Manganese Doping in Cobalt Oxide Nanorods Promotes Catalytic Dehydrogenation
Qingping Ke, Yi Ding, Yangxin Jin, Fei Lu, Bo Zhou, Fei Zhan, Yijun Yang, Denglei Gao, Pengfei Yan, Chao Wan, Ping Cui, Dmitri Golberg, Jiannian Yao, Xi Wang
Abstract
Heteroatom doping in nanomaterials can import new active sites and promote catalytic activity. Here we report that Mn-doped Co3O4 nanorods (Mnx-Co3O4) via substituting Mn3+ (t2g3-eg1) for Co3+ (t2g6-eg0) exhibit ∼100% yield for 4-methyl benzyl alcohol dehydrogenation catalysis at 60 °C and no decay (8 cycles), compared with only 1.4% of activity for bare Co3O4 catalysts. We characterize the fine structures of Mnx-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. Mnx-Co3O4 catalysts rapidly dehydrogenate alcohols into aldehydes/ketones for 19 reactions with >99.9% selectivity and 14 examples with >90.2% yield.