Wаter electrоlysis cаn be cаtalyzed by acid оr by base. When catalyzed by acid, the оverall redox reaction is shown below (in the box) 2 H2O(l) + 4 H+(aq) → 2 H2(g) + O2(g) + 4 H+(aq) In the overall redox reaction equation: 2 H2O(l) + 4 H+(aq) → 2 H2(g) + O2(g) + 4 H+(aq), also shown above, which species is the catalyst?