Abstract:The reduction mechanism of Sb3+ in H2SO4-NH4F-SbF3 electrolyte system was studied by means of electrochemical methods, including chronopotentiometry and alternating current impedance. Analysis of potential-time transients clearly shows that antimony (Ⅲ) could be reduced to antimony metal via two-steps irreversible electron transfer process in H2SO4-NH4F-SbF3 system. The relationship between iτ1/2 and i calculated by chronopotentiometry indicates that the trivalent antimony complex undergoes chemical transformation reaction before its reduction in the cathode. The impedance results confirm the above conclusion and indicate that the adsorption states which are the middle product of trivalent antimony have different influences on two electron transfer steps.