Toward More Energy Efficient Renewable Hydrogen Production. Novel Hydrogen‐Generating Nickel Electrodes Whose Catalytic Surfaces Remain Bubble‐Free in Liquid Electrolyte

We report that coating a Ni sheet electrode with a patterned mosaic of PTFE islands having uniform diameters (0.10–0.15 mm) and proximity to each other, and which cover 2% of the area of the electrode, decreases its overpotential for hydrogen production by a remarkable 0.15–0.21 V at current densities of 2–15 mA cm −2 in 1 M KOH (PTFE = polytetrafluoroethylene). This correlates to a ≈20‐fold amplification in the rate of hydrogen generation by the electrode at a fixed electrode voltage of −1.15 V (vs. Hg/HgO) relative to control bare electrodes. The effect originates in the low surface energy of PTFE, which induces newly produced hydrogen to preferentially form bubbles on the PTFE surfaces, leaving the adjacent, uncoated Ni surface free of bubbles and able to catalyse hydrogen production with high energy efficiency. Fifteen different patterns of PTFE islands, incorporating three distinct island diameters, that covered 2%–20% of the electrode surface, were prepared and systematically studied in five replicates each, on large Ni sheet electrodes. The studies demonstrate statistically significant declines in overpotentials and onset potentials for electrochemical hydrogen production. Ni electrodes are widely used in commercial alkaline water electrolysis cells to produce renewable (‘green’) hydrogen.