Conversion of Co-Mn-Al hydrotalcites in highly active spinel-type catalysts for peroxide decomposition

Abstract

The fast decomposition of peroxides (M2O2, where M = H+, Li+) at room temperature has gained increased attention given its relevance, from propulsive systems to metal-O2 conversion batteries. This study describes, by a rational design of experiment, the influence of selected parameters such as: pH, initial concentration of K2CO3, precipitate aging, precipitate washing, and thermal treatment for the hydrotalcite co-precipitation, characterizing it for each synthesis variable. The results show that hydrotalcites can efficiently be converted in Co-Mn-Al spinels and as a result, a new highly active Co2Mn0.5Al0.5O4 spinel oxide was synthesized after thermal treatment. Its activity and mechanical resistance were tested in a micro-thruster reactor where it showed total decomposition (> 98%) of H2O2 and in a Li-O2 battery, with increased cyclability, been able to reduce the charging potential in ~200 mV. These encouraging results enhance the importance not only of this class of material, but also, the importance of robust synthesis methodologies for reproducible results.