Construction of Active Rh–TiO x Interfacial Sites on RhFeO x /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 RhFeO x catalysts supported on TiO2 with different crystal phase compositions (anatase, rutile, and P25), which were applied for the selective CO2 hydrogenation to ethanol. The RhFeO x /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 RhFeO x /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 RhFeO x /P25 catalyst also provides an attractive route for highly efficient ethanol synthesis via CO2 hydrogenation.