Surface Cleaning and Protection Engineering via Functionalization to Awaken the Intrinsic Catalytic Activity of Co_3O_4

摘要

The inherent catalytic activity of transition metal oxide catalysts is constrainedby the presence of surface hydroxyl groups, which are typical destructive poisonsthat are difficult to be completely removed. So, previous studies generallyfocused on reducing the accumulation of hydroxyl groups on the surfaceby introducing additional elements. In this study, a simple reflux treatment inmethanol considerably increases the CO oxidation activity, water resistance,and stability of Co_3O_4. According to the density functional theory calculations,the cleaning of hydroxyl groups by methanol is spontaneous, and the assembledmethanol has little effect on the surface chemical properties. In addition,the molecular dynamics simulations indicate that methanol molecules haveformed hydrophobic entrances in the pores of Co_3O_4, which further protectthe internal surface from erosion by water. Furthermore, methanol functionalizationmaintains the original CO oxidation mechanism on the clean Co_3O_4surface. As a result, the inherent catalytic activity of Co_3O_4 is awakenedwhile the water resistance and stability are improved. Collectively, this studyestablishes an atomic-level description for the surface cleaning and protectionmechanism on Co_3O_4 surface through functionalization by small organicmolecules, which provides a new theoretical guidance for the modificationstrategies of transition metal oxide catalysts.