Multifunctional barium/carbon spheres-lanthanum oxide for water splitting and supercapacitor applications

The advancement of sustainable and renewable energy sources, including water splitting for oxygen and hydrogen production in an alkaline medium and various energy storage devices, particularly high-power density and eco-friendly supercapacitors, has become essential for energy safety due to prevailing environmental issues. This study explores the use of nanomaterials for energy production and storage applications. For this purpose, a simple co-precipitation method was employed to synthesize lanthanum oxide (La₂O₃) doped with a constant amount (3 wt %) of carbon spheres (CS), and different weight ratios (2 and 4 wt %) of barium (Ba). The optimized 4 % Ba/CS-La₂O₃ sample demonstrates effective oxygen evolution reaction (OER) kinetics with a minimal overpotential of 243 mV at 10 mA cm⁻² and a Tafel slope of 72.8 mV dec⁻¹ in an alkaline medium. The optimized electrocatalyst reveals a significant value (304.24 cm²) of electrochemical active surface area (ECSA), indicating a larger number of active sites. For hydrogen production, 4 % Ba/CS-La₂O₃ electrocatalyst reveals a lower overpotential of 226 mV at 10 mA cm⁻² in an alkaline medium. Moreover, the 4 % Ba-doped electrocatalyst shows a specific capacitance of 92.69 Fg^-1 at 1 Ag^-1 calculated from chronopotentiometry (CP).