Synthesis and electrocatalytic properties of LaFe1-xZnxO3 perovskites

In this work, perovskite-type oxides of general formula LaFe1-xZnxO3(0 <= x <= 0.3) prepared by a sol-gel route were investigated as electrocatalysts for the oxygen evolution reaction (OER) in alkaline KOH solutions. X-ray diffraction analysis of samples indicates that the pure cubic structure was obtained for composition lower than x = 0.2. The OER studies indicate that substitution of iron by zinc increases the electrocatalytic activity of the resulting material significantly. The highest activity was achieved for x = 0.1, whereas the obtained current density was 9.02 mA cm(-2) at 0.66 V, which is approximately three times higher than that of the base oxide. The Tafel slopes values for OER on each oxide in 1 M KOH are found to be similar to 89, 52, and 64 mV dec(-1) for LaFeO3, LaFe0.9Zn0.1O3, and LaFe0.8Zn0.2O3, respectively. The stability of LaFe0.9Zn0.1O3 electrode is studied in the process of 1000 successive cycles at a current density of 10 mA.cm(-2) of the OER. A small change in overpotential was found, ranged between 11 and 19 mV, indicating clearly its long electrochemical durability. These results suggest clearly that LaFe0.9Zn0.1O3 electrode is a promising anode material for the OER in water electrolysis. Graphical Abstract Linear sweep voltammetry of LaFe1-xZnxO3 electrodes in 1 M KOH, at a scan rate of 50 mV/s; inset shows the OER current density at 0.66 V vs. Hg/HgO. [GRAPHICS] .