Producing Hydrogen to Function as a Lift Gas Answered
The short version: I want to make hydrogen to fill model airship envelopes with, because screw helium. Help me make a cheap electrolysis device that can do this in under an hour (ideally), or come up with an even better system for production. My immediate problem is that I need a high-surface electrode that won't fail in a solution of sodium hydroxide.
The long version:
I've devoted a fair portion of my time to contemplating airships, primarily because they're awesome. Fell out of use with the rise of much faster aircraft, and the technology its fate sealed by the extraordinarily bad rep the Hindenburg gave it. It is still far from useless, however, in that lighter-than-air systems can lay claim to flight times measured in days, and sometimes months, thanks to the fact that they literally float in the air like a boat floats in water.
Their day may have come and gone, but I still want to experiment with the technology and create some model airships of my own. Helium works okay as a lifting gas, but it remains expensive and isn't going to get any cheaper in the foreseeable future. It is for this reason that I am pursuing hydrogen, in the hope that I might be able to produce a cheap lifting gas for my projects. Unfortunately for my aspirations, hydrogen is surprisingly hard to get cheaply in decent quantities. Here's what I've figured out so far.
For one, it is absurdly hard to find sites that don't veer into fringe science when talking about hydrogen. HHO production, Joe cells, power your car with water...it all keeps cropping up, and not only does none of this do what I want, the concepts are often poorly documented or riddled with problems. However, I have been able to glean some information from my research. First off, one of the easiest methods (and the one I'll be pursuing the most) of hydrogen production is through electrolysis. For those of you unfamiliar with the concept, you can basically take two electrodes, stick them in water, add some electrolyte (like regular table salt), and apply a decent voltage. You'll get hydrogen gas streaming out of the negative electrode and oxygen out of the positive electrode. Fancier systems use large tanks, platinum electrodes, and a strong acid or base as the electrolyte. To increase efficiency (yeah, it's not 100% efficient), there is ongoing experimentation with high-temperature electrolysis and ongoing research into an effective electrocatalyst.
Now, when I did my research, I thought "Hey! This sounds easy! I'll just set the system up like explained, and away we go!" Unfortunately, those exclamation marks were unwarranted. My first attempt showed that production is mind-numbingly slow with small electrodes. Using salt had the wonderful side-effect of producing chlorine and sodium hydroxide, a.k.a. caustic soda. It's called that for a reason, and I'm lucky I didn't run it too long or I might have a chemical burn now. Now I know. Choosing a good electrode turns out to be a problem too, as most conductors oxidize quickly or dissolve in the solution (now I know why everybody uses platinum when possible). My aluminum foil electrodes in a sodium hydroxide solution? Yeah, that didn't work AT ALL. I had better luck with steel mesh, but I recently found that it seems to fail over time too. The only thing that isn't disappointing is the container and the collection apparatus: an inverted plastic bottle with some airtight hose running off it, connected to a gas valve. If the bottle is placed such that forming gas causes the internal water level to be lower than the external container water level, the gas will be pushed through the hose (no pumping necessary!). There was one good thing I discovered, however. Apparently there was a bit of soap or something left over in the container, and I ended up forming a bit of explosive foam as well. The hydrogen foam blows up like nothing else, and the oxygen foam makes a loud pop and sends (slightly) caustic foam all over the place. Totally useless but still somewhat cool, so long as you're not fool enough to do it in large quantities.
So, as of right now, I've got a good container and collection system, but my electrodes suck and production rates are so low that it'd take me hours and hours to inflate a good-sized balloon anyway. I'll be using sodium hydroxide in the future as the electrolyte, skipping the chlorine production and observing the proper safety procedures. My top priority is finding a good electrode, my next is finding a good way to increase surface area, and my last is getting a higher voltage source than the 12V power supply I had lying around. Any ideas?