[Dolphinsiu]

http://antoine.frostburg.edu/chem/senese/101/redox/faq/print-h2o2-iodide-reaction.shtml

Given mechanisms for Harcourt-Essen Reaction:
HI + H2O2 --> HIO + H2O (r.d.s step)
HI + HIO --> I2 + H2O

From the above website, it mentions that the free radical mechanism is occurred in presence of (homogenous) catalyst (NH4)2MoO4. Then, what is the mechanism? (I have found many website but not successful)