Engineering Co3+-rich Crystal Planes on Co3O4 Hexagonal Nanosheets for CO and Hydrocarbons Oxidation with Enhanced Catalytic Activity and Water Resistance

Abstract Crystal facet engineering plays a key role in the development of non-noble metal-based catalysts to be applicable in removal of atmospheric pollutants. Herein, we report a facile and effective reflux strategy for manipulating the exposed {1 1 2} crystal facets of Co3O4 hexagonal nanosheets with enhanced catalytic activity and water resistance for CO and hydrocarbons (methane and toluene) oxidation. Temperature-programmed techniques and density functional theory (DFT) calculations demonstrate the process that surface lattice oxygen on Co3O4 (1 1 2) activates the first C–H bond to form oxygen vacancies (1.84 eV) is easier than that (3.12 eV) on Co3O4 (1 1 1) while activation barrier (2.00 eV) on Co3O4 (1 1 2) from CO2 to bicarbonates is higher than that (0.60 eV) on Co3O4 (1 1 1), as a result of boosting catalytic oxidation and water resistance. The present work demonstrates that crystal facet engineering is a potential route to improve water resistance of Co3O4 catalysts with highly promising in practical application.