Triggering photocatalytic performance of La 2 Co x Mn 2-x O 6 via heat activation

Abstract

The La-based perovskite (LaBO 3 ) 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 La 2 Co x Mn 2-x O 6 perovskites. Additionally, we demonstrate that photocatalysis is the main contributor to substrate conversion in the selective oxidation of toluene and reduction of CO 2 . Particularly, La 2 Co 1.5 Mn 0.5 O 6 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.