Summary

Water Electrolysis Apparatus

I printed all in clear PETG at 100% fill and build-plate supports. Both the electrolyzer and the rinser need to be sliced with a pause added two slices before the end of the hollow tubes. Then two ¾” ¼-20 bolts with five 14-20 nuts on them are dropped into place (four sets all together per part). I added a bunch of drops of super glue so the part will not rattle later. Then hit “resume” on the printer to seal the weights in place. This is needed to keep your parts from floating.

It is intended for KOH electrolyte, but would work in NaCl too, with some chlorine coming off with the oxygen. I use 33% KOH, being the eutectic; so most electrochemically active electrolyte.

I used 250 ml beakers with the electrolyzer filled to 200 ml and the rinser filled to 150 ml. The rinser is not needed for most applications, but mine required no residual KOH coming through as droplets in the hydrogen.

Be careful of the KOH solution. It is non-toxic, but is VERY caustic and will burn the skin and seriously damage the eyes if a drop gets in, so be careful.

Also, remember that the mixture of the resulting hydrogen and oxygen are at their stoichiometric perfect mix to explosively recombine into water. So be careful not to mix them.

The picture of the finished electrolyzer was before I improved the CAD to include the tubes to carry the stainless-steel wires. I used 5-minute epoxy to secure the wires.

The electrolyzing electrodes are very fine stainless steel (SS) mesh with SS wire as a current collector. The mesh I used was purchased from Amazon (“TIMESETL 304 Stainless Steel Woven Wire 200 Mesh - 12"X 40" Filter Screen Sheet Filtration Cloth”) and the wire was .041” (1.0 mm) wire from RioGrande (but any would work). The screen started as a, 8 x 2.5” rectangle, then tootsie-rolled after crimping on the current collecting wire.