Electrocatalytic activity and stability of Ti/IrO2+MnO2 anode in 0.5 M NaCl solution

摘要

Ti/IrO2(x)+MnO2(1-x) anodes have been fabricated by thermal decomposition of a mixed H2IrCl6 and Mn (NO3)2 hydrosolvent. Cyclic voltammetry (CV) and polarization curve have been utilized to investigate the electrochemical behavior and electrocatalytic activity of Ti/IrO2(x)+ MnO2(1-x) anodes in 0.5 M NaCl solution (pH=2). Ti/ IrO2+MnO2 anode with 70 mol% IrO2 content has the maximum value of q*, indicating that Ti/IrO2(0.7)+ MnO2(0.3) anode has the most excellent electrocatalytic activity for the synchronal evolution of Cl2 and O2 in dilute NaCl solution. Tafel lines displayed two distinct linear regions with one of the slope close to 62 mV dec1 in the low potential region and the other close to 295 mV dec1 in the high potential region. Electrochemical impedance spectroscopic is employed to investigate the impedance behavior of Ti/IrO2(x)+MnO2(1-x) anodes in 0.5 M NaCl solution. It is observed that as the Rct, Rs and Rf values for Ti/IrO2(0.7)+ MnO2(0.3) anode become smaller, electrocatalytic activity of Ti/IrO2(0.7)+MnO2(0.3) anode becomes better than that of other Ti/IrO2+MnO2 anodes with different compositions. Ti/IrO2(0.7)+MnO2(0.3) anode fabricated at 400 °C has been observed to possess the highest service life of 225 h, whereas the accelerated life test is carried out under the anodic current of 2 A cm2 at the temperature of 50 °C in 0.5 M NaCl solution (pH=2).