Understanding the Effects of Ultrasound (408 kHz) on the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) on Raney-Ni in Alkaline Media

Foroughi, Faranak; Bernäcker, Christian Immanuel; Röntzsch, Lars; Pollet, Bruno G.

doi:10.1016/j.ultsonch.2022.105979

Cited by 21 publications

(12 citation statements)

References 53 publications

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“…Ultrasound generates heat, and it is necessary to circulate cooling water to keep the bulk electrolyte temperature ( T ) constant. In this regard, a refrigerated circulator (JULABO, Germany) was connected to the sonoelectrochemical cell to maintain the temperature at 298 ± 1 K. This sonoelectrochemical cell employed in this study, also called the Besançon cell , has been described in detail elsewhere. ,, The working electrode (WE) was a replaceable, disc-shaped solid electrode (E5TQ series, Pine) which in this case was polycrystalline Ni (99.99% in purity, Goodfellow; Ø = 5.00 mm) having a geometric surface area ( A geom ) of 0.196 cm 2 . The reference electrode (RE) was a custom-made reversible hydrogen electrode (RHE) .…”

Section: Methodsmentioning

confidence: 99%

“…Its surface area was at least 10× greater than that of the WE. , The distance between the ultrasonic probe and the WE was ca. 30 mm (half the length of the ultrasound wave from the oscillator). , The experimental setup is shown in Figure S1. The experiments were carried out in 1.0 M (pH = 13.7) aqueous KOH (Sigma-Aldrich, 99.99% in purity) solution outgassed using ultrahigh-purity N 2 (g) (99.999% in purity).…”

Section: Methodsmentioning

confidence: 99%

“…We initially investigated the effects of ultrasonication on polycrystalline platinum, Pt(poly), in acidic electrolytes and on Raney-Ni in alkaline electrolytes and observed that the HER was greatly enhanced. , In these studies, continuous ultrasonication was employed during the electrochemical HER and OER experiments.…”

Section: Introductionmentioning

confidence: 99%

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In Situ Sonoactivation of Polycrystalline Ni for the Hydrogen Evolution Reaction in Alkaline Media

Foroughi

Tintor

Faid

et al. 2023

ACS Appl. Energy Mater.

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In this investigation, we report on the development of a method for activating polycrystalline metallic nickel (Ni(poly)) surfaces toward the hydrogen evolution reaction (HER) in N2-saturated 1.0 M KOH aqueous electrolyte through continuous and pulsed ultrasonication (24 kHz, 44 ± 1.40 W, 60% acoustic amplitude, ultrasonic horn). It is found that ultrasonically activated Ni shows an improved HER activity with a much lower overpotential of −275 mV vs RHE at −10.0 mA cm–2 when compared to nonultrasonically activated Ni. It was observed that the ultrasonic pretreatment is a time-dependent process that gradually changes the oxidation state of Ni and longer ultrasonication times result in higher HER activity as compared to untreated Ni. This study highlights a straightforward strategy for activating nickel-based materials by ultrasonic treatment for the electrochemical water splitting reaction.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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In Situ Sonoactivation of Polycrystalline Ni for the Hydrogen Evolution Reaction in Alkaline Media

Foroughi

Tintor

Faid

et al. 2023

ACS Appl. Energy Mater.

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“…The rapid carbon dioxide (CO 2 ) emissions associated with increased fossil fuel consumption have led to global warming and the energy crisis. − Electrocatalytic reduction of CO 2 into fuels and chemical feedstocks is an important approach to address this global issue. − Electrocatalyst and reaction interface microenvironment optimization are commonly used strategies to promote the CO 2 reduction reaction (CO 2 RR) in efficiency and selectivity. − Increasing the reaction temperature is thought to promote the CO 2 RR because the kinetics of the elementary reaction is generally exponentially dependent on the temperature according to the Arrhenius law. − Unfortunately, as the temperature increases, the solubility of CO 2 decreases, and the reaction rate of the hydrogen evolution reaction (HER), a major competing reaction to the CO 2 RR, increases. , As a result, the CO 2 RR can be performed only at relatively low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Superhydrophobicity-Enabled Efficient Electrocatalytic CO₂ Reduction at a High Temperature

Li,

Zou,

Zhang

et al. 2023

ACS Catal.

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Enhancing the electrocatalytic CO2 reduction reaction (CO2RR) by a temperature increase is very attractive, but lower CO2 solubility and the more intense competitive hydrogen evolution reaction limit the practical implementation. Herein, we report an efficient CO2RR at relatively high temperatures using a superhydrophobic electrode with a solid–liquid–gas three-phase interface microenvironment. Based on the three-phase electrode, the partial current density of the reduction product CO was increased by 240% from 8 to 60 °C. A mathematical model was developed to explore the CO2RR process, which demonstrated that the high CO2 level and rapid CO2 diffusion rate determine the CO2RR performance. The interfacial CO2 concentration of the three-phase electrode is approximately 26.2 times higher than that of the two-phase electrode at 60 °C.

