Could I speed up the reaction of electrlysis by using a catalyst?
why not? The rate of an electrolysis reaction depends on the type of electrode involved, there's an activation energy associated with reactions at the surface....I'm not aware of specific examples though.
And could I therefore save electricity? Where before the activation rate was higher and needed x amount of electricity, now to make the same amount of hydrogen I would only need y amount of electricity, where y<x.
yeah, also you'll need to consider the overpotential and polarization factors, by taking these into account you can significantly improve the electrical efficiency. Here's a nice site
If I use a catalyst, would I will be lowering the overpotential?
if it's suitable yes (it may have to do with reactions on the electrode surface), but there are other ways to lower the overpotential in addition.
What are some practical ways? Because the website says to lower the voltage input, but if I have a catalyst, won't the catalyst just use all that extra voltage anyways?
I heard sodium hydroxide is a good catalyst for the electrolysis of water.
sodium hydroxide increases the conductivity of the solution, thus this increases the efficiency of the electrolysis, but salt bridges are always a problem, because they aren't 100% efficient, you'll have problems with the formation of junction potentials, so that's another way to improve the efficiency-by considering better salt bridges. Catalysts don't "use up the voltage" so I'm not quite sure what you're referring to here.
They are actually many ways and factors to consider, some of these factors are interrelated so you'll need to find the optimum conditions and voltage. The reason they say to lower the voltage stems from the polarization effect with high voltages.
I'll try looking into this a bit more later, at the moment I'm a bit preoccupied with something else. You can keep asking general questions, but as far as specific methods go, I don't have one in mind at the moment; also be more specific and detailed about what you wish to achieve.
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