Both phenazines and quinoxalines are used in DB solutions. I have some patents here, but they are not in my usual repertoire. Kodak and Ilford have many patents on the subject. There are other classes of catalysts as well. In my research disclosure (Haist, King and Mowrey) you will see that no catalyst was used. Actually, one of the developing agents acted as an electron transport and did it as well or better than anything else. And, it was low in toxicity.