Synthesis And Physicochemical Properties Of Oxides Based On Lanthanum And Transitions Metals

Résumé: Developing economical and highly efficient electrode material is crucial for water electrolysis and supercapacitors associated with energy conversion and storage. For this purpose, we successfully elaborated a new series of LaCo1 xZnxO3 oxides (x = 0, 0.03, 0.05, 0.1, 0.2, 0.3 and 0.4) via a facile sol gel route. We investigated, for the first time, their structural, morphological and electrochemical properties for possible use as electrode material toward oxygen evolution reaction and supercapacitor in a basic solution. Among the developed materials, the LaCo0.9Zn0.1O3 electrocatalyst displays a remarkable performance; an overpotential of merely 327 mV is needed to generate a specified current density of 10 mA.cm 2geo; a current density of around 73.41 mA.cm−2 at 450 mV, almost twice as high compared to the pristine electrocatalyst; a faster reaction kinetic with a lower Tafel slope of ~92 mV.dec−1 and an activity loss of less than 4 % after 24 hours of utilization. On the other hand, the LaCo0.95Zn0.05O3 electrode provides the best specific capacitance (300.47 F/g); this is almost four times higher compared to the undoped electrode (75.36 F/g). The electrode material also shows excellent capacitance retention of 85.73% after 5000 cycles at 5 A/g. In addition, a hybrid supercapacitor with high energy density was constructed by combining LaCo0.95Zn0.05O3 with activated carbon. The LaCo0.95Zn0.05O3//activated carbon hybrid device offers a high energy density of 36.12 Wh.kg 1 at a power density of 390.35 W.kg 1. The device is characterized by outstanding retention of the capacitance of 81% after being subjected to 5000 successive charge discharge cycles.

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