Structural Effects on the Oxygen Reduction Reaction on Pt Single-Crystal Electrodes Modified with Melamine

Wada, Naoya; Nakamura, Masashi; Hoshi, Nagahiro

doi:10.1007/s12678-020-00584-0

Cited by 28 publications

(31 citation statements)

References 23 publications

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“…However, the electrocatalytic performance of these metal−melamine interfaces has seldomly been explored. 21,22 In this work, we deposited a melamine adlayer on a Pt(111) surface [Pt(111)−M ad ] following the concept adopted and improved by our research group, that is, electrocatalyst surface modification by foreign chemical species, 8,23−25 and tested the ability of this interface to selectively block larger anions from poisoning the surface, while allowing ORR to proceed unhindered. Sulfuric acid was chosen as the acidic media with the well-known strongly adsorbing anions, that is, (bi)sulfate species.…”

Section: ■ Introductionmentioning

confidence: 99%

Improved Rate for the Oxygen Reduction Reaction in a Sulfuric Acid Electrolyte using a Pt(111) Surface Modified with Melamine

Zorko

Martins

Connell

et al. 2021

ACS Appl. Mater. Interfaces

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The feasible commercialization of alkaline, phosphoric acid and polymer electrolyte membrane fuel cells depends on the development of oxygen reduction reaction (ORR) electrocatalysts with improved activity, stability, and selectivity. The rational design of surfaces to ensure these improved ORR catalytic requirements relies on the so-called "descriptors" (e.g., the role of covalent and noncovalent interactions on platinum surface active sites for ORR). Here, we demonstrate that through the molecular adsorption of melamine onto the Pt( 111) surface [Pt(111)−M ad ], the activity can be improved by a factor of 20 compared to bare Pt(111) for the ORR in a strongly adsorbing sulfuric acid solution. The M ad moieties act as "surface-blocking bodies," selectively hindering the adsorption of (bi)sulfate anions (well-known poisoning spectator of the Pt(111) active sites) while the ORR is unhindered. This modified surface is further demonstrated to exhibit improved chemical stability relative to Pt(111) patterned with cyanide species (CN ad ), previously shown by our group to have a similar ORR activity increase compared to bare Pt(111) in a sulfuric acid electrolyte, with Pt(111)−M ad retaining a greater than ninefold higher ORR activity relative to bare Pt(111) after extensive potential cycling as compared to a greater than threefold higher activity retained on a CN ad -covered Pt(111) surface. We suggest that the higher stability of the Pt(111)−M ad interface stems from melamine's ability to form intermolecular hydrogen bonds, which effectively turns the melamine molecules into larger macromolecular entities with multiple anchoring sites and thus more difficult to remove.

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Section: ■ Introductionmentioning

confidence: 99%

Improved Rate for the Oxygen Reduction Reaction in a Sulfuric Acid Electrolyte using a Pt(111) Surface Modified with Melamine

Zorko

Martins

Connell

et al. 2021

ACS Appl. Mater. Interfaces

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“…54 We have modified Pt single crystal electrodes with melamine to determine the surface structure that is activated by melamine most markedly. 55 Figure 15 shows j K at 0.90 V(RHE) on the low index planes and n(111)-(111) series of Pt with and without melamine modification. Melamine increases the ORR activity on all the surfaces examined.…”

Section: Melaminementioning

confidence: 99%

Enhancement of the Activity for the Oxygen Reduction Reaction on Well-defined Single Crystal Electrodes of Pt by Hydrophobic Species

Hoshi

Nakamura

2020

Chemistry Letters

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The activity for the oxygen reduction reaction (ORR), which is the reaction at the air electrode of fuel cells, depends on the surface structure of the electrode markedly. This review summarizes the effects of hydrophobic species on the activity for the ORR on single crystal electrodes of Pt. We have examined the effects of aliphatic and aromatic molecules on the ORR. Structural effects on the increase of the activity and the factors of the enhancement are discussed.

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“…14,15 Alkyl amines, melamine and tetra-n-hexylammonium cation (THA + ) also enhance the ORR activity of Pt single crystal electrodes. [16][17][18] Especially, melamine and THA + increase the activity of the stepped surfaces of Pt as well as Pt(111). Thus we have adopted melamine and THA + as modification species of Nb-doped TiO 2 single crystal electrodes.…”

Section: Introductionmentioning

confidence: 99%

The Oxygen Reduction Reaction on Nb-doped Titanium Dioxide Single Crystal Electrodes

2021

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Structural effects on the oxygen reduction reaction (ORR) have been studied on the low index planes of rutile TiO 2 doped with Nb (0.05-1 wt%) in 0.1 M HClO 4. The order of the ORR activity at 0.20 V (vs. RHE) is TiO 2 (100) < TiO 2 (111) < TiO 2 (110), and the activity increases with increasing Nb concentration. The activity of TiO 2 (110) is 5.6 times as high as that of TiO 2 (100) at Nb concentration 1%. The order of the ORR activity does not correlate with the amount of oxygen vacancy defects that are known as the active sites of the ORR of TiO 2 nanoparticles. The ORR activity of 1%Nb-doped TiO 2 (100) modified with melamine is 2.1 times higher than that of the unmodified one. The activity of 1%Nb-doped TiO 2 (110) modified with melamine is the highest in the low index planes of TiO 2. Modification by tetra-n-hexylammonium cation (THA +) affects the ORR activity slightly.

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Structural Effects on the Oxygen Reduction Reaction on Pt Single-Crystal Electrodes Modified with Melamine

Cited by 28 publications

References 23 publications

Improved Rate for the Oxygen Reduction Reaction in a Sulfuric Acid Electrolyte using a Pt(111) Surface Modified with Melamine

Improved Rate for the Oxygen Reduction Reaction in a Sulfuric Acid Electrolyte using a Pt(111) Surface Modified with Melamine

Enhancement of the Activity for the Oxygen Reduction Reaction on Well-defined Single Crystal Electrodes of Pt by Hydrophobic Species

The Oxygen Reduction Reaction on Nb-doped Titanium Dioxide Single Crystal Electrodes

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