Sonochemical and sonoelectrochemical production of hydrogen

Islam, Hujjatul; Burheim, Odne Stokke; Pollet, Bruno G.

doi:10.1016/j.ultsonch.2018.08.024

“…173,174 Ultrasound has been used to enhance the rate of electrochemical processes by increasing mass transfer in the liquid electrolyte due to the acoustic streaming, and in some cases by actively removing bubbles from electrodes during reactions. 175,176,177,178,179,180,181 More specifically, the complex phenomena associated to sonication can disrupt the diffusion layer, enhance mass transfer of ions through the double layer, and enhance the activity of the electrode surface (see Figure 12). Under ultrasonic irradiation, and below a specific acoustic power (depending on pressure amplitude, frequency, gas concentration in the liquid, etc.)…”

Section: Acoustic Fieldsmentioning

confidence: 99%

Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors

Angulo

¹

,

Linde

²

,

Gardeniers

³

et al. 2020

Joule

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Bubbles are known to influence energy and mass transfer in gas evolving electrodes. However, we lack a detailed understanding on the intricate dependencies between bubble evolution processes and electrochemical phenomena.This review discusses our current knowledge on the effects of bubbles on electrochemical systems with the aim to identify opportunities and motivate future research in this area. We first provide a base background on the physics of bubble evolution as it relates to electrochemical processes. Then we outline how bubbles affect energy efficiency of electrode processes, detailing the bubble-induced impacts on activation, ohmic and concentration overpotentials.Lastly, we describe different strategies to mitigate losses and how to exploit bubbles to enhance electrochemical reactions. Context & ScaleElectrochemical reactors will play a key role in the electrification of the chemical industry and can enable the integration of renewable electricity sources with chemical manufacturing. Most large-scale industrial electrochemical processes, including chloro-alkali and aluminum production, involve gas evolving electrodes. The evolution of bubbles at the surface of redox reaction sites often lead to the reduction of the active electrode area, the increase of ohmic resistance in the electrolyte and the formation of undesirable concentration gradients. All of these effects result in energy losses which reduce the efficiency of electrochemical systems. This review synthesizes our current understanding on the relationship between bubble evolution and energy losses in electrochemical reactors. By presenting a thorough account on the state of the research in this area, we aim to provide a common ground for the research community to improve our understanding on the complex processes involved in multiphase electrochemical systems. Increasing our knowledge on the relationship between bubbles and electrochemistry will lead to new strategies to mitigate and exploit bubble-induced phenomena leading to design guidelines for high-performing electrochemical reactors.

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“…Ultrasonic applied to electrochemically promoted reactions is known to not only influence gas bubble removal from surfaces but also offers many other advantages. [23,24] An increase in electrode cleanliness, metal depassivation, and enhanced mass-transport of electroactive species to the electrode surface will result in enhanced electrochemical diffusion processes, in an increase in a) electrochemical rates and yields, b) process efficiencies, as well as in a decrease of electrode overpotentials; this overall leads to improved electroplated and electrodeposited materials (hardness, porosity, and thickness). [25] We would like to emphasize at this point that we employed ultrasound solely for the fabrication of the HER electrode and not when the ready-made electrode was used as a hydrogen forming electrode.…”

Section: Ultrasonic Conditionsmentioning

confidence: 99%

From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes

Ring

¹

,

Pollet

²

,

Chatenet

³

et al. 2019

Self Cite

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The electrodeposition of noble metals using corresponding dissolved metal salts represents an interesting process for the improvement of the electrocatalytic hydrogen evolution reaction (HER) properties of less active substrate materials. The fact that only a small fraction of the dissolved noble metals reaches the substrate represents a serious obstacle to this common procedure. We therefore chose a different path. It was found that the HER activity of Ni42 alloy drastically increased (η=140 mV at j=10 mA cm−2; pH 1) when a platinum counter electrode was used during polarization experiments in acid. This improvement was caused by a platinum transfer from the platinum anode to the steel cathode, a process which occurred simultaneously to the hydrogen evolution. The negligible accumulation of Pt (26 μg) in the electrolyte turns this straight‐forward transfer procedure into a highly cost‐effective, environmentally friendly, and waste reducing approach for the generation of cheap, stable and effective HER electrodes.

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“…In order to overcome and circumvent these problems, ultrasonication (80 kHz, 48–72 W) was used. Ultrasonic applied to electrochemically promoted reactions is known to not only influence gas bubble removal from surfaces but also offers many other advantages . An increase in electrode cleanliness, metal depassivation, and enhanced mass‐transport of electroactive species to the electrode surface will result in enhanced electrochemical diffusion processes, in an increase in a) electrochemical rates and yields, b) process efficiencies, as well as in a decrease of electrode overpotentials; this overall leads to improved electroplated and electrodeposited materials (hardness, porosity, and thickness)…”

Section: Resultsmentioning

confidence: 99%

From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes

Ring

¹

,

Pollet

²

,

Chatenet

³

et al. 2019

Self Cite

View full text Add to dashboard Cite

The electrodeposition of noble metals using corresponding dissolved metal salts represents an interesting process for the improvement of the electrocatalytic hydrogen evolution reaction (HER) properties of less active substrate materials. The fact that only a small fraction of the dissolved noble metals reaches the substrate represents a serious obstacle to this common procedure. We therefore chose a different path. It was found that the HER activity of Ni42 alloy drastically increased (η=140 mV at j=10 mA cm−2; pH 1) when a platinum counter electrode was used during polarization experiments in acid. This improvement was caused by a platinum transfer from the platinum anode to the steel cathode, a process which occurred simultaneously to the hydrogen evolution. The negligible accumulation of Pt (26 μg) in the electrolyte turns this straight‐forward transfer procedure into a highly cost‐effective, environmentally friendly, and waste reducing approach for the generation of cheap, stable and effective HER electrodes.

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Sonochemical and sonoelectrochemical production of hydrogen

Cited by 142 publications

References 118 publications

Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors

Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors

From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes

From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes

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