I also noticed that gas evolution decreases as the AC frequency increases but the potassium hydroxide electrolyte was much more forgiving of frequency than salt.
Yes, I also use potassium or sodium hydroxide in small concentrations in my experiments.
Potassium hydroxide (KOH) can generally show slightly higher efficiency at low-frequency AC compared to salt (NaCl) for several reasons:
Higher Ionic Conductivity: KOH solutions generally offer high ionic conductivity, which reduces ohmic losses and allows the system to reach the "critical current density" required for gas evolution more easily, even during low-frequency AC pulses.
Lower Overpotential: KOH has a lower activation overpotential for the oxygen and hydrogen evolution compared to salt, meaning chemical reactions can initiate faster within each AC cycle.
Ion Activity: The specific activity of the potassium ion in alkaline media is often cited as more effective for hydrogen production than sodium ions in common salts.
In principle, it seems to me that almost the same thing can be achieved with a solution of ordinary baking soda.
But surprisingly, distilled and even deionized water can be used to effectively produce hydrogen...
I'm sure many of you have seen advertisements about the health benefits of drinking hydrogen water.
I doubt it's beneficial, but the hydrogen in the bottle on my desk produces bubbles that glow beautifully under the RGB LED lights.
Distilled and deionized water can be used in modern hydrogen bottles because they utilize solid polymer electrolyte PEM (Proton Exchange Membrane) technology.
Unlike older electrolysis methods that require solution of electrolytes in the water to conduct electricity, PEM use a solid polymer membrane that acts as the electrolyte itself. This allows the device to split even the purest water molecules into hydrogen and oxygen without needing dissolved ions for conductivity. Using distilled or deionized water offers several advantages:- pure water prevents mineral scale from building up on the electrodes and membrane, which significantly extends the bottle's lifespan.
But there's a problem: these membranes are primarily produced by one company, Nafion, and for some reason they're expensive.
Graphite powder electrodes—the cathode and anode—are formed directly on the membrane; a platinum catalyst must be added to the graphite powder. The binding component for this is also produced by Nafion.
Oxygen is released from the reverse side of the membrane, which is relatively dry; water doesn't leak out, or leaks in small amounts, so only pure hydrogen ends up in the water in the bottle.
You can learn more about this technology from test reviews of hydrogen bottles on YouTube.
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Topic: Horvath Patents and Improved Electrolysis Efficiency (Read 9161 times)
