Electrochemical Behavior of Hydrazine Borane in Methanol Solution

Electrochemical behavior of hydrazine borane (HB) was investigated on gold electrode in 0.5 M LiClO4 solution in methanol using cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and chronoamperometry. Two irreversible peaks at 164 and 530 mV are attributed to direct electro-oxidation of HB on gold electrode in methanol. Both EIS results and CV data at different scan rates indicate a diffusion controlled electron transfer reaction. Furthermore, the Tafel slope (b = 0.191 V) and charge transfer coefficient (alpha = 0.69) were obtained for the HB oxidation at the gold/solution interface. A possible ECE (electrochemical-chemical-electrochemical) mechanism is proposed for the irreversible two electron transfer reaction. This mechanism was also confirmed by the results of Nicholson-Shain test. Additionally, diffusion coefficient of HB was found to be 1.6 x 10(-5) cm(2).s(-1) using chronoamperometry. First oxidation peak of HB appears at a lower potential than that of ammonia borane (AB), clearly indicating that HB is a stronger reducing agent as compared to AB in methanol solution. (C) 2014 The Electrochemical Society. All rights reserved