▎ 摘　　要

alpha-MnO2 nanocrystals supported on graphene oxide (alpha-MnO2/GO) was prepared through a soft chemical route and evaluated for the first time as a novel, eco-friendly and efficient catalyst in the coupling reaction of alcohols and amines to imines. The well-organized alpha-MnO2/GO was characterized using various techniques. The results show that MnO2 nanocrystals are highly dispersed on the GO sheets and interconnected with each other, leading to large available surface area, which greatly enhances the catalytic performance of conventional MnO2. Under mild conditions, the catalyst exhibits excellent catalytic activity and selectivity with O-2 serving as terminal oxidant. Various imines can be smoothly obtained in good to excellent yield. Importantly, the catalyst is easily recovered and can be reused six times with no significant loss of activity.