http://en.wikipedia.org/wiki/Catalyst

Water electrolysis is just a chemical reaction, so everything in the article above will hold.

yeah the use of a catalyst should make the process more efficient, it will speed it up and not get used, not sure about this but i heard somewhere that it takes about 44 Kj to break one more of H₂O with a catalyst compared to 66 Kj.

anything that will not get used up during the process but speed it up is a catalyst.  you could several kinds of metals, you could even some dilute amounts of acid  to water to speed up the process, atleast that is what my teacher told me.

probably not, but as you said it will make the reaction faster.

The acid looks interesting, as long as it doesn't affect the gases in any way. They need to be as pure as possible.

The acid looks interesting, as long as it doesn't affect the gases in any way. They need to be as pure as possible.

this is were it depends on what you will be using to carry the electrolysis process.  some catalysts are not good to work around impure substances because they will be dissolved in your product, and that is the reason that platinum is so widely used as a catalyst, it tends to leave the impurities behind in the electrolysis process/

I do not fully agree with the acid being a catalyst. A real catalyst has a uniform effect, with net zero-consumption locally at any location in the reaction mix.

However, that is not the definition of a catalyst.  Look at the production of Nitric Acid.  At one point, ammonia is passed over a platinum gauze catalyst.  The reaction, however, only occurs locally at the point where the ammonia and oxygen contact the platinum gauze.  Everywhere else the reaction is not sped up at all, yet the gauze is considered to be a catalyst.  

Thinking about it a bit further, in reality during the electrolysis of water the electrons themselves are a catalyst.  They catalyze the reaction of 2H2O => 2H2 + O2.  In the end, all of the electrons are recovered and not "used up" by the process.  

However, that is not the definition of a catalyst.  Look at the production of Nitric Acid.  At one point, ammonia is passed over a platinum gauze catalyst.  The reaction, however, only occurs locally at the point where the ammonia and oxygen contact the platinum gauze.  Everywhere else the reaction is not sped up at all, yet the gauze is considered to be a catalyst.  

Thinking about it a bit further, in reality during the electrolysis of water the electrons themselves are a catalyst.  They catalyze the reaction of 2H2O => 2H2 + O2.  In the end, all of the electrons are recovered and not "used up" by the process.  

I still do not feel comfortable with the definition. I agree with the example you give. I also call his gauze a catalyst. I did not word it precisely enough in my previous post. The reaction at the gauze still is such that no gauze-metal is consumed, while in the electrolysis reaction, H(+) ions are produced on one side, and OH(-) ions are produced on the other side.

The example with the electrons also is not a real good example to my opinion. At one side, electrons are consumed and at the other side, electrons are produced (by the power supply). You can even demonstrate this nicely. Split up your electrolyte in two beakers and between the beakers, insert a bridge, not a salt bridge, but a large electrolytic capacitor, one end dipped in one beaker, and the other end dipped in the other beaker (if you do this experiment in reality, please be careful about polarity of the elco, otherwise it may explode!). You'll see a positive charge buildup in one beaker and a negative charge buildup in the other beaker, accompanied with temporary evolution of gas at the electrodes. How this charge is built up, depends on the electrolyte and it most likely will be in the form of positive ions in the anode beaker and in the form of negative ions in the cathode beaker.
Now, if you remove the power supply, but leave the capacitor in contact with the two beakers, and then close the circuit between cathode and anode, then you'll observe formation of gas in both cells. Ions loose electrons and H2 is formed and O2 is formed. In order to see this, you need a large elco, 100000 uF / 16V would be nice, use a 12 V power supply.

So, electrons really are consumed and produced. A real catalyst is different. Imagine a sphere, of any size, placed at any position in 3D space. Whatever the placement of the sphere and whatever its precise size, inside such a sphere, there is an amount of catalyst. The amount of catalyst inside the sphere, as function of time, ONLY depends on the flux of catalyst through the surface of the sphere. In mathematical terms, the catalyst is conserved locally. Just perform the thought experiment, place your little spheres anywhere and with a normal chemical reaction, you'll quickly see that nowhere in space, catalyst is produced or consumed. Of course, in the chemical reaction mechanism it will be produced or consumed, but the net amount is constant (of course disregarding inward or outward flux, due to convection).  In the case of electrolysis, this cannot be said. Electrons are produced somewhere, and consumed at another place.

I think that we agree on the actual mechanisms and the chemistry behind it. It is a matter of wording and definition. I just post this lengty post here, in order to make clear the subtle difference.