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“…[ 25 ] Au was intentionally chosen as the electrode material as it is a well‐studied, stable but yet relatively poor performing HER catalyst, therefore allowing us to highlight the simple potential of the SRBWs in improving a generic catalyst. [ 18,26 ] The significant performance improvement that will be shown—an approximate 14‐fold increase in current density as a consequence of the acoustic‐forcing reducing the kinetic overpotential of the system—cannot be merely explained through conventional sonoelectrochemical mechanisms [ 27,28 ] that involve the use of lower frequency (20 kHz–3 MHz) bulk ultrasound to overcome diffusive mass transport limitations by inducing convective flow (acoustic streaming), and which therefore have been limited to operation under acidic [ 29 ] and alkaline [ 30 ] conditions. That the higher MHz frequency excitation does not lead to the generation of cavitation bubbles [ 31 ] (unlike in conventional sonoelectrochemistry), in addition to being practically beneficial in reducing erosion and pitting of the electrodes, further reduces both diffusion limitations and Ohmic resistance due to bubble build‐up at the electrodes, but is inadequate in itself to fully explain the order‐of‐magnitude improvement in performance observed.…”

Section: Introductionmentioning

confidence: 99%

Acoustically‐Induced Water Frustration for Enhanced Hydrogen Evolution Reaction in Neutral Electrolytes

Ehrnst

Sherrell

Rezk

et al. 2022

Advanced Energy Materials

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Despite its appeal of green H 2 production using energy from renewable sources, water electrolysis currently only accounts for a small percentage of global H 2 production due to the need for expensive electrocatalysts to compensate for Ohmic losses associated with the kinetic overpotential of the system. [4][5][6] At present, H 2 production via electrolysis is predominantly carried out in strong acidic/alkaline electrolytes using state-of-the-art platinum group metal (PGM) electrocatalysts, which enables hydrogen evolution reactions (HER) to be conducted at the lowest onset potential, albeit at practically insurmountable industrial costs due to the metal's scarcity. [7,8] To attain industrially-relevant current densities (200-500 mA cm −2 ), an overpotential between 1.8 and 2.5 V is typically required. [9] At these levels though, acidic electrolytes-while providing an abundant source of protons (H + ) and hydronium (H 3 O + ) ions-produce acid fog under high temperatures that can corrode the electrolyzer and contaminate the product. [10] Alkaline electrolysis, on the other hand, is commonly plagued by unstable electrocatalysts and the need for expensive pH-tolerant membranes. [11][12][13] It is therefore desirable to carry out electrolysis in neutral or near-neutral electrolytes (pH 5-9) with non-PGM electrocatalysts. [14] The HER rate under these conditions is, nevertheless, significantly lower than those for electrolytes with extreme pH levels. In addition to diffusion limitations, this is due to the rapid consumption of H 3 O + , which creates a bottleneck that limits the extent of reaction until higher overpotentials are able to drive H 2 O reduction. [10,[15][16][17] Even with the best electrodes (i.e., PGMs), H 2 production is several orders of magnitude lower under neutral conditions, [7] such that the overpotential required to reach a current density of −4 mA cm −2 exceeds 0.25 V in a 0.1 M KClO 4 electrolyte compared to as little as 30 mV in 0.5 M H 2 SO 4 . [18,19] Similarly poor performance is obtained with the use of nickel-based electrocatalysts, which are generally favored for alkaline conditions, given their affinity for OH − adsorption. [20] To circumvent these limitations, novel electrocatalysts have been designed, in which the electrode is doped to tailor its catalytic sites for both H* and OH* adsorption to complement the electrolytic conditions, [21][22][23] or through the introduction of complex architectures that facilitate more favorable local pH environments, [24] although these strategies A novel strategy utilizing high-frequency (10 MHz) hybrid sound waves to dramatically enhance hydrogen evolution reactions (HER) in notoriously difficult neutral electrolytes by modifying their network coordination state is presented. Herein, the practical limitations associated with existing electrolyzer technology is addressed, including the need for highly corrosive electrolytes and expensive electrocatalysts, by redefining conceptually-poor hydrogen electrocatalysts in neutral electrolytes. The impro...

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Understanding the Effects of Ultrasound (408 kHz) on the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) on Raney-Ni in Alkaline Media

Cited by 21 publications

References 53 publications

In Situ Sonoactivation of Polycrystalline Ni for the Hydrogen Evolution Reaction in Alkaline Media

In Situ Sonoactivation of Polycrystalline Ni for the Hydrogen Evolution Reaction in Alkaline Media

Superhydrophobicity-Enabled Efficient Electrocatalytic CO₂ Reduction at a High Temperature

Acoustically‐Induced Water Frustration for Enhanced Hydrogen Evolution Reaction in Neutral Electrolytes

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Understanding the Effects of Ultrasound (408 kHz) on the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) on Raney-Ni in Alkaline Media

Cited by 21 publications

References 53 publications

In Situ Sonoactivation of Polycrystalline Ni for the Hydrogen Evolution Reaction in Alkaline Media

In Situ Sonoactivation of Polycrystalline Ni for the Hydrogen Evolution Reaction in Alkaline Media

Superhydrophobicity-Enabled Efficient Electrocatalytic CO2 Reduction at a High Temperature

Acoustically‐Induced Water Frustration for Enhanced Hydrogen Evolution Reaction in Neutral Electrolytes

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Product

Resources

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Superhydrophobicity-Enabled Efficient Electrocatalytic CO₂ Reduction at a High Temperature