Urchin-like core-shell TiO₂/α-MnO₂ nanostructures as an active catalyst for rechargeable lithium-oxygen battery

A selection of appropriate electrocatalysts with a unique design is a promising solution to promote oxidation and reduction reactions in lithium-oxygen (Li-O₂) batteries. Here, an effective integrated design of urchin-like core-shell TiO₂/α-MnO₂ nanostructure is constructed to develop an efficient catalyst electrode for Li-O₂ batteries. For this purpose, TiO₂ nanoparticles are biosynthesized by an eco-friendly process using flower extract of Matricaria chamomilla as both reducing and stabilizing agents. Then, MnO₂ nanocrystals are grown on the surface of TiO₂ nanoparticles under different reaction times to observe their evolution in terms of morphology and crystalline structure of MnO₂. The electrochemical behavior of the as-prepared core-shell TiO₂/α-MnO₂ nanostructures is evaluated in Li-O₂ cells. The TiO₂/α-MnO₂ electrode is exhibited a lower overpotential and higher specific capacity than the bare TiO₂ electrode. This could have resulted from the bifunctional catalytic activity of TiO2 and α-MnO₂ coupled with urchin-like MnO₂ nanostructures. Furthermore, the internal resistance of the cell is recorded using electrochemical impedance spectroscopy technique, and reactions of the Li⁺ and O₂ on the cathode surface are investigated by cyclic voltammetry.