Hydrogen Bubble Size Distribution on Nanostructured Ni Surfaces: Electrochemically Active Surface Area Versus Wettability

Krause, Lukas; Skibińska, Katarzyna; Rox, Hannes; Baumann, Robert; Marzec, Mateusz; Yang, Xuegeng; Mutschke, Gerd; Żabiński, Piotr; Lasagni, Andrés Fabían; Eckert, Kerstin

doi:10.1021/acsami.2c22231

Cited by 13 publications

(18 citation statements)

References 60 publications

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“…For example, the average bubble departure diameters on the flat electrode are 90, 104, 122, 143, and 146 μm at increasing current densities of −10, −30, −40, −70, and −100 mA/cm 2 , respectively. These average bubble departure diameters are consistent with findings reported by Krause et al, which range approximately from 80 to 140 μm. Previous studies attributed this to the enhanced local surface tension, greater drag force on bubbles, and a higher likelihood of adjacent bubble coalescence at high voltages or current densities.…”

Section: Resultssupporting

confidence: 92%

Roles of Wettability and Wickability on Enhanced Hydrogen Evolution Reactions

Zhao,

Gong,

Zhang

et al. 2024

ACS Appl. Mater. Interfaces

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Bubble dynamics significantly impact mass transfer and energy conversion in electrochemical gas evolution reactions. Micro-/nanostructured surfaces with extreme wettability have been employed as gas-evolving electrodes to promote bubble departure and decrease the bubble-induced overpotential. However, effects of the electrodes’ wickability on the electrochemical reaction performances remain elusive. In this work, hydrogen evolution reaction (HER) performances are experimentally investigated using micropillar array electrodes with varying interpillar spacings, and effects of the electrodes’ wettability, wickability as well as bubble adhesion are discussed. A deep learning-based object detection model was used to obtain bubble counts and bubble departure size distributions. We show that microstructures on the electrode have little effect on the total bubble counts and bubble size distribution characteristics at low current densities. At high current densities, however, micropillar array electrodes have much higher total bubble counts and smaller bubble departure sizes compared with the flat electrode. We also demonstrate that surface wettability is a critical factor influencing HER performances under low current densities, where bubbles exist in an isolated regime. Under high current densities, where bubbles are in an interacting regime, the wickability of the micropillar array electrodes emerges as a determining factor. This work elucidates the roles of surface wettability and wickability on enhancing electrochemical performances, providing guidelines for the optimal design of micro-/nanostructured electrodes in various gas evolution reactions.

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Section: Resultssupporting

confidence: 92%

Roles of Wettability and Wickability on Enhanced Hydrogen Evolution Reactions

Zhao,

Gong,

Zhang

et al. 2024

ACS Appl. Mater. Interfaces

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“…Furthermore, the area of the CV curves obtained by the CuSn-30-3000 electrode is the largest (Figure c), suggesting that the as-fabricated CuSn-30-3000 electrode possesses the highest capacitance. This is possibly ascribed to its larger electrochemically active surface area (ECSA), as confirmed by the measurement of electrochemical double layer capacitance ( C dl ), which is positively correlated with ECSA . The C dl values of all electrodes were determined from the CV data by calculating the slopes of the current density versus scan rates in the non-Faradaic electrochemical double-layer region (SI, Figure S5), and these results are presented in Figure d.…”

Section: Resultsmentioning

confidence: 82%

Direct Electrocatalytic Reduction of As(III) on CuSn Alloy Electrode: A Green and Sustainable Strategy to Recover Elemental Arsenic from Arsenic Wastewater

Zheng,

Li,

et al. 2024

Ind. Eng. Chem. Res.

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Arsenic contamination in groundwater and industrial wastewater poses a significant threat to human health and the ecosystem. Electrochemical reduction of highly mobile As(III) species into less toxic elemental arsenic (As(0)) has emerged as a promising method to effectively recover arsenic from water. In this study, a novel CuSn alloy nanowire array-modified copper foam (CuSn NAs/CF) electrode was fabricated for the direct electrochemical reduction of As(III) to As(0). The electrocatalytic reduction of As(III) was systematically investigated under various reaction conditions, including current densities, solution pH, electrolytes, and initial As(III) concentrations. The CuSn NAs/CF electrode was proven to effectively suppress the hydrogen evolution reaction and greatly enhance the electrochemical reduction of As(III). The recovery yield of As(0) on the CuSn NAs/CF electrode reached 3.67 mg/cm 2 at 90 min of electrolysis in a 0.1 M Na 2 SO 4 at pH 11, which was 2.75 times higher than that of the Cu NAs-modified electrode. Furthermore, the as-prepared electrode also demonstrated excellent electrochemical stability and a longer service life, maintaining a recovery yield of As(0) at 2.62 mg/cm 2 even after 6 cycles. The reduction reaction mechanism of As(III) was ascribed to the synergistic effect of direct electrolysis and hydrogen radicals (•H) formation, as revealed by ESR and radical scavenger experimental results. This study not only provides convincing evidence for the direct electrochemical conversion of As(III) to As(0) on an innovative CuSn alloy electrode, but also offers a promising strategy to recover and reuse waste arsenic resources. This contributes to a sustainable and environmentally friendly approach to arsenic-containing wastewater treatment.

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“…The associated enhanced bubble detachment from the hydrophilic metal surface is also advantageous for other parts of the electrolyzer. For example, it was demonstrated that a quicker bubble detachment based on the hydrophilicity of laser-generated structures increases the performance of the electrocatalyst surface. , …”

Section: Discussionmentioning

confidence: 99%

Functionalization of Ti64 via Direct Laser Interference Patterning and Its Influence on Wettability and Oxygen Bubble Nucleation

Heinrich,

Ränke,

Schwarzenberger

et al. 2024

Langmuir

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The nucleation of bubbles on solid surfaces is an important phenomenon in nature and technological processes like electrolysis. During proton-exchange membrane electrolysis, the nucleation and separation of the electrically nonconductive oxygen in the anodic cycle plays a crucial role to minimize the overpotential it causes in the system. This increases the efficiency of the process, making renewable energy sources and the "powerto-gas" strategy more viable. A promising approach is to optimize gas separation by surface functionalization in order to apply a more advantageous interface to industrial materials. In this work, the connection between the wettability and bubble nucleation of oxygen is investigated. For tailoring the wettability of Ti64 substrates, the direct laser interference patterning method is applied. A laser source with a wavelength of 1064 nm and a pulse duration of 12 ps is used to generate periodic pillar-like structures with different depths up to ∼5 μm. The resulting surface properties are characterized by water contact angle measurement, scanning electron microscopy, confocal microscopy, and X-ray photon spectroscopy. It was possible to generate structures with a water contact angle ranging from 20°up to nearly superhydrophobic conditions. The different wettabilities are validated based on X-ray photon spectroscopy and the different elemental composition of the samples. The results indicate that the surface character of the substrate adapts depending on the surrounding media and needs more time to reach a steady state for deeper structures. A custom setup is used to expose the functionalized surfaces to oxygen-oversaturated solutions. It is shown that a higher hydrophobicity of the structured surface yields a stronger interaction with the dissolved gas. This significantly enhances the oxygen nucleation up to nearly 350% by generating approximately 20 times more nucleation spots, but also smaller bubble sizes and a reduced detachment rate.

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Hydrogen Bubble Size Distribution on Nanostructured Ni Surfaces: Electrochemically Active Surface Area Versus Wettability

Cited by 13 publications

References 60 publications

Roles of Wettability and Wickability on Enhanced Hydrogen Evolution Reactions

Roles of Wettability and Wickability on Enhanced Hydrogen Evolution Reactions

Direct Electrocatalytic Reduction of As(III) on CuSn Alloy Electrode: A Green and Sustainable Strategy to Recover Elemental Arsenic from Arsenic Wastewater

Functionalization of Ti64 via Direct Laser Interference Patterning and Its Influence on Wettability and Oxygen Bubble Nucleation

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