Exploration of atomic interfaces with inherent oxygen vacancies in zirconia for toluene oxidation

Abstract

Constructing interfacial sites in catalysts is an effective strategy to improve catalytic performance. Here, we insert cerium atoms into zirconia via a co-precipitation method. Cerium atoms exist in the form of a single atom in zirconia, and extensive atomic interfaces along with oxygen vacancies were generated, thus greatly improving the low-temperature reducibility and surface oxygen mobility of the inserted catalysts. DFT calculations verified that molecular oxygen was easily adsorbed on the defective tetragonal ZrO₂ (011) facets with an energy of −0.53 eV and the distance of the O–O bond was elongated to 1.46 Å, forming the highly active oxygen species with a superoxide-type character. By comparing with pure zirconia and the corresponding impregnated sample, the inserted catalyst not only exhibited excellent catalytic activity, high specific reaction rate and low activation energy, but also possessed satisfactory stability in long-term, water and sulfur resistance tests. In situ DRIFTS spectra further revealed that the defective atomic interface could elevate ring-opening ability and accelerate the toluene reaction process, thus significantly promoting the catalytic performance.