning

confidence: 85%

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Impact of Carbon N-Doping and Pyridinic-N Content on the Fuel Cell Performance and Durability of Carbon-Supported Pt Nanoparticle Catalysts

Hornberger

Merzdorf

Schmies

et al. 2022

ACS Appl. Mater. Interfaces

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Cathode catalyst layers of proton exchange membrane fuel cells (PEMFCs) typically consist of carbon-supported platinum catalysts with varying weight ratios of proton-conducting ionomers. N-Doping of carbon support materials is proposed to enhance the performance and durability of the cathode layer under operating conditions in a PEMFC. However, a detailed understanding of the contributing N-moieties is missing. Here, we report the successful synthesis and fuel cell implementation of Pt electrocatalysts supported on N-doped carbons, with a focus on the analysis of the N-induced effect on catalyst performance and durability. A customized fluidized bed reduction reactor was used to synthesize highly monodisperse Pt nanoparticles deposited on N-doped carbons (N−C), the catalytic oxygen reduction reaction activity and stability of which matched those of state-of-the-art PEMFC catalysts. Operando high-energy X-ray diffraction experiments were conducted using a fourth generation storage ring; the light of extreme brilliance and coherence allows investigating the impact of N-doping on the degradation behavior of the Pt/N−C catalysts. Tests in liquid electrolytes were compared with tests in membrane electrode assemblies in single-cell PEMFCs. Our analysis refines earlier views on the subject of Ndoped carbon catalyst supports: it provides evidence that heteroatom doping and thus the incorporation of defects into the carbon backbone do not mitigate the carbon corrosion during high-potential cycling (1−1.5 V) and, however, can promote the cell performance under usual PEMFC operating conditions (0.6−0.9 V).

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Section: ■ Results and Discussionmentioning

confidence: 85%

“…The strongest relative contraction of the lattice is found for Pt/N-V-400 followed by Pt/N-V-800 and Pt/V, respectively. Previous studies on Pt nanoparticle strain dynamics revealed that lattice parameter contraction is associated with desorption of various charged species from the surface. , HISPEC3000 showed no such contraction.…”

Section: Resultsmentioning

confidence: 87%

Impact of Carbon N-Doping and Pyridinic-N Content on the Fuel Cell Performance and Durability of Carbon-Supported Pt Nanoparticle Catalysts

Hornberger

Merzdorf

Schmies

et al. 2022

ACS Appl. Mater. Interfaces

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“…Rietveld refinement of the WAXS patterns was used to reveal the electrochemical strain dynamics (variations of the lattice constant) during three consecutive cycles of electrode polarization at 5 mV s –1 after the different conditioning steps (Figure d–f). As discussed in detail in dedicated previous contributions, , the enhanced surface-to-volume ratio of nanoparticles allows adsorption processes to be monitored by the “bulk” X-ray diffraction technique. Briefly, the lattice constant of Pt nanoparticles was found to be minimum (maximum compressive strain) at the potential of zero total charge (pztc), where the surface is (rather) free of adsorbates.…”

Section: Introductionmentioning

confidence: 99%

Break-In Bad: On the Conditioning of Fuel Cell Nanoalloy Catalysts

et al. 2022

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Preliminary testing of fuel cell catalysts in a model laboratory environment is an essential step in the technology readiness level progression of material candidates toward the commercial device. However, in the case of platinum alloy catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs), there is no consensus on the protocol employed for catalyst conditioning (activation or break-in), leading to important discrepancies in the literature. Here, the effects of electrochemical conditioning on the PtNi nanocatalyst structure, chemical composition, and performance for the ORR are investigated using operando high-energy X-ray diffraction in both the liquid-electrolyte and solid-electrolyte X-ray transparent PEMFCs, online inductively coupled plasma mass spectrometry, and the rotating disk electrode (RDE) techniques, respectively. Our results show that for PtNi/C materials, the cost in ORR performance associated to complete surface stabilization at the potential of the ORR can be dramatic but can also be mitigated by adjusting the initial chemistry and structure of the catalyst. Overall, this study reveals how uncomplete catalyst conditioning in the RDE leads to highly erroneous conclusions regarding its performance and stability to be possibly found in a realistic PEMFC device and proposes simple strategies to close this gap.

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“…Platinum (Pt) and Pt-based compounds are considered as the state-of-the-art electrocatalysts for ORR in the past decades, − but their widespread implementation is still severely restricted by the high cost and reserve scarcity. Besides, another challenge is the durability problem of Pt, which tends to dissolve in the acidic electrolyte under long-term operating conditions. , Therefore, it is essential to rationally design higher-ORR performance and longer-lifetime Pt-based nanocatalysts with low Pt usage for fuel cells.…”

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confidence: 99%

Exploring the Effect of Pd on the Oxygen Reduction Performance of Pt by In Situ Raman Spectroscopy

et al. 2022

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Directly monitoring the oxygen reduction reaction (ORR) process in situ is very important to deeply understand the reaction mechanism and is a critical guideline for the design of high-efficiency catalysts, but there is still lack of definite in situ evidence to clarify the effect between adsorbed intermediates and the strain/electronic effect for enhanced ORR performance. Herein, in situ surface-enhanced Raman spectroscopy (SERS) was employed to detect the intermediates during the ORR process on the Au@Pd@Pt core/shell heterogeneous nanoparticles (NPs). Direct spectroscopic evidence of the *OOH intermediate was obtained, and an obvious red shift of the *OOH frequency was identified with the controllable shell thickness of Pd. Detailed experimental characterizations and density functional theory (DFT) calculations demonstrated that such improved ORR activity after inducing Pd into Au@Pt NPs can be attributed to the optimized adsorbate−substrate interaction due to the strain and electronic effect, leading to a higher Pt−O binding energy and a lower O−O binding energy, which was conducive to O−O dissociation and promoted the subsequent reaction. Notably, this work illustrates a relationship between the performance and strain/electronic effect via the intermediate detected by SERS and paves the way for the construction of ORR electrocatalysts with high performance.

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Electrochemical Strain Dynamics in Noble Metal Nanocatalysts

Cited by 25 publications

References 46 publications

Impact of Carbon N-Doping and Pyridinic-N Content on the Fuel Cell Performance and Durability of Carbon-Supported Pt Nanoparticle Catalysts

Impact of Carbon N-Doping and Pyridinic-N Content on the Fuel Cell Performance and Durability of Carbon-Supported Pt Nanoparticle Catalysts

Break-In Bad: On the Conditioning of Fuel Cell Nanoalloy Catalysts

Exploring the Effect of Pd on the Oxygen Reduction Performance of Pt by In Situ Raman Spectroscopy

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