Engineering Interfacial Oxygen Vacancies of Zn–Cr Sites for CO<sub>2</sub> Activation and Hydrogenation
Jiaming Liang, Lei Jiang, Hengyang Liu, Bowei Meng, Zhiliang Jin, Lisheng Guo, Zhihao Liu, Teng Li, Wenhang Wang, Chengwei Wang, Ying Shi, Guangbo Liu, Kai Sun, Yingluo He, Bing Liang, Noritatsu Tsubaki
Abstract
Understanding the influence of oxygen vacancies is of great significance for revealing molecular adsorption and rational catalyst design. However, for the catalysts with multiple phases, the properties and intrinsic catalytic mechanism of oxygen vacancies on varied active sites have not been studied thoroughly. Herein, Zn–Cr catalysts with different oxygen vacancy distributions and contents are synthesized by engineering interfacial oxygen vacancies for CO 2 hydrogenation. Characterization and DFT calculations illustrate that although the oxygen vacancies are not prone to being generated on the monointerface between ZnO and ZnCr 2 O 4 compared with the spinel or metal oxide phases, the ZnO/ZnCr 2 O 4 –O v interfacial oxygen vacancy sites reduce the energy barriers of crucial HCOO* and H 3 CO* intermediate formation for CH 3 OH synthesis. With the assistance of the well-dispersed interface oxygen vacancies, 3Zn1Cr displays the highest methanol selectivity (80.5%) as well as the highest CO 2 conversion (19.2%) among all of the ratios of Zn–Cr catalysts. After further combination of 3Zn1Cr with modified β zeolite, the composite catalyst showed a superior liquefied petroleum gas selectivity of 84.0% at a CO 2 conversion of 30.2%. The proposed strategy here sheds light on the efficient composite catalyst design via a methanol-mediated route for C1 chemistry.