Vacancy-rich Ti3C2Ox (MXene)-anchored Co nanocluster catalyst enhances the selective hydrogenation of cinnamaldehyde

Abstract

The efficient selective hydrogenation of carbonyls in unsaturated aldehydes by non-noble metal catalysts is still a severe challenge. Herein, a Co nanocluster catalyst anchored on vacancy-rich Ti₃C₂O_x (TCOs) was designed and prepared by a simple chemical reduction method for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol. The Co/TCOs-H₂ catalyst showed superior catalytic activity, with a TOF of 23.6 h⁻¹, and reached a cinnamaldehyde conversion of 96.7% and a cinnamyl alcohol selectivity of 65.5% at low cobalt loading. Furthermore, the characterization results demonstrated that Co nanoclusters were successfully anchored on TCOs, where the presence of surface oxygen vacancies (VOs) promoted their vertical adsorption properties for cinnamaldehyde. Importantly, density functional theory calculations revealed that VOs enhanced the selective adsorption of CO on Co nanoclusters by modifying the electronic structure of Co atoms, resulting in an increase in the difference in the adsorption energy for conjugated double bonds and a lower energy barrier for H₂ dissociation on Co nanocluster sites. This work develops a feasible strategy for constructing highly active metal nanocluster sites on two-dimensional MXenes and provides insight into the role of VOs on MXenes in metal nanoclusters during hydrogenation reactions.