Hadikhani Pooria, Hashemi S Mohammad H, Schenk Steven A, Psaltis Demetri
Optics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL) Lausanne Switzerland
Computational Science & Engineering Laboratory, ETH Zurich Zurich Switzerland.
Sustain Energy Fuels. 2021 Mar 15;5(9):2419-2432. doi: 10.1039/d1se00255d.
Membrane-less electrolyzers utilize fluidic forces instead of solid barriers for the separation of electrolysis gas products. These electrolyzers have low ionic resistance, a simple design, and the ability to work with electrolytes at different pH values. However, the interelectrode distance and the flow velocity should be large at high production rates to prevent gas cross over. This is not energetically favorable as the ionic resistance is higher at larger interelectrode distances and the required pumping power increases with the flow velocity. In this work, a new solution is introduced to increase the throughput of electrolyzers without the need for increasing these two parameters. The new microfluidic reactor has three channels separated by porous walls. The electrolyte enters the middle channel and flows into the outer channels through the wall pores. Gas products are being produced in the outer channels. Hydrogen cross over is 0.14% in this electrolyzer at flow rate = 80 mL h and current density () = 300 mA cm. This cross over is 58 times lower than hydrogen cross over in an equivalent membrane-less electrolyzer with parallel electrodes under the same working conditions. Moreover, the addition of a surfactant to the electrolyte further reduces the hydrogen cross over by 21% and the overpotential by 1.9%. This is due to the positive effects of surfactants on the detachment and coalescence dynamics of bubbles. The addition of the passive additive and implementation of the porous walls result in twice the hydrogen production rate in the new reactor compared to parallel electrode electrolyzers with similar hydrogen cross over.
无膜电解槽利用流体动力而非固体屏障来分离电解气体产物。这些电解槽具有低离子电阻、设计简单以及能够在不同pH值的电解质中工作的特点。然而，在高生产率下，电极间距和流速应该较大，以防止气体交叉。这在能量上并不有利，因为在较大的电极间距下离子电阻较高，并且所需的泵送功率会随着流速增加。在这项工作中，引入了一种新的解决方案，无需增加这两个参数即可提高电解槽的产量。新的微流体反应器有三个由多孔壁分隔的通道。电解质进入中间通道，并通过壁孔流入外部通道。气体产物在外部通道中产生。在流速 = 80 mL/h和电流密度（）= 300 mA/cm²的情况下，该电解槽中的氢气交叉率为0.14%。在相同工作条件下，这种交叉率比具有平行电极的等效无膜电解槽中的氢气交叉率低58倍。此外，向电解质中添加表面活性剂可进一步将氢气交叉率降低21%，过电位降低1.9%。这是由于表面活性剂对气泡的脱离和聚并动力学具有积极影响。与具有相似氢气交叉率的平行电极电解槽相比，添加被动添加剂和采用多孔壁使得新反应器中的氢气产生速率提高了一倍。
