Boosting Electrode Performance and Bubble Management via Direct Laser Interference Patterning.

Laser-structuring techniques like Direct Laser Interference Patterning show great potential for optimizing electrodes for water electrolysis. Therefore, a systematic experimental study is performed to analyze the influence of the spatial period and the aspect ratio between spatial period and structure depth on the electrode performance for pure Ni electrodes. Using a statistical design of experiments approach, it is found that the spatial distance between the laser-structures is the decisive processing parameter for the improvement of the electrode performance. Thus, the electrochemically active surface area could be increased by a factor of 12 compared to a nonstructured electrode. For oxygen evolution reaction, a significantly lower onset potential and overpotential (≈ -164 mV at 100 mA cm) is found. This is explained by the superhydrophilic surface of the laser-structures and the influence of the structured surface on the bubble growth, which leads to a lower number of active nucleation sites and, simultaneously, larger detached bubbles. Combined with the fully wetted electrode surface, this results in reduced electrode blocking and thus, lower ohmic resistance.