“…Thus, the proposal of cheaper, highly efficient, alternative catalysts is a challenge of relevant interest. Most studies have been focused on the use of transition metal oxides, namely nickel [9,10], manganese [11,12], copper [13] or iron [14]. However, it is widely accepted that spinel cobalt oxide (Co 3 O 4 ) is the most attractive oxide phase for the lean methane catalytic combustion owing to the presence of variable valance states (Co 3+ /Co 2+ ), its lower bonding energy of Co-O bonds and the high mobility of active oxygen species capable of activating the C-H bond [15][16][17].…”