Manganese Doping in Cobalt Oxide Nanorods Promotes Catalytic Dehydrogenation

Heteroatom doping in nanomaterials can import new active sites and promote catalytic activity. Here we report that Mn-doped Co3O4 nanorods (Mn-x-Co3O4) via substituting Mn3+- (t(2g)(3)-e(g)(1)) for Co3+ (t(2g)(6)-e(g)(0)) exhibit similar to 100% yield for 4-methyl benzyl alcohol dehydrogenation catalysis at 60 degrees C and no decay (8 cycles), compared with only 1.4% of activity for bare Co(3)O(4 )catalysts. We characterize the fine structures of Mn-x-Co3O4 at the atomic level and demonstrate that the superior catalytic performance is strongly related to the Mn3+-induced Jahn-Teller (J-T) effect, which is a geometric distortion that has generally been considered to be disadvantageous for applications. Experimental observations and theoretical calculations reveal that unsaturated Mn3+ with J-T distortion acts as an active site, and readily reacts with -OH groups of benzyl alcohol adsorbed nearby, simultaneously promoting dehydrogenation to directly yield benzaldehyde. Mn-x-Co3O4 catalysts rapidly dehydrogenate alcohols into aldehydes/ketones for 19 reactions with >99.9% selectivity and 14 examples with >90.2% yield.