Construction of isolated Co–Nx and dual Con–CoNx sites for the regulation of hydrogenation and hydrodeoxygenation selectivity of biomass-derived chemicals

The rational design and synthesis of high-performance catalysts for the conversion of biomass is crucial for practical applications, such as the production of high-value chemicals and fine products. In this study, we fabricated two catalysts (Co–N/C-400 and Co–N/C-500) made up of an isolated Co single atom (Co–N4) and a Co single atom together with Co nanoparticles (Con–CoNx) by a synthetic control method. Compared with the single Co–N4 sites, the dual Con–CoNx sites on Co–N/C-500 can significantly improve the hydrodeoxygenation efficiency of biomass-derived model compounds. Further computational calculations suggested that the dual sites on Co–N/C-500 work in synergy to lower the activation energy of each key meta-stable step, while it is hard to overcome the barrier of the deoxygenation reaction over Co single-atom sites on Co–N/C-400 during the consecutive hydrogenation process. This study provides valuable clues for developing efficient catalysts for the C=O hydrogenation and C–O cleavage of biomass feedstocks and other consecutive reactions.