Tailoring interaction between rhodium and CeO2 by crystal facets selection to enhance ethanol synthesis via CO2 hydrogenation
The hydrogenation of carbon dioxide to produce high-value fuels such as ethanol is currently a research hotspot, but addressing the low selectivity for ethanol remains a challenge. Herein, morphology-controlled CeO 2 with different exposed crystal facets, including nanorods (220), nanocubes (200) and nanoplatelets (111), were prepared and impregnated with rhodium (Rh) to obtain Rh/CeO 2 catalysts, and then the catalytic performance of CO 2 hydrogenation was investigated. Rh/CeO 2 -r (nanorods) exhibits high efficacy for CO 2 hydrogenation to ethanol, giving a high ethanol selectivity of 20.9% with a moderate CO 2 conversion of 11.2%, and the one-pass ethanol productivity reaches 69.2 mmol/(g Rh ·h). Characterization results reveal that tuning the exposed crystal facets of the CeO 2 can tailor the interaction between Rh and CeO 2 , and adjust the chemical state of the Rh species. Due to the abundant oxygen vacancies occupied on the exposed (220) facets of CeO 2 nanorods, multi-level interactions arise between Rh and CeO 2 -r, and produce more content of Rh + species. This interface facilitates the transformation of carbonate species into HCOO* and CO* simultaneously, finally boosting the ethanol formation by the C−C coupling reaction.
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