Making Copper Oxide

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• Even though there are still a couple of t's to cross and i's to dot, this section is mostly complete and ought to be enough to get most folks on the road to making their own copper oxide.
• If you try this, please be very careful. Inattentiveness to the setup/process could lead to overheating and possibly start a fire. Watch what you're doing.

The finished "product".

First off, you need a DC power source. The higher the power rating, the better. Small transformers (i.e. the canonical wall warts) might work if you have nothing else, but try to find something bigger if you can. "Wall wart" transformers have no fuse protection and the electrolysis approach to making copper oxide can, in my experience, result in drawing relatively high currents (i.e. a couple of amps, although this is not typical). If you're not careful, you could start a fire.

Hooking things up. The basic approach is simple:

• Take two pieces of copper wire and place them both in a jar of water with some of the wire extending above the water surface. DO NOT LET THE WIRES TOUCH.
• Connect one wire to the positive terminal of the power supply and the other to the negative terminal.

  

  The Setup

• Turn on the power supply and after a few minutes you should see begin to see some blue wispy material form near the positive terminal (this might be copper carbonate...I'm not entirely sure on this point).
  Also, you should see bubbles forming on the cathode (i.e. the negative terminal); this is hydrogen gas, which is flammable (remember the Hindenburg?). As long as you're careful, this is unlikely to be a problem. (NOTE: if you've a mind to conduct a little home-brewed science experiment, a little jury-rigging should allow you to collect this gas...think inverted 2-liter bottle, initially filled with water, lowered over the cathode. As the gas collects, it displaces the water. What you do with it after that is up to you:)

  

  Starting Electrolysis

  
  
  For my setup, the initial current draw for a six-inch long anode (i.e. the positive terminal) is only about 25 milliamps (this will probably drop off with time as the wire begins to corrode).
  How much current your setup draws may(?) depend to some degree on the chemistry of the water you use. Whether the water is hard or soft might play a role due to the differing level of electrolytes dissolved in it. (I didn't conduct any experiments to test this possibility, so your results may or may not be similar to mine.)
• Over time, the positive electrode will also start to corrode and turn dark brown...this is copper oxide...this is what you're after.

  

  Copper Oxide Formation

• You may notice the water surface starts to develop a brownish scum. If the entire surface scums over between the electrodes, my experience suggests this may provide a relatively lower resistance pathway for current. This could result in two potential problems:

  

  Scum at the surface can cause "shorts". 

  1. If there is a lower resistance path along the surface of the water, it could act as something like a "short" and draw a *lot* of current. If you don't have some type of fuse protection in place, things could heat up and even catch fire. Not good.
  2. Even if the current draw remains relatively low, my experience suggests that the copper wire anode will corrode more quickly at the air-water interface. This can result in the wire "breaking off" prematurely leaving you with less oxide and more wire (now sitting on the bottom of the container).
     The image to the right shows a simple device that shields the cathode (negative terminal) from the build up of scum at the air/water interface. Its nothing more than a short length of PVC pipe with some holes below the water level. Its still a good idea to keep a close eye on things. If you own and know how to use an ammeter, its a good idea to keep tabs on the current.
     
     
• How long it takes to produce a usable amount of copper oxide will depend on your set up, but even if it takes a month, this is still a shorter time frame than putting bare wire directly into acid.

  

  A shield to prevent shorting.

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