Samenvatting
This study examines the impact of 2D perforated plates and 3D-structured nickel electrodes on electrochemical performance and bubble behavior in a zero-gap alkaline water electrolyzer. 2D nickel electrodes with 0.5, 1.0, and 2.0 mm perforation diameters exhibit similar area-ohmic resistance of ∼0.55 Ω cm2 at 0.4 A/cm2, while a 3D-structured electrode with pillar features achieves the lowest ohmic resistance of 0.33 Ω cm2 at 0.4 A/cm2. Video analysis reveals microbubble coalescence and detachment dynamics, correlating with electrochemical performance. Most bubbles have a diameter under 400 μm, making 2D perforated plates with perforations of 0.5 mm or larger comparable in performance. Bubbles trapped in the imperfect zero-gap may significantly contribute to the total ohmic resistance. When perforations are smaller than the average bubble diameter, bubbles cannot escape, leading to increased ohmic resistance. The good performance of the electrode with pillar features is attributed to effective bubble management in a close to zero-gap configuration. The findings underscore the potential of 3D structured electrodes to enhance efficiency, reduce material usage, and enable green hydrogen production using non-noble materials at high current densities.
| Originele taal-2 | Engels |
|---|---|
| Artikelnummer | 236116 |
| Aantal pagina's | 11 |
| Tijdschrift | Journal of Power Sources |
| Volume | 630 |
| DOI's | |
| Status | Gepubliceerd - 28 feb. 2025 |
Bibliografische nota
Publisher Copyright:© 2025 The Authors
Financiering
The electrochemical surface areas of the nickel perforated plate (1 mm hole diameter), ZP200689 and ZP200696 were estimated from the averaged double layer capacitance using cyclic voltammetry in the non-faradaic region. For more information regarding the ECSA measurements, please refer to the supporting information S4. Table 2 summarizes all double layer capacitance values and its corresponding ECSA values including one standard deviation. All nickel-based electrodes have ECSAs in the same order of magnitude.The electrochemical performances of two nickel-based electrodes with a 3D-structured geometry from VECO Precision B.V., namely ZP200689 and ZP200696 were also evaluated. The 3D-structured electrode pillars were placed facing the electrolyte and not the diaphragm in a zero-gap configuration. The I-V curve is shown in Fig. 4 (a) for a cell equipped with Zirfon Perl UTP 500 using a 27 wt% KOH electrolyte with 50 \u03BCmol/L Fe, flowing by natural convection at room temperature and near atmospheric pressure. From the I-V curve, it is noticed that the slope of the curve for the electrolyzer using ZP200696 as electrodes is slightly lower compared to the electrode ZP200689 and the other electrodes shown in Fig. 3. This suggests that ZP200696 has the lowest ohmic resistance. Besides the I-V curve slope analysis, the area-ohmic resistance can be obtained from I-V curve fitting [36,38]. The fitted values are shown in the supporting information S6 and they confirm that ZP200696 has the lowest fitted area-ohmic resistance of 0.389 \u03A9 cm2 when compared to all others investigated electrode materials (0.54\u20130.67 \u03A9 cm2). Nyquist plots of EIS measurements are presented in Fig. 4 (b) confirming that ZP200696 has a resistance of 0.33 \u03A9 cm2 at 0.4 A/cm2. The average area-ohmic resistance (\u00B1 two standard deviations) obtained via EIS as a function of the logarithm of current density is shown in Fig. 4 (c) confirm that the electrode ZP200696 shows a minor increase of the area-ohmic resistance with current density, with a bubble effect of 10 % from low to high current densities (area-ohmic resistances at 0.4 and 0.004 A/cm2 are compared to estimate the bubble effect), while the bubble effect is around 40 % for ZP200689 and 55 % for the average of all nickel perforated plates. Voltage-time curves provided in supporting information S5 emphasize that electrochemical performance of ZP200696 is barely influenced by bubbles at 0.3 A/cm2, showing less voltage fluctuations over time when compared to ZP200689. Fig. 4 (d) depicts the iR-corrected cell voltage as a function of current density and shows that all electrodes have a similar iR-corrected curve, showing comparable electrocatalytic activity, even though the ECSA is slightly different.The authors thankfully acknowledge both the Topsector Energie funding by the Netherlands Enterprise Agency (AlkaliBoost project: TWAS118004; and Hyscaling project: MOOI42010) and funding by Nobian and HyCC. The authors thankfully acknowledge both the Topsector Energie funding by the Netherlands Enterprise Agency (AlkaliBoost project: TWAS118004; and Hyscaling project: MOOI42010) and funding by Nobian and HyCC.
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