electroless Ni-P on copper

[Roza.h]

Hi.
I have a question
what is the mechanism of surface activator in electroless Ni-P on copper ?
in this paper suggested that we can use inducer such as Al,Fe,... but I want to know what is the mechanism of Fe and how shift the potential which allows the adsorption and homolysis of the reducing agent?and how shifting optential taking place?
thanks for your help