Eco-friendly energy-storage systems are needed to lower the fossil-fuel dependence and environmental contamination. Among energy storage technologies, metal air batteries offer a good and cheap perspective for the energy supply in small devices. However, its efficiency is low due to the slow kinetics of key reactions namely oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The same reactions occur in a reversible fuel cell. Perovskites have emerged as a promising candidate for alkaline condition due to the diversity in crystal structure, possibility of tuning electronic properties, low cost and earth abundance. Different catalytic descriptors for these ABO₃-type systems are for instance e_g orbital filling on B-site metals [1], high structural and chemical stability [2], oxygen vacancies [3], B-site metal oxygen covalency [4] and crystal structure [5]. Thus, a variation of the B-site is an effective strategy in order to enhance the catalytic properties [4][6].

In this work, LaFe_xCo_1-xO_3-δ (x = 0 to 1) perovskites have been synthesized using a sol-gel approach and are characterized by several physicochemical techniques to identify the composition, structure and electronic state of iron and cobalt. We will discuss to what extent the activity depends on the descriptors as discussed above. Moreover, for our best performing material, its performance in Zn air battery was evaluated.

References:

[1] Suntivich, Y. S. Horn et al., Nat. Chem. 3 (2011) 7, 546–550.

[2] Suntivich, Y. S. Horn et al., Science 334 (2011) 6061, 1383-1385.

[3] T. Mefford, K. J. Stevenson et al., Nat. Commun. 7 (2016) 11053.

[4] Duan, Z. J. Xu et al., Chem. Mater. 29 (2017) 24,10534–10541.

[5] Zhou and J. Sunarso, J. Phys. Chem. Lett. 4 (2013) 17, 2982–2988.

[6] Wang, Z. Feng et al., ACS Appl. Mater. Interfaces 11 (2019) 6, 5682-5686.