Why isn't iron(III) oxide an effective catalyst for decomposing hydrogen peroxide? I've been working on a project involving the catalyst iron(III) oxide for decomposing hydrogen peroxide. 
It barely seemed to produce any oxygen.  

This YouTube video also seems to suggest that iron(III) oxide isn't a very effective catalyst.
But why?
Ah but iron(III) does act as a catalyst in peroxide decomposition (YouTube video).

It can be improved by the addition of some copper.

Some hydrogen peroxide is mixed with inhibitors (radical scavengers or chelating agents) to suppress the decomposition.