Electrochemical reactions of La(Ni, Cr)O_3 and La(Ni, Fe)O_3 in acidic aqueous solutions

摘要

Voltammetry of immobilised microcrystalline perovskites La(Ni, Cr)O_3 and La(Ni,Fe)O_3 revealed that these oxides yield three types of reactions in acidic aqueous solutions (0.1 M HClO_4):irreversible oxidative dissolution of Crrich oxides, irreversible reductive dissolution of Fe-rich oxides, and a quasireversible reaction most likely related to alteration of the valencies of Cr, Fe and/or Ni in the solid state. The sample of La(Cr_(1-x)Ni_x)O_3 with x=0.3 and 0.5 especially showed limited cycling stability that is particularly surprising in the very strongly acidic solution.