Yes.
you will need 2 pencils, a 9 volt battery, a thin gauge wire, a clear glass, a paper cut into a circle with 2 holes in it, and water.
electrolysis
By electrolysis
No, filtration will not separate water into hydrogen and oxygen. Hydrolysis is the process most commonly used.
How to Improve Hydrogen Fuel Cell Output - Part 2
How to Improve Hydrogen Fuel Cell Output
How to Test 9 Cup HHO Fuel Cell
How to Assemble a 9 Cup HHO Fuel Cell