Construction of Active Rh–TiOx Interfacial Sites on RhFeOx/P25 for Highly Efficient Hydrogenation of CO2 to Ethanol
Hydrogenation of CO2 to ethanol is an efficient process for the utilization of CO2 along with the production of value-added chemicals. However, CO2 hydrogenation to ethanol is a complicated reaction, requiring the catalyst to activate CO2 efficiently and accurately regulate the C–C coupling to achieve a high ethanol selectivity simultaneously. Herein, we report the synthesis of RhFeOx catalysts supported on TiO2 with different crystal phase compositions (anatase, rutile, and P25), which were applied for the selective CO2 hydrogenation to ethanol. The RhFeOx/P25 catalyst presented a high dispersion of Rh nanoparticles on the P25 support with abundant Rh0–Rhδ+–OV–Ti3+ (OV: oxygen vacancy) interfacial sites over the anatase/rutile junction. The optimized RhFeOx/P25 catalyst exhibited a high ethanol space–time yield of 18.7 mmol gcat–1 h–1 and a high Rh turnover frequency of 544.8 h–1 with 90.5% ethanol selectivity. An in-depth investigation via various ex situ and in situ characterizations as well as H2/D2 exchange and C2H4 pulse hydrogenation experiments demonstrated that the Rh0–Rhδ+–Ov–Ti3+ interfacial sites played a crucial role in the conversion of CO2 to ethanol. The surface Rh0 sites facilitated the CO2 activation and hydrogenation, while the Rh0–Rhδ+–Ov–Ti3+ interfacial sites boosted the C–C coupling to produce ethanol. The high-performance RhFeOx/P25 catalyst also provides an attractive route for highly efficient ethanol synthesis via CO2 hydrogenation.
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