Not only iron reacts in alcaline surroundings and oxygen oversupply to form strong, unstable oxidisers. Keep in mind that mixing ingredients may not yield the required result, any catalysts need to be in the right place in the right time in any reaction to work the best. Simple mixing might not suffice.

"A green substance, potassium manganate, is obtained after about 10 minutes when melting manganese(IV) oxide with an alkaline salt and adding oxidizing agents like saltpeter (potassium nitrate KNO3) or potassium perchlorate (KClO4). Potassium manganate (K2MnO4) can be purified by vacuum distilling with a metal "finish" to give dark green crystals (rhombic prisms). Potassium manganate is only soluble in alkali; in non-alkali conditions it will disproportionate into potassium permanganate (KMnO4-) and manganese(IV) oxide (MnO2)."


What comes to my mind is to wet the iron oxide with KMnO4 so that it will be coated with atomic-sized MnO2 after decomposition. We can do something similar with KNO3, pour KMnO4 solution into it, mix well and dry it afterwards, pulverise after drying.
This is the ordinary procedure for preparations of many catalysts. (followed by activation, which I will not discuss here)