Caffeinated Interfaces Enhance Alkaline Hydrogen Electrocatalysis

Intikhab, Saad; Rebollar, Luis; Li, Yawei; Pai, Rahul; Kalra, Vibha; Tang, Maureen H.; Snyder, Joshua C.

doi:10.26434/chemrxiv.12100599.v1

Cited by 7 publications

(9 citation statements)

References 35 publications

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“…We first verified that adding 10 -5 M caffeine into 0.1 M KOH electrolyte markedly improved the HER/HOR activity of Pt/C (TKK, 47.7 wt%) (Fig. S1A) in a RDE as originally reported by Snyder and co-workers (18). We then tested 10 -5 M 1,3-dimethyluracil and 1methylimidazole, the left and right parts of caffeine, respectively, to specify which part(s) of caffeine contribute to the improvement.…”

supporting

confidence: 81%

“…S9). The same phenomenon was also observed for caffeine (18). This phenomenon indicates that N-methylimidazoles inhibit rather than facilitate hydroxide adsorption like Ru (6).…”

supporting

confidence: 71%

“…Most recently, Snyder's group (18) found that adding caffeine into alkaline solution substantially improved the HER/HOR activity of Pt in base, but the improvement mechanism was unclear. This work inspired us to seek other organic compounds that promote the HER/HOR of Pt in alkaline solution and then identify their promoting roles to understand the sluggish HER/HOR kinetics of Pt.…”

mentioning

confidence: 99%

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Mechanistic insights into pH-dependent hydrogen electrocatalysis by flipping interfacial water

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Oliveira

Tyukhtenko

et al. 2021

Preprint

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A grand challenge in electrochemistry is to understand and promote electrochemical processes by exploring and exploiting the interface. Herein, we promoted the hydrogen evolution and oxidation reactions (HER/HOR) of platinum in base by employing N-methylimidazoles to reorientate interfacial water against the interfacial electric field as evidenced by in situ spectroscopic characterization of the interface. We accordingly established a unified mechanism by which the HER/HOR in acid and base proceeds via diffusion of proton and hydroxide, respectively, through interface via interfacial water by the Grotthuss mechanism. This mechanism accounts for the pH-dependent HER/HOR kinetics of platinum, a long-standing puzzle. Furthermore, we demonstrated 40% performance improvement of an anion exchange membrane electrolyzer by adding 1,2-dimethylimidazole into the alkaline solution fed into its Pt cathode.

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supporting

confidence: 81%

“…S9). The same phenomenon was also observed for caffeine (18). This phenomenon indicates that N-methylimidazoles inhibit rather than facilitate hydroxide adsorption like Ru (6).…”

supporting

confidence: 71%

mentioning

confidence: 99%

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Mechanistic insights into pH-dependent hydrogen electrocatalysis by flipping interfacial water

Sun

Oliveira

Tyukhtenko

et al. 2021

Preprint

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“…1−4 Electrocatalysis is one of the most powerful methods to promote the reaction efficiency. 5,6 It has been shown that most noble metals exhibit good catalytic water-splitting performance due to their low potential and high chemical activity. However, their high cost and scarcity hinder further large-scale application.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Investigation of Catalytic Water Splitting by the Arene-Anchored Actinide Complexes

et al. 2022

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Actinide complexes, which could enable the electrocatalytic H2O reduction, are not well documented because of the fact that actinide-containing catalysts are precluded by extremely stable actinyl species. Herein, by using relativistic density functional theory calculations, the arene-anchored trivalent actinide complexes (Me,MeArO)3 ArAn (marked as [AnL]) with desirable electron transport between metal and ligand arene are investigated for H2 production. The metal center is changed from Ac to Pu. Electron-spin density calculations reveal a two-electron oxidative process (involving high-valent intermediates) for complexes [AnL] (An = P–Pu) along the catalytic pathway. The electrons are provided by both the actinide metal and the arene ring of ligand. This is comparable to the previously reported uranium catalyst (Ad,MeArO)3 mesU (Ad = adamantine and mes = mesitylene). From the thermodynamic and kinetic perspectives, [PaL] offers appreciably lower reaction energies for the overall catalytic cycle than other actinide complexes. Thus, the protactinium complex tends to be the most reactive for H2O reduction to produce H2 and has the advantage of its experimental accessibility.

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“…9−11 It has also been demonstrated that CO 2 reduction selectivity may be tuned when catalytically active surfaces are confined by flat organic molecules. 12−14 Specifically, for hydrogen evolution, HER rates are enhanced when Pt(111) is covered by flat caffeine molecules, 15 and electrode stability is improved when Pt is confined by SiO x nanomembranes. 16−18 The effect of overlayer confinement on single crystals has also been studied with density functional theory (DFT) calculations.…”

Section: Introductionmentioning

confidence: 99%

Electrocatalysis under Cover: Enhanced Hydrogen Evolution via Defective Graphene-Covered Pt(111)

2021

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The production of hydrogen via water electrolysis using renewable electricity is a promising carbon-neutral technology. In this contribution, we report insights into the hydrogen evolution reaction (HER) in H 2 SO 4 on Pt(111) and graphene-covered Pt(111), in addition to the electrochemical properties of graphene overlayers. As-prepared graphene overlayers are selectively permeable to H + ions in the electrolyte, allowing H + ions into the confined layer between graphene and Pt(111) while excluding SO 4 2− and other anions. We demonstrate that defects in these as-prepared graphene overlayers can be generated from oxidation at high overpotentials or reduction from the production of H 2 bubbles and postulate that HER occurs locally at only Pt(111) in the proximity of defects in graphene overlayers on asprepared G/Pt(111) electrodes, and as defects in graphene increases, more of the Pt(111) surface becomes utilized for HER. Kinetically, the addition of defective graphene overlayers can increase the geometric HER rate by up to 200%, while Tafel slopes and [H + ] reaction orders remain unchanged. These results shed kinetic insight into the nature of graphene overlayers and their effect on HER catalysis and also demonstrate the promise of confinement modifications in designing catalysts with properties closer to achieving optimum rates.

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Caffeinated Interfaces Enhance Alkaline Hydrogen Electrocatalysis

Cited by 7 publications

References 35 publications

Mechanistic insights into pH-dependent hydrogen electrocatalysis by flipping interfacial water

Mechanistic insights into pH-dependent hydrogen electrocatalysis by flipping interfacial water

Theoretical Investigation of Catalytic Water Splitting by the Arene-Anchored Actinide Complexes

Electrocatalysis under Cover: Enhanced Hydrogen Evolution via Defective Graphene-Covered Pt(111)

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