Triggering photocatalytic performance of La₂Co_xMn_2-xO₆ via heat activation

The La-based perovskite (LaBO₃) exhibits excellent optical properties. However, its valence band (VB) potential is not sufficiently positive to reach the oxidation potential required for the cleavage of chemical bonds (such as benzylic C-H), limiting its application in photocatalysis. Herein, we report the unconventional effects of heat activation on the reduction of the dissociation energy of benzylic C-H and aqueous H-O, thereby triggering the photocatalytic activity of La₂Co_xMn_2-xO₆ perovskites. Additionally, we demonstrate that photocatalysis is the main contributor to substrate conversion in the selective oxidation of toluene and reduction of CO₂. Particularly, La₂Co_1.5Mn_0.5O₆ shows excellent performance with a product yield of 550.00 mmol g_cat^-1 and a toluene conversion of 22,866.67 μmol g_cat^-1 h^-1. To the best of our knowledge, this is the highest reported product yield for the selective oxidation of benzylic C-H bond of toluene. Our findings provide insight into the specific role of heat activation in photocatalysis, which is crucial for breaking and overcoming the VB barrier to realize challenging reactions.