CO oxidation is the primary approach for eliminating CO from incomplete combustion, and the catalytic performance is dependent on the structure of catalysts. Herein, to explore the structure promotion in the CO oxidation reaction, polymethyl methacrylate was synthesized as the hard template to fabricate the three-dimensional ordered microporous (3DOM) Au/CeO 2 and compared the catalytic performance with the Au/CeO 2 rod catalyst. The 3DOM Au/CeO 2 catalyst could realize complete CO oxidation at 90 °C while 110 °C for Au/CeO 2 rod catalyst. The 3DOM Au/CeO 2 catalyst also showed outstanding stability for 60 h reaction. The achieved high performance could be attributed to the pore structures and the better metal-support interaction that facilitates abundant oxygen vacancies . Additionally, the Au distribution and oxygen vacancies promoted by the macropores structures were discovered using a series of characterizations. This work highlights the promotion of oxygen vacancies and metal-support interaction by 3DOM structure in CO oxidation reaction.
Exploring eco-friendly and cost-effective strategies for structure engineering at the nanoscale is important for boosting heterogeneous catalysis but still under a long-standing challenge. Herein, multifunctional polyphenol tannic acid, a low-cost natural biomass containing catechol and galloyl species, was employed as a green reducing agent, chelating agent, and stabilizer to prepare Au nanoparticles, which were dispersed on different-shaped CeO2 supports (e.g., rod, flower, cube, and octahedral). Systematic characterizations revealed that Au/CeO2-rod had the highest oxygen vacancy density and Ce(III) proportion, favoring the dispersion and stabilization of the metal active sites. Using isopropanol as a hydrogen-transfer reagent, deep insights into the structure–activity relationship of the Au/CeO2 catalysts with various morphologies of CeO2 in the catalytic nitrobenzene transfer hydrogenation reaction were gained. Notably, the catalytic performance followed the order: Au/CeO2-rod (110), (100), (111) > Au/CeO2-flower (100), (111) > Au/CeO2-cube (100) > Au/CeO2-octa (111). Au/CeO2-rod displayed the highest conversion of 100% nitrobenzene and excellent stability under optimal conditions. Moreover, DFT calculations indicated that nitrobenzene molecules had a suitable adsorption energy and better isopropanol dehydrogenation capacity on the Au/CeO2 (110) surface. A reaction pathway and the synergistic catalytic mechanism for catalytic nitrobenzene transfer hydrogenation are proposed based on the results. This work demonstrates that CeO2 structure engineering is an efficient strategy for fabricating advanced and environmentally benign materials for nitrobenzene hydrogenation.
Photothermal reverse-water-gas-shift is realized with high conversion rate and selectivity of CO in the case of Au/CeO 2 catalyst. Moreover, photothermal reaction rate is much higher (>10 times) than that performed under thermal condition. As indicated by the results of in-situ infrared spectroscopy and kinetic experiments, the special role of light is found to be related with the promotion of hydrogen-splitting step. The robust Au/CeO 2 catalyst exhibits stable activity and CO selectivity under long-term light irradiation. It is expected that the combination of catalysts and light may afford new perspectives for the CO 2 hydrogenation.
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