Constructing Co@N-doped graphene shell catalyst via Mott-Schottky effect for selective hydrogenation of 5-hydroxylmethylfurfural

At present, the increasing consumption of fossil fuels as well as the expanding of more effective avenues to prepare carbon materials have inspired scholars' confidence to seek for alternative carbon sources. To address this issue, a N-doped graphene shell encapsulated metallic Co (Co@NGs) catalyst was fabricated using glucose and melamine as carbon source and nitrogen source via carbonization and employed for 5-hydroxylmethylfurfural (HMF) hydrogenation to produce 2,5-dimethylfuran (DMF) biofuel. Here, the prepared Co@NGs catalyst which possessed striking Mott-Schottky effect presented strong electronic interaction at the interface of surface metallic Co and doped N, leading to the electron transfer from metallic Co to doped N on carbon substrate. Experimental results indicated that the decreased electron density of metallic Co was more conductive to selective catalytic hydrogenation of HMF to form DMF. More importantly, the catalytic activity of the Mott-Schottky-type Co@NGs catalyst could be regulated by adjusting the nitrogen content. That is, the high nitrogen content increased the work function of Co@NGs and thus the enhanced rectifying response at the interface by which to enhance the catalytic performance. The best Co@NGs catalyst exhibited both high HMF conversion (close to 100 %) and DMF selectivity (94.7 %), much better than those of conventional N-doped carbon supported Co catalysts